Process variable
Value of a given part of a monitored or controlled process
In control theory, a process variable (PV; also process value or process parameter) is the current measured value of a particular part of a process which is being monitored or controlled. An example of this would be the temperature of a furnace. The current temperature is the process variable, while the desired temperature is known as the setpoint (SP).
01Control system use
Measurement of process variables is essential in control systems to controlling a process. The value of the process variable is continuously monitored so that control may be exerted.
Four commonly measured variables that affect chemical and physical processes are: pressure, temperature, level and flow, but there are in fact a large number of measurement quantities which, for international purposes, use the International System of Units (SI)
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 PID controller.
Sources and credits
This article is adapted from the Wikipedia article “Process variable”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Set-point control.png by Brews ohare, CC0
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