Yaskawa SGDS Sigma III Servo Amplifier - Manual (Page 313)

10 Inspection, Maintenance, and Troubleshooting
10.1.5 Troubleshooting for Malfunction without Alarm Display
10-24
Overtravel
(OT)
(Movement
over the zone
specified by
the host con-
troller) An overtravel signal does not change
{(P-OT (1NC-7) or N-OT (1CN-8) is
at “H”}. Check if the voltage of input signal external
power supply (+24 V) is correct. Connect to the external +24 V power supply.
Check if the overtravel limit switch (SW)
operates properly. Correct the overtravel limit SW.
Check if the overtravel limit switch (SW) is
connected correctly. Correct the overtravel limit SW wiring.
The overtravel signal does not
operate normally (P-OT or N-OT
signal sometimes changes). Check the fluctuation of the input signal
external power supply (+24 V) voltage. Stabilize the external +24 V power supply voltage.
Check if the overtravel limit switch (SW)
activate correctly. Adjust the overtravel limit SW so that it operates
correctly.
Check if the overtravel limit switch wiring
is correct. (check for damaged cables or
loosen screws.) Correct the overtravel limit SW wiring.
Incorrect P-OT signal selection Check the P-OT signal selection Pn50A.3. Correct the setting of P-OT signal selection Pn50A.3.
Check the N-OT signal selection Pn50B.0. Correct the setting of N-OT signal selection Pn50B.0.
Incorrect servomotor stop method
selection Check if “coast to stop” in servo OFF status
is selected. Check Pn001.0 and Pn001.1.
Check if “coast to stop” in torque control
mode is selected. Check Pn001.0 and Pn001.1.
Improper LS overtravel position
setting The distance to the LS overtravel (OT) is
too short considering the coasting distance. Correct the LS OT position.
Noise interference due to improper
encoder cable specifications The encoder cable specifications must be:
Tinned annealed copper twisted-pair or
twisted-pair shielded wire with core 0.12
mm
2 (0.0002 in 2 ) min.
Use encoder cable with the specified specifications.
Noise interference because the
encoder cable distance is too long. The wiring distance must be 20 m(65.6 ft)
max. The encoder cable distance must be within the specified
range.
Noise influence due to damaged
encoder cable Check if the encoder cable is bent or its
sheath is damaged. Correct the encoder cable layout.
Excessive noise interference to
encoder cable Check if the encoder cable is bundled with a
high-current line or near high-current line. Change the encoder cable layout so that no surge is
applied.
FG varies because machine such as
welder installed on servomotor side. Check if grounding of the machine is made
correctly. Ground the machine separately from PG side FG.
SERVOPACK pulse count error due
to noise Check if the signal line from the encoder is
influenced by noise. Take a measure against noise for the encoder wiring.
Excessive vibration and shock to the
encoder Machine vibration occurred or servomotor
mounting such as mounting surface
precision, fixing, alignment is incorrect. Reduce the machine vibration or mount the servomotor
securely.
Encoder fault An encoder fault occurred. Replace the servomotor.
SERVOPACK fault A SERVOPACK fault occurred. Replace the SERVOPACK.
Position error
(without
alarm) 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
input signal cable specifications The input signal cable specifications must
be:
Twisted-pair or twisted-pair shielded wire
with core 0.12 mm
2 (0.0002 in 2 ) min. and
tinned annealed copper twisted wire.
Use input signal cable with the specified specifications.
Encoder fault (pulse count does not
change) An encoder fault occurred. (pulse count
does not change) Replace the servomotor.
Servomotor
Overheated Ambient temperature too high Measure servomotor ambient temperature. Reduce ambient temperature to 40 °C (104 °F) max.
Servomotor surface dirty Check visually. Clean dust and oil from motor surface.
Overloaded Run under no load. Reduce load or replace with larger capacity servomotor.
Table 10.5 Troubleshooting for Malfunction without Alarm Display (Cont’d)
Symptom Cause
Inspection Corrective Actions
: Turn OFF the servo system before executing operations.