Carrier 33ZCVAVTRM Specifications download pdf (Page 238)

If after careful adjustment of the proportional and integral gains,

your application does require a derivative term (indicated by

excessive overshoot), set it to a value approximately 25% of the

proportional gain, and re-test and re-adjust (by +/- 50% intervals)

until overshoot is reduced to a satisfactory level.

As was the case with dual loop tuning, the entire system (controls,

mechanical equipment, etc.) must be thoroughly evaluated before

proceeding. The throttling range must also be determined using the

procedure described in Determination of Throttling Range above.

When those steps are completed, the actual tuning procedure may

commence.

The AOAdaptive Single Loop PID is the only single loop algo-

rithm in the Universal Controller. The optimum loop timing (set via

the Block Iteration decision) will vary based on the nature of the

application. The default value of 10 seconds may not be appropriate

for all applications. The user is advised to adjust this value to reflect

the actual time constant of the controlled process (the time it takes to

stabilize after a step change of output to the controlled device).

The following steps apply to single loops only. During the follow-

ing procedure, if the output responds in reverse of what is expected,

reverse the polarity of the proportional, integral, and derivative gains

(+/-). In all cases, the polarity of the proportional, integral, and

derivative gains must be the same. An example of the output re-

sponding in reverse of what is expected is when the reference

requires heat, but the valve goes closed or moves towards closed.

1. Set the Starting Value.

Verify the correct starting value as outlined previously in the

Determination of Throttling Range section of this chapter.

2. Force the Output.

Force the output to its minimum position.

3. Set the Master Integral Gain to 0.

4. Set the Proportional Gain.

Single Loop PID Tuning

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Carrier 33ZCVAVTRM Specifications Page 238