YASKAWA SGD7S-1R9D Product Manual page 540

15.4 Troubleshooting Based on the Operation and Conditions of the Servomotor
Problem
Position
Deviation
(without
Alarm)
15-60
Possible Cause
Noise interference occurred
because of incorrect Encoder
Cable specifications.
Noise interference occurred
because the Encoder Cable
is too long.
Noise interference occurred
because the Encoder Cable
is damaged.
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.
Confirmation
Turn OFF the Servo Sys-
tem. Check the Encoder
Cable to see if is satisfies
specifications. Use a
shielded twisted-pair wire
cable or a screened
twisted-pair cable with
conductors of at least
2
0.12 mm .
Turn OFF the Servo Sys-
tem. Check the length of
the Encoder Cable.
Turn OFF the Servo Sys-
tem. Check the Encoder
Cable to see if it is
pinched or the sheath is
damaged.
Turn OFF the Servo Sys-
tem. Check to see if the
Encoder Cable is bundled
with a high-current line or
installed near a high-cur-
rent line.
Turn OFF the Servo Sys-
tem. Check to see if the
machines are correctly
grounded.
Turn OFF the Servo Sys-
tem. Check to see if there
is noise interference on
the I/O signal line from
the encoder or Serial
Converter Unit.
Continued from previous page.
Correction Reference
Use cables that satisfy
–
the specifications.
• 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.
Replace the Encoder
Cable and correct the
–
cable installation envi-
ronment.
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
–
or Serial Converter Unit
wiring.
Continued on next page.