9.2 Troubleshooting
9 -33
Symptom
Remedy
Inspection
Cause
Servomotor Speed
Unstable
Wiring connection to motor
defective
Check connection of power
lead (U, V, and W phases) and
encoder connectors.
Tighten any loose terminals or
connectors.
Servomotor Vibrates at
Approximately 200 to
400 Hz.
Speed loop gain value too
high.
---
Reduce speed loop gain
(Pn100) preset value.
400 Hz.
Speed/position reference input
lead too long.
---
Minimize length of speed/posi-
tion reference input lead, with
impedance not exceeding sev-
eral hundred ohms
Speed/position reference input
lead is bundled with power
cables.
---
Separate reference input lead
at least 30 cm from power
cables.
High Rotation Speed
Overshoot on Starting
and Stopping.
Speed loop gain value too
high.
---
Reduce speed loop gain
(Pn100) preset value.
Increase integration time
constant (Pn101).
Speed loop gain is too low
compared to position loop
gain.
---
Increase the value of user
constant Pn100 (speed loop
gain).
Reduce the integration time
constant (Pn101).
Servomotor Overheated
Ambient temperature too high
Measure Servomotor ambient
temperature.
Reduce ambient temperature
to 40
°
C max.
Servomotor surface dirty
Visual check
Clean dust and oil from motor
surface.
Overloaded
Run under no load.
Reduce load or replace with
larger capacity Servomotor.
Abnormal Noise
Mechanical mounting incor-
rect
Servomotor mounting screws
loose?
Tighten mounting screws.
Coupling not centered?
Center coupling.
Coupling unbalanced?
Balance coupling.
Bearing defective
Check noise and vibration near
bearing.
Consult your Yaskawa repre-
sentative if defective.
Machine causing vibrations
Foreign object intrusion, dam-
age or deformation of sliding
parts of machine.
Consult with machine
manufacturer.
Speed Reference 0 V but
Servomotor Rotates.
Speed reference voltage offset
applied
---
Adjust reference offset.
Refer to section
s 7.2.4
and
7.2.5
9
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