Instrumentation Instrumentation Questions

[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
   deviation
      output
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 comments

brahmaji September 20, 2013 at 5:24 pm

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

Bijaya kumar Sutar September 21, 2013 at 3:08 am

Pls post instrument question & answer.

Salehhudin Mohd Noh September 21, 2013 at 6:05 am

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

Olajide Solademi November 17, 2013 at 4:37 pm

Z is Position

saji raju June 2, 2014 at 6:13 pm

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

AcuteSoft November 4, 2014 at 3:08 pm

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
1.P-controller
2.I-controller
3.D-Controller
and they can also be used by combinations like PI-controller and PD-controller

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