tag:blogger.com,1999:blog-819711486941036012024-03-24T01:35:41.482-07:00Industrial Instrumentation and ControlIndustrial Process Measurement, Control and Automation TechniquesJohn Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.comBlogger62125tag:blogger.com,1999:blog-81971148694103601.post-26366116297955620602023-12-13T16:22:00.000-08:002023-12-14T04:05:12.837-08:00The Fundamentals of Semiconductor Junction Thermometers<p><span style="font-size: 18pt;">Temperature
sensors can be fabricated with semiconductor processing technology by employing
the temperature characteristics of the pn junction. </span><span style="font-size: 18pt;"> </span><span style="font-size: 18pt;">The batch processing and well-defined
manufacturing processes associated with semiconductor technology can provide
low cost and consistent quality temperature sensors.</span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">Most
<a href="https://www.electricalandcontrol.com/the-basics-of-semiconductor-physics-as-the-foundation-of-electronics/" target="_blank">semiconductor junction</a> temperature sensors utilize a <a href="https://www.electricalandcontrol.com/semiconductor-diodes/" target="_blank">diode-connected</a> bipolar
<a href="https://www.electricalandcontrol.com/bipolar-junction-transistors-bjt/" target="_blank">transistor</a> (short-circuited collector-base junction). A constant current passed
through the base-emitter junction produces a junction voltage between the base
and emitter (V<sub>be</sub>) that is a linear function of the absolute
temperature. The overall forward voltage drop has a temperature coefficient of
approximately 2 mV </span><span style="font-size: 18pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">°</span><span style="font-size: 18pt; line-height: 115%;">C<sup>-1</sup>.</span></p><p class="MsoNormal"></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLOAoUhbWOXMYvSN-SZNRbtMd9R7iOCFDyf5szwqNW5cj9LJAxvqKir6n9-EsuQ47mm1x24dtdWJt9oqaNGsFz7DCm98n18kUTpgbitU7Ln-TcEeSH1g-hFnKeqYqIY3CuCEmLLYLscTdQ4Khhx4x0Jb3wdMKdT3xr4SBndnsTGbt1Mv6bgvtj1FpbrjLL/s382/Semiconductor%20Junction%20Thermometer.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Bipolar transistor configured as a temperature sensor" border="0" data-original-height="382" data-original-width="362" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLOAoUhbWOXMYvSN-SZNRbtMd9R7iOCFDyf5szwqNW5cj9LJAxvqKir6n9-EsuQ47mm1x24dtdWJt9oqaNGsFz7DCm98n18kUTpgbitU7Ln-TcEeSH1g-hFnKeqYqIY3CuCEmLLYLscTdQ4Khhx4x0Jb3wdMKdT3xr4SBndnsTGbt1Mv6bgvtj1FpbrjLL/w379-h400/Semiconductor%20Junction%20Thermometer.PNG" title="Bipolar transistor configured as a temperature sensor" width="379" /></a></td></tr></tbody></table><p></p><p class="MsoNormal"><span style="line-height: 27.6px;"><span style="font-size: medium;">Fig: Bipolar transistor configured as a temperature sensor</span><span style="font-size: 18pt;"><o:p></o:p></span></span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td class="tr-caption" style="text-align: center;"><p class="MsoNormal" style="text-align: left;"></p></td></tr></tbody></table>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">In the above
figure, the base of the transistor is shorted to the collector. A constant
current flowing in the remaining pn (base to emitter) junction produces a
forward voltage drop V<sub>F</sub> proportional to temperature. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">The temperature
coefficient of a semiconductor sensor is larger but still quite small when compared
to a <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/how-thermocouples-work.html" target="_blank">thermocouple</a> or <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/temperature-transducers.html" target="_blank">resistive temperature device/detector (RTD)</a>. Furthermore,
the semiconductor sensor’s forward voltage has an offset that varies
significantly from unit to unit. Nonetheless, the semiconductor junction
voltage versus temperature is much more linear than that of a thermocouple or
RTD. Also, the temperature-sensing element, circuitry is easily integrated to
produce a monolithic temperature sensor with an output that can be easily
interfaced to a <a href="https://www.electricalandcontrol.com/microcontrollers/" target="_blank">microcontroller</a> and to provide features that are useful in
particular applications. For instance, by using an embedded temperature sensor
with additional circuitry, protection features can be added to integrated
circuits (ICs). A temperature sensor becomes an embedded item in a
semiconductor product when it has a secondary or supplemental purpose instead
of the primary function. <o:p></o:p></span></p>John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-19708994214384302372023-05-21T23:02:00.012-07:002023-07-21T11:07:21.254-07:00Flowmeter Calibration Methods for Liquids<p> <span style="font-size: 18pt;">The major
principles employed for liquid flowmeter calibration are:</span></p>
<p class="MsoListParagraphCxSpFirst"></p><ul style="text-align: left;"><li><span style="font-size: 18pt; line-height: 115%;">In-situ calibration methods {Insertion-point velocity and Dilution
gauging/tracer technique}</span></li><li><span style="font-size: 18pt; line-height: 115%;">Laboratory methods {master meter, volumetric gravimetric and pipe prover}</span></li></ul><p></p>
<h2><span style="font-size: 20pt; line-height: 115%;"><u>In-situ calibration methods</u><o:p></o:p></span></h2>
<p class="MsoNormal"><b><span style="font-size: 18pt; line-height: 115%;">Insertion-point velocity </span></b><span style="font-size: 18pt; line-height: 115%;">– this is one of the simplest methods
of in-situ flowmeter calibration. It utilizes point-velocity measuring devices
where the calibration device selected is positioned in the flow stream adjacent
to the flowmeter being calibrated, such that the mean flow velocity can be
measured. In difficult situations a flow traverse can be carried out to
establish the flow profile and mean flow velocity. <o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size: 18pt; line-height: 115%;">Dilution gauging/Tracer method</span></b><span style="font-size: 18pt; line-height: 115%;"> – this method can be applied to
closed-pipe and open-channel flowmeter calibration. An appropriate tracer
(chemical or radioactive) is injected at an accurately measured constant rate
and samples are taken from the flow stream at a point downstream of the
injection point where complete mixing of the injected tracer will have taken
place. By measuring the tracer concentration in the samples the tracer dilution
can be determined and from this dilution and the injection rate the volumetric
flow can be calculated.</span></p><p class="MsoNormal"></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPcRx_TPCw1QZ380Gq0thghKf_fCSlu17NFLQUY9fWRS2talDfmOSRcetZU1UHmukIS9l6L_fy-xWASTl_r2huv34OUiF8E7Jh41mODh2VifvsYFZ3Ox0qHYVCFXan3kv32tB6DPBF2i1qfkc5BrFZiEEkPfBbWfmZ0zHPEeOD-oGZH7__wMuYPjzh0g/s706/Dilution%20gauging%20by%20tracer%20injection.png" style="margin-left: auto; margin-right: auto;"><img alt="Dilution gauging by tracer injection" border="0" data-original-height="227" data-original-width="706" height="119" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPcRx_TPCw1QZ380Gq0thghKf_fCSlu17NFLQUY9fWRS2talDfmOSRcetZU1UHmukIS9l6L_fy-xWASTl_r2huv34OUiF8E7Jh41mODh2VifvsYFZ3Ox0qHYVCFXan3kv32tB6DPBF2i1qfkc5BrFZiEEkPfBbWfmZ0zHPEeOD-oGZH7__wMuYPjzh0g/w400-h119/Dilution%20gauging%20by%20tracer%20injection.png" title="Dilution gauging by tracer injection" width="400" /></a></td></tr></tbody></table><p></p><p class="MsoNormal"><span style="line-height: 27.6px;"><span style="font-size: medium;"> Figure 1.0 Dilution gauging by tracer injection</span><span style="font-size: 18pt;"><o:p></o:p></span></span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td class="tr-caption" style="text-align: center;"><p class="MsoNormal" style="text-align: left;"></p></td></tr></tbody></table>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">Alternatively
a pulse of tracer material may be added to the flow stream and the time taken
for the tracer to travel a known distance and reach a maximum concentration is
a measure of the flow velocity. <o:p></o:p></span></p><p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;"><b><span style="color: #800180;">Related: </span></b><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/instrument-errors-and-calibration_13.html" target="_blank">Instruments Errors and Calibration</a></span></p>
<h2><span style="font-size: 20pt; line-height: 115%;"><u>Laboratory calibration methods</u><o:p></o:p></span></h2>
<p class="MsoNormal"><b><span style="font-size: 18pt; line-height: 115%;">Master meter</span></b><span style="font-size: 18pt; line-height: 115%;"> – for this method a meter of known
accuracy is used as a calibration standard. The meter to be calibrated and the
master meter are connected in series and are then subjected to the same flow
regime. Note that, to ensure consistent accurate calibration the master meter
itself must be subject to periodic calibration. <o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size: 18pt; line-height: 115%;">Volumetric method</span></b><span style="font-size: 18pt; line-height: 115%;"> – in this technique, the flow of
liquid through the meter being calibrated is diverted into a tank of known
volume. When full, this known volume can be compared with integrated quantity
registered by the flowmeter being calibrated. <o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size: 18pt; line-height: 115%;">Gravimetric method</span></b><span style="font-size: 18pt; line-height: 115%;"> – where the flow of liquid through
the meter being calibrated is diverted into a vessel that can be weighed either
continuously or after a predetermined time, the weight of the liquid is
compared with the registered reading of the flowmeter being calibrated.</span></p><p class="MsoNormal"></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirc2PofCGcf1Woc2hzLe1Xclv4lMnXmtGoXtX8Z1jXVm24LqfFl9wGYLQWy8yrTZ_wVzKFWuWwvRV9Kn_cO-vrUgma7PVCiOlSp-i21zY0JClB7Wk6eK6VCqcoCdVdVHwO-rZ3yRoz6yqKHIazAOM1yggtxR7m_AiUuOdH40CPpYbtN4sKT6Pw-P4eRQ/s596/Calibrating%20a%20flowmeter%20by%20weighing%20.png" style="margin-left: auto; margin-right: auto;"><img alt="calibrating a flowmeter by weighing" border="0" data-original-height="373" data-original-width="596" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirc2PofCGcf1Woc2hzLe1Xclv4lMnXmtGoXtX8Z1jXVm24LqfFl9wGYLQWy8yrTZ_wVzKFWuWwvRV9Kn_cO-vrUgma7PVCiOlSp-i21zY0JClB7Wk6eK6VCqcoCdVdVHwO-rZ3yRoz6yqKHIazAOM1yggtxR7m_AiUuOdH40CPpYbtN4sKT6Pw-P4eRQ/w400-h240/Calibrating%20a%20flowmeter%20by%20weighing%20.png" title="calibrating a flowmeter by weighing" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="text-align: left;"><span style="font-size: medium;">Figure 1.1 calibrating a flowmeter by weighing</span></span></td></tr></tbody></table><br /><span style="font-size: 18pt; line-height: 115%;"><br /></span><p></p>
<b><span face=""Calibri","sans-serif"" style="font-size: 18pt; line-height: 115%; mso-ansi-language: EN-ZA; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin;">Pipe
prover</span></b><span face=""Calibri","sans-serif"" style="font-size: 18pt; line-height: 115%; mso-ansi-language: EN-ZA; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin;"> –
this device also known as a meter prover, consists of a U-shaped length of pipe
and a piston or elastic sphere. The flowmeter to be calibrated is installed on
the inlet to the prover and the sphere is forced to travel to the length of the
pipe by the flowing liquid. Switches are inserted near both ends of the pipe
and operate when the spheres passes them. The swept volume of the pipe between
the two switches is determined by initial calibration and this known volume is
compared with that registered by the flowmeter during calibration.</span><div><span style="font-size: 24px;"><br /></span><div><span face=""Calibri","sans-serif"" style="font-size: 18pt; line-height: 115%; mso-ansi-language: EN-ZA; mso-ascii-theme-font: minor-latin; mso-bidi-font-family: "Times New Roman"; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US; mso-fareast-theme-font: minor-latin; mso-hansi-theme-font: minor-latin;"><span style="color: #800180;">Also Read:</span> <a href="https://industrialinstrumentationsolutions.blogspot.com/2023/03/the-principle-of-operation-electromagnetic-flowmeter.html" target="_blank">Electromagnetic Flowmeter Working Principle</a></span></div></div><div><br /></div><div><span style="color: red; font-family: georgia, serif; font-size: 24px;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif; font-size: 24px;" target="_blank">here.</a></div>John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-20418507895502942462023-03-16T11:56:00.016-07:002023-07-21T11:07:02.513-07:00The Operation of Linear Variable Differential Transformer (LVDT) <p> <span style="font-size: 18pt;">Linear
variable differential transformer (LVDT) is an inductive transducer that is
commonly used to translate linear motion into electrical signals.</span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">An
illustration of LVDT circuit is shown below:</span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEPPJ-K1WQ_thoSTVbsz8UFwB5bNLYC2lwWWGQzAe2HoxoBZaQXBHDWkmxlBZBrucET-nKw9aZ_HU8aEPQIGr59UBsGWtFtNmctaiKlCnYfk71lJ8Prf-bCGy4cem6kNU1a0TuBeY4ZfqE0k-gGROOE1HabjwR8jIC9cufKWVIsVn3TdTxv-KsQiWOgw/s695/Operation%20of%20LVDT.png" style="margin-left: auto; margin-right: auto;"><img alt="LVDT" border="0" data-original-height="452" data-original-width="695" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEPPJ-K1WQ_thoSTVbsz8UFwB5bNLYC2lwWWGQzAe2HoxoBZaQXBHDWkmxlBZBrucET-nKw9aZ_HU8aEPQIGr59UBsGWtFtNmctaiKlCnYfk71lJ8Prf-bCGy4cem6kNU1a0TuBeY4ZfqE0k-gGROOE1HabjwR8jIC9cufKWVIsVn3TdTxv-KsQiWOgw/w400-h260/Operation%20of%20LVDT.png" title="Linear variable differential transformer (LVDT)" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">Fig 1.0 LVDT
connection circuit<o:p></o:p></span></p></td></tr></tbody></table>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">The transformer
consists of a single primary winding P and two secondary windings S<sub>1</sub>
and S<sub>2</sub> wound on a cylindrical former. A sinusoidal voltage of
amplitude 3 to 15 volt and frequency 50 to 20 kHz is employed to excite the
primary winding. The two secondary windings have equal number of turns and are
identically placed on either side of the primary winding. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">The primary
winding is connected to an alternating current source. A movable soft-iron core
is placed inside the former. The displacement to be measured is applied to the
arm attached to the soft iron core. The core is usually made of high
permeability, nickel iron. This is slotted longitudinally to reduce eddy
current losses. The assembly is placed in a stainless steel housing to provide
electrostatic and electromagnetic shielding. The frequency of ac signal applied
to primary winding can be between 50 Hz and 20 kHz. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">As the
primary winding is excited by an alternating current source, it produces an
alternating magnetic field which in turn induces alternating voltages in the
two secondary windings. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">The output
voltage of secondary S<sub>1</sub> is ES<sub>1</sub> and that of secondary S<sub>2</sub>
is E<sub>S2</sub>. In order to convert the outputs from S<sub>1</sub> and S<sub>2</sub>
into a single voltage, the two secondary S<sub>1</sub> and S<sub>2</sub> are connected
in series opposition. The differential output voltage is: <o:p></o:p></span></p>
<p class="MsoNormal" style="tab-stops: 270.6pt;"><span style="font-size: 18pt; line-height: 115%;">E<sub>0</sub> = ES<sub>1</sub> – ES<sub>2<span style="mso-tab-count: 1;"> </span><o:p></o:p></sub></span></p>
<h2><span style="font-size: 18pt; line-height: 115%;">Operation of LVDT<o:p></o:p></span></h2>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">When the
core is at its normal (NULL) position, the flux linking with both the secondary
windings is equal and hence equal voltages are induced in them. Therefore at
null position: E<sub>S1</sub> = E<sub>S2</sub>. Thus, the output voltage E<sub>0</sub>
is zero at null position.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">If the core
is moved to the left of the null position, more flux links with S<sub>1</sub>
and less with winding S<sub>2</sub>. Correspondingly, output voltages E<sub>S1</sub>
is greater than E<sub>S2</sub>. The magnitude of output voltage is thus,</span></p><p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;"> E<sub>0</sub>
= E<sub>S1</sub> – E<sub>S2</sub> and we can say, it is in phase with primary
voltage. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">In the same
way, when the core is moved to the right of the null position E<sub>S2</sub>
will be more than E<sub>S1</sub>. Therefore the output voltage </span></p><p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">E<sub>0</sub> =
E<sub>S1</sub> – E<sub>S2</sub> and 180</span><span style="font-size: 18pt; line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">°</span><span style="font-size: 18pt; line-height: 115%;"> out of phase with primary voltage. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;">The amount
of voltage change in either secondary winding is proportional to the amount of
movement of the core. Thus, we have an indication of amount of linear motion. By
noticing whether output voltage is increased or decreased, we can determine the
direction of motion. <o:p></o:p></span></p><p class="MsoNormal"><span style="font-size: 18pt; line-height: 115%;"> <span style="color: #800180;">Related: </span><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/instrumentation-sensors-and-transducers.html" target="_blank">Transducers and Sensors </a></span></p>
<h2><span style="font-size: 20pt; line-height: 115%;">Merits of LVDT<o:p></o:p></span></h2>
<p class="MsoNormal"></p><ul style="text-align: left;"><li><span style="font-size: 18pt; line-height: 115%;">Output is
quite high. Hence, immediate amplification is not necessary. </span></li><li><span style="font-size: 18pt; line-height: 115%;">Output
voltage is step-less and hence the resolution is very good. </span></li><li><span style="font-size: 18pt; line-height: 115%;">The
sensitivity is high (about 40 V/mm). </span></li><li><span style="font-size: 18pt; line-height: 115%;">It does not
load the measured mechanically. </span></li><li><span style="font-size: 18pt; line-height: 115%;">Linearity is
good up to 5 mm of displacement.</span></li><li><span style="font-size: 18pt; line-height: 115%;">It consumes
low power and low hysteresis loss. </span></li></ul><p></p>
<h2 style="text-align: left;"><span style="font-size: 20pt; line-height: 115%;">The Limitations of LVDT</span></h2>
<p class="MsoNormal"></p><ul style="text-align: left;"><li><span style="font-size: 18pt; line-height: 115%;">It is
affected by stray electromagnetic fields. Thus, proper shielding of the device
is required. </span></li><li><span style="font-size: 18pt; line-height: 115%;">LVDT has large
threshold. </span></li><li><span style="font-size: 18pt; line-height: 115%;">The ac
inputs generate noise. </span></li></ul><div><span style="font-size: 24px;"><span style="color: #800180;">Also read: </span><a href="https://industrialinstrumentationsolutions.blogspot.com/2019/03/types-of-signal-converters-commonly.html" target="_blank">Signal Converters commonly used in Industrial Instrumentation</a></span></div><div><br /></div><div><span style="color: red; font-family: georgia, serif; font-size: 24px;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif; font-size: 24px;" target="_blank">here.</a></div><p></p>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-59210300827115696372023-03-15T14:06:00.018-07:002023-07-21T11:06:17.924-07:00The Principle of Operation of an Electromagnetic Flowmeter <p><span style="font-size: large;"><span>Electromagnetic
flowmeters are widely used in industrial process flow measurement. These meters
come with several features for example: they offer non-invasive flow
measurement, they can measure reverse flows and are insensitive to viscosity,
density and flow disturbances. Additionally, electromagnetic flowmeters can respond
swiftly to flow changes and are linear devices for a wide range of
measurements.</span></span></p>
<h2 style="text-align: left;"><span style="font-size: large; line-height: 115%;">Working Principle of the
Electromagnetic Flowmeter</span></h2>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">Electromagnetic
flowmeter operation is based on Faraday’s law of electromagnetic induction. The
induced voltages in an electromagnetic flow meter are linearly proportional to
the mean velocity of liquids or to the volumetric flow rates. As in the case in
many applications, if the pipe walls are made from non-conducting elements,
then the induced voltage is independent of the properties of the fluid. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">Faraday’s
law of induction states that if a conductor of length l (m) is moving with a
velocity v (m/s) perpendicular to a magnetic field of flux density B (Tesla)
then the induced voltage (e) across the ends of a conductor can be expressed
by: <o:p></o:p></span></p>
<p class="MsoNormal" style="tab-stops: center 225.65pt;"><i style="mso-bidi-font-style: normal;"><span style="font-size: large; line-height: 115%;"><span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span>e =
Blv<span style="mso-tab-count: 1;"> </span><o:p></o:p></span></i></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">This is
demonstrated in the figure below: <o:p></o:p></span></p><p class="MsoNormal"></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlmNIVjc-ENNSYtk-vZ6hG6W-0bOBmBAooQR6CJ6s-ACS5f45px3YA1x28Vytc8F43qcs3HgCQAra0PcH4y3jCRhPJQp7AkOxZAWiZxaXIZn_ynk26NWAgAUZREucnsxOmoa6YDX0aqMEfP307z8n-1S1VYj3AdqInC_3XKA34IjJe3TLex9-ku-8KYQ/s397/Operating%20principle%20of%20electromagnetic%20flowmeter.png" style="margin-left: auto; margin-right: auto;"><span style="font-size: large;"><img alt="The operating principle of electromagnetic flowmeter" border="0" data-original-height="343" data-original-width="397" height="345" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlmNIVjc-ENNSYtk-vZ6hG6W-0bOBmBAooQR6CJ6s-ACS5f45px3YA1x28Vytc8F43qcs3HgCQAra0PcH4y3jCRhPJQp7AkOxZAWiZxaXIZn_ynk26NWAgAUZREucnsxOmoa6YDX0aqMEfP307z8n-1S1VYj3AdqInC_3XKA34IjJe3TLex9-ku-8KYQ/w400-h345/Operating%20principle%20of%20electromagnetic%20flowmeter.png" title="Operation of electromagnetic flowmeter" width="400" /></span></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large; text-align: left;">Figure 1.0 The Operational principle of electromagnetic flowmeter</span></td></tr></tbody></table><span style="font-size: large;"><br /></span><p></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">In the above
illustration, the magnetic field, the direction of the movement of the
conductor, and the induced emf are all perpendicular to each other. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">Let’s consider
a simplified electromagnetic flowmeter construction below:</span></p><p class="MsoNormal"></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxzwiTTeH-JfYi0mnBH5-A4-dDHGMnJK6EqPyiMWDiVXi4CH6uklw4SXxJTaiRTCQaBVOCqRh3fmnvAmsdZgTa6_ADOwLhWQUWrNqy9jvk0-qRZkMEn4QbIxTA744cd7eE0FZsK5qJSbFRcC630cpOrvh4p2WyEMVR78QOM99ODtS5p2tOi33DYD4GzA/s605/Electromagnetic%20flowmeter.png" style="margin-left: auto; margin-right: auto;"><span style="font-size: large;"><img alt="Construction of a practical electromagnetic flowmeter" border="0" data-original-height="455" data-original-width="605" height="301" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxzwiTTeH-JfYi0mnBH5-A4-dDHGMnJK6EqPyiMWDiVXi4CH6uklw4SXxJTaiRTCQaBVOCqRh3fmnvAmsdZgTa6_ADOwLhWQUWrNqy9jvk0-qRZkMEn4QbIxTA744cd7eE0FZsK5qJSbFRcC630cpOrvh4p2WyEMVR78QOM99ODtS5p2tOi33DYD4GzA/w400-h301/Electromagnetic%20flowmeter.png" title="Construction of a practical electromagnetic flowmeter" width="400" /></span></a></td></tr></tbody></table><p></p><p class="MsoNormal"><span style="font-size: large; line-height: 27.6px;">Figure 1.1 Construction of practical electromagnetic flowmeter</span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">The
externally located electromagnets create a homogenous magnetic field (B)
passing through the pipe and the liquid inside it. When a conducting flowing
liquid cuts through the magnetic field, voltage is generated along the liquid
path between the two electrodes positioned on the opposite sides of the pipe. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">The
conductor is the liquid flowing through the pipe, and the length of the
conductor is the distance between the two electrodes, which is equal to the
tube diameter (D). The velocity of the conductor is proportional to the mean
flow velocity (v) of the liquid. Hence, the induced voltage becomes:<o:p></o:p></span></p>
<p class="MsoNormal"><i style="mso-bidi-font-style: normal;"><span style="font-size: large; line-height: 115%;"><span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span>e = BDv<o:p></o:p></span></i></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">If the
magnetic field is constant and the diameter of the pipe is fixed, the magnitude
of the induced voltage will be proportional to the velocity of the liquid. If
the ends of the conductor, in this case the sensors that are connected to an
external circuit, the induced voltage causes a current, i to flow, which can be
processed appropriately as a measure of the flow rate.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">Electromagnetic
flowmeters are often calibrated to determine the volumetric flow of the liquid.
