8-26
8-2-12 Stable PID Control is Not Possible or Control
Fails
H PID control is not possible with vibration or hunting.
·PID control gain adjustment is insufficient.
Check the frequency of vibration and adjust the proportional (P) control, integral (I)
control, and derivative (D) control of the Inverter. Refer to 6-3-7 PID Adjustments.
H PID control diverges.
·No feedback is input.
Ifthedetectedvalueis0withnofeedbackinput,thePIDcontrolfunctionwillnotoper-
ate. As a result, the output of the Inverter will diverge and the motor will increase its
speed up to the maximum frequency.
Check that the set value in n164 for PID feedback input block selection conforms
with the actual input and that the PID constants are set properly. Refer to 6-3-6 PID
Control Settings.
·Level adjustments of the target and detected values are imperfect.
The Inverter in PID control adjusts the deviation between the target and detected
values so that the deviation will be zero. Therefore, the target and detected values
must be adjusted so that they will have the same input level. Set the detected value
gain in n129 after making the proper level adjustments.
·The relationship between the output frequency and detected value of the Inverter is
opposite.
PID control will result in diversion if the detected value decreases when the output
frequency of the Inverter increases. If that happens, set n128 for PID control selec-
tion to negative characteristics (e.g., if 1 has been set, change it to 5).
8-2-13 Inverter Vibrates in Energy-saving Control
·The energy-saving settings are incorrect.
Check the frequency of vibration.
Ifthefrequencycoincideswiththepoweraveragingtimeinn143,theInverterisnotin
smoothprobeoperation.Setthe probe operation voltage limitto0 inn144todisable
the probe operation of the Inverter or reduce the set values of n145 (100% probe-
control voltage step) and n146 (5% probe-control voltage step) so that the voltage
change range will be narrower.
Maintenance Operations Chapter 8
To Next Page
Loading...
