Yaskawa Sigma-5 User Manual: Design and Maintenance - Rotary Motors - Manual (Page 296)

9.3 Troubleshooting Malfunction Based on Operation and Conditions of the Servomotor
9-31
T
roubleshooting
Overtravel (OT)
Forward or reverse run prohibited
signal is input.
Check the external power supply
(+24 V) voltage for the input signal. Correct the external power supply
(+24 V) voltage.
Check if the overtravel limit switch
operates properly.
Correct the overtravel limit switch.
Check if the overtravel limit switch
is wired correctly. Correct the overtravel limit switch
wiring.
Check the settings for Pn50A and
Pn50B.
Set the parameters correctly.
Forward or reverse run prohibited
signal is malfunctioning.
Check the fluctuation of the input
signal external power supply (+24
V) voltage.
Stabilize the external power supply
(+24 V) voltage.
Check if the overtravel limit switch
operates correctly. Stabilize the operation of the over-
travel limit switch.
Check if the overtravel limit switch
wiring is correct. (check for dam-
aged cables or loose screws.)
Correct the overtravel limit switch
wiring.
Incorrect forward or reverse run
prohibited signal (P-OT/N-OT)
allocation (parameters Pn50A.3,
Pn50B.0)
Check if the P-OT signal is allo-
cated in Pn50A.3. If another signal is allocated in
Pn50A.3, select P-OT.
Check if the N-OT signal is allo-
cated in Pn50B.0. If another signal is allocated in
Pn50B.0, select N-OT.
Incorrect servomotor stop method
selection
Check Pn001.0 and Pn001.1 when
the servomotor power is OFF. Select a servo mode stop method
other than “coast to stop.”
Check Pn001.0 and Pn001.1 when
in torque control. Select a servo mode stop method
other than “coast to stop.”
Improper Position
to Stop by
Overtravel (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 improper
encoder cable specifications
The encoder cable must be tinned
annealed copper twisted-pair or
shielded twisted-pair cable with a
core of 0.12 mm
2 min.
Use encoder cable with the speci-
fied specifications.
Noise interference due to length of
encoder cable
Check the encoder cable length.
The encoder cable length must be
less than 20 m.
Noise influence due to damaged
encoder cable Check if the encoder cable is bent or
if its sheath is damaged. Replace the encoder cable and cor-
rect the encoder cable layout.
Excessive noise interference to
encoder cable
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Change the encoder cable layout so
that no surge is applied.
FG potential varies because of
influence of machines such as weld-
ers at the servomotor.
Check if the machines are correctly
grounded.
Ground machines correctly, and
prevent diversion to the FG at the
PG side.
SERVOPACK pulse count error due
to noise
Check if the input/output 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
twisted-pair or shielded twisted-pair
cable with a core of 0.12 mm
2 min.
and tinned annealed copper twisted
wire.
Use input signal cable with the
specified specifications.
(cont’d)
Problem Probable Cause Investigative Actions Corrective Actions