The volume of liquid flow Q can be related to the average fluid velocity as: <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">Q = Av <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">Where A is
the area of the pipe, which can be written as: <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large;"><!--[if gte msEquation 12]><m:oMathPara><m:oMath><i
style='mso-bidi-font-style:normal'><span style='font-size:18.0pt;line-height:
115%;font-family:"Cambria Math","serif"'><m:r>A</m:r><m:r>= </m:r></span></i><m:f><m:fPr><span
style='font-size:18.0pt;mso-ansi-font-size:18.0pt;mso-bidi-font-size:18.0pt;
font-family:"Cambria Math","serif";mso-ascii-font-family:"Cambria Math";
mso-hansi-font-family:"Cambria Math";font-style:italic;mso-bidi-font-style:
normal'><m:ctrlPr></m:ctrlPr></span></m:fPr><m:num><i style='mso-bidi-font-style:
normal'><span style='font-size:18.0pt;line-height:115%;font-family:"Cambria Math","serif"'><m:r>π</m:r></span></i><m:sSup><m:sSupPr><span
style='font-size:18.0pt;mso-ansi-font-size:18.0pt;mso-bidi-font-size:
18.0pt;font-family:"Cambria Math","serif";mso-ascii-font-family:"Cambria Math";
mso-hansi-font-family:"Cambria Math";font-style:italic;mso-bidi-font-style:
normal'><m:ctrlPr></m:ctrlPr></span></m:sSupPr><m:e><i style='mso-bidi-font-style:
normal'><span style='font-size:18.0pt;line-height:115%;font-family:"Cambria Math","serif"'><m:r>D</m:r></span></i></m:e><m:sup><i
style='mso-bidi-font-style:normal'><span style='font-size:18.0pt;
line-height:115%;font-family:"Cambria Math","serif"'><m:r>2</m:r></span></i></m:sup></m:sSup></m:num><m:den><i
style='mso-bidi-font-style:normal'><span style='font-size:18.0pt;
line-height:115%;font-family:"Cambria Math","serif"'><m:r>4</m:r></span></i></m:den></m:f></m:oMath></m:oMathPara><![endif]--><br /></span></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf9I4punk25maxmLQ8WtN4NdRNOEBoPBsU0QelQFcDhwIc-hF-oZQTbPtwOF4ZtMGEunBWWUY22tjd8ZGRk9KhapIsIX-hmyYpd-XB6MGFmJcGXH8QZy2PqxZZwk8-L558OE6iQHTGWoR7kufLe_P0STGrviIpL7RdWQ0-yxiFg95box-5Mm3IBxP-9Q/s176/Pipe%20Area.png" style="margin-left: 1em; margin-right: 1em;"><span style="font-size: large;"><img alt="Pipe Area" border="0" data-original-height="118" data-original-width="176" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhf9I4punk25maxmLQ8WtN4NdRNOEBoPBsU0QelQFcDhwIc-hF-oZQTbPtwOF4ZtMGEunBWWUY22tjd8ZGRk9KhapIsIX-hmyYpd-XB6MGFmJcGXH8QZy2PqxZZwk8-L558OE6iQHTGWoR7kufLe_P0STGrviIpL7RdWQ0-yxiFg95box-5Mm3IBxP-9Q/s16000/Pipe%20Area.png" title="Pipe Area" /></span></a></div><span style="font-size: large;"><br />
</span><p class="MsoNormal"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">That gives the induced
voltage as a function of the flow rate: <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">We know that fluid velocity
v = Q/A <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">We can derive the
induced voltage as: <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large;"><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;"><span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span></span><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;"><span style="mso-spacerun: yes;"> </span></span></span></p><div class="separator" style="clear: both; text-align: center;"><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;"><span style="font-size: large; mso-spacerun: yes;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig8wlDLnz2Z5z0SgleDqR_BDBpKd3jN9pUouuLLVd4fUVHrVZOX0MkX64ZVULQOk5Q8YjgW1vaj9YEwDa7mBlhRAkUXtSBjOkazYXkVi--vJIErfxzJL4vaOA3N69GAKnsAI4av8NzqBQYaXjCJp9C3vulFSw2EJ9Ndv_K8dELgIQbZzaKc7pIS5U3JA/s553/Induced%20voltage%20-%20electromagnetic%20flowmeter.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Induced voltage in electromagnetic flowmeter" border="0" data-original-height="98" data-original-width="553" height="71" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig8wlDLnz2Z5z0SgleDqR_BDBpKd3jN9pUouuLLVd4fUVHrVZOX0MkX64ZVULQOk5Q8YjgW1vaj9YEwDa7mBlhRAkUXtSBjOkazYXkVi--vJIErfxzJL4vaOA3N69GAKnsAI4av8NzqBQYaXjCJp9C3vulFSw2EJ9Ndv_K8dELgIQbZzaKc7pIS5U3JA/w400-h71/Induced%20voltage%20-%20electromagnetic%20flowmeter.png" title="Induced voltage in an electromagnetic flowmeter" width="400" /></a></span></span></div><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;"><br /><o:p></o:p></span><p></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">Equation 1.4 indicates
that in a well-designed electromagnetic flowmeter, if all other parameters are
kept constant, the induced voltage is linearly proportional to the liquid flow
only. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">Even though the induced
voltage is directly proportional to the mean value of the liquid flow, the main
problem in the use of electromagnetic flowmeters is that the amplitude of the
induced voltage is small relative to extraneous voltages and noise. The noise
sources include:</span></p><p class="MsoNormal"></p><ul style="text-align: left;"><li><span style="font-size: large;"><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast; text-indent: -0.25in;">Capacitive coupling between signal and
power circuits.</span></span></li><li><span style="font-size: large;"><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast; text-indent: -0.25in;">Stray voltage in the process liquid.</span></span></li><li><span style="font-size: large;"><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast; text-indent: -0.25in;">Capacitive coupling in connection leads.</span></span></li><li><span style="font-size: large;"><span style="line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast; text-indent: -0.25in;">Inductive coupling of the magnets within
the flowmeter.</span></span></li><li><span style="font-size: large;">Electromechanical emf induced in the
electrodes and the process fluid.</span></li></ul>
<h2 style="text-align: left;"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">Key Merits of
Electromagnetic Flowmeters</span></h2><p class="MsoNormal"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">The electromagnetic
flowmeters have the following advantages:</span></p><p class="MsoNormal"></p><ul style="text-align: left;"><li><span style="text-indent: -0.25in;"><span style="font-size: large;">The output (voltage) is linearly
proportional to the input (flow).</span></span></li><li><span style="font-size: large;">There is no obstacle to the flow path
which may cause reduction in pressure.</span></li><li><span style="font-size: large;">The electromagnetic flowmeter can measure
flow in pipes of any size provided a powerful magnetic field can be produced.</span></li><li><span style="font-size: large;">The output is not affected by changes in
the characteristics of the liquid such as pressure, viscosity, and temperature.</span></li></ul><span style="font-size: large;"><span style="color: #800180; text-indent: -0.25in;">You can also read:</span><span style="text-indent: -0.25in;"> </span><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/the-working-principle-of-ultrasonic.html" style="text-indent: -0.25in;" target="_blank">Working Principle of Ultrasonic Flowmeter</a></span><p></p>
<h2 style="text-align: left;"><span style="font-size: large; line-height: 115%; mso-fareast-font-family: "Times New Roman"; mso-fareast-theme-font: minor-fareast;">Shortcomings of
Electromagnetic Flowmeters</span></h2>
<p class="MsoNormal"><span style="font-size: large; line-height: 115%;">The electromagnetic
flowmeters have the following limitations:</span></p><p class="MsoNormal"></p><ul style="text-align: left;"><li><span style="font-size: large;"><span style="line-height: 115%; text-indent: -0.25in;">The conductivity of the liquid being
measured should not be less than 10 </span><span style="line-height: 115%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; text-indent: -0.25in;">μꭥ</span><span style="line-height: 115%; text-indent: -0.25in;">/m.<span style="mso-spacerun: yes;">
</span>It is important to note that most water based/aqueous solutions are
adequately conductive while a majority of hydrocarbons solutions are not
sufficiently conductive.</span></span></li><li><span style="font-size: large;">The operating cost is usually very
high in an electromagnetic flowmeter specifically if heavy slurries are
handled.</span></li></ul><span style="font-size: large;"><span style="color: #800180; text-indent: -0.25in;">Related resource: </span><a href="https://read.amazon.com/kp/embed?asin=B07YRVYVW9&preview=newtab&linkCode=kpe&ref_=cm_sw_r_kb_dp_X34ODbTF4FZ58&tag=1984makec-20" rel="nofollow" style="text-indent: -0.25in;" target="_blank">Ultimate guide to Industrial flow Instruments</a></span><div><span style="font-size: large;"><br /></span></div><div><span style="color: red; font-family: georgia, serif; font-size: 24px;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif; font-size: 24px;" target="_blank">here.</a><span style="font-size: large;"><br /></span><p></p><p class="MsoListParagraphCxSpLast" style="mso-list: l2 level1 lfo3; text-indent: -0.25in;"><span style="font-size: 18pt; line-height: 115%;"><br /></span></p></div>John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-1200157908095176332019-08-15T13:08:00.007-07:002023-07-21T10:41:55.996-07:00How a VFD works and when to use it<div dir="ltr" style="text-align: left;" trbidi="on">
<div align="center" class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Did you know you
could save on energy consumption and costs by using a VFD? You can also tighten
your processes, increase production, reduce maintenance, and extend the life of
your equipment.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">But what is a
VFD, you ask? Let’s take a look.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<b style="mso-bidi-font-weight: normal;"><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Defining VFD</span></b><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">VFD stands for
variable frequency drive. It’s a motor controller for electric motors. VFDs are
also known as adjustable speed drives, adjustable frequency drives, AC drives,
microdrives, inverters, and variable speed drives.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">The word
“frequency” in the name relates to the frequency of the power delivered to the
motor, which is measured in hertz. Changing the frequency changes the speed of
the motor shaft.<span style="mso-spacerun: yes;"> </span>If your electric motor
doesn’t need to run at full speed for the entire process, you can save some
juice and some wear and tear by installing a VFD to vary the speed of the
motor.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A variable
frequency drive can also get a motor started and ramp it up to speed at a
controlled acceleration rate. This makes the start-up smooth, while also saving
on electricity and motor life.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A VFD allows one
motor to be used for processes that may require or allow different speeds.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8xnC121-O46cSMiRxeaZH3q9Hj-YQ3RpW205nUjwK0EfzpfBRimfB5Kjn14EZTbBB0YMd19cb1757k6ihv1BbyJ7Y8lxAKimmjVSj0MDjK3M-uXHPEvi9g6eepSkDjYPiHS58oWlN0DRp/s1600/Variable+Speed+Drives.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Variable Speed Drive in Operation" border="0" data-original-height="413" data-original-width="660" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8xnC121-O46cSMiRxeaZH3q9Hj-YQ3RpW205nUjwK0EfzpfBRimfB5Kjn14EZTbBB0YMd19cb1757k6ihv1BbyJ7Y8lxAKimmjVSj0MDjK3M-uXHPEvi9g6eepSkDjYPiHS58oWlN0DRp/w496-h320/Variable+Speed+Drives.PNG" title="Variable Speed Drive in Operation" width="496" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: medium;">Variable Speed Drive</span></td></tr>
</tbody></table>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><br /></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<b style="mso-bidi-font-weight: normal;"><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">How Does a VFD Operate?</span></b><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A VFD converts
fixed frequency AC line voltage to DC, then makes new AC at whatever voltage
and frequency are needed to run the motor at the desired speed. The VFD
consists of a converter section, a filter section, an inverter section and
control section.<span style="mso-spacerun: yes;"> </span><o:p></o:p></span></div>
<div class="MsoNormal">
</div>
<ul style="text-align: left;">
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><span style="mso-spacerun: yes;">The Control section operates the entire VFD, monitors the VFD and motor for safe operation, and interact with the machine operator or automation control system. </span></span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><span style="mso-spacerun: yes;">The Converter uses diodes and/or SCRs to change AC utility power to DC</span></span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><span style="mso-spacerun: yes;">The Filter ''Cleans'' the DC power with inductors and capacitors</span></span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><span style="mso-spacerun: yes;">The Inverter makes new AC power for the motor using transistors as switches</span></span></li>
</ul>
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<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Those switches
are what allow the VFD to function at different speeds. The transistorized
switches let the VFD adjust the frequency and voltage of the power supplied to
the motor. As the frequency changes, so does the motor speed.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<b style="mso-bidi-font-weight: normal;"><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">What’s It For?</span></b><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Anytime you have
a system run by an AC electric motor, you may have a need for a VFD. For
example, a common use is controlling the speed of a water pump. If the pump is
part of a water treatment process, a low demand for water can mean that the
water doesn’t exit the plant at the same speed it enters for treatment.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">To slow down the
supply-side, a VFD is used to slow the water pump. </span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">As mentioned
before, a VFD can be used to get a motor started and smoothly accelerate it to
operating speed. Energy usage is reduced if operating speed is below full
speed.<span style="mso-spacerun: yes;"> </span>There is less strain on the
motor, less wear and tear on the machinery, and it doesn't just start with a
jolt. Using VFDs on conveyors and belts eliminates those jerky starts and
increases throughput without damaging equipment.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">VFDs can be
regulated with a PLC instead of manual adjustment. It’s an easy way to automate
a repetitive task and reduce labor cost.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A VFD is a handy
little gadget that can help you tighten your process controls, increase
production, and minimize mistakes. Your maintenance and repair needs go down,
and so does your electricity bill. At the end of the shift, your company has
made a little more money than it did before. </span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span><br />
<span face=""calibri" , "sans-serif"" lang="EN-US" style="color: red; font-size: 18pt;">You can also read: </span><br />
<br />
<ul style="text-align: left;">
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="color: red; font-size: 18pt;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2019/03/types-of-signal-converters-commonly.html">Types of Signal Converters used in Instrumentation Control systems</a></span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="color: red; font-size: 18pt;"><a href="https://amzn.to/33pF2Qa">The Basics of Industrial Instrumentation Systems</a></span></li>
</ul>
</div>
<div class="MsoNormal">
<br /></div><div class="MsoNormal"><span style="color: red; font-family: georgia, serif; font-size: 24px;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif; font-size: 24px;" target="_blank">here.</a></div>
<div class="MsoNormal" style="margin-bottom: 12.0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 12.0pt; margin: 12pt 0cm;">
<b style="mso-bidi-font-weight: normal;"><u><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">About the Author:</span></u></b></div>
<div class="MsoNormal" style="margin-bottom: 12.0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 12.0pt; margin: 12pt 0cm;">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">With over 25 years of experience in the industrial automation repair
industry, Jeff Conner is the Dallas Service Manager for</span><span lang="EN-US" style="font-size: 18pt;"><a href="https://www.controlconceptstexas.com/about-us/dallas"><span face=""calibri" , "sans-serif"" style="text-decoration: none;"> </span></a><a href="https://www.controlconceptstexas.com/about-us/houston" target="_blank"><span face=""calibri" , "sans-serif"" style="color: #1155cc; mso-bidi-font-family: Calibri; mso-fareast-font-family: Calibri;">Control Concepts</span></a></span><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"> and serves on
the Advisory Committee for the Electronics Technologies Department at Texas
State Technical College.</span></div>
<div class="MsoNormal" style="margin-bottom: 12.0pt; margin-left: 0cm; margin-right: 0cm; margin-top: 12.0pt; margin: 12pt 0cm;">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Control Concepts helps design, fabricate, install, test, and program
control systems. They service almost any brand of control found in automated
systems and can send an experienced technician anywhere, wherever one is needed 24 hours
a day, 7 days a week.</span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-12304264130384236262019-07-29T10:40:00.006-07:002023-07-21T10:42:31.484-07:00Why you should modernize your Relay Control System with a PLC<div dir="ltr" style="text-align: left;" trbidi="on">
<span face=""calibri" , sans-serif" style="font-size: 24px;">If you are still running a hard-wired relay control system, it may be time to consider modernizing with programmable logic controllers, or PLCs. PLCs have gotten smaller and more efficient over the years, and they can replace a complex relay system and provide a host of benefits.</span><br />
<div align="center" class="MsoNormal" style="text-align: center;">
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<b><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Defining PLCs</span></b><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A programmable
logic controller is what it sounds like - a small, special-use computerized
control device used in industrial systems. It handles sequential controls,
counters, timers, and more. PLCs are more widely used than special-purpose
digital computers and have found a place in industrial manufacturing and civil
applications.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A PLC
continuously monitors input values from sensors, operator controls, etc. and
produces outputs to operate machinery based on programming.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
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<b><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">How Does a PLC Work?</span></b><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">A PLC is made up
of a CPU module, a power supply, and one or more I/O modules. There is no hard
drive since the program is stored in internal memory. A touch screen or other HMI (Human Machine
Interface) is optional. The PLC stays inside a control panel and
uncomplainingly does its job. </span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">It performs
several steps as part of a typical scan cycle:</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span><br />
<br />
<ul style="text-align: left;">
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Cycles the operating system and monitors time</span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Reads data from the input module and checks all input statuses</span></li>
<li><span face=""calibri" , sans-serif"><span style="font-size: 24px;">Executes user or application program</span></span></li>
<li><span face=""calibri" , sans-serif"><span style="font-size: 24px;">Performs all internal diagnostics and communication tasks</span></span></li>
<li><span face=""calibri" , sans-serif"><span style="font-size: 24px;">Writes data into the output module</span></span></li>
</ul>
</div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">As long as the
PLC is on, it repeats the cycle until the programming or process comes to an
end.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAHtCW6R1pLRZmY9kHK18bIwfq8cMcdnCx-M3EuCusgOpQkSOx27i2UBRe9IAcp3GJbMw4i2ZPWp6NR5IAq-s8yuny995zNqQX8QYA02t5GT-muBCOLjC75SgTFTPJ3uhpxTQsJzrf24Vn/s1600/PLC.JPG" style="margin-left: 1em; margin-right: 1em;"><img alt="Programmable Logic Controllers" border="0" data-original-height="365" data-original-width="707" height="295" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAHtCW6R1pLRZmY9kHK18bIwfq8cMcdnCx-M3EuCusgOpQkSOx27i2UBRe9IAcp3GJbMw4i2ZPWp6NR5IAq-s8yuny995zNqQX8QYA02t5GT-muBCOLjC75SgTFTPJ3uhpxTQsJzrf24Vn/w573-h295/PLC.JPG" title="Programmable Logic Controllers" width="573" /></a></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><br /></span></div>
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<b><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">The Benefits of PLCs</span></b><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">One benefit has
already been mentioned. A PLC is used across multiple industries and in smaller
machinery. But there are other benefits as well. PLCs are:</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span><br />
<br />
<ul style="text-align: left;">
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Robust and durable</span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Easy to program</span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Reliable </span></li>
<li><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Easy to use</span></li>
</ul>
</div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">The I/O module
doesn’t even need to be near the CPU. They can be miles apart and still operate
connected by data cables. Your PLC isn’t stuck to a single cabinet or building.
