YASKAWA SGD7S series Product Manual page 117

Problem Possible Cause
The Encoder Cable was sub-
jected to excessive noise
interference.
There is variation in the FG
potential because of the
influence of machines on the
Servomotor side, such as a
welder.
There is a SERVOPACK
pulse counting error due to
noise.
Abnormal
Noise from
Servomotor
The encoder was subjected
to excessive vibration or
shock.
A failure occurred in the
encoder.
A failure occurred in the
Serial Converter Unit.
A failure occurred in the linear
encoder.
The servo gains are not bal-
anced.
The setting of Pn100 (Speed
Loop Gain) is too high.
Servomotor
Vibrates at
The setting of Pn102 (Posi-
Frequency
tion Loop Gain) is too high.
of Approx.
200 Hz to
400 Hz.
The setting of Pn101 (Speed
Loop Integral Time Con-
stant) is not appropriate.
The setting of Pn103
(Moment of Inertia Ratio or
Mass Ratio) is not appropri-
ate.
4.1 SERVOPACKs with Analog Voltage/Pulse Train References
4.1.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
Confirmation
Check to see if the
Encoder Cable is bundled
with a high-current line or
installed near a high-cur-
rent line.
Check to see if the
machines are correctly
grounded.
Check to see if there is
noise interference on the
signal line from the
encoder.
Check to see if vibration
from the machine
occurred. Check the Ser-
vomotor installation
(mounting surface preci-
sion, securing state, and
alignment).
Check the linear encoder
installation (mounting sur-
face precision and secur-
ing method).
–
–
–
Check to see if the servo
gains have been cor-
rectly tuned.
Check the setting of
Pn100.
The default setting is Kv =
40.0 Hz.
Check the setting of
Pn102.
The default setting is Kp
= 40.0/s.
Check the setting of
Pn101.
The default setting is Ti =
20.0 ms.
Check the setting of
Pn103.
Continued from previous page.
Correction Reference
Correct the cable lay-
out so that no surge is
–
applied by high-current
lines.
Properly ground the
machines to separate
–
them from the FG of
the encoder.
Implement counter-
measures against noise
–
for the encoder wiring.
Reduce machine vibra-
tion. Improve the
mounting state of the
–
Servomotor or linear
encoder.
Replace the Servomo-
–
tor.
Replace the Serial Con-
–
verter Unit.
Replace the linear
–
encoder.
Perform autotuning
*
without a host refer-
ence.
Set Pn100 to an appro-
–
priate value.
Set Pn102 to an appro-
–
priate value.
Set Pn101 to an appro-
–
priate value.
Set Pn103 to an appro-
–
priate value.
Continued on next page.
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