Process variable

<h2 id="control-system-use">Control system use</h2>

<p>Measurement of process variables is essential in <a href="/facts/Control_system/8CEjIDlS">control systems</a> to controlling a process. The value of the process variable is continuously monitored so that control may be exerted.
</p><p>Four commonly measured variables that affect chemical and physical processes are: <a href="/facts/Pressure/eyc37GRG">pressure</a>, <a href="/facts/Thermodynamic_temperature/JXeJJPa6">temperature</a>, level and flow. but there are in fact a large number of measurement quantities which for international purposes use the <a href="/facts/International_System_of_Units/S7YLglNz">International System of Units</a> (SI)
</p><p>The SP-PV error is used to exert control on a process so that the value of PV equals the value of the SP. A classic use of this is in the 
<a href="/facts/PID_controller/7XcYk0CH">PID controller</a>.
</p>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>B. Wayne Bequette (2003). Process Control: Modeling, Design, and Simulation. Prentice Hall Professional. p. 5. ISBN 9780133536409. <a href="9780133536409" target="_blank">9780133536409</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Process variable open-in-new

Process variable