please anybody can explain to me this matter:
in tank level control i have been told that i can not use derevitive action in level control, and another friend said we can use derivitive.
so plese can anyone explain when i should use derivitive in level control and when i can not,and why.

if the explenation with examples i appretiated.
thanks to all

 

Hello;
Derivative action in a PID feedback loop is used for "anticipation" of the rate of change of the error. Which does not explain much at first glance.

But please follow this link, it will take you to one of the best non-mathematical explanations of the workings of a PID loop that I know of. The gentleman's name is Ron Beaufort, he is a professional trainer on AB PLCs, and he has taken time to write down his teaching experience on the subject.
http://www.ronbeaufort.com/sample_lessons.htm

He has various articles on the PID loop, the one that you should look at is "What is D in PID" for a rapid look at your problem. But I do recommend you spend some time on the others as well.

Hope this helps,
Daniel Chartier