From Practical Process Control for Engineers and Technicians

E.8.1 Objective

This exercise will give some practical experience in the closed loop tuning method. Figure Ex. 8.1 shows the diagram of a typical control loop. The steps for tuning are explained in the Chapter 5 tuning of closed loop control systems .

Ex. 8.1: Single loop control

E.8.2 Operation

Call up the training application General single loop with interactive PID (real form).

Then, call up the detail display F3 and change MODE to MANUAL. Set the OP to 50% and wait for the process to settle down. Make a good judgment about noise observed on PV and set the digital noise filter (TD) accordingly. A good value of TD will result in a still noticeable but very small magnitude of noise in the PV term. The noise filter has to be set up before tuning in order to have it included in the results of the tuning exercise. Practically, the noise filter becomes part of the process as far as loop tuning is concerned.

For the closed loop tuning method, we have to change the tuning constants in such a way as to obtain P-control only. Change T INT to 999, T DER to 0 and K to a relatively low value of 0.5. Then, change MODE back to AUTO and make a small change of SPE in order to find out how sensitive the process is in responding. We have to find a value for K so that the closed loop will oscillate with...

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Topics of Interest

E.9.1 Objective This exercise will introduce the student to the two major types of OP-limit calculations. The one kind, with OP-limits, allows a saturation value of the OP, based on P-control and...

E.6.1 Objective The objective of this exercise is to demonstrate the direct relationship between process lag and stability, and to make students aware of the great difference between noise and...

E.2.1 Objective This exercise will introduce the main control action of controllers proportional control. Special emphasis is placed on the fact that there is a remaining offset condition, if...

E.4.1 Objective This exercise will introduce a combined proportional and integral control action of controllers. Special emphasis is given to the elimination of the remaining offset of proportional...

E.3.1 Objective This exercise will introduce the integral control action of controllers. Special emphasis is given to the task of eliminating the remaining offset term of proportional control. It...

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