Process Control
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BASICS OF ON/OFF CONTROLLER
Introduction In control theory, an on/off controller, also known as a hysteresis controller, is a feedback controller that switches abruptly…
Read More » Basics of PID controller (Proportional – Integral – Derivative)
PID (Proportional – Integral – Derivative ) Controller Proportional The proportional term makes the current error signal multiplied with a…
Read More »Override Control
Override It is sometimes necessary to limit a variable in order to maintain safe operation or protect process equipment. If…
Read More »Feedforward Control System
Feedforward A Feedforward control system measures a disturbance in variable, predicts its effect on the process and applies corrective action.…
Read More »Cascade Control System
Cascade In cascade control system two controllers are cascaded to each other as shown in the diagram below. Primary…
Read More »Ratio Control
Ratio Control In Ratio Control, the controlled variable is the ratio of two measured variables. Control is effected by adjusting…
Read More »Common Control Loops
Common Control Loop 1.Flow Liquid flow processes are fast, typically 0.5 sec response or less. Gas flow is…
Read More »Derivative Or Rate Control
Derivative Control Derivative control (also called rate control) responds to the rate of change of the controlled variable. For example,…
Read More »Process Control – Integral Control
Integral (or Reset) Control Integral control (also called Reset control) can be used when unacceptable amounts of offset…
Read More »Process Control – Proportional Control
Proportional Control In some processes, the fluctuations around the set point (called oscillation) may be too severe to achieve the…
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