[Instrumentation interview question ]What is a ‘controller’? Area of application?

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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  1. What are the different types of controllers? and List of them?

  2. Hi there, can u describe what is "Z" mean exmple : 61-ZIT-8001
    What exactly is mean

  3. please give correct answer about PID controller and where it is used and Its working principle.

  4. 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