YASKAWA SGMJV User Manual page 360

10 Troubleshooting
Problem
Improper Position
to Stop by
Overtravel (OT)
Signal
Position Error
(Without Alarm)
Servomotor
Overheated
10-28
Probable Cause
Improper limit switch position and
dog length
The overtravel limit switch position
is too short for the coasting
distance.
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 count error due
to noise
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 twisted-pair or
shielded twisted-pair cable with a
2
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 the input/output signal line
from the encoder is influenced by
noise.
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
twisted-pair or shielded twisted-pair
2
cable with a core of 0.12 mm
and tinned annealed copper twisted
wire.
Check the I/O signal cable length.
−
−
Measure the servomotor ambient
temperature.
Visually check the surface.
Check the load status with monitor.
Corrective Actions
Install the limit switch at the
appropriate position.
Install the overtravel limit switch at
the appropriate position.
Use encoder cable with the speci-
fied specifications.
The encoder cable length must be
no more than 20 m.
Replace the encoder cable and cor-
rect the encoder cable layout.
Change the encoder cable layout so
that no surge is applied.
Ground machines correctly, and
prevent diversion to the FG at the
PG side.
Take measures against noise in the
encoder wiring.
Reduce the machine vibration or
mount the servomotor securely.
Secure the coupling between the
machine and servomotor.
Use input signal cable with the
min.
specified specifications.
The I/O signal cable length must be
no more than 3 m.
Replace the servomotor.
Replace the SERVOPACK.
Reduce the ambient temperature to
40°C or less.
Clean dust and oil from the surface.
If overloaded, reduce load or
replace with larger capacity servo-
motor.