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11. Change the set point slightly and check the transient behavior. If necessary, retune KP
and TN until the closed loop shows a satisfactory control behavior.
Proceed as follows for a P controller
1. Switch to manual mode (
2. In the CNTR menu, set the function -CO- C.PID = P CP.YP.
3. In the PAR menu, set the parameter KP = 0.1.
4. In the operating level, set the set point W to the required value.
to select W and use the cursor keys (
Î Press
5. In the operating level, change the manipulated variable Y so that the controlled variable
X has the same value as the set point W (error Xd = 0).
Î Press
to select Y and use the cursor keys (
The output Y reading is the operating point of the manipulated variable.
6. In the PAR menu, set the Y.PRE parameter to the previously determined operating point of
the manipulated variable Y.
Note
For a P controller, every time the set point is changed, the change of the operating point is
also necessary if no steady-state error is to exist.
7. Switch to automatic mode (
8. In the PAR menu, step up the KP parameter until the controlled variable shows an har-
monic oscillation pattern.
Every time the KP increases, let the controlled system oscillate, e.g. by making small
changes to the set point.
9. Write down the adjusted KP value as the critical proportional-action coefficient K
10. Multiply K
by the factor 0.5 and use the result to set KP at the controller (KP = 0.5 x
P,crit
K
).
P,crit
P controller
11. Change the set point slightly and check the transient behavior. If necessary, retune KP un-
til the closed loop shows a satisfactory control behavior.
EB 6493 EN
).
).
KP
0.5 x K
P, crit
Start-up and configuration at the device
,
). to set the value.
,
) to set the value.
TN
–
.
P,crit
TV
–
7-21
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