A PLC can have more than just digital inputs & relay outputs. Improvements over
the years have given PLCs the ability to work with a wide variety of analog
signals as well as Ethernet and serial communications protocols.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">PLCs give your
production lines flexibility that you don't get with relays. If you need to
retool your line, you can easily reprogram your PLCs to handle the new process.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">PLCs are found in
such industries as chemical, automotive, steel, food/beverage and more. </span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<br /></div>
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<b><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Why you should modernize your Relay Control Systems with a PLC</span></b></div>
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<br /></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">As you have
probably experienced, relays use a ton of electricity. They take up space, and
they’re noisy and tend to fail a lot. All those electrical connections between
relay & socket & interconnecting wires mean more downtime for
maintenance. Mechanical relay systems fail more often than PLCs.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">If all you need
to do is turn an electrical motor on and off safely, a relay may be all you
need. But most industrial processes today involve more than that. You need
something modern and smart to make your processes energy-efficient and
cost-effective. </span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
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<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Modern industry
leverages the power of the computer revolution to improve almost every step of
any process. Modernize your relay control systems with a PLC, and you'll wonder
why it took you so long.</span><span lang="EN-US" style="font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal">
<span face=""calibri" , sans-serif" style="color: red;"><span style="font-size: 24px;">You can also read:</span></span><br />
<ul style="text-align: left;">
<li><span face=""calibri" , sans-serif" style="color: red;"><span style="font-size: 24px;"><a href="https://amzn.to/35wQRpD">The Basics of Instrumentation and Control Systems</a></span></span></li>
<li><span face=""calibri" , sans-serif" style="color: red;"><span style="font-size: 24px;"><a href="https://amzn.to/38wDTIX">The Transition from Relays to PLC systems Explained</a></span></span></li>
<li><span face=""calibri" , sans-serif" style="color: red;"><span style="font-size: 24px;"> <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/how-to-integrate-plc-into-your-control.html">How to Integrate a PLC into your Control System</a></span></span></li>
</ul><div><span style="color: red; font-family: georgia, serif; font-size: 24px;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif; font-size: 24px;" target="_blank">here.</a></div>
</div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"><br /></span></div>
<div class="MsoNormal">
<span face=""calibri" , sans-serif"><span style="font-size: 24px;"><b><u>About the Author:</u></b></span></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">With over 25
years of experience in the industrial automation repair industry, Jeff Conner
is the Dallas Service Manager for </span><span lang="EN-US" style="font-size: 18pt;"><a href="https://www.controlconceptstexas.com/about-us/dallas" target="_blank"><span face=""calibri" , "sans-serif"" style="color: #1155cc; mso-bidi-font-family: Calibri; mso-fareast-font-family: Calibri;">Control Concepts</span></a></span><span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;"> and serves on
the Advisory Committee for the Electronics Technologies Department at Texas
State Technical College.<o:p></o:p></span></div>
<div class="MsoNormal">
<br /></div>
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</div>
<div class="MsoNormal">
<span face=""calibri" , "sans-serif"" lang="EN-US" style="font-size: 18pt;">Control Concepts
helps design, fabricate, install, test, and program control systems. They
service almost any brand of control found in automated systems and can send an
experienced technician anywhere one is needed 24 hours a day, 7 days a week.<o:p></o:p></span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-21502028358065795532019-05-03T03:48:00.002-07:002023-07-21T11:11:52.824-07:00Turning Fork Level Switches<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: georgia, serif; font-size: 18pt;">This level switch uses a metal tuning fork
structure to detect the presence of a liquid or solid (powder or granules) in a
vessel.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkgeuJNy6pd5I42YpXDEkb9pGwnnqtOYQ9Vo6CbQdJ_LXNp0p5M3IGJ9NPMid9o0oVEYaMAek3B2UO589MeSX5C3oLmO8AV6hu8cJHr-RCtq58yxx0AACNECj1JUL854FQ90rwqcO3WOiZ/s1600/Turning+Fork+Level+Switch.jpg"><img alt="Turning Fork Level Switch" border="0" data-original-height="327" data-original-width="319" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkgeuJNy6pd5I42YpXDEkb9pGwnnqtOYQ9Vo6CbQdJ_LXNp0p5M3IGJ9NPMid9o0oVEYaMAek3B2UO589MeSX5C3oLmO8AV6hu8cJHr-RCtq58yxx0AACNECj1JUL854FQ90rwqcO3WOiZ/s320/Turning+Fork+Level+Switch.jpg" title="Turning Fork Level Switch" width="312" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><v:shapetype coordsize="21600,21600" filled="f" id="_x0000_t75" o:preferrelative="t" o:spt="75" path="m@4@5l@4@11@9@11@9@5xe" stroked="f">
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">An electronic circuit continuously excites the
tuning fork, causing it to mechanically vibrate. When the prongs of the fork
contact anything with substantial mass, the resonant frequency of the structure
dramatically decreases. The circuit detects this change and indicates the
presence of material contacting the fork. The fork’s vibrating motion tends to
shake off any accumulated material such that this style of level switch tends
to be resistant to fouling.</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2019/02/ultrasonic-level-switches.html">Ultrasonic Level Switches</a></span></span></div><div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;"><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" target="_blank">here.</a></span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com1tag:blogger.com,1999:blog-81971148694103601.post-74924835826534139442019-03-19T06:46:00.007-07:002023-07-21T10:43:29.987-07:00Types of Signal Converters Commonly used in Industrial Control<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 12.6pt; mso-outline-level: 1;">
<span style="background-color: white; color: #1a1a1a; font-family: Georgia, serif; font-size: 18pt;">Signal converters change a signal from one form to
another. In most cases, we have standard inputs and output ranges.</span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTm8_XJc_YnjtMDhTkNDrWVNzles9QVIAYhpMc6PsTE4rUCgM5PYRD1arTDKCzU98HsQ1j0mfc2l5ZjQ5SrS66bJXsE4i5cMLOHTIl2qF9GB-6wQ4sP06IOGp9NXhiVDjVEZVqtnom4vnI/s1600/Signal+Converters.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Types of signal converters" border="0" data-original-height="311" data-original-width="369" height="388" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTm8_XJc_YnjtMDhTkNDrWVNzles9QVIAYhpMc6PsTE4rUCgM5PYRD1arTDKCzU98HsQ1j0mfc2l5ZjQ5SrS66bJXsE4i5cMLOHTIl2qF9GB-6wQ4sP06IOGp9NXhiVDjVEZVqtnom4vnI/w462-h388/Signal+Converters.png" title="Types of signal converters" width="462" /></a></div>
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</v:imagedata></v:shape></span><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">Most signal converters have two adjustments-zero
and range.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">Examples of Signal converters</span></b></div>
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<span style="color: red; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">Nozzle-flapper and differential pressure cells</span></div>
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<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">The nozzle-flapper system is widely used in D.P.
Cells. An example is shown below, that converts differential pressure (e.g. from a </span><span style="font-size: 18pt;"><span style="color: #007acc; font-family: "Georgia","serif"; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA; text-decoration: none; text-underline: none;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/11/differential-pressure-transmitters-dp.html">differential Pressure</a> </span></span><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">flow meter into a standard pneumatic signal). This
is widely used in the control of air operated pipeline valves.<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBS-SMnpqWKowNISQ-m2XsZVnC8INvUkBg-4ZoyIf-qiSELNxOEWaVmoEG_2a3bdor6Y_UtdGT20FeK6Jtb5k64895QmQU-nemLavBtc3CsCeY8h-Jw29FlvNanuH5ZtqodiG4-5SDNfwU/s1600/Signal+Converters+1.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Flapper Nozzle System" border="0" data-original-height="346" data-original-width="515" height="315" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBS-SMnpqWKowNISQ-m2XsZVnC8INvUkBg-4ZoyIf-qiSELNxOEWaVmoEG_2a3bdor6Y_UtdGT20FeK6Jtb5k64895QmQU-nemLavBtc3CsCeY8h-Jw29FlvNanuH5ZtqodiG4-5SDNfwU/w470-h315/Signal+Converters+1.png" title="Flapper Nozzle System" width="470" /></a></div>
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<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA; mso-no-proof: yes;"><v:shape alt="Signal Converters" id="Picture_x0020_2" o:spid="_x0000_i1029" style="height: 211.2pt; mso-wrap-style: square; visibility: visible; width: 326.4pt;" type="#_x0000_t75">
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</v:imagedata></v:shape></span><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">The bellows respond to the differential pressure
and moves the lever. This moves the flapper towards or a way from the nozzle.
The air supply passes through a restrictor and leaks out of the nozzle. The
output pressure hence depends on how close the flapper is to the end of the
nozzle. The range of the instrument is adjusted by moving the pivot and zero
position is adjusted by moving the relative position of the flapper and nozzle.
This system is used in a variety of forms. Instead of bellows, a bourdon tube
might be used and this is operated by an expansion type temperature sensor to
produce a temperature-pneumatic signal converter.<o:p></o:p></span></div>
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<span style="font-family: Georgia, serif; font-size: 18pt;"><span style="color: magenta;">You can also read:</span><span style="color: #351c75;"> <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/12/types-of-proximity-sensors-used-in.html">Types of Proximity Sensors used in Industrial Control</a></span></span></div>
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<span style="color: red; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">Current/Pressure conversion </span></div>
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<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">The figures below show typical units for converting
4-20 mA into 0.2-1 bar or 3-15 psi. They contain adjustments for range and
zero. They are widely used for converting the standard pneumatic and electric
signals back and forth. They can also be adjusted to work with non standard
inputs to convert them into a standard form.<o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjraqWXGhV7eEl_6cGuZLjVF-syoZzpp932hvxacjcQ3QJHiamrc_fjmG1x5BtI9671ypuqcPGwB1wsQL_RGWcsg43ldnbfzzu9FV96UMQbKyiFzCOJ5XMiYGnCRhFknD4CF7XDUg8xfAG8/s1600/Signal+Converters+2.png" style="margin-left: auto; margin-right: auto;"><img alt="Current to Pressure Converter (C/P)" border="0" data-original-height="390" data-original-width="397" height="392" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjraqWXGhV7eEl_6cGuZLjVF-syoZzpp932hvxacjcQ3QJHiamrc_fjmG1x5BtI9671ypuqcPGwB1wsQL_RGWcsg43ldnbfzzu9FV96UMQbKyiFzCOJ5XMiYGnCRhFknD4CF7XDUg8xfAG8/s400/Signal+Converters+2.png" title="Current to Pressure Converter (C/P)" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: medium;">Current to Pressure Converter</span></td></tr>
</tbody></table>
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<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgbpMjsmfDr3zU3F4MegIWGHIjqafuogK1CzayEGTfXfZIgPnBqoSE-ymgWa5wkO79RFim1fQtA-tkJASnHb-kyGB60G0TnLTRiHFxCkBbmi9ylUbMgz8qQlQMW9rJ_fBE-Qv7YcimG58N/s1600/Signal+Converters+3.png" style="margin-left: auto; margin-right: auto;"><img alt="Pressure to Current Converter (P/C)" border="0" data-original-height="381" data-original-width="462" height="327" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgbpMjsmfDr3zU3F4MegIWGHIjqafuogK1CzayEGTfXfZIgPnBqoSE-ymgWa5wkO79RFim1fQtA-tkJASnHb-kyGB60G0TnLTRiHFxCkBbmi9ylUbMgz8qQlQMW9rJ_fBE-Qv7YcimG58N/s400/Signal+Converters+3.png" title="Pressure to Current Converter (P/C)" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: medium;">Pressure to Current Converter</span></td></tr>
</tbody></table>
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<span style="color: red; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><br />Electric D.P. Cells</span><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">They provide the same functions as the pneumatic
versions but they are given an output of 4-20 mA using electrical pressure
transducers. They are typically used with D.P. Flow meters.<o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXXKNRdJ7W4X1sldQLWxxLjtWtQY3WSQKje6k-Uy-lvgqW8X6rWN34KQWyDn-OD_mu3BGGGmYTv-zPJrOcyWtTybFSIRyVqVKLlZoNZ2pjI1QqPBwwmbgyWfVCKk14U_H11nzXX9vQHV3N/s1600/Signal+Converters+4.png" style="margin-left: auto; margin-right: auto;"><img alt="Differential Pressure Transmitter" border="0" data-original-height="483" data-original-width="428" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXXKNRdJ7W4X1sldQLWxxLjtWtQY3WSQKje6k-Uy-lvgqW8X6rWN34KQWyDn-OD_mu3BGGGmYTv-zPJrOcyWtTybFSIRyVqVKLlZoNZ2pjI1QqPBwwmbgyWfVCKk14U_H11nzXX9vQHV3N/s400/Signal+Converters+4.png" title="Differential Pressure Transmitter" width="353" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: medium;">Differential Pressure Transmitter</span></td></tr>
</tbody></table>
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<span style="color: red; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><br />Analogue -Digital Converters</span><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">Analogue to digital conversion is a process of turning
an analogue voltage or current into a digital pattern which can read by a
computer and processed, this is done by analogue -digital converters.
Lets look at the Binary Numbers, a number may be represented in digital form by
simply setting a pattern of voltages on a line high or low. It is normal to use
4, 8, 16 or 32 lines. An 8 bit binary pattern is shown in the below figure:<o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgATA2RgVxJHQes2SF_wXMOdauUMxRG3hMJ-lboEwHP9pGa_MadlCvVWYfzKd_XWLd7k80OZhldcOC-tMu3kXSXsy1WE9qsHiqnxgbMn1i8acLZ5QwPruaSYWDmakQPvlwaPu8eYRgbiwKS/s1600/Signal+Converters+5.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Binary Numbers" border="0" data-original-height="308" data-original-width="481" height="347" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgATA2RgVxJHQes2SF_wXMOdauUMxRG3hMJ-lboEwHP9pGa_MadlCvVWYfzKd_XWLd7k80OZhldcOC-tMu3kXSXsy1WE9qsHiqnxgbMn1i8acLZ5QwPruaSYWDmakQPvlwaPu8eYRgbiwKS/w544-h347/Signal+Converters+5.png" title="Binary Numbers" width="544" /></a></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">The total pattern is called a word and the one
above is an 8 bit word. The pattern may be stored in an 8 bit register. A
register is a temporary store where the word may be manipulated. The Bit zero
is called the least significant bit (LSB) and the bit with highest value is
called the most significant bit (MSB). Each bit has a value of zero when off
(LOW) or the value shown when on (HIGH). The maximum value for an 8 bit word is
255.<o:p></o:p></span></div>
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<span style="color: red; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">Digital to Analogue Converters</span><span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">These are devices for converting a binary number
into an analogue voltage. The change in the binary value from zero to a maximum
corresponds with a change in the analogue value from 0 to maximum.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "Georgia","serif"; font-size: 18pt; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA;">One of the manufacturers of signal converters
is </span><span style="font-size: 18pt;"><span style="color: #007acc; font-family: "Georgia","serif"; mso-bidi-font-family: "Times New Roman"; mso-fareast-font-family: "Times New Roman"; mso-fareast-language: EN-ZA; text-decoration: none; text-underline: none;"><a href="http://www.omega.com/">Omega.</a></span></span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-56172310370896409082019-03-10T06:42:00.003-07:002023-07-21T10:40:45.739-07:00The Inputs and Outputs of Process Measurement Instruments Commonly used in Control Systems <div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Basically when you are doing the troubleshooting of
any instrumentation system you assume that every instrument has at least
one input and at least one output and that the output(s) should accurately
correspond to the input (s). In normal circumstances, if the instrument’s
output is not corresponding to its input according to the instrument’s design
function, then there could be something wrong with the instrument. Lets
consider the inputs of the following examples of instruments that are
commonly used in process control systems:</span><br />
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</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Differential Pressure transmitter</span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Temperature Transmitter</span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Controller</span></li>
</ul>
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdtezhvkXYg0PtHORyFkdNPghhx1A8taT6MRdEq2tLlSE7Dt5oG_qGZJTsXj267XHzpZ2bX-tp2C6JVIJUxz2KX-mQPxiDuXL0TcAL5oLa_n_6HEumZJLU_Fbcd-6MtvOSQmRszAZg518P/s1600/Differential+Pressure+Transmitter+%2528Inputs-Outputs%2529.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="Process measurement instruments" border="0" data-original-height="671" data-original-width="775" height="514" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdtezhvkXYg0PtHORyFkdNPghhx1A8taT6MRdEq2tLlSE7Dt5oG_qGZJTsXj267XHzpZ2bX-tp2C6JVIJUxz2KX-mQPxiDuXL0TcAL5oLa_n_6HEumZJLU_Fbcd-6MtvOSQmRszAZg518P/w547-h514/Differential+Pressure+Transmitter+%2528Inputs-Outputs%2529.jpg" title="Process Measurement instruments" width="547" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7zDnExysO-nZDfk_Fs894XKXuWEr-tTRQgW1_tgGiWqNt6IMtr8RRs_I3ir8zDDkqFwVXkRUwOdE20Najj1IyED2_qK0hnAZqU_wVpK9Yh6ToNg4fJAggpExBj-r_j2Uqyl9ETcWeCUQJ/s1600/Differential+Pressure+Transmitter+%2528Inputs-Outputs%25291.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="Controller" border="0" data-original-height="649" data-original-width="1002" height="338" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7zDnExysO-nZDfk_Fs894XKXuWEr-tTRQgW1_tgGiWqNt6IMtr8RRs_I3ir8zDDkqFwVXkRUwOdE20Najj1IyED2_qK0hnAZqU_wVpK9Yh6ToNg4fJAggpExBj-r_j2Uqyl9ETcWeCUQJ/w524-h338/Differential+Pressure+Transmitter+%2528Inputs-Outputs%25291.jpg" title="Controller" width="524" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Each of the above instruments takes in (input) data
and generates the (output) data. In an instrumentation loop, the output
of one instrument feeds into the input of the next. Such information is passed
from one instrument to another.<o:p></o:p></span></div>
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<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">You can also read:</span><br />
<br />
<ul style="text-align: left;">
<li><span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;"><a href="https://amzn.to/35wQRpD">The Basics of Industrial Instrumentation and Control Systems</a></span></li>
<li><span style="font-size: 18pt;"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/how-to-use-test-diodes-to-measure-4-20.html" target="_blank">How to
Troubleshoot a 4-20 mA Loop Current with Test Diodes</a></span></span></li>
</ul>
</div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">By intercepting the data communicated between components
of an instrument system, we are able to locate and isolate faults. For us to
able to properly understand the intercepted data, we must understand the inputs
and outputs of the respective instruments and the basic functions of those
instruments. From the above diagrams, we are able to highlight the kind
of inputs and outputs for each of the instruments indicated.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">To be able to check the right correspondence
between the instrument inputs and outputs, we must therefore use appropriate
test equipment to intercept the signals into and out of these instruments e. g.
in case of analogue instruments using 4-20 mA signals we can use the electrical
meters capable of measuring the current and voltage.<o:p></o:p></span></div>
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<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">So what are some of the key considerations when using milliameters to
measure loop current?</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">For you to measure the loop current, you have to
break the circuit to connect the milliameter, in series with the current, and
which means the current will fall to 0 mA until the meter is connected.
