9 Inspection, Maintenance, and Troubleshooting
9.1.4 Troubleshooting for Malfunction without Alarm Display
9-20
Overtravel
(OT)
(Movement
over the zone
specified by
the host con-
troller)
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 overtravel position set-
ting
The distance to the position of OT
(overtravel) is too short relative to coast-
ing distance.
Correct the 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 wires 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 maximum allowable cable length is
20 m (65.6 ft).
The encoder cable distance must be within the speci-
fied 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-cur-
rent 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
correctly grounded.
Ground encoder to FG; do not share a ground with a
machine.
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
Vibration from the machine or servomo-
tor due to incorrect installation
Reduce vibration for the machine or mount the servo-
motor securely.
Encoder fault
Encoder fault
Replace the servomotor.
SERVOPACK fault
SERVOPACK fault
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 servomo-
tor.
Secure the coupling between the machine and servo-
motor.
Noise interference due to improper
input signal cable specifications
The input signal cable specifications
must be:
Tinned annealed copper twisted-pair or
twisted-pair shielded wires with core
0.12 mm
2
(0.0002 in
2
) min.
Use input signal cable with the specified specifica-
tions.
Noise interference because the
input signal cable distance is too
long.
The maximum allowable cable length is
3 m (9.84 ft).
The input signal cable distance must be within the
specified range.
Encoder fault (pulse count does
not change)
Encoder fault.
Replace the servomotor.
Servomotor
Overheated
Ambient temperature too high
Measure servomotor ambient tempera-
ture.
Reduce ambient temperature to the maximum allow-
able value