Jason K. Firth, C.E.T.

Instrumentation, Control, and Automation

All you need to know about PID controller

Feb 272017

27 Feb 2017

I'm Jason Firth.


I recently commissioned this article explaining the function of a PID controller by freelance writer Sophia O'Connor. It's one of a few pieces I've commissioned recently. It's partially a test to see how well commissioning freelancers can work, and partially a public service to get some stuff written about some basic concepts. Enjoy!


A proportional integral derivative (PID) controller is an instrument that is used mainly in the industrial control applications. PID controller involves three controllers i.e. p-controller, D-controller and I-controller. All these controllers are combined in a way that they produce a control signal. The main purpose of using a PID controller is to control the speed, temperature, pressure, flow and other variables that needs to be processed. It can be installed near the control regulation devices. Moreover, a PID controller is monitored through an SCADA system.

Working of a PID controller:

As explained above, a PID controller involves the working of three different controllers that are combined together to perform different tasks. The main purpose of installing a PID controller is to control the operations. Although a simple machine with the ON and OFF option can be easily used for this purpose. However, when it comes to something complex, the only thing that can be used is the PID controller. It will provide with the maximum opportunity to control the overall system.

A PID controller is responsible for the controlling of the output. Moreover, the desired output can also be achieved with the help of this. The three basic controls have their own working in the PID controller, they all work together to achieve a common goal. The working of these controls is explained below:

Functions of the Proportional controller:

P-controller is responsible for providing the output that is required. The output that is achieved is proportional to the current error value. The main working of a P-controller involves the comparison of the desired set point with the actual value or the value that is achieved through the feedback process. So, if the error value of this controller is zero, the output value of the controller is also zero. Moreover, this type of controller requires a manual resetting every time.

Functions of the Derivative controller:

The requirement of the controlling system involves the prediction of the future behaviour as well. This will not be done with the I-controller. D-controller is the one that will solve this problem. The output value of this controller is dependent on the rate of change of error with the time. It works as a kick start for the output system hence increasing its system response.

Functions of the integral controller:

There are certain limitations with the p-controller that are fulfilled with the help of I-controller. It is needed in this controller system because it will provide with necessary actions that are required for the elimination of the steady state error. It is responsible for integrating the error for a period of time so that the error value reaches to zero value.


All of these controller works together to form a perfect controller that can be used in the process control application.



Thanks for reading!

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