Interrupting the current means interrupting the flow of information that is
conveyed by that current, be it a process measurement or a command signal to a
final control element. This can have adverse effects on the control system
unless certain preparations are made before hand. The preparations can be
in form of:<o:p></o:p></span></div>
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</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Informing the personal in charge that signal will be interrupted - state the number of times you intend to do the interruption.</span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">For case, where the signal is coming from a process transmitter to a controller, the controller should be placed in manual mode, so that it will not cause an upset in the process. </span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">If the current drives process shutdown alarms, these should be disabled on temporarily basis, so that nothing shuts down upon the interruption of the signal.</span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">All process alarms should be temporarily disables so that they do not cause panic.</span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">If the current signal to be interrupted is a command signal from a controller to a final control element, the final control element either needs to be manually overridden so as to hold a fixed setting while the signal varies or it needs to be bypassed completely by some other devices (s)</span></li>
</ul>
<div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-65465666825400415562019-02-07T06:26:00.001-08:002023-04-29T19:53:45.804-07:00Ultrasonic Level Switches<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
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<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">This type of level switch uses ultrasonic sound
waves to detect the presence of process material either solid or liquid at one
point.</span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Working Principle</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Sound waves pass back and forth within the gap of
the probe, sent and received by piezoelectric transducers. The presence of any
substance other than gas within the gap detects the received audio power, thus
signalling to the electronic circuit within the bulkier portion of the device
that process level has reached the detection point.<o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzE_Krl1OjP5pfv4Gq3R0sa8Mj4Lu9jxjvNZmIZI7Cl9athtSxMw6rKFIjl5mhO43f_VimwMShKB_77miIlVPv40SxkosLNLqJ5zkZ1JCSYrJkXN7sbBF251sthFNkmjFiOu6M9i64fhXV/s1600/Ultrasonic+Level+switches.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Ultrasonic Level Switches" border="0" data-original-height="574" data-original-width="735" height="311" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzE_Krl1OjP5pfv4Gq3R0sa8Mj4Lu9jxjvNZmIZI7Cl9athtSxMw6rKFIjl5mhO43f_VimwMShKB_77miIlVPv40SxkosLNLqJ5zkZ1JCSYrJkXN7sbBF251sthFNkmjFiOu6M9i64fhXV/s400/Ultrasonic+Level+switches.PNG" title="Ultrasonic Level Switches" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Fig 1</span></td></tr>
</tbody></table>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeHTquWrP7zRHIkrCBHisL4THdg1NfPgOSdWZ2i_1x8qsG8Y5Z0pSvXOwVIb5iYduURShdHRSTFkPIJmpB5EQk2TpKWyzbMOFkuqj_UK5uUCP6Hg2sXRXoFsFEDDfVqBi8T9tgAK8xO-jO/s1600/Ultrasonic+Level+switches+2.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Ultrasonic Level Switches" border="0" data-original-height="516" data-original-width="662" height="311" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeHTquWrP7zRHIkrCBHisL4THdg1NfPgOSdWZ2i_1x8qsG8Y5Z0pSvXOwVIb5iYduURShdHRSTFkPIJmpB5EQk2TpKWyzbMOFkuqj_UK5uUCP6Hg2sXRXoFsFEDDfVqBi8T9tgAK8xO-jO/s400/Ultrasonic+Level+switches+2.jpg" title="Ultrasonic Level Switches" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Fig 2</span></td></tr>
</tbody></table>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br />In Fig 1, the sound passes through the gap when
filled with liquid (wet gap).<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In Fig 2, the sound cannot pass through an
air-filled gap (dry gap).<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The lack of moving parts makes this probe quite
reliable although it may be become fooled by heavy fouling.<o:p></o:p></span></div>
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<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/the-working-principle-of-ultrasonic.html">The Working Principle of Ultrasonic Flow Meters</a></span></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Some of the industrial applications of Ultrasonic level switches include:</span></b></div>
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<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Leak detection</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">As an overfill alarm</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Detection of presence of liquids in pipeline</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Pump Protection</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Engine oil level control</span></span></li>
</ul>
<br /></div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-66721749371212841972019-02-05T05:27:00.002-08:002023-07-21T11:05:54.042-07:00The Components that make up a 4-20 mA Current Loop<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">The 4-20 mA current</span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"> loop is an important aspect of process
measurement and control circuits. The important components that make up this
loop are:</span><br />
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<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The Sensor</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The Transmitter</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The Power Source</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The Loop itself</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The Receiver</span></span></li>
</ul>
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<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The following diagram shows each component with its
function:<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr8t7wHGRJbiPB3l898dSUfTfGCYIzU3Jv5hZlfYq7ebu9WM_BW6cZVnv1yPW7f6AEelrq3JAug1Zoq_rrxI0xRPVmNv7YtijckIS4XOcclntueN48WenADmJ4qyg8eOKwnu30IqXwIeCH/s1600/Compontent+that+make+up+4-20+mA+loop.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="Components in a 4-20 mA current loop" border="0" data-original-height="433" data-original-width="794" height="348" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgr8t7wHGRJbiPB3l898dSUfTfGCYIzU3Jv5hZlfYq7ebu9WM_BW6cZVnv1yPW7f6AEelrq3JAug1Zoq_rrxI0xRPVmNv7YtijckIS4XOcclntueN48WenADmJ4qyg8eOKwnu30IqXwIeCH/s640/Compontent+that+make+up+4-20+mA+loop.jpg" title="Components in a 4-20 mA current loop" width="640" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
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<br /></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This is a simple illustration of a 4-20 mA current
Loop System.<o:p></o:p></span></div>
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<span style="font-size: 18pt; line-height: 115%;"><o:p> <span style="color: red;">You can also read:</span></o:p></span></div>
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</div>
<ul style="text-align: left;">
<li><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/11/how-to-wire-4-20-ma-current-loop.html" style="font-size: 18pt;">How to wire a 4-20 mA current loop with a PLC</a></li>
</ul>
<br />
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com1tag:blogger.com,1999:blog-81971148694103601.post-79642494564026229742018-12-27T04:06:00.004-08:002023-06-25T19:30:30.762-07:00Key Applications of Thermal Mass Flowmeters<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Thermal mass flowmeters work on the principle that
when you place a heated object in the midst of a fluid flow stream and measure
how much heat the fluid transfers away from the heated object, then you can be able
to determine the mass flow rate. Industrial thermal mass flowmeters consists of
a specially designed flow tube with two temperature sensors inside: One that is
heated and one that is unheated. The heated sensor acts as the mass flow sensor
(cooling down as flow rate increases) while the unheated sensor serves to
compensate for the “ambient” temperature of the process fluid. The
following diagram shows an example of a thermal mass flowmeter from </span><span style="font-size: 18pt;"><a href="http://magnetrol.com/"><span style="color: #007acc; font-family: "georgia" , serif; text-decoration-line: none;">Magnetrol</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">.</span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixrGeN4Yay3w6SidH5iQ4RJvt7UvuXnuQXuMsaqUVViAVF2IEwSzI64LbQxkPOQo7bm_gZzMoaVL64izzebROv__ep4RG7NtQIl3NQXxSH0hHk8HQDl4wZfzAE49WeMU-uy4Jxjbaiwqfn/s1600/Magnetrol+Thermal+Flowmeter.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Magnetrol Thermal Flowmeter" border="0" data-original-height="489" data-original-width="399" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixrGeN4Yay3w6SidH5iQ4RJvt7UvuXnuQXuMsaqUVViAVF2IEwSzI64LbQxkPOQo7bm_gZzMoaVL64izzebROv__ep4RG7NtQIl3NQXxSH0hHk8HQDl4wZfzAE49WeMU-uy4Jxjbaiwqfn/s640/Magnetrol+Thermal+Flowmeter.PNG" title="Magnetrol Thermal Flowmeter" width="522" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Magnetrol Thermal Flowmeter</span></td></tr>
</tbody></table>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">An important factor in the calibration of a thermal
mass flowmeter is the specific heat of the process fluid. Fluid with high
specific heat values make good coolants because they are able to remove much
heat energy from hot objects without experiencing great increases in
temperature. Since thermal mass flowmeters work on the principle of convective
cooling, this means a fluid having a high specific heat value will elicit a
greater response from thermal mass flowmeter than exact same mass flow rate of
a fluid having a lesser specific heat value. Therefore it is paramount that you
know the specific heat value of the fluid you plan to measure with a thermal
mass flowmeter and be assured that its specific heat value will remain
constant. For this reason, thermal mass flowmeters are not suitable for
measuring the flow rates of fluid streams whose chemical composition is likely
to change over time.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Another potential limitation of thermal flowmeters
is the sensitivity of some designs to changes in flow regime. Since the measurement
principle is based on heat transfer by fluid convection, any factor influencing
the convective heat-transfer efficiency will translate into a perceived
difference in mass flow rate. Turbulent flows are more efficient at heat
convection than laminar flows. Therefore, a change in flow regime from
turbulent to laminar will cause a calibration shift for this design of thermal
mass flowmeters.<o:p></o:p></span></div>
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<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">So what are some of the applications where thermal flowmeters are used?</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Generally thermal flowmeters are used in
applications where the composition of the fluid is known especially in purified
gases. Having said that, lets look at some of the areas where thermal
flowmeters are commonly used:<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Natural Gas</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Flow </span><span style="font-size: 18pt;"><a href="http://www.instrumentationsolutions.tech/category/process-measurements/"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;">measurement</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> of natural gas fuel usage is important for
combustion efficiency as well as general energy management projects for both
industrial and commercial facilities. Thermal mass flowmeters will monitor the
flow to individual combustion sources.</span></div>
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<b><span style="font-family: "georgia" , serif; font-size: 18pt;">Air Efficiency</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In combustion applications, thermal mass flow
meters can ensure repeatability of air flow measurements to obtain an efficient
air-to-fuel ratio. On compressed air, it is common to measure for plant
allocation or to determine leaks.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Tank Blanketing</span></b></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Nitrogen is frequently used to maintain an inert
environment in the vapor space of a tank. Thermal meters are ideally suited for
measuring the flow of nitrogen in such applications because they support mass
measurement, they are easily installed into the pipe & are excellent at
measuring low flow rates.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: </span></span><br />
<br />
<ul style="text-align: left;">
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"><a href="https://read.amazon.com/kp/embed?asin=B07YRVYVW9&preview=newtab&linkCode=kpe&ref_=cm_sw_r_kb_dp_X34ODbTF4FZ58&tag=1984makec-20">The Ultimate Guide to Industrial Flow Instruments</a></span></span></li>
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/11/how-pitot-tubes-are-used-in-flow.html">How Pitot Tubes are used In Flow Measurement</a></span></span></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Flare & Vent Gas</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Thermal mass meters are a particularly good fit for
flare measurement. Flares can range from vent gases at atmospheric pressure to
high flow applications needing extended turn down. Oil and Gas is a common
industry here.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">Follow this blog for updates on instrumentation articles or
subscribe <a href="http://eepurl.com/dOUtI9">here.</a></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Biogas</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Both the landfills and anaerobic digesters at
wastewater plants produce a mixture primarily composed of methane and carbon
dioxide. Excellent low flow sensitivity, hot tap capabilities and mixed gas
calibration make thermal mass flow measurement a popular technology.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Source: Magnetrol</span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com1tag:blogger.com,1999:blog-81971148694103601.post-45475359694325195702018-12-13T04:21:00.002-08:002022-10-14T21:02:34.103-07:00Types of Proximity Sensors used in Industrial Control<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Almost every automated manufacturing operation has sensors
that ensure that the system is working correctly.</span><br />
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Examples of Sensors that are used in industrial
control are:<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Non-Contact Presence
Sensors (Proximity Sensors)<o:p></o:p></span></b></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Contact sensors are often avoided in automated
systems because wherever parts touch there is wear and a potential for eventual
failure of the sensor. Automated systems are increasingly being designed with
non-contact sensors. The three most common types of non-contact sensors in use
today are:<o:p></o:p></span></div>
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</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Inductive proximity sensor</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Capacitive proximity sensor</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Optical proximity sensor</span></span></li>
</ul>
<br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The above sensors are actually transducers, but
they include control circuitry that allows them to be used as switches. The
circuitry changes an internal switch when the transducer output reaches a
certain value.<o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHbBnYCCvc99AszsaA1BYv4QpBpbWYMhSZMTI7PZoXXzU9IwWb4WcG2cH8p9S2048P7Pcl3QV1LIjpqEYE1t5ubNvDHsW2ZVzriAxgBymooPZk10-vvzIliH05Y3UMyqrolU1qpjd8LeNy/s1600/Proximity+Sensors.png" style="margin-left: auto; margin-right: auto;"><img alt="Hall Effect Limit Switches" border="0" data-original-height="195" data-original-width="471" height="264" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHbBnYCCvc99AszsaA1BYv4QpBpbWYMhSZMTI7PZoXXzU9IwWb4WcG2cH8p9S2048P7Pcl3QV1LIjpqEYE1t5ubNvDHsW2ZVzriAxgBymooPZk10-vvzIliH05Y3UMyqrolU1qpjd8LeNy/s640/Proximity+Sensors.png" title="Hall Effect Limit Switches" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Hall Effect Limit Switch</td></tr>
</tbody></table>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br />The inductive Sensor</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This is the most widely used non-contact sensor due
to its small size, robustness, and low-cost. This type of sensor can only
detect the presence of electrically conductive materials.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The DC power supplied is used to generate AC in an
internal coil, which in turn causes an alternating magnetic field. If no conductive
materials are near the face of the sensor, the only impedance to the internal
AC is due to the inductance of the coil. If however, a conductive material
enters the changing magnetic field, eddy currents are generated in that
conductive material, and there is a resultant increase in the impedance to the
AC in the proximity sensor. A current sensor, also built into the proximity
sensor detects when there is a drop in the internal AC current due to increased
impedance. The current controls a switch providing the output.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 0cm;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh52PMGh9oQhOtPaMvo3YP3-5Bm_OzLwINfYNWU0V4uc360so-w2RjJvjvAPK55dhImaPt8hyphenhyphenG3_2C6EikbdMIGwQ5SqDvfl8kH-qeTX9NSVTajx4WLbtMaxJNLaJwW1BuQooh7IwJNngmY/s1600/Proximity+Sensors+1.png" style="margin-left: auto; margin-right: auto;"><img alt="Inductive Sensor" border="0" data-original-height="168" data-original-width="571" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh52PMGh9oQhOtPaMvo3YP3-5Bm_OzLwINfYNWU0V4uc360so-w2RjJvjvAPK55dhImaPt8hyphenhyphenG3_2C6EikbdMIGwQ5SqDvfl8kH-qeTX9NSVTajx4WLbtMaxJNLaJwW1BuQooh7IwJNngmY/s640/Proximity+Sensors+1.png" title="Inductive Sensor" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Inductive Sensor</td></tr>
</tbody></table>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p><br /> </o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Capacitive proximity Sensors</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">These sensors sense the target objects due to
the target’s ability to be electrically charged. This works both on conductors
and non-conductors.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Inside the <a href="https://www.biomedicalinstrumentationsystems.com/tag/biomedical-sensors/" target="_blank">sensor </a>is a circuit that uses the supplied
DC power to generate AC, to measure the current in the internal AC circuit, and
to switch the output circuit when the amount of AC current changes. Unlike the
inductive sensor, the AC does not drive a coil, but instead tries to charge a
capacitor. The AC can move current into and out of this plate only if there is
another plate nearby that can hold the opposite charge. The target being sensed
acts as the other plate.<o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCi8W2pnwo16AD9pAxxm4WmO4w2z-SaNFHQXOj0qvy6fUGEIrOF1d2_1uD2txsMt4EuCKaMffhYXrQ9gikbPXy3Et6nm7yb1AGREzcSnoqFSZl8n_ZtQZbqrkwLrHWAqouXrOguCGpbeGI/s1600/Proximity+Sensors+2.png" style="margin-left: auto; margin-right: auto;"><img alt="Capacitive Proximity Sensor" border="0" data-original-height="222" data-original-width="455" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCi8W2pnwo16AD9pAxxm4WmO4w2z-SaNFHQXOj0qvy6fUGEIrOF1d2_1uD2txsMt4EuCKaMffhYXrQ9gikbPXy3Et6nm7yb1AGREzcSnoqFSZl8n_ZtQZbqrkwLrHWAqouXrOguCGpbeGI/s640/Proximity+Sensors+2.png" title="Capacitive Proximity Sensor" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Capacitive Proximity Sensor</td></tr>
</tbody></table>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<br /></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">If this object is near enough to the face of the
capacitive sensor to be affected by the charge in the sensor’s internal
capacitor plate, it will respond by becoming oppositely charged near the
sensor, and the sensor will then be able to move significant into and out of
its internal plate.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Optical Proximity Sensors</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">These are widely used in automated systems because
they have been available longer and some can fit into small locations. They are
commonly known as light beam sensors of the thru-beam type or of the
retro-reflective type. A complete optical proximity sensor includes a light
source, and a sensor that detects the light. The light source is supplied
because it is usually critical that the light be tailored for the light sensor
system. The light source generates a light of a particular frequency which is
able to be detected by the light sensor in use. Infra-red light is used in most
optical sensors. To make the light sensing system more foolproof, most optical
proximity sensor light sources pulse the infra-red light on and off at a fixed
frequency. The light sensor circuit is designed so that light that is not
pulsing at this frequency is rejected.<o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7z69e2Ae8jdeiGwHHQ4Mu6C4IJ9CZ1jUZsV7OSuZ5ORCuSAL7U7SOkfIT_XUk26oxq0JLhpFzjcTWb1oXXhzkVOtG1SNQUsaYRmiEpojcNyiRgBIBeRpwug4jVyINaCLby_hRNe1e3Zwq/s1600/Proximity+Sensors+3.png" style="margin-left: auto; margin-right: auto;"><img alt="Optical Sensors" border="0" data-original-height="185" data-original-width="531" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7z69e2Ae8jdeiGwHHQ4Mu6C4IJ9CZ1jUZsV7OSuZ5ORCuSAL7U7SOkfIT_XUk26oxq0JLhpFzjcTWb1oXXhzkVOtG1SNQUsaYRmiEpojcNyiRgBIBeRpwug4jVyINaCLby_hRNe1e3Zwq/s640/Proximity+Sensors+3.png" title="Optical Sensors" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Optical Proximity Sensors</td></tr>
</tbody></table>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br />The light sensor is a semiconductor device such as
a photo diode which generates a small current when light energy strikes it or
more commonly a photo transistor or a photodarlington that allows current to
flow if light strikes it.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/the-use-of-smart-sensors-in-industrial.html">Use of Smart Sensors in Industrial Measurement and Control Systems</a></span></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Some of the manufacturers of proximity sensors
include:<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;"><span style="color: #007acc; font-family: "georgia" , serif; text-decoration-line: none;"><a href="http://www.industry.siemens.nl/automation/nl/en/sensor-systems/industrial-sensors/Pages/Default.aspx" style="font-family: "Times New Roman";">Siemens</a></span></span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;"><span style="color: #007acc; font-family: "georgia" , serif; text-decoration-line: none;"><a href="http://www.ia.omron.com/products/category/sensors/proximity-sensors/" style="font-family: "Times New Roman";">Omron</a></span></span></span></li>
</ul>
<br />
<div class="MsoNormal">
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com1tag:blogger.com,1999:blog-81971148694103601.post-77290675030036910712018-12-10T05:22:00.005-08:002023-04-29T19:55:41.271-07:00Programmable Logic Controllers (PLC)<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Programmable logic controllers (PLC) play an
important role in automation sector. Various industries like Food &
Beverage, Chemical, Petrochemical, Power generation etc. use PLC.</span><br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">We have several types of PLC designs:<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Compact PLC: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This is built by several modules within a single
case. The I/O capabilities are decided by the manufacturer and not the user.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Modular PLC: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This is built with several components that are
plugged into a common rack or bus with extended I/O capabilities. It contains
power supply module, CPU and other I/O modules that are plugged together in the
same rack, which are from the same manufacturers or from different
manufacturers.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Soft PLC: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This is an advanced PLC system that consists of
compact, rack mounted components such as power supplies, I/O modules and a CPU
which embeds a powerful PLC Control software.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Programming Languages of PLC</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">There are several programming languages used to
write programs in a PLC. They include but not limited:<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Ladder Diagram</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Instruction List</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Functional Block Diagram</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Sequential Function Chart</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Structured Text</span></span></li>
</ul>
<br />
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<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">So what are some of the components that make up a Programmable Logic
Controllers?</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibpAHU5BanOaZJh2Lx9sl-0RF7BlL2v8fGRAvPm76LF2uHEbFjpjALPaC47HYXeUQxkOA_OENt2p4e1tbOcJYtFlEunisoRSAnQViU8wSuiwlKYJUEz4JEeyi14GG5VHZQtH68xR99L-6q/s1600/PLC+1.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Components that make up a PLC system" border="0" data-original-height="396" data-original-width="732" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibpAHU5BanOaZJh2Lx9sl-0RF7BlL2v8fGRAvPm76LF2uHEbFjpjALPaC47HYXeUQxkOA_OENt2p4e1tbOcJYtFlEunisoRSAnQViU8wSuiwlKYJUEz4JEeyi14GG5VHZQtH68xR99L-6q/w551-h298/PLC+1.PNG" title="Components that make up a PLC system" width="551" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">PLC System</span></td></tr>
</tbody></table>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br />Functions of each component:</span></b><br />
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br />
</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">CPU – This the unit that contains
microprocessors<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Input and Output Sections – This is where the processor
receives information from external devices and communicates information to
external devices.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Power Supply Unit– It converts the Main AC voltage
to low DC voltage.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Programming device – Used to enter the required
program into the memory of the processor.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Memory Unit – This is where the program is stored
that is used to control actions.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Operation of a PLC</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">Check the input status: </span><span style="color: black; font-family: "georgia" , "serif"; font-size: 18pt;">First
the PLC takes a look at each I/O to determine if it is on or off.</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">Execute Program: </span><span style="color: black; font-family: "georgia" , "serif"; font-size: 18pt;">Next the PLC executes
the program one instruction at a time. </span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">Update output status: </span><span style="color: black; font-family: "georgia" , "serif"; font-size: 18pt;">Finally
the PLC updates the outputs. It updates the outputs based on which inputs were
on during the first step. </span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><v:shape alt="Programmable Logic Controllers" id="Picture_x0020_4" o:spid="_x0000_i1025" style="height: 337.8pt; mso-wrap-style: square; visibility: visible; width: 450pt;" type="#_x0000_t75">
<v:imagedata o:title="Programmable Logic Controllers" src="file:///C:\Users\zamulinj\AppData\Local\Temp\msohtmlclip1\01\clip_image002.jpg">
</v:imagedata></v:shape></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEESwZjyN7eaPNwIJOGKiw5yv6aOuLq_9aGELMv2l3CHfM2bo7KKetGllUy1I_fctinh5GTgZomFWbxRLMqqDMhvxG33pxdS9r0_YIOUPbuVPtZu3rcELML5osD4N4ZfHeVpD35wmzh-qr/s1600/PLC+1.PNG" style="margin-left: auto; margin-right: auto;"><img alt="How a PLC system works" border="0" data-original-height="440" data-original-width="799" height="322" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEESwZjyN7eaPNwIJOGKiw5yv6aOuLq_9aGELMv2l3CHfM2bo7KKetGllUy1I_fctinh5GTgZomFWbxRLMqqDMhvxG33pxdS9r0_YIOUPbuVPtZu3rcELML5osD4N4ZfHeVpD35wmzh-qr/w585-h322/PLC+1.PNG" title="How a PLC system works" width="585" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">The Working of a PLC system</span></td></tr>
</tbody></table>
</span></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<o:p></o:p><br />
