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04.10.2021
20210927 QC-PC-PID-01-Bedienungsanleitung engl.
Parameterization according to Ziegler & Nichols
With this Ziegler & Nichols method, the controller is operated for the first time as a pure P controller.
Starting with a small gain factor KP, this is slowly increased until the gain factor is found for which the
control is just becoming unstable. This means that the regulation is just starting to oscillate.
Method:
-
Start up the controller as described
-
Switch off the output
-
Leave the controller switched off until the temperature is stable. The controller has now
reached the temperature T
Medium
dictated by the cooling medium.
-
Switch to the PARAMETER-MENU
-
Set KP to 100 (or less. This value should not cause any oscillation yet)
-
Set TN to 000
-
Set TV to 000 (The controller now has pure P characteristics)
-
Set T1 to a value just (about 10 Kelvin) above T
Medium
-
Set T2 to a value just (about 10 Kelvin) below T
Medium
-
Confirm the changes
-
Touch the area
“jump to target1”
-
Observe the temperature development. The controller should not reach the target value,
otherwise reduce KP.
-
Touch the area “jump to target
2
”
-
Observe the temperature development. The controller should not reach the target value,
otherwise reduce KP
-
Increase the KP value
-
Touch the area “jump to target1”
-
Observe the temperature development.
-
In this way, increase the KP value until the controller begins to oscillate around the target
temperature. This KP-
value is the „critical gain factor“ KP
Krit
.
-
Determine the period of one oscillation. This is the time T
Krit
in seconds that elapses during a
full oscillation.
-
According to Ziegler & Nichols, the controller now has the following parameters:
o
KP = 0,6 KP
Krit
TN = 5 T
Krit
TV = 1,25 T
Krit
If you enter these values in the controller, the control should work well.
