Standalone controller (PID)

A controller is an instrument used for controlling a process variable (measurement). Its continuously monitors the error signal and gives a corrective output to the final control element.

a    measurement variable
      desired variable
Measurement variable: It is the demand variable measured and controlled.
Desired Variable: it is the demand signal (set point) to which the process variable is controlled.
Deviation: it is the error signal caused by the difference between the measurement and the demand signal.
Output: It is the corrective signal from the controller to the final control element.
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6 thoughts on “[Instrumentation interview question ]What is a ‘controller’? Area of application?

  1. PID controller means Proportional Integral and Derivative controller. The difference between a measured value and set point value can be calculated by a PID controller and it will minimize the error by its manipulated variables.

    There are mainly three types of PID Controllers
    and they can also be used by combinations like PI-controller and PD-controller

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