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Advantages of PLC:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">More flexibility</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Lower cost</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Increased reliability</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Faster response</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Easier to troubleshoot</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Communication capability</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Remote control capability</span></span></li>
</ul>
<br />
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Disadvantages:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">They can render some jobs redundant</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">They have a high initial cost</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">If a Programmable logic controller stops, then the production stops<span style="color: red; font-size: 18pt;"> </span></span></span></li>
</ul>
<br />
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Industrial Applications of PLCs</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Food and Beverage industry</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Gas and Water Filling Stations</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Power Sector</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Bottling Plants</span></span></li>
</ul>
<br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: </span></span></b><br />
<br />
<ul style="text-align: left;">
<li><b><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/how-to-integrate-plc-into-your-control.html">How to Integrate PLC into your Control System</a></span></span></b></li>
<li><b><span style="font-family: "georgia" , serif; font-size: 18pt;"><a href="https://amzn.to/38wDTIX">The Transition from Relays to PLC systems</a></span></b></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Some of the Top PLC Brands in the
world include:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="font-size: 24px;"><a href="http://www.geautomation.com/products/programmable-automation-controllers" style="font-family: Georgia, serif;">General Electric</a></span></li>
<li><span style="background-color: white; color: #007acc; font-family: "georgia" , serif; font-size: 24px;"><a href="https://www.toshiba.com/tic/other-products/plcs" style="background-color: white; font-size: 24px;">Toshiba</a></span></li>
<li><span style="background-color: white; color: #007acc; font-family: "georgia" , serif; font-size: 24px;"><a href="https://www.siemens.com/global/en/home/products/automation/systems/industrial/plc.html" style="background-color: white; font-size: 24px;">Siemens</a></span></li>
<li><span style="background-color: white; color: #007acc; font-family: "georgia" , serif; font-size: 24px;"><a href="http://ab.rockwellautomation.com/Programmable-Controllers" style="background-color: white; font-size: 24px;">Allen Bradley</a></span></li>
<li><span style="background-color: white; color: #007acc; font-family: "georgia" , serif; font-size: 24px;"><a href="https://www.ia.omron.com/products/category/automation-systems/programmable-controllers/" style="background-color: white; font-size: 24px;">Omron</a></span></li>
</ul>
<div>
<span style="color: red; font-family: "georgia" , serif;"><span style="font-size: 24px;">Don't miss out on our Control and Automation articles, join our Newsletter list <a href="http://eepurl.com/dOUtI9">here. </a></span></span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-60152026454071906662018-12-07T06:16:00.001-08:002023-01-10T18:27:05.287-08:00How to upgrade your Legacy Equipment for industry 4.0<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Scholar and leadership expert </span><span style="font-size: 18pt;"><a href="https://www.goodreads.com/author/quotes/4993165.Warren_G_Bennis"><span style="color: #007acc; font-family: "georgia" , serif; text-decoration-line: none;">Warren Bennis</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"> once said, “In life, change is inevitable. In
business, change is vital.” This wisdom resonates with every business owner,
but none more than the manufacturer.</span><br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">We are in the midst of a new industrial revolution,
one which will significantly impact the manufacturing industry. Experts are
calling it Industry 4.0, the fourth wave in the industrial revolution behind
steam power, electricity and computing.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">According to <a href="https://www.techradar.com/news/what-is-industry-40-everything-you-need-to-know"><span style="color: #007acc; text-decoration: none;">TechRadar</span></a>,
Industry 4.0 is “the label given to the gradual combination of traditional
manufacturing and industrial practices with the increasingly technological
world around us.” Industry 4.0 is ushering in a new era of production where
automation and data exchange are integrated into the manufacturing process to
streamline productivity.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Sounds great, right? It is, if you can upgrade your
legacy equipment. Nobody enjoys the process of upgrading, let alone talking
about it, but this is a revolution you don’t want to miss. Here’s how you can
upgrade your legacy equipment to successfully ride the wave of Industry 4.0.<i> </i><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 10.2pt; margin-left: 0cm; margin-right: 0cm; margin-top: 20.35pt; margin: 20.35pt 0cm 10.2pt; mso-outline-level: 1;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Industrial Internet of
Things<o:p></o:p></span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Industrial Internet of Things (IIoT) is the
interconnection between manufacturing and production equipment. This equipment
uses sensors and internet connectivity to communicate with themselves and one
another to create a more efficient production output. As a result, equipment
can consider factors like stress on the electrical grid and projected weather
to determine the most efficient way to operate at any given time.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">According to </span><span style="font-size: 18pt;"><a href="https://www.gartner.com/newsroom/id/3185623"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;">Gartner</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">, a leading research and advisory company, more
than half of major new business processes and systems will incorporate some
element of the IIoT by 2020. What’s more, </span><span style="font-size: 18pt;"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;"><a href="https://www.mckinsey.com/~/media/McKinsey/Business%20Functions/McKinsey%20Digital/Our%20Insights/Disruptive%20technologies/MGI_Disruptive_technologies_Full_report_May2013.ashx">McKinsey Global Institute</a> </span></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">reported that in the last five years, the number of
connected machines has grown by 300 percent.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">These businesses are onto something; there are
many </span><span style="font-size: 18pt;"><a href="https://techwireasia.com/2018/08/what-manufacturers-need-to-know-about-iiot/"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;">benefits</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> of integrating the IIoT into manufacturing
processes. Information gleaned from the IIoT provides access to real-time data
and insights on equipment’s performance and use. Operators can also closely
track the lifespan of their machinery in order to proactively plan for
maintenance and upgrades. IIoT integration also aids in the automation process.
Digitally connecting the machinery creates a mesh that seamlessly translates
into full automation. Finally, clients can more readily track the progress of
their order with insights provided by the IIoT.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Integrating the IIoT with existing equipment can be
challenging, but it isn’t impossible. Most legacy equipment can be retrofitted
with sensors and other online monitoring devices.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 10.2pt; margin-left: 0cm; margin-right: 0cm; margin-top: 20.35pt; margin: 20.35pt 0cm 10.2pt; mso-outline-level: 1;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Smart Factories<o:p></o:p></span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In the past, many manufacturing facilities relied
on Manufacturing Operations Management (MOM) software to integrate the many
independent facets of the production process. Unfortunately, this technology is
not able to manage production processes in real-time.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-size: 18pt;"><a href="https://www.manufacturingglobal.com/technology/digitisation-manufacturing-industry"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;">Smart Factory</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> software integrates every part of the
production process, including production, resources, supply chain, maintenance
and human resources, in order to create a single, efficient output.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This technology enables factory managers to examine
data once unavailable, informing decisions about production and other business
processes. With Smart software, operators can be more responsive to several
factors, including resource availability and cost, consumer demand, market fluctuations,
and more.<i> </i> <o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 10.2pt; margin-left: 0cm; margin-right: 0cm; margin-top: 20.35pt; margin: 20.35pt 0cm 10.2pt; mso-outline-level: 1;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifZe0rHLSJezoz2QLYUNdKWq8MJfukjaWmraES2OrLYeTDya658xLp8AqQGcSRf1vek693oFDpHyA451Lp8t_Bi-dyoyhWyy-77-YTiDYg55WgHl81eAwr7Elt5_aKdKkWWIFJ6ebBsv8P/s1600/Wireless+HART+mesh+network.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Wireless HART network" border="0" data-original-height="651" data-original-width="858" height="390" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifZe0rHLSJezoz2QLYUNdKWq8MJfukjaWmraES2OrLYeTDya658xLp8AqQGcSRf1vek693oFDpHyA451Lp8t_Bi-dyoyhWyy-77-YTiDYg55WgHl81eAwr7Elt5_aKdKkWWIFJ6ebBsv8P/w557-h390/Wireless+HART+mesh+network.PNG" title="Wireless HART network" width="557" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An Example of Wireless HART mesh network</td></tr>
</tbody></table>
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></b>
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Digital Supply Chains<o:p></o:p></span></b></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Digital supply chains aren’t simple A to B, B to C,
C to D processes. In these systems, relationships between different parts of
the overall production process are affected by changes or events elsewhere in
the system <i>and</i> able to adapt to those changes.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">To create a truly digital supply chain, the
facility must consider all factors that could potentially impact each part of
the supply chain, all the while remedying any issues that may impede the supply
chain from operating as designed. Insights from a digital supply chain give
manufacturers a real-time overview of every link in the supply chain. As a
result, they can quickly respond to problems and simulate scenarios to
proactively plan for the future.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">To do this well, factories must integrate every
step of the product life cycle. This includes everything from sourcing and
shipping raw materials, to ordering packaging, advertising the product, and
scheduling employees on the factory floor. The digital supply chain system
acknowledges that creating a product isn’t black and white. It is a highly
sophisticated process that involves many interconnected variables.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> </span><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/introduction-to-industrial-automation.html">Introduction to Industrial Automation</a></span><span style="color: #1a1a1a;"><o:p></o:p></span></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Industry 4.0 is here to stay. Upgrades can cause
growing pains, but in the end, change is almost always a good thing. Be a part
of the next industrial revolution. Integrate your equipment and transform your
business. <o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">About the Author:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Page Long is the Marketing Operations Director
at </span><span style="font-size: 18pt;"><a href="http://pdfsupply.com/"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;">PDF Electric & Supply</span></a></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">, which is based out of Cary, NC. PDF Electric
& Supply is an automation supplier specializing in Legacy GE PLCs.<o:p></o:p></span></div>
<div class="MsoNormal">
<span style="color: red;"><span style="font-size: 24px;">Don't miss out on our updates on Industrial automation and Control, join our newsletter list <a href="http://eepurl.com/dOUtI9">here. </a></span></span></div>
<br /></div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-87891082261738010652018-12-05T05:26:00.002-08:002021-03-11T15:17:24.717-08:00Key Considerations when Specifying Displacer Level Transmitters<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Displacer level transmitter is used in </span><span style="font-size: 18pt;">Process</span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"> measurements
of liquids across many process industries. In this article we discuss the
Principle of operation and industrial level applications that displacer
transmitter technology offers.</span><br />
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Principle of Operation</span></b></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifLn5b3Ah6qlVNLtMvsqPsQH87ygme2WY1kLLRkFgkUh7R-5ZKm2EDmEwaSunkVECnTStzjkU5d-YYX8m3B_bQ86MWA9XSkMr7kZx3iHpqr877A98kdhl01UM4xdKNFygKaeQXT3ZwmQDW/s1600/Displacer+Level+Transmitter.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Displacer Level Transmitter" border="0" data-original-height="552" data-original-width="197" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifLn5b3Ah6qlVNLtMvsqPsQH87ygme2WY1kLLRkFgkUh7R-5ZKm2EDmEwaSunkVECnTStzjkU5d-YYX8m3B_bQ86MWA9XSkMr7kZx3iHpqr877A98kdhl01UM4xdKNFygKaeQXT3ZwmQDW/s640/Displacer+Level+Transmitter.png" title="Displacer Level Transmitter" width="228" /></a></div>
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<br /></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Operation is based on buoyancy force. The buoyancy
force works on the displacer which will vertically move in (increasing liquid
level) and out (decreasing liquid level) the linear differential transformer
(LVDT). Due to this movement, voltages are induced in the secondary winding of
the LVDT. These signals are then processed in the electronic circuitry and used
to control the output signal.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Industrial Applications</span></b></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Displacer transmitters are ideal solution for
liquids or slurries, clean or dirty and light hydrocarbons to heavy acids with
a specific gravity (SG) of 0.23 to 2.20.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Displacer transmitter technology works well in a
variety of vessels including process & storage, bridles, bypass chambers,
interfaces, sumps and pits up to unit pressure and temperature ratings. They
can also handle most liquid conditions including varying dielectric, vapors,
turbulence, foam, buildup, bubbling or boiling and high fill/empty rates.<o:p></o:p></span></div>
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<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">Some of the specific industrial applications include:</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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<b><span style="color: black; font-family: "georgia" , "serif"; font-size: 18pt;">Boiler control – </span></b><span style="color: black; font-family: "georgia" , "serif"; font-size: 18pt;">The displacer unit provides a stable output signal
for valve control on turbulent surface applications, such as feed water heaters,
flash tanks, and reactors. </span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Interface control on storage tanks
– </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The displacers are tolerant of
emulsions. They can track towards middle of emulsion, and are tolerant of
unstable interface. They also ignore vapor/liquid interface point above
displacer.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Mixing Tank – </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The displacer transmitter can also be used in harsh
production environments like those in a mixing tank. It provides a stable
output, easier to configure and is resistant to heavy surging caused by the
mixer.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Water elevation – </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The displacer can be used to maintain a water
elevation at a given height by sending out a proportional 3-15 PSIG signal
(over a 14 ″ control band) to a control valve to maintain water level at
midpoint by regulating the water flow rate out of the separator. The control
valve is fully open at 15 PSIG input and fully closed at 3 PSIG input. <o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/ultrasonic-level-measurement.html">Ultrasonic Level Measurement Technology</a></span></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In Summary the advantages and
limitations of Displacer transmitter include:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Advantages</span></b></div>
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</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Stable signal in turbulent applications</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">High Pressure/Temperature capabilities</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">No flexure of pressure boundary part</span></span></li>
</ul>
<br />
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Limitations</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
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</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Shifting SG can affect this technology</span></span></li>
</ul>
<br />
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<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Some of the manufactures of Displacer level
transmitters include:</span></div>
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</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;"><span style="color: #007acc; font-family: "georgia" , serif; text-decoration-line: none;"><a href="http://magnetrol.com/" style="font-family: "Times New Roman";">Magnetrol</a></span></span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;"><span style="background-color: white; color: #007acc; font-family: "georgia" , serif;"><a href="http://emerson.com/" style="background-color: white; font-family: "Times New Roman";">Emerson-Fisher</a></span></span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;"><span style="background-color: white; color: #007acc; font-family: "georgia" , serif;"><a href="https://www.se.com/ww/en/" style="background-color: white; font-family: "Times New Roman";">Schneider Electric-Foxboro</a></span></span></span></li>
</ul>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Sources: Magnetrol</span></div>
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<span style="color: red; font-family: "georgia" , serif;"><span style="font-size: 24px;">Don't miss out on our Instrumentation updates, join our newsletter list <a href="http://eepurl.com/dOUtI9">here</a></span></span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-32190890345040845062018-12-04T06:11:00.000-08:002019-03-20T03:08:28.112-07:00How to Troubleshoot Servo Drives<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Servo drives are used to control devices including
robotics, model airplanes, aerospace technology and multiple industrial
applications. The drive is a component in a closed-loop system, and uses an
amplified control signal to send power to the device motor. They are
primarily used to control the output torque, speed and position of a motor
shaft.</span><br />
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Most servo drives in use in 2017 are digital, and
like all other electronic equipment, they can malfunction at the most inconvenient
times. A breakdown can disrupt an entire production schedule and cause
significant loss of revenue, or it can cause problems like overheating and
result in damage to the systems it supports.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Common Problems with Servo Drives</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Most of the typical servo drive issues you’re
likely to experience have common causes, which helps to make troubleshooting
less frustrating. Here are some malfunctions to watch for:</span><br />
<br />
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "symbol"; font-size: 10pt; text-indent: -18pt;"><span style="mso-list: Ignore;"><span style="font-family: "times new roman"; font-size: 7pt; font-stretch: normal; font-variant-east-asian: normal; font-variant-numeric: normal; line-height: normal;"> </span></span></span><b style="text-indent: -18pt;"><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">System
instability: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt; text-indent: -18pt;">If any of your settings are
incorrect, the servo drive may not operate correctly. There are numerous
parameters to check related to motor tuning as well as speed and current
loops. If you’re getting noise transmitted into the control wiring,
you’re likely to see erratic movement of the motor shaft.</span></li>
<li><b style="text-indent: -18pt;"><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Inability to reach
the right levels of acceleration or deceleration: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt; text-indent: -18pt;">This can occur for several reasons, such as when
the servo amplifier’s capabilities are insufficient for the system
inertia, or the friction is excessive.</span></li>
<li><b style="text-indent: -18pt;"><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Not responding to a
velocity command: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt; text-indent: -18pt;">The reason for a
lack of response is usually easily identifiable, and common causes are problems
with the control interface, system or motor malfunctions, incorrect voltage
supply (or none at all), or the motor thermal protection has tripped.</span></li>
<li><b style="text-indent: -18pt;"><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Noise on signal
wires: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt; text-indent: -18pt;">This is typically caused by incorrect
wiring or grounding, but can also be caused by electromagnetic interference
from nearby equipment.</span></li>
<li><b style="text-indent: -18pt;"><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">System runs
uncontrollably: </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt; text-indent: -18pt;">This issue develops when there are
problems with the velocity command signal, when the motor speed/position
feedback signal is erratic or missing, or when there is an internal malfunction
in the servo drive.</span></li>
</ul>
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOoI_X81KMYPYoVoBYiwDiHrnHJmSsliY4VoofXYqckstalDvcKq_0BfgGGeNrv_PS3uxaiNmub6nwST1IC7lryMxheRh0Xjc-zScc2e1JJg_k7cqWAqGVJgyajU8N4XKS8KLAZemXJjMe/s1600/Motor+Drive.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Motor Drive" border="0" data-original-height="559" data-original-width="660" height="540" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOoI_X81KMYPYoVoBYiwDiHrnHJmSsliY4VoofXYqckstalDvcKq_0BfgGGeNrv_PS3uxaiNmub6nwST1IC7lryMxheRh0Xjc-zScc2e1JJg_k7cqWAqGVJgyajU8N4XKS8KLAZemXJjMe/s640/Motor+Drive.PNG" title="Motor Drive " width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">AN EXAMPLE OF A MOTOR DRIVE SYSTEM</td></tr>
</tbody></table>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><br /></span></b></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Troubleshooting: What to Look
For </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Correct identification of the problem is critical
for effective troubleshooting of your servo drives. Here are some tips on how
to go about determining causes of common issues, and measures you can take
to try and resolve them.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">#1: Review the display on the drive. If it
doesn’t come up, check the power supply. If you see an alarm on the display,
use the instruction manual to investigate the possible causes.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">#2: Verify that the feedback device (resolver,
encoder, etc.) is functioning properly. Use an oscilloscope to check
waveforms and pay special attention to noise, missing channels, incorrect wave
shapes, or low levels. Look for breaks or bad splices in the feedback cable.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">#3: Check the line voltage to ensure that the
incoming power to the drive is balanced and the correct voltage. For
common DC bus systems, check the intermediate dc voltage as well. Use an oscilloscope
to check for noise, voltage fluctuations, etc.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">#4: Don’t forget the possibility of a mechanical
problem. Problems such as friction or vibration in the machine can cause issues
in the servo drive and motor.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Run all the tests recommended in the manual and
record the results for future reference. If these initial measures don’t work,
it’s time to consider getting a professional service company to help.</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: red; font-family: "georgia" , serif;"><span style="font-size: 24px;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/stepper-and-servomotors_16.html">Stepper and Servo motors </a></span></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">About the Author</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">With over 25 years of experience in the industrial
automation repair industry, Jeff Conner is the Dallas Service Manager for
Control Concepts and serves on the Advisory Committee for the Electronics
Technologies Department at Texas State Technical College. Control Concepts
offers around the clock service and support anywhere you need it. To learn
more, visit </span><span style="font-size: 18.0pt;"><span style="color: #007acc; font-family: "georgia" , "serif"; text-decoration: none;"><a href="http://www.controlconceptstexas.com/">http://www.controlconceptstexas.com</a></span></span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-25987415619251788292018-11-27T01:38:00.002-08:002020-03-07T05:35:00.191-08:00Key Components used in Industrial Control<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Understanding the different components involved in
a given process control is important especially for its proper application, and
troubleshooting. In this article we look at the most common discrete components
used in industrial control applications.</span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLO2SQ8_Oz1F3wrjhvB85v_GHYqHdQOPWHOdbD9HY4aVwkMvAG5oUiwgOVIymQ-LINpyNzxYXLINjwFGDa4SaCHeNnkfz-tNqgDk-RRBcctqslo_EWq_CxwdOIkesHWBbGhUUnXYdyD003/s1600/Key+Components+in+Industrial+Control.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Electrical Symbols of Components commonly used in Industrial Control" border="0" data-original-height="752" data-original-width="691" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLO2SQ8_Oz1F3wrjhvB85v_GHYqHdQOPWHOdbD9HY4aVwkMvAG5oUiwgOVIymQ-LINpyNzxYXLINjwFGDa4SaCHeNnkfz-tNqgDk-RRBcctqslo_EWq_CxwdOIkesHWBbGhUUnXYdyD003/s640/Key+Components+in+Industrial+Control.PNG" title="Electrical Symbols of Components commonly used in Industrial Control" width="588" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">COMMON ELECTRICAL SYMBOLS</td></tr>
</tbody></table>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><br /></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Contactors</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Power consuming devices like Motors are usually
controlled by contactors having heavy duty contacts that can switch the power
circuits safely. The contactor will be actuated by an electromagnetic solenoid
(coil) which pulls the contacts closed when energized. They have an
arc-suppressing cover to quench the arc formed when the contacts open under
load. Note that AC contactors should never be used to break the current of a
loaded DC power circuit. It is more difficulty to quench the arc from a DC
power load because there is no AC ''zero crossing'' to interrupt the
current flow. DC contactors are designed to specifically handle DC current. You
will find they have embedded magnets, or special blow-out coils that are used
to stretch the arc long enough to break the DC current flow.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Devices using AC solenoids will have one or more
single turn coil (s), called a shading ring, embedded in the face of their
magnetic armature assembly. When the solenoid is energized, the magnetic field
has continuous reversals matching the alternating current that is been applied.
