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Sigma II User's Manual
Symptom
Servomotor vibrates
at approximately 200
to 400Hz.
High rotation speed
overshoot on starting
and stopping.
Servomotor over-
heated
Abnormal noise
Speed Reference 0V
but Servomotor
Rotates.
Cause
Speed loop gain value too
high.
Speed/position reference
input wire too long.
Speed/position reference
inputwire is bundled with
power cables.
Speed loop gain value too
high.
Speed loop gain is too low
compared to position loop
gain.
Ambient temperature too
high
Servomotor surface dirty
Overloaded
Incorrect mechanical
mounting
Bearing defective
Machine causing vibra-
tions
Speed reference voltage
offset applied
Chapter 9: Inspection, Maintenance, and Troubleshooting
Comment
–––
–––
–––
–––
–––
Measure servomotor ambient
temperature.
Visual check
Run under no load.
Servomotor mounting screws
loose?
Coupling not centered?
Coupling unbalanced?
Check noise and vibration
near bearing.
Foreign object intrusion, dam-
age, or deformation of sliding
parts of machine.
–––
9-36
Solution
Reduce speed loop gain
(Pn100) preset value.
Minimize length of speed/
position reference input
lwire, with impedance not
exceeding several hundred
ohms
Separate reference input
wire at least 30cm from
power cables.
Reduce speed loop gain
(Pn100) preset value.
Increase integration time
constant (Pn101).
Increase the value of
parameter Pn100 (speed
loop gain).
Reduce the integration time
constant (Pn101).
Reduce ambient tempera-
ture to 40°C maximum.
Clean dust and oil from
motor surface.
Reduce load or replace with
larger capacity servomotor.
Tighten mounting screws.
Center coupling.
Balance coupling.
Consult your Yaskawa rep-
resentative if defective.
Consult with machine man-
ufacturer.
Adjust reference offset.
Refer to sections 7.2.4 and
7.2.5
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