Yaskawa Sigma-5 User Manual: Design and Maintenance - Rotary Motors - Analog Voltage and Pulse Train Reference - Manual (Page 376)

10.3 Troubleshooting Malfunction Based on Operation and Conditions of the Servomotor
10-29
10
Trou
blesh
ooting
Improper Stop Po-
sition by Overtrav-
el (OT) Signal
Improper limit switch position and
dog length
−
Install the limit switch at the
appropriate position.
The overtravel limit switch position
is too short for the coasting
distance.
−
Install the overtravel limit switch at
the appropriate position.
Position Error
(Without Alarm)
Noise interference due to incorrect
encoder cable specifications
The encoder cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
2
min.
Use the specified encoder cable.
Noise interference due to length of
encoder cable. Check the length of the encoder
cable.
The encoder cable must be no more
than 50 m.
Noise influence due to damaged
encoder cable. Check if the encoder cable is bent
and the sheath is damaged. Replace the encoder cable and mod-
ify the cable layout.
Excessive noise to encoder cable.
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Change the cable layout so that no
surge is applied.
The FG potential varies because of
influence from machines on the ser-
vomotor side such as the welder.
Check if the machines are correctly
grounded. Properly ground the machines
encoder FG.
SERVOPACK pulse count error due
to noise Check if the I/O signal line from the
encoder is influenced by noise. Take measures against noise in the
encoder wiring.
Excessive vibration and shock to
the encoder
Check if vibration from the machine
occurred or servomotor installation
is incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
Reduce the machine vibration or
mount the servomotor securely.
Unsecured coupling between
machine and servomotor
Check if a position error occurs at
the coupling between machine and
servomotor.
Secure the coupling between the
machine and servomotor.
Noise interference due to improper
I/O signal cable specifications
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
2
min.
Use input signal cable with the
specified specifications.
If the reference pulse input multipli-
cation switching function is being
used, noise may be causing the I/O
signals (/PSEL and /PSELA) used
for this function to be falsely
detected.
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
2
min.
Use input signal cable that satisfy
specifications.
Noise interference due to length of
I/O signal cable
Check the I/O signal cable length.
The I/O signal cable length must be
no more than 3 m.
An encoder fault occurred. (The
pulse count does not change.)
− Replace the servomotor.
A SERVOPACK fault occurred. − Replace the SERVOPACK.
Servomotor Over-
heated
Ambient operating temperature too
high Measure the servomotor ambient
operating temperature. Reduce the ambient operating tem-
perature to 40
°C or less.
Servomotor surface dirty Visually check the surface. Clean dust and oil from the surface.
Servomotor overloaded Check the load status with monitor.
If overloaded, reduce load or
replace with larger capacity SER-
VOPACK and servomotor.
(cont’d)
Problem Probable Cause Investigative Actions Corrective Actions