This will produce a noticeable hum or chatter because the magnetic structure is
not energized continuously. As the magnetic field reverses, it induces a current
in the shading ring, which in turn produces a secondary reversing magnetic
field. The secondary field is out of phase with that of the applied power, and
holds the armature faces sealed continuously between power reversals, and
minimizes the noise. Over time, shading rings tend to crack from the pounding
of the armature faces. When this happens, the solenoid will become very noisy,
coil current will increase, and premature failure will result. In an emergency,
one can remove the damaged ring and replace it temporarily with a shorted turn
of copper wire. <o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Solenoids</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Solenoids are used to actuate brake/ clutch
mechanisms, hydraulic valves, air valves, steam valves or other devices that
require a push-pull button. Some solenoids can be quite large, requiring
contactors rated for their high current draw. Smaller pilot valves may draw no
more current than a simple relay. Some heavy duty units operate on DC current.
The DC solenoids are often specified for operation in dirty or corrosive areas
because current is controlled by circuit resistance, and will not rise if the
air-gap is fouled. AC solenoids depend upon the impedance of the circuit. If
the air-gap is not sealed properly, inductance reactance is reduced and coil
will draw excess current and over-heat. Shading rings must also be switched for
possible failures.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: </span></span><br />
<br />
<ul style="text-align: left;">
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"><a href="https://amzn.to/35wQRpD">The Basics of Industrial Instrumentation and Control Systems</a></span></span></li>
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/electrical-power-distribution-automation.html">Electrical Power distribution Automation </a></span></span></li>
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><a href="https://amzn.to/38wDTIX">The Transition from Relay Control Systems, to PLCs explained</a></span></li>
</ul>
</div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Relays</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Relays have a similar construction to contactors,
but since they switch low-current logic signals, they do not have a requirement
for the heavy-duty contacts and arc-suppression hardware. Most relays contacts
have AC continuous ratings of no more than 10 A. They can close on an inrush
current of 150%, but only break 15% at 120 volts AC (vac). A NEMA A600 rating
limits the in-rush to 7200 volt-amperes (va), and a circuit breaking rating of
720 volt-amperes. As higher voltages are used, the current capacity goes down
proportionately. This difference in <b>make</b> and<b> break </b>ratings
closely matches the typical ratio of inrush and holding currents of AC control
coils. AC coils have relatively low resistance, allowing high in-rush currents.
As the coil is energized, the AC current builds up inductive reactance. Total
impedance (ohms), the vector sum of resistance and reactance, limits the
continuous holding current. The ratio of in-rush to holding current is often
5:1 or more. Maximum impedance is attained when the air gap in the magnetic
armature assembly has sealed closed. A failure to close this gap will reduce
the inductive reactance, allowing more current, which will overheat the coil,
causing premature coil failure. A <b>shading ring </b>fracture will
also lead to overheating and coil failure.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">The same 10A contacts are only rated at 0.4 A DC,
at 125V, and 0.2 A DC at 250 V (50 va) because the small air-gaps are not
adequate to break a sustained DC arc. Voltages for DC logic controls seldom
exceed 24 volts with typical current in the milliamp ranges.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Relays may have multiple coils for latching and
unlatching of the contacts. Contacts may be normally open (NO), and or normally
closed (NC). The number of contacts usually varies from 1-8. Some relays use
contact cartridges which can be converted for either NO or NC operation. Most
standard relays will have totally isolated contacts. Some miniature relays have
type ”C” contacts where a NO and NC contact share a common terminal. This
construction requires careful planning to match the schematic wiring diagram to
actual relay construction.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Occasionally the required load on relay contacts
may be slightly higher than their normal rating. One can increase the current
capacity by connecting contacts in parallel, and improve the arc suppression by
connecting multiple contacts in series. When multiple contacts are used this
way, they should be on the same relay, because relay coils operating in
parallel may have a slight difference in their time-constant. If one
relay closes late, its contacts will take all the inrush punishment. If a
relay opens early, it will suffer more damage from breaking most of the full
load current.</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Timers</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Timers are a type of relay that have pneumatic or
electronic, time contacts to meet various sequencing requirements. They may be,
”stand-alone” relays or attachments to standard relays. On-delay timers actuate
the contacts at a preset time after the coil is energized, and reset instantly
with power off. Off-delay times actuate the contacts instantly when
energized, and reset a preset time after de-energizing. NO and/or NC contacts
may be time-closed or time-opened. Many timers also include instantaneous
contacts, actuated with no time delay. Instantaneous contacts may also be added
as a modification kit in some cases to stand-alone timers.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">The coils of contactors and relay may be rated at a
different voltage than the circuits being switched. This provides isolation
between the low voltage logic circuits and higher voltages power circuits.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Push Buttons</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Push-buttons may have a single contact block, or an
assembly of multiple contacts depending upon the complexity of the requirement.
Most push-buttons have a momentary change of state when depressed, then return
to normal when released. Some may have a push-pull actuator that latches in
each position. They are often used as a control-power master-switch with a
Pull-on/Push-off action.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Selector Switches</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Many selector switches have the same construction
as push buttons, except that the contacts are actuated by rotating a handle or
key-switch. The rotating cam may be arranged with incremental indices so that
multiple positions and contact patterns can be used to select exclusive
operations. Contacts of push-buttons, selector switches, and limit switches
usually have the same rating as the logic relays 10A continuous at 120 (vac).<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Limit Switches</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 18pt;">Mechanical limit switches have many configurations.
Most will have both NO and NC contacts available. The contacts are switched
when the layer arm is rotated a few degrees by a moving cam or slider. The
conventional drawing will show the contact conditions when the machine is un-</span><span style="font-size: 18pt;">powered and at rest. It is assumed that the cam will normally strike the arm
on the switch to change the state of the contact(s). <o:p></o:p></span></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">Please don't miss out on Instrumentation & Automation updates, join our Newsletter list <a href="http://eepurl.com/dOUtI9">here. </a></span></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Non-Contact Limit Switches</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">There are a number of electronic limit switches
that are used where it is not practicable to have an actuator arm physically
contact a product or machine part. The switches include: Photocells, and
Proximity switches (inductive, magnetic, and capacitive). In each case, a
control signal is activated whenever an object enters its operating field.
These devices require additional wiring to energize their power.</span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-54596958964385012922018-11-24T09:40:00.001-08:002023-07-21T11:03:55.061-07:00The Basics of a Process Control System<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: georgia, serif; font-size: 18pt;">Instrumentation is a science that deals with
measurements and control of processes. Instrumentation is applied in almost any
field from Medical, Manufacturing of pharmaceutical drugs, to simple processes
like temperature control in homes using Thermostats. Note that if we can’t
measure it then we have no need of controlling it.</span><br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-size: 18pt;"><span style="font-family: "georgia" , serif;">Measurements </span></span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">can be in form of Fluid pressure, Fluid
volume, Fluid Flow rate, Temperature, Electrical voltage or current, Chemical
concentration etc. Once we have the quantity of the measured value, we
then transmit a signal representing this quantity to an indicating or
computing device where either human or automated action then takes place. If
the controlling action is automated, the computer sends a signal to a final
controlling device which then influences the quantity being measured. The final
control device can be in the form of:</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Electric motor</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Control valve-for throttling the flow rate of a fluid</span></span></li>
<li><div>
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"><span style="background-color: white;">Electric heater</span></span></div>
</li>
</ul>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The measurement device and the final control device
connect to some physical system called the process.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWrqCh1sS-jkFJfFCrti8c0UMVbAz3QOUnOR6Q8ehDrp69x_Uj8MJxi3mBLAXJk-fMJddwVINfNTZUHqiC9xnvWnQmyUyr_eITL4C5LqN5P1LA5sskCrBhTUCLElID7bcK9a5QPH5ayDOz/s1600/Process+Control+basics.PNG" style="margin-left: auto; margin-right: auto;"><img alt="Process Control Basics" border="0" data-original-height="455" data-original-width="674" height="432" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWrqCh1sS-jkFJfFCrti8c0UMVbAz3QOUnOR6Q8ehDrp69x_Uj8MJxi3mBLAXJk-fMJddwVINfNTZUHqiC9xnvWnQmyUyr_eITL4C5LqN5P1LA5sskCrBhTUCLElID7bcK9a5QPH5ayDOz/s640/Process+Control+basics.PNG" title="Process Control Basics" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Block Diagram of a Process Control System</td></tr>
</tbody></table>
</span><br />
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: georgia, serif;"><span style="font-size: 24px;">The measuring device senses</span></span></li>
<li><span style="color: #1a1a1a; font-family: georgia, serif;"><span style="font-size: 24px;">The Controller decides</span></span></li>
<li><span style="color: #1a1a1a; font-family: georgia, serif;"><span style="font-size: 24px;">The final control device influences the process</span></span></li>
<li><span style="color: #1a1a1a; font-family: georgia, serif;"><span style="font-size: 24px;">The process reacts to the influence of the final control</span></span></li>
</ul>
<br />
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read:</span></span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"> <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/basics-of-control-loop.html">Basics of a Control Loop</a></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">So in a nutshell this is what we call a Process
control system.</span></div><div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;"><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" target="_blank">here.</a></span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-44951921590867814912018-11-23T11:48:00.001-08:002023-07-21T11:03:38.533-07:00Key differences between PLC and DCS systems<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">We have so many people with questions as to what
are the similarities and differences if any between PLC and DCS systems. We
will try to describe the working of these two systems and in the process help
you understand the functions of each system.</span><br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Initially DCS was focused only on process control
with analog signals that were used as main control system in process industries
like Refining, Chemicals, and Petrochemicals etc. while PLC was focused on
discrete automation with discrete on-off signals, that were used for example in
Factory assembly lines and bottle lines but today DCS supports discrete I/O and
some logic functions and PLCs support analog I/O with some control functions.
In some instances Both PLC and DCS are used in the same plant i.e. PLCs are
used on separate units on a plant floor which are then integrated with main
plant-wide DCS for Control and Monitoring.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Let us now look at each system separately to help
us understand more how they work.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">PLC</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Programmable Logic Controllers (PLCs) comes in
different sizes which means various I/O and program capacities. Smallest sized
PLCs are typically referred to as nano PLCs, micro PLCs and mini PLCs. They
have fixed I/O and mainly used in stand-alone applications.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Large PLC support redundancy for CPU, power supply
and possibly the control network, but typically not for I/O cards though there
are large PLCs that support I/O redundancy by using duplicate I/O-subsystems
with separate backplanes where the field instruments are wired in parallel to
both I/O subsystems. The control network is typically a standard industrial
Ethernet application protocol over Ethernet media and IP. The Field cabling
comes directly onto the I/O card.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">PLC usually support very fast scan times as
required in discrete manufacturing but PID loops add to the CPU load, much more
than discrete load thus making the scan time slower.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Loops are not handled individually in a PLC.
Addition or change to loop requires a download of the entire program which
affects other loops in the CPU as well.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">PLCs are built around a given native protocol, this
maybe: PROFIBUS, Modbus, DeviceNet etc. The PLC comes with its own native
interface cards for native protocol supported by the PLC maker but relies on
third-party interface cards for other Fieldbus protocols. The engineering
software therefore automatically configures the communication interface card
for the native protocol.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: </span></span><br />
<br />
<ul style="text-align: left;">
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/11/the-working-of-distributed-control.html">How Distributed Control Systems work</a></span></span></li>
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><a href="https://amzn.to/38wDTIX">The Journey from Relay Control Systems, to PLC Systems, how the Transition was done</a></span></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Key Points to note on PLC</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">PLCs were designed to eliminate assembly-line
relays during model changeovers. PLC is easier to change than relay panels;
this has reduced the installation and operational cost of the control system
compared with electromechanical relay systems.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 0cm;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoZ8dPnVnTnZwR65Atmxk_wlTDmVmZxH58A3G4m4hdhWnPv-C8xbllSGw-P0xZXdzxHRMT3GBzKLFvYNOJwBuUEA_n18kuNIXJNoUChIz6pC3rdvQLaPvUATsftTEZfVbupXPYhwNLMNb9/s1600/PLC+Block+Diagram.PNG" style="margin-left: auto; margin-right: auto;"><img alt="A basic block diagram of PLC system" border="0" data-original-height="314" data-original-width="665" height="302" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgoZ8dPnVnTnZwR65Atmxk_wlTDmVmZxH58A3G4m4hdhWnPv-C8xbllSGw-P0xZXdzxHRMT3GBzKLFvYNOJwBuUEA_n18kuNIXJNoUChIz6pC3rdvQLaPvUATsftTEZfVbupXPYhwNLMNb9/s640/PLC+Block+Diagram.PNG" title="A basic block diagram of PLC system" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">BLOCK DIAGRAM OF A PLC SYSTEM</td></tr>
</tbody></table>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 0cm;">
<br /></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">PLC offers the following advantages:</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Ease of programming and reprogramming in the plant</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Programming language is based on relay wiring symbols familiar to most plant electrical and instrumentation personnel</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">High Reliability and minimal maintenance</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Small physical size</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Ability to communicate with computer systems in the plant</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Moderate to low initial investment cost</span></span></li>
<li><div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="font-size: 18pt;">Available in modular designs</span></div>
</li>
</ul>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">DCS</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Distributed Control System (DCS) supports
redundancy for controllers, power supply and control network as well as
redundant I/O cards including fieldbus interface cards in the same backplane.
The control network supports peer-to-peer communication between controllers.
The control network is typically a proprietary application protocol over
Ethernet media and IP. The field cabling in DCS lands on a Field Terminal
Assembly (FTA) where a special system cable with a connector takes the signals
to the I/O card.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Loops in a DCS are executed individually. The scan
time in a DCS is set individually for each loop. Most loops run at 1000ms although
250ms is common for pressure and flow loops in refining and petrochemicals and
even 100ms is also possible. The scan time is constant, and does not change
with task loading. This is important for PID control and time-based functions
such as integration/totalizing and lead-lag dynamic compensation.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Loops in a DCS are managed individually. A change
and download to one loop doesn’t affect the other loops.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">A DCS has an integrated development environment
where I/O control strategy and operator graphics are created together and
stored in a single database. This means once a tag is created in the DCS it
automatically becomes available everywhere in the system with the same human
readable tag name for use in basic control, advanced control, graphics, faceplates,
trending, alarming, and turning etc. Without mapping data through
registers or other tag names makes it easy to do changes or additions.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Sensor & Actuator level “H1” Fieldbus
network supported by DCS is basically FOUNDATION fieldbus for instrumentation
and PROFIBUS-DP for motor controls.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The DCS comes with its own native Fieldbus
interface cards. The engineering software therefore automatically configures
the communication interface cards for the variables used in the control
strategy and graphics.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Key Points to Note on DCS</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">DCS is miniaturized version of the multitasking,
multivariable, multi-loop controller used for process control. It is
functionally and geographically processing distributed system. Equipment making
up a DCS is separated by function and is installed in two different work areas
of a processing installation. Equipment for operator to monitor process
condition and to manipulate the set point of the process operation is located
in a central control room; from where the operator can view information
transmitted from the process area and displayed on a video display unit and can
change control condition from a keyboard. DCS systems are suitable for the
following processes:<o:p></o:p></span><br />
<br />
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Where a single centralized system is not adequate i.e. Power, Steel, Pulp & Paper plants, Fertilizer etc.</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Processes of different level of hierarchy</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Processes which can be divided into different and functionally independent sections, based on functional scope and geographical distribution</span></span></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">DCS offers the following Advantages:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Compact to contain ON/OFF controllers</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Reduced complexity and easy expandability</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">High Speed of the control processing</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Control Algorithms changes do not call for hardware changes</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Continuous trend data is available</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">User friendly but higher data security</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Plant data are transparent on the network</span></span></li>
<li><div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Sequential, batching and feedback control are possible</span></div>
</li>
</ul>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: georgia, serif; font-size: 24px;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif; font-size: 24px;" target="_blank">here.</a></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Differences between PLC and DCS based
Systems</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<table border="1" cellpadding="0" cellspacing="3" class="MsoNormalTable" style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .25pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .75pt; mso-border-right-alt: .25pt; mso-border-style-alt: solid; mso-border-top-alt: .75pt; mso-cellspacing: 1.5pt; mso-yfti-tbllook: 1184;">
<tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;"> <b>PLC</b><o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;"> <b> DCS</b><o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 1;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Redundancy not possible or
limited<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Redundancy possible at every
level<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 2;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">It is used for low loop count<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">It is used for any loop count<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 3;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Performance drops with
increasing loop count<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">No change in performance with
increasing loop count<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 4;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Purely free running mode<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Highly efficient multitasking
mode<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 5;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Analog processing simulated
through digital computer<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Analog processing done in real
frequency domain function<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 6;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">No interplant connectivity<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Fully Functional Inter-plant
connectivity<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 7;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Individual database for every
node<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">System-wide global database<o:p></o:p></span></div>
</td>
</tr>
<tr style="mso-yfti-irow: 8; mso-yfti-lastrow: yes;">
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Typical performance: 100 PID
loops/sec<o:p></o:p></span></div>
</td>
<td style="border: 1pt solid rgb(209, 209, 209); mso-border-bottom-alt: .75pt; mso-border-color-alt: #D1D1D1; mso-border-left-alt: .25pt; mso-border-right-alt: .75pt; mso-border-style-alt: solid; mso-border-top-alt: .25pt; padding: 5.25pt;"><div class="MsoNormal" style="line-height: normal; margin-bottom: 21pt;">
<span style="font-family: "times new roman" , "serif"; font-size: 18pt;">Typical Performance: More than
1000 PID loops/sec.<o:p></o:p></span></div>
</td>
</tr>
</tbody></table>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br />
Do you have comments or questions on PLC or DCS? Feel free to post them in the
comments section below. </span></b></div>
<br />
<br /></div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-73940742166225128102018-11-19T06:49:00.003-08:002023-01-10T18:29:45.715-08:00Components in a Controlled Automation System<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Essential components in any controlled automation
system include:</span><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 12.6pt; mso-outline-level: 1;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The actuator (which does the work)</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The controller (which ”tells” the actuator to do the work)</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">The sensor (which provides the feedback to the controller so that it knows the actuator is doing work)</span></span></li>
</ul>
<br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">An example of a simple controlled automation system
is shown below:<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><!--[if gte vml 1]><v:shapetype
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<v:stroke joinstyle="miter"/>
<v:formulas>
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<v:f eqn="sum @0 1 0"/>
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<v:f eqn="sum @0 0 1"/>
<v:f eqn="prod @6 1 2"/>
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<v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"/>
<o:lock v:ext="edit" aspectratio="t"/>
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alt="Automation System" style='width:255pt;height:2in;visibility:visible;
mso-wrap-style:square'>
<v:imagedata src="file:///C:\Users\zamulinj\AppData\Local\Temp\msohtmlclip1\01\clip_image001.jpg"
o:title="Automation System"/>
</v:shape><![endif]--><!--[if !vml]--><!--[endif]--></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHyVhq7c6Aibi1uyBvxu_5BUUjCSrC3_OeedSj52P9nAykZ9jHmtS6MbzGgRyNym5jbW8PLX6jkiRJdecd3flPwPOhXDOUqNTfUsmOIwJeX2OXXsUkKESyjeT-nPo-dKwvlZgFTlGavInO/s1600/Components+-controlled+AS.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="Controlled Automation System" border="0" data-original-height="192" data-original-width="340" height="336" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHyVhq7c6Aibi1uyBvxu_5BUUjCSrC3_OeedSj52P9nAykZ9jHmtS6MbzGgRyNym5jbW8PLX6jkiRJdecd3flPwPOhXDOUqNTfUsmOIwJeX2OXXsUkKESyjeT-nPo-dKwvlZgFTlGavInO/w597-h336/Components+-controlled+AS.jpg" title="Controlled Automation System" width="597" /></a></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 18pt;">A controlled system may either be analog controlled
system or digital controlled system. </span><span style="font-size: 24px;">Let's</span><span style="font-size: 18pt;"> consider the following analog controlled
system:<o:p></o:p></span></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><!--[if gte vml 1]><v:shape id="Picture_x0020_2"
o:spid="_x0000_i1026" type="#_x0000_t75" alt="Automation System" style='width:252pt;
height:229.8pt;visibility:visible;mso-wrap-style:square'>
<v:imagedata src="file:///C:\Users\zamulinj\AppData\Local\Temp\msohtmlclip1\01\clip_image003.jpg"
o:title="Automation System"/>
</v:shape><![endif]--><!--[if !vml]--><!--[endif]--></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9_EtuBAu6aIEKcU2pYez-Xm8dnyMwxPbw1CffGVO9t2liS2EYWiofAs34zTituPKw52px97nAipG-RhaOks7cC_-Kg9tHJJnYRbyW_9Cak4PmjABiivVFCgSvfdd7C19XLJ8bnbfmJYmv/s1600/Components+-controlled+AS+1.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="Controlled Automation System" border="0" data-original-height="306" data-original-width="336" height="538" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9_EtuBAu6aIEKcU2pYez-Xm8dnyMwxPbw1CffGVO9t2liS2EYWiofAs34zTituPKw52px97nAipG-RhaOks7cC_-Kg9tHJJnYRbyW_9Cak4PmjABiivVFCgSvfdd7C19XLJ8bnbfmJYmv/w560-h538/Components+-controlled+AS+1.jpg" title="Controlled Automation System" width="560" /></a></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The actuator is a hydraulic servovalve and a fluid
motor. The servovalve opens proportionally with the voltage it receives from
the controller and the fluid motor rotates faster if it receives more hydraulic
fluid. There is a speed sensor connected to the motor shaft, which outputs a
voltage signal proportional to the shaft speed. The controller is programmed to
move the output shaft at a given speed until a load is at given position. When
the program requires the move to take place, the controller outputs an
approximately correct voltage to the servovalve, then monitors the sensor’s
feedback signal. If the speed sensor’s output is different from expected i.e.
