YASKAWA SGD7S series - Page 539

12.4 Troubleshooting Based on the Operation and Conditions of the Servomotor
12-63
12
Maintenance
Position
Deviation
(without
Alarm)
Noise interference occurred
because of incorrect Encoder
Cable specifications.
Check the Encoder Cable
to see if it satisfies speci-
fications. Use shielded
twisted-pair cables or
screened twisted-pair
cables with conductors of
at least 0.12 mm
2
(stranded wire).
Use cables that satisfy
the specifications.
–
Noise interference occurred
because the Encoder Cable
is too long.
Check the length of the
Encoder Cable.
• Rotary Servomotors:
The Encoder Cable
length must be 50 m
max.
• Linear Servomotors:
Make sure that the
Serial Converter Unit
cable is no longer
than 20 m and that
the Linear Encoder
Cable and the Sensor
Cable are no longer
than 15 m each.
–
Noise interference occurred
because the Encoder Cable
is damaged.
Check the Encoder Cable
to see if it is pinched or
the sheath is damaged.
Replace the Encoder
Cable and correct the
cable installation envi-
ronment.
–
The Encoder Cable was sub-
jected to excessive noise
interference.
Check to see if the
Encoder Cable is bundled
with a high-current line or
installed near a high-cur-
rent line.
Correct the cable lay-
out so that no surge is
applied by high-current
lines.
–
There is variation in the FG
potential because of the
influence of machines on the
Servomotor side, such as a
welder.
Check to see if the
machines are correctly
grounded.
Properly ground the
machines to separate
them from the FG of
the encoder.
–
There is a SERVOPACK
pulse counting error due to
noise.
Check to see if there is
noise interference on the
I/O signal line from the
encoder or Serial Con-
verter Unit.
Implement counter-
measures against noise
for the encoder wiring
or Serial Converter Unit
wiring.
–
The encoder was subjected
to excessive vibration or
shock.
Check to see if vibration
from the machine
occurred.
Check the Servomotor
installation (mounting sur-
face precision, securing
state, and alignment).
Check the linear encoder
installation (mounting sur-
face precision and secur-
ing method).
Reduce machine vibra-
tion. Improve the
mounting state of the
Servomotor or linear
encoder.
–
The coupling between the
machine and Servomotor is
not suitable.
Check to see if position
offset occurs at the cou-
pling between machine
and Servomotor.
Correctly secure the
coupling between the
machine and Servomo-
tor.
–
Noise interference occurred
because of incorrect I/O sig-
nal cable specifications.
Check the I/O signal
cables to see if they sat-
isfy specifications. Use
shielded twisted-pair
cables or screened
twisted-pair cables with
conductors of at least
0.12 mm
2
(stranded wire).
Use cables that satisfy
the specifications.
–
Continued on next page.
Continued from previous page.
Problem Possible Cause Confirmation Correction Reference