YASKAWA S-V Series User Manual page 194

9 Troubleshooting
Problem
Position Error
(Without Alarm)
Servomotor
Overheated
9-24
Probable Cause
Noise interference due to improper
encoder cable specifications
Noise interference due to length of
encoder cable
Noise influence due to damaged
encoder cable
Excessive noise interference to
encoder cable
FG potential varies because of
influence of machines such as weld-
ers at the servomotor.
SERVOPACK pulse counting error
due to noise interference
Excessive vibration and shock to
the encoder
Unsecured coupling between
machine and servomotor
Noise interference due to improper
I/O signal cable specifications
Noise interference due to length of
I/O signal cable
An encoder fault occurred. (The
pulse count does not change.)
A SERVOPACK fault occurred.
Ambient temperature too high
Servomotor surface dirty
Servomotor overloaded
Investigative Actions
The encoder cable must be tinned
annealed copper shielded twisted-
pair or shielded multi-core twisted-
pair cable with a core of 0.12 mm
min.
Check the encoder cable length.
Check if the encoder cable is bent or
if its sheath is damaged.
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Check if the machines are correctly
grounded.
Check if there is noise interference
on the I/O signal line from the
encoder.
Check if vibration from the machine
occurred or servomotor installation
is incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
Check if a position error occurs at
the coupling between machine and
servomotor.
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or shielded multi-core twisted-
pair cables with a core of 0.12 mm
min.
Check the I/O signal cable length.
–
–
Measure the servomotor ambient
temperature.
Visually check the surface.
Check the load status with monitor.
Corrective Actions
Use the specified encoder cable.
2
The encoder cable must be no lon-
ger than 20 m.
Replace the encoder cable and cor-
rect the encoder cable layout.
Correct the encoder cable layout so
that no surge from high-current
lines is applied.
Ground machines correctly, and
prevent diversion to the FG at the
PG side.
Take measures against noise in the
encoder wiring.
Reduce vibration from the machine,
or secure the servomotor installa-
tion.
Secure the coupling between the
machine and servomotor.
Use the specified I/O signal cable.
2
The I/O signal cable must be no lon-
ger than 3 m.
Replace the servomotor.
Replace the SERVOPACK.
Lower the ambient temperature to
40°C or less.
Clean dust and oil from the surface.
If overloaded, reduce load or
replace with larger capacity SER-
VOPACK and servomotor.
(cont'd)