indicating wrong motor speed, the controller increases or decreases the voltage
supplied to the servovalve until the correct feedback is achieved. The motor
speed is controlled until the move finishes. As with any other control system,
the program may include a function to notify a human operator if speed control
isn’t working. <o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: "georgia" , serif;"><span style="font-size: 18pt;">You can also read: </span></span><br />
<br />
<ul style="text-align: left;">
<li><span style="color: red; font-family: "georgia" , serif;"><span style="font-size: 18pt;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/introduction-to-industrial-automation.html">Introduction to Industrial Automation</a></span></span></li><li><a href="https://amzn.to/38wDTIX" style="font-family: georgia, serif;">The Transition from Relays to PLCs</a></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 18pt;">Having looked at analog controlled system above, </span><span style="font-size: 24px;">let's</span><span style="font-size: 18pt;"> now consider an example of a digital controlled system:<o:p></o:p></span></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><!--[if gte vml 1]><v:shape id="Picture_x0020_3"
o:spid="_x0000_i1025" type="#_x0000_t75" alt="Automation system" style='width:249pt;
height:229.8pt;visibility:visible;mso-wrap-style:square'>
<v:imagedata src="file:///C:\Users\zamulinj\AppData\Local\Temp\msohtmlclip1\01\clip_image005.jpg"
o:title="Automation system"/>
</v:shape><![endif]--><!--[if !vml]--><!--[endif]--></span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0MUi9qtCsLBwuC89Y5lb2-h4-Z1LhO5EwPBjrTtpBT4v25elC01X3JSNLemg5aSF5nS-xAjuituIsOHCMOaNRLIodUzNlZMmQb1vAnAsDEkxoOnfyllLzWr9gI5oWAvem8zm2uy7DDoWb/s1600/Components+-controlled+AS+2.jpg" style="margin-left: 1em; margin-right: 1em;"><img alt="Controlled Automation System" border="0" data-original-height="306" data-original-width="332" height="507" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0MUi9qtCsLBwuC89Y5lb2-h4-Z1LhO5EwPBjrTtpBT4v25elC01X3JSNLemg5aSF5nS-xAjuituIsOHCMOaNRLIodUzNlZMmQb1vAnAsDEkxoOnfyllLzWr9gI5oWAvem8zm2uy7DDoWb/w552-h507/Components+-controlled+AS+2.jpg" title="Controlled Automation System" width="552" /></a></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The above figure represents a simple digital
controlled system in which the actuator consists of a pneumatic valve and a
pneumatic cylinder that must be either fully extended or retracted. The
controller is a PLC that has been programmed to extend the cylinder during some
more complicated process and to go on to the next step in the process only
after the cylinder extends. When it is time to extend the cylinder, the PLC
supplies voltage to the valve, which should open to provide air to the
cylinder, which then extend. If all goes well, after a short time the PLC will
receive a change in voltage level from the limit switch, allowing it to execute
the next step in the process. If the voltage from the switch does not change
for any reason ( faulty valve or cylinder or switch, break in a wire,
obstruction preventing full cylinder extension etc.), the PLC will not execute
the next step. The PLC may even be programmed to turn on a “fault” light when
such a delay occurs.</span><br />
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span>
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">Don't miss out on our Industrial Instrumentation & Automation updates, join our Newsletter list <a href="http://eepurl.com/dOUtI9">here.</a></span></div>
</div>
John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-69572784246956542752018-11-18T15:10:00.000-08:002020-04-15T07:24:11.461-07:00Key Features and Applications of Remote Terminal Units (RTU)<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">Remote Terminal Units also called Remote Telemetry
Units or Remote Telecontrol Units are Microprocessor controlled devices that
interfaces in the physical world to either SCADA (Supervisory Control and Data
acquisition) system or DCS (Distributed and Control system). They
transmit data to a master system and uses messages from the master supervisory
system to control objects connected to the system.</span><br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">They are designed for use in applications in remote
locations unattended. These locations may have limited to no power, hence RTUs
are designed to consume low power than DCS and PLC & this enables operation
on solar power and batteries.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">In application where supervision is done from
distant central location, the SCADA software sits in the central office
connected over a backhaul network typically using radio communication to the
RTUs located far away and in most cases geographically spread out. The
communication may be interrupted for long periods of time therefore RTUs have
on-board data storage continuing local data collection for more than a
month if backhaul communication is lost as well as “history backfill’’
uploading this data once the connection is established again. Report by exception
communication mechanisms are often used to minimize backhaul communication
using Wide Area Networks e.g. Mobile, Microwave, Satellite.<o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiCWb4UVTBlNCnZkrYbBIEkXjdSVAYhKVmp3fa7_eW8ao_urJ5LGNbQLm5TMs4EDgOP4kcI-OF73djP-kT84wwR2g1oaRcehUIBp6Se3033kSlXtMFuwCSqpijpB7uf1xrF9W0K-P1iBk6/s1600/RTU-Multidrop+Communication+System.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="RTU in Multidrop Communication System" border="0" data-original-height="267" data-original-width="495" height="344" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiCWb4UVTBlNCnZkrYbBIEkXjdSVAYhKVmp3fa7_eW8ao_urJ5LGNbQLm5TMs4EDgOP4kcI-OF73djP-kT84wwR2g1oaRcehUIBp6Se3033kSlXtMFuwCSqpijpB7uf1xrF9W0K-P1iBk6/s640/RTU-Multidrop+Communication+System.PNG" title="RTU in Multidrop Communication System" width="640" /></a></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><br /></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Remote Terminal Units
(RTU) Configuration</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">The RTU configuration software is separate from the
HMI (Human Machine Interface) software from a third-party manufacturer i.e. two
separate databases. RTU is configured first; next the OPC server is configured.
For a native OPC server this happens automatically, but for OPC server from a
third-party, manual data mapping is required which can be time-consuming
and error prone requiring thorough testing. In most cases native OPC server is
preferred. To finalize, the HMI database has to be configured for graphics,
alarms, and trends etc.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">The 4-20 mA AI and AO cards for a RTU optionally
support native HART pass through hence separate HART multiplexer (MUX) hardware
and associated work is not required. Native HART pass through AI and AO cards
are much easier to integrate and should be specified if 4-20 mA is used. Since
RTUs are generally used in very slow monitoring applications that don’t require
fast control, some applications do not use the real-time analog 4-20 mA but
only the digital HART communication multi-drop topology. This means the field
instruments draw less than 4 mA instead of up to 20 mA hence further reducing
the overall power consumption.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read:</span></span><br />
<br />
<ul style="text-align: left;">
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;"> <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/09/electrical-power-distribution-automation.html">Electrical Power Distribution and Automation System</a></span></span></li>
<li><span style="font-family: "georgia" , serif; font-size: 18pt;"><a href="https://amzn.to/38wDTIX">The Transition from Relays to PLCs explained</a></span></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Applications of Remote Terminal Units (RTU)</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18.0pt;">Remote terminal units are commonly used in the
following applications:</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21.0pt;">
</div>
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Electrical Power Transmission Networks and Associated Equipment.</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 24px;">Remote Monitoring of Functions and the whole Instrumentation Network in Oil and Gas (offshore platforms, onshore oil wells, Pump Stations on Pipelines)</span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 24px;">Water and Wastewater collection and supply networks including the Pumping stations.</span></li>
</ul>
<div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-61324763474919162182018-11-18T07:29:00.005-08:002023-09-09T09:44:47.694-07:00How Triacs are used in Industrial Control Applications<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 12.6pt; mso-outline-level: 1;">
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;">The Triac is a three-terminal device that is
similar to the <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/11/how-silicon-controlled-rectifiers-scrs.html">SCR</a></span><span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"> except that the Triacs can conduct
current in both directions. Its primary use is to control power to AC loads
such as turning AC motors on and off or varying the power for lighting and
heating systems. The Triac is a solid state device that acts like two SCRs that
have been connected in parallel with each other (inversely) so that one SCR
will conduct the positive half-cycle and the other will conduct the negative
half-cycle. Before the triac was designed as a single component, two SCRs were
actually used for this purpose.</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The figure 1 below shows the symbol for the triac,
and its pn Structure. The terminals of the triac are identified as main
terminal 1 (MT1), main terminal 2 (MT2), and gate. The multiple pn structure is
actually a combination of two four-layer (pnpn) junctions.</span><br />
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikVsNB5vqadS09JVdOPEI3KQodVCaDMqfpFJYkGPKzFnYkC6haTtREQHHcduWhOACp0oGTsr7k8wtEkqyOeaDQdcCe8AqMsVpY1CDXy97Jbo8nwEf66Xet0efV293dp409Y-s10Fu9VaNa/s1600/TRIACS.png" style="margin-left: auto; margin-right: auto;"><img alt="Triacs" border="0" data-original-height="164" data-original-width="224" height="292" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikVsNB5vqadS09JVdOPEI3KQodVCaDMqfpFJYkGPKzFnYkC6haTtREQHHcduWhOACp0oGTsr7k8wtEkqyOeaDQdcCe8AqMsVpY1CDXy97Jbo8nwEf66Xet0efV293dp409Y-s10Fu9VaNa/s400/TRIACS.png" title="Triacs" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Figure 1</span></td></tr>
</tbody></table>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<br /></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">As the name suggests, the load current passes
through the main terminals, and the gate controls the flow. Figure 2 below
shows the equivalent circuit of the triac, which consists of two back-to-back
SCRs with a common gate.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 0cm;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsMpuE3FuUL9_lkrhFsxYlRxGknHO-WL_esTss1TgW0exdgQZviAN94TneOBfwIXTyPNR9Hp0oTiwuUZSzhSDDA2s9TEcRHr3LTA-r4fjT3HCa2z7DFcTlyJZWOVBaI7D0e3zUh2KVsUdA/s1600/Triacs+1.png" style="margin-left: auto; margin-right: auto;"><img alt="Triacs" border="0" data-original-height="150" data-original-width="197" height="304" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsMpuE3FuUL9_lkrhFsxYlRxGknHO-WL_esTss1TgW0exdgQZviAN94TneOBfwIXTyPNR9Hp0oTiwuUZSzhSDDA2s9TEcRHr3LTA-r4fjT3HCa2z7DFcTlyJZWOVBaI7D0e3zUh2KVsUdA/s400/Triacs+1.png" title="Triacs" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Figure 2</span></td></tr>
</tbody></table>
</div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Operation of the Triac</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The operation of the triac can be explained by the
two-SCR model in Figure 2. From the figure, you can see the SCRs are
connected in an inverse parallel configuration. One of the SCRs will conduct
positive voltage and the other will conduct negative voltage.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">When MT2 is more positive, the current flows
through first SCR; when MT1 is more positive the current flows through Second
SCR.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Unlike the two SCRs, the Triac is triggered by a
single gate. This prevents problems of one SCR not firing at the correct time
and overloading the other.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The operating characteristics of the Triac are best
explained using the characteristic curve shown in Figure 3:<o:p></o:p></span><br />
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfb2_sGMyJL-vFPlq-NklTNaOa1FoTt51NsP2EfiF5n6Pu_RsQNSrXJBqgAFf-9r_bD_SQabQz50YjjGJaGM7YPaMR60W3XUd-G8laE4Hxsq_AQQ8lTL8EHIKeole2bRzp70RMHoJqnMI1/s1600/Triacs+2.png" style="margin-left: auto; margin-right: auto;"><img alt="Triacs" border="0" data-original-height="224" data-original-width="568" height="221" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfb2_sGMyJL-vFPlq-NklTNaOa1FoTt51NsP2EfiF5n6Pu_RsQNSrXJBqgAFf-9r_bD_SQabQz50YjjGJaGM7YPaMR60W3XUd-G8laE4Hxsq_AQQ8lTL8EHIKeole2bRzp70RMHoJqnMI1/w568-h221/Triacs+2.png" title="Triacs" width="568" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Figure 3</span></td></tr>
</tbody></table>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In the figure above, you can see that the triac can
conduct both positive and negative current. The Voltage is shown along the
horizontal x-axis, and current is shown along the vertical y-axis. This diagram
also shows a second graph with four quadrants. These quadrants are used to
explain the operation of the triac as polarity to its MT1 and MT2 and gate
changes.<o:p></o:p></span></div>
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="margin-left: 1em; margin-right: 1em;"></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="margin-left: 1em; margin-right: 1em;"></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="margin-left: 1em; margin-right: 1em;"></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="margin-left: 1em; margin-right: 1em;"></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="margin-left: 1em; margin-right: 1em;"></a></div>
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Notice that the right half of the graph (in
quadrant 1) looks just like the SCR curve; no current flows until either the
break over voltage is reached or the gate is triggered (indicated by dashed
line).<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">This same pattern is repeated in quadrant 3 (for
voltage and current of the opposite direction). Also, like the SCR, once the
triac is triggered on, it will remain on by itself until the load current drops
below the holding current value (IH)<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">A Single cycle of AC has a positive and a negative
half-cycle. The triac requires a trigger pulse at the gate for each half-cycle
and works best if the trigger is positive for the positive half-cycle and
negative for the negative half-circle (Although in most cases the triac will
also trigger if the gate goes negative in the positive half-cycle and if it
goes positive in the negative half-cycle.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">You can also read:</span><br />
<br />
<ul style="text-align: left;">
<li><span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;"><a href="https://amzn.to/33pIYAy">Basics of Instrumentation and Control Systems</a></span></li>
<li><span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;"><a href="https://industrialinstrumentationsolutions.blogspot.com/2018/11/how-silicon-controlled-rectifiers-scrs.html">How Silicon Controlled Rectifiers (SCRs) are used in Industrial Control</a></span></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Applications of Triacs</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Triac is required in circuits where AC Voltage
and Current need to be controlled like the SCR controls dc current. Another
difference between the triac and SCR is that the Triac can be turned on either
by a positive or negative gate pulse. The gate pulse need only be momentary and
the Triac will remain in conduction until the conditions for commutation are
satisfied.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">A triac can be used as an-off solid-state switch
for AC loads or to regulate power to an AC load, such as dimmer switch.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Triacs are available in various packages, some of
which can handle currents up to 50 A (which is considerably less than the SCR).</span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-17756365164827811322018-11-18T07:06:00.005-08:002023-09-09T09:46:34.482-07:00How Silicon Controlled Rectifiers (SCRs) are used in Industrial Control<div dir="ltr" style="text-align: left;" trbidi="on">
<br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 12.6pt; mso-outline-level: 1;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Brief Background on Industrial
Electronics</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Silicon Controlled Rectifiers (SCRs), Triacs and
other high –powered transistors are used in many types of circuits to control
large voltages and currents. Many of these use 480 VAC 3 Phase circuits and can
control over 50 A. These devices offer control circuits for general purpose
power supplies, AC and DC Variable speed motor drives, Servo motor controls,
Stepper motor controls, high frequency power supplies, welding power supplies
etc. SCRs, Triacs, and any other solid-state devices used for switching larger
voltages and currents on and off are commonly called <b>thyristors. </b>Thyristors
control switching in an on-off manner similar to a light switch which is
different from a transistor that can vary the amount in its emitter-collector
circuit by changing the bias on its base. The amount of current that flows
through a thyristor must be controlled by adjusting the point in a sine wave
where the device is turned on.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Silicon Controlled Rectifiers (SCRs)</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The figure 1 below shows a symbol for the SCR and
identifies the anode, cathode, and gate terminals. The cathode is identified by
the letter C or K. The diagram also shows several types of SCRs.<o:p></o:p></span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVPjG_W98Te2pxxRu5uFviY1QLZhYFEQkx8rxUtW0s75qa4WgU3B5Z-YOpHUN8KiXBZ_RcUnMCW_zZRowxRuSqBFRbdFQx38otOny3OGFOGaQlRsKZX1xaQBrym6GgbWS3QY5FbupHqGz-/s1600/SCR.png" style="margin-left: auto; margin-right: auto;"><img alt="Silicon Controlled Rectifiers" border="0" data-original-height="279" data-original-width="336" height="331" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVPjG_W98Te2pxxRu5uFviY1QLZhYFEQkx8rxUtW0s75qa4WgU3B5Z-YOpHUN8KiXBZ_RcUnMCW_zZRowxRuSqBFRbdFQx38otOny3OGFOGaQlRsKZX1xaQBrym6GgbWS3QY5FbupHqGz-/s400/SCR.png" title="Silicon Controlled Rectifiers" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Figure 1</td></tr>
</tbody></table>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">How Silicon Controlled Rectifiers
Work</span></b></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="margin-left: 1em; margin-right: 1em;"></a></div>
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The SCR acts like a solid-state switch in that the
current will pass through its anode-cathode circuit to a load if a signal is
received at its gate. The SCR is different from a traditional switch in that the
SCR will change ac voltage to dc voltage (rectify) if ac voltage is used as the
power supply. The SCR is also different from a traditional switch in that the
amount of time the SCR conducts can be varied so that the amount of current
provided to the load will be varied from near zero to maximum of the power
supply.</span><br />
<span style="color: #1a1a1a; font-family: "georgia" , serif; font-size: 18pt;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgn95bKojKWD8ZdfVAarqJDUIlp89CEiEfobGxPn9G5ZFmM7xXO-mC4nHP7ZkNm5OWhKSnwktjgTw9sYRww9vxM0Bw8R5PggePCe-5rGPYF_MGnGEcO7JtY3cXZuiEXEyqka5WmEv4AlJ_M/s1600/SCR1.png" style="margin-left: auto; margin-right: auto;"><img alt="Silicon Controlled Rectifiers" border="0" data-original-height="161" data-original-width="231" height="278" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgn95bKojKWD8ZdfVAarqJDUIlp89CEiEfobGxPn9G5ZFmM7xXO-mC4nHP7ZkNm5OWhKSnwktjgTw9sYRww9vxM0Bw8R5PggePCe-5rGPYF_MGnGEcO7JtY3cXZuiEXEyqka5WmEv4AlJ_M/s400/SCR1.png" title="Silicon Controlled Rectifiers" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Figure 2</span></td></tr>
</tbody></table>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The SCR can vary the amount of current that is
allowed to flow to the resistive load by varying the point in the positive
half-cycle where the gate signal is applied. If the SCR is turned on
immediately, it will conduct full voltage and current for the half-cycle
(180°). If the turn-on point is delayed to the 90° point in the half-cycle
waveform, the SCR will conduct approximately half of the voltage and current to
the load. If the turn-on point is delayed to the 175° point in the half cycle,
the SCR will conduct less than 10% of the power supply voltage and current to
the load, since the half-cycle will automatically turn off the SCR at the 180°
point. This implies that the gate of the SCR can be used to control the amount
of voltage and current the SCR will conduct from zero to maximum.<o:p></o:p></span><br />
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span>
<span style="color: red; font-family: "georgia" , "serif"; font-size: 18pt;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/how-to-use-test-diodes-to-measure-4-20.html">How Test Diodes are used to Measure loop Currents</a> </span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Operation of SCR explained by the
four-layer (Two-Transistor) Model</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><a href="https://www.blogger.com/blogger.g?blogID=81971148694103601" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The SCR is a four-layer thyristor made of PNPN
material; in fact the proper name for the SCR is the reverse blocking triode
thyristor.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 0cm;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihd7A8v6tAEgra2Y5kk-HdnBMGE1kDzkSgrAGyE31EC6LdtTjNcjPX22OrN4kPGABfCPTN_sQtWQm4XPWtZ5NVwprScfxjTObdiTfOTr8yDGxPe26V1jXZqGXFW5Ig0bNOXWmG7HhKSYiZ/s1600/SCR2.png" style="margin-left: auto; margin-right: auto;"><img alt="Silicon Controlled Rectifiers" border="0" data-original-height="438" data-original-width="268" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihd7A8v6tAEgra2Y5kk-HdnBMGE1kDzkSgrAGyE31EC6LdtTjNcjPX22OrN4kPGABfCPTN_sQtWQm4XPWtZ5NVwprScfxjTObdiTfOTr8yDGxPe26V1jXZqGXFW5Ig0bNOXWmG7HhKSYiZ/s400/SCR2.png" title="Silicon Controlled Rectifiers" width="243" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Figure 3</span></td></tr>
</tbody></table>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The Figure 3 above shows the PNPN material split
apart as two transistors, a PNP and a NPN. The figure (c) shows the SCR as two
transistors.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The anode is at the emitter of the PNP Transistor
(T2), and the cathode is at the emitter of the NPN transistor (T1). The gate is
connected to the base of the NPN Transistor. Since the anode is the emitter of
the PNP, it must have a positive voltage to operate and since the cathode is
the emitter of the NPN transistor, it must be negative to operate.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">When a positive pulse is applied to the gate, it
will cause collector current Ic to flow through the NPN transistor (T1). This
current will provide bias voltage to the base of the PNP transistor (T2). When
the bias voltage is applied to the base of the PNP transistor, it will begin to
conduct Ic which will replace the bias voltage on the base that the gate signal
originally supplied. This allows the gate signal to be a pulse which is then
removed since the current through SCR anode to cathode will flow and replace
the base bias on transistor T1.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Methods of turning on an SCR</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Normally the SCR is turned on by a pulse to its
gate but we have 3 other methods you can also use to turn it on.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">These methods include:<o:p></o:p></span><br />
<br />
<ul style="text-align: left;">
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Exceeding the forward break over voltage</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">By Excessive heat that allows leakage current</span></span></li>
<li><span style="color: #1a1a1a; font-family: "georgia" , serif;"><span style="font-size: 24px;">Exceeding the dv/dt level (allowable voltage change per time change) across the junction.</span></span></li>
</ul>
</div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Methods of turning off/Commutating
SCRs</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Once an SCR is turned on, it will continue to
conduct until it is turned off (commuted). Commutation will occur in an SCR
only if the overall current gain drops below unity (1). This means that the
current in the anode-cathode circuit must drop below the minimum (near zero) or
a current of reverse polarity must be applied to the anode-cathode. Since the
ac sine wave provides both of these conditions near the 180° point in the wave,
the main method to commutate an SCR is to use ac voltage as the supply voltage.
In an ac circuit, the voltage will drop to zero and across over to the reverse
direction at the 180° point during each sine wave. This means that if the
supply voltage is 60 Hz, this will happen every 16 msec. Each time the SCR is
commutated, it can be triggered at a different point along the firing angle,
which will provide the ability of the SCR to control the ac power between 0° to
180°. The main drawback with using ac voltage to commutate the SCR arises when
higher-frequency voltages are used as the supply voltage. Note that, the SCR
requires approximately 3-4 msec. to turn off; therefore the maximum frequency
is dependent on the turn-off time.<o:p></o:p></span><br />
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh40xbq1hFosxwFRb-rJi5q11xq07Q4urInOB8QVxlgI0pWr3mIxgcunMaD-isp9Qw2JeSte8WCb_q_58Ny8pQqY8ai9McfE0wBwv1dEcqTw-EP0z0plt1QpfVp80OOKpgiXRMkHZKgoEVB/s1600/SCR3.png" style="margin-left: auto; margin-right: auto;"><img alt="Silicon Controlled Rectifiers" border="0" data-original-height="594" data-original-width="284" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh40xbq1hFosxwFRb-rJi5q11xq07Q4urInOB8QVxlgI0pWr3mIxgcunMaD-isp9Qw2JeSte8WCb_q_58Ny8pQqY8ai9McfE0wBwv1dEcqTw-EP0z0plt1QpfVp80OOKpgiXRMkHZKgoEVB/s400/SCR3.png" title="Silicon Controlled Rectifiers" width="190" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: large;">Figure 4</span></td></tr>
</tbody></table>
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 0cm;">
<br /></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Figure 4 (a) A switch is used to
commutate the SCR in a dc circuit by interrupting current flow. This type
of circuit is used to provide control in alarms or emergency dc voltage
lighting circuits, (b) A series of RL resonant circuit circuit used
to commutate an SCR and (c) A parallel RL resonant circuit used to
commutate an SCR. </span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">SCRs are also used in the inverter section where
the dc voltage is turned back into ac voltage. Since the devices must provide
both the positive and the negative half-cycles, a diode is connected in inverse
parallel to provide the hybrid ac switch. This combination of devices is not
frequently used currently as larger Triacs and Power transistors can do better
job in this kind of applications.</span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com0tag:blogger.com,1999:blog-81971148694103601.post-47872716201358760282018-11-16T04:38:00.002-08:002023-07-21T11:03:10.313-07:00Differential Pressure Transmitters (DP)<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; color: #1a1a1a; font-family: georgia, serif; font-size: 18pt;">One of the most common and useful pressure
measuring instrument used in most industrial measurement applications is the
differential Pressure transmitter. This device senses the difference in
pressure between two ports and outputs a signal representing that pressure in
relation to a calibrated range.</span><br />
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Differential Pressure transmitters constructed for
industrial measurement applications typically consists of a strong (forged
metal) body housing the sensing element(s), topped by a compartment housing the
mechanical and/or electronic components necessary to translate the sensed
pressure to a standard instrumentation signal e.g. 3-15 PSI, 4-20 mA, Digital
Fieldbus codes as shown in the below Diagrams:<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqM7HKIg8cwG6vRtGjQaX7_McBK1CWhznXTyhm5jr_8-U9k-uiOK8oETpzgJsDfiiHmZ76glU2zuJquqJC_FrTfBMSC9dSp1s4ryK0JAN0sUFSxnV4gMu847VtD1F9ZHn9J2DoMFMRn34k/s1600/Differential+Pressure+Transmitters.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitters" border="0" data-original-height="331" data-original-width="808" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqM7HKIg8cwG6vRtGjQaX7_McBK1CWhznXTyhm5jr_8-U9k-uiOK8oETpzgJsDfiiHmZ76glU2zuJquqJC_FrTfBMSC9dSp1s4ryK0JAN0sUFSxnV4gMu847VtD1F9ZHn9J2DoMFMRn34k/w611-h250/Differential+Pressure+Transmitters.PNG" title="Differential Pressure Transmitters" width="611" /></a></div>
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<br /></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In the below example of Rosemount differential
pressure transmitter, the pressure-sensing element is housed in the bottom half
of the device (forged-steel structure) while the electronics are housed in the
top half (the coloured, round, cast-aluminium structure)<o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiMfbfrqImwgzfwh2tqNd-LMIClT_nGYlMZ_Bb3I4I9ooKHHb_Rfu7qsJkjTul9N9H8keNyvKdBqnZJzft1SHyJnxa8DH_lUxqgVRosBR3dp0Kc72cCyeeTSVtO5i1NggZd29oMWwBYFv3D/s1600/Differential+Pressure+Transmitter+01.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter" border="0" data-original-height="681" data-original-width="1024" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiMfbfrqImwgzfwh2tqNd-LMIClT_nGYlMZ_Bb3I4I9ooKHHb_Rfu7qsJkjTul9N9H8keNyvKdBqnZJzft1SHyJnxa8DH_lUxqgVRosBR3dp0Kc72cCyeeTSVtO5i1NggZd29oMWwBYFv3D/s400/Differential+Pressure+Transmitter+01.png" title="Differential Pressure Transmitter" width="400" /></a></div>
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<br /></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Every differential Pressure (DP, d/p or ∆P)
transmitter has two pressure ports to sense different process fluid pressures.
These ports typically have ¼ inch female NPT threads to readily accept
connections to the process. One of these ports is labelled “high” and the other
is labelled “low’’. This labeling does not necessarily mean that the “high”
port must always be at a greater pressure than the “low’’ port. What these
labels represent is the effect any increasing fluid Pressure applied to that
port will have on the direction of the output signal’s change. Note that, a
differential pressure instrument responds only to differential pressure while
ignoring the common-mode pressure (gauge pressure common to both ports).<o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIQeoAkcQVZfzOYcO7OWdTlcPbb7YIlvYoq3savvoqh2IPUG7cVBVpJLzoxxu9tE2DBQVkVNw5uUPc-4ZR9K2J51pJF-o2_HUcIWexLUZhLe6D_5IaHZ4Ny0DLV0DVhRLe3lGd_pGJN7tx/s1600/Differential+Pressure+Transmitter+02.png" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitters Low and High Ports" border="0" data-original-height="271" data-original-width="600" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIQeoAkcQVZfzOYcO7OWdTlcPbb7YIlvYoq3savvoqh2IPUG7cVBVpJLzoxxu9tE2DBQVkVNw5uUPc-4ZR9K2J51pJF-o2_HUcIWexLUZhLe6D_5IaHZ4Ny0DLV0DVhRLe3lGd_pGJN7tx/w578-h260/Differential+Pressure+Transmitter+02.png" title="Differential Pressure Transmitters Low and High Ports" width="578" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The most common sensing element used by modern DP
transmitters is the diaphragm. One side of this diaphragm receives process
fluid pressure from the “high’’ port while the other receives process fluid
pressure from the “low’’ port. Any difference of pressure between the two ports
causes the diaphragm to flex from its normal resting (center) position. This
flexing is then translated into an output signal by any number of different
technologies depending on the manufacturer and the transmitter model.</span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Differential Pressure (DP)
Transmitter Applications</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The combination of two differential pressure ports
makes the DP transmitter very versatile as a pressure-measuring device. This
one instrument can be used to measure pressure differences, positive (gauge)
pressures, negative (vacuum), and even absolute pressures, just by connecting
the “high” and “low” sensing ports differently.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">In every DP transmitter application, there must be
some means of connecting the transmitter’s pressure-sensing ports to the points
in a process. Metal or plastic tubes (or pipes) work well for this purpose, and
are commonly called <b>impulse lines </b>or <b>gauge lines </b>or <b>sensing
lines. </b>Typically these tubes are connected to the transmitter and to
the process by means of compression fittings which allow for relatively easy
disconnection and re-connection of tubes.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Key applications of DP transmitters
include:</span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Measuring Process Vessel Clogging
– </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">We may use the DP transmitter to
measure an actual difference pressure across a process vessel such as a filter,
a heat exchanger, or a chemical reactor. The diagram below shows the use of a
DP transmitter to measure clogging of a water filter:<o:p></o:p></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxrtFVY0OZj5VM2Wz78m2a3iI15usF09TTW0B4_2gyBYDwpRLK_Q1gVW_KM5x-uVhXRBnEvnMM7WRfK5a4t7t7hmyO8Z_D4GerZ0iTzr8LpaCrCFNL0b2jQe5aTURu8KCFVLiULp2tYmfS/s1600/Differential+Pressure+Transmitter+03.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter Industrial Applications" border="0" data-original-height="570" data-original-width="892" height="383" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxrtFVY0OZj5VM2Wz78m2a3iI15usF09TTW0B4_2gyBYDwpRLK_Q1gVW_KM5x-uVhXRBnEvnMM7WRfK5a4t7t7hmyO8Z_D4GerZ0iTzr8LpaCrCFNL0b2jQe5aTURu8KCFVLiULp2tYmfS/w601-h383/Differential+Pressure+Transmitter+03.PNG" title="Differential Pressure Transmitter Industrial Applications" width="601" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><br /></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">From the diagram above, you can see the high side
of the DP transmitter connects to the upstream side of the filter and the low
side of the transmitter to the down side of the filter. This way, increased
filter clogging will result in an increased transmitter output. Since the
transmitter’s internal pressure-sensing diaphragm only responds to differences
in pressure between “high” and “low” ports, the pressure in the filter and pipe
relative to the atmosphere is completely irrelevant to the transmitter’s output
signal. The filter could be operating at a line pressure of 15 PSI or 15000 PSI
– the only variable the DP transmitter measures is the pressure drop across the
filter. If the upstream side is 15 PSI and the downstream side is 14 PSI, the
differential pressure will be 1 PSI sometimes labelled PSID, where “D” is
differential. If the upstream pressure is 15000 PSI and the downstream pressure
is 14,999 PSI, the DP transmitter will still see a differential pressure of
just 1 PSID.<o:p></o:p></span></div>
<div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;">
<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Measuring positive gauge pressure
– </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">DP instruments can also serve as
gauge pressure instruments. If we simply connect the “high” side of a DP
instrument to a process vessel using an impulse tube, while leaving the “low”
side vented to atmosphere, the instrument will interpret any positive pressure
in the vessel as a positive difference between the vessel and the atmosphere. </span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmt4D4q94YjAeTN9d6i8fel9rq0xU5dcGXK6B086YKrZB5A9gVlPYGrXPLCDs-Uzpv9Ao7DGNj1PgbkRDehNbwCEjql3YCmZFdH1s-Gln2-mjZ788zmSXR_9EPalfk5aKGky92BHU_kxeo/s1600/Differential+Pressure+Transmitter+04.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter Industrial Applications" border="0" data-original-height="629" data-original-width="813" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmt4D4q94YjAeTN9d6i8fel9rq0xU5dcGXK6B086YKrZB5A9gVlPYGrXPLCDs-Uzpv9Ao7DGNj1PgbkRDehNbwCEjql3YCmZFdH1s-Gln2-mjZ788zmSXR_9EPalfk5aKGky92BHU_kxeo/s400/Differential+Pressure+Transmitter+04.PNG" title="Differential Pressure Transmitter Industrial Applications" width="400" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Most DP instrument manufacturers offer gauge
pressure versions of their differential instruments with “high” side port open
for connection to an impulse line and the “low’’ side of the sensing element
capped off with a special vented flange, effectively performing the same
function as in the above figure.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Measuring absolute Pressure – </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Absolute pressure is defined as the difference
between a given fluid pressure and a perfect vacuum. We may build an absolute
pressure sensing instrument by taking a DP transmitter and sealing the “low”
side of its pressure-sensing element in connection to a vacuum chamber as shown below. This
way, any pressure greater than a perfect vacuum will register as a positive
difference.<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_l7wn6mwntI4pltYovzQV1sGzFjBcB9n1kwwGpWZdfHA9LHXyUcIx5Z6X7_3Z6MFjDYlJhw_LbmabsDT2db6-_vqp6rbEJ0f2Crnh5evIOiS_-MoaaCw49teOk6twIWypno73qjOmW3qJ/s1600/Differential+Pressure+Transmitter+05.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter Industrial Applications" border="0" data-original-height="192" data-original-width="464" height="264" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_l7wn6mwntI4pltYovzQV1sGzFjBcB9n1kwwGpWZdfHA9LHXyUcIx5Z6X7_3Z6MFjDYlJhw_LbmabsDT2db6-_vqp6rbEJ0f2Crnh5evIOiS_-MoaaCw49teOk6twIWypno73qjOmW3qJ/s640/Differential+Pressure+Transmitter+05.PNG" title="Differential Pressure Transmitter Industrial Applications" width="640" /></a></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Measuring Vacuum – </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">The same principle of connecting one port of a DP
device to a process and venting the other works as well as a means of
measuring <b>vacuum (</b>Pressure below that of atmosphere). All we need
to do is connect the “low” side to the vacuum process and vent the ‘’high” side
to the atmosphere as shown below: <o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjD_nvNBsfHtMO_VT4ynbo8StXVNEHTDwH5LcZrRXgMiXLEz4gLKA3XT-_xa7azSpyiAHAAOClKNti6FZEFk1_AOifCCQhZG7HFBe6cEkd_XK2VVjJMTbuI_j3gVKLhYAMw785DsZGRsgUz/s1600/Differential+Pressure+Transmitter+06.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter Industrial Applications" border="0" data-original-height="653" data-original-width="829" height="315" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjD_nvNBsfHtMO_VT4ynbo8StXVNEHTDwH5LcZrRXgMiXLEz4gLKA3XT-_xa7azSpyiAHAAOClKNti6FZEFk1_AOifCCQhZG7HFBe6cEkd_XK2VVjJMTbuI_j3gVKLhYAMw785DsZGRsgUz/s400/Differential+Pressure+Transmitter+06.PNG" title="Differential Pressure Transmitter Industrial Applications" width="400" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Any pressure in the process less than atmospheric
will register to the DP transmitter as a positive difference (with P-high <sub> </sub> greater
than P-Low<sub> ). </sub>Thus the stronger the vacuum in the process
vessel, the greater the signal output by the transmitter.<o:p></o:p></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Inferring liquid level – </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Liquids generate pressure proportional to height
(depth) due to their weight. The pressure generated by a vertical column of
liquid is proportional to the column height (h), and liquid’s mass density (ρ),
and the acceleration of gravity (</span><span style="color: #1a1a1a; font-family: "times new roman" , "serif"; font-size: 18pt;">ɡ</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">):
</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> </span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">P=</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">ρ</span><span style="color: #1a1a1a; font-family: "times new roman" , "serif"; font-size: 18pt;">ɡ</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">h<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhi3nKx_c9LIkT3ZOi0iX-75IK8-7vZ72Z5HMrP9zZ5Q0OewZP4GXhCouaW8NofcDDSyoFaCEGGej_B1PaFLxOgr-Wn-UjRHfkapOVGJvR40O2AOtrAbJE4FC7OvF5rfNM7tb7LgqWubV9v/s1600/Differential+Pressure+Transmitter+07.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter Industrial Applications" border="0" data-original-height="457" data-original-width="742" height="344" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhi3nKx_c9LIkT3ZOi0iX-75IK8-7vZ72Z5HMrP9zZ5Q0OewZP4GXhCouaW8NofcDDSyoFaCEGGej_B1PaFLxOgr-Wn-UjRHfkapOVGJvR40O2AOtrAbJE4FC7OvF5rfNM7tb7LgqWubV9v/w560-h344/Differential+Pressure+Transmitter+07.PNG" title="Differential Pressure Transmitter Industrial Applications" width="560" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">As the liquid in the vessel increases, the amount
of hydrostatic pressure applied to the transmitter’s ‘’high’’ port increases in
direct proportion. The width of the vessel is irrelevant to the amount of
pressure produced only the liquid height (h), density (ρ), and gravity (</span><span style="color: #1a1a1a; font-family: "times new roman" , "serif"; font-size: 18pt;">ɡ</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">) are significant. Thus the transmitter</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">’</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">s increasing signal represents the
height of liquid inside the vessel no matter the size or shape of the vessel.<o:p></o:p></span></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">h = P/ρ</span><span style="color: #1a1a1a; font-family: "times new roman" , "serif"; font-size: 18pt;">ɡ</span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> </span><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"> <o:p></o:p></span></div>
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<span style="font-family: "georgia" , serif; font-size: 18pt;"><span style="color: red;">You can also read: <a href="https://industrialinstrumentationsolutions.blogspot.com/2018/10/advantages-and-disadvantages-of.html">Advantages and Disadvantages of Pneumatic Instruments</a></span></span></div>
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<b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Inferring gas and Liquid Flow – </span></b><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">DP transmitters are widely used in measurement of
fluid flow. Pressure dropped across a constriction in the pipe varies in
relation to flow rate (Q) and fluid density (ρ). So long as fluid density
remains fairly constant, we may measure pressure drop across a piping
constriction and use that measurement to infer flow rate. The most common form
of constriction is the orifice plate. This is a metal plate with a precisely
machined hole in the center. As fluid passes this hole, its velocity changes,
causing a pressure drop to form.<o:p></o:p></span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjr0RTkb0eaIg_ziQxGZeM9jvSKDxGlC0NCr7ibEC1fndhEqjU10Km_KCVRKk-C5Nj_T6xZsoMMykscA7VwD8swhpSmIrjaPBoFMdchvgKXydEdGumDyKzHUPp46bdkpEXIYpSZN0TjilzH/s1600/Differential+Pressure+Transmitter+08.PNG" style="margin-left: 1em; margin-right: 1em;"><img alt="Differential Pressure Transmitter Industrial Applications" border="0" data-original-height="380" data-original-width="617" height="378" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjr0RTkb0eaIg_ziQxGZeM9jvSKDxGlC0NCr7ibEC1fndhEqjU10Km_KCVRKk-C5Nj_T6xZsoMMykscA7VwD8swhpSmIrjaPBoFMdchvgKXydEdGumDyKzHUPp46bdkpEXIYpSZN0TjilzH/w614-h378/Differential+Pressure+Transmitter+08.PNG" title="Differential Pressure Transmitter Industrial Applications" width="614" /></a></div>
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<span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;">Since both ports of the transmitter connect to the
same process line, static fluid pressure within that line has no effect on the
measurement. Only differences of pressure between the upstream and downstream
sides of the constriction (orifice plate) cause the transmitter to register
flow.</span></div><div class="MsoNormal" style="background: white; line-height: normal; margin-bottom: 21pt;"><span style="color: #1a1a1a; font-family: "georgia" , "serif"; font-size: 18pt;"><span style="color: red; font-family: georgia, serif;">Don't miss out on key updates, join our newsletter list </span><a href="http://eepurl.com/dOUtI9" rel="nofollow" style="font-family: georgia, serif;" target="_blank">here.</a></span></div>
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John Mulindihttp://www.blogger.com/profile/15635579807650017816noreply@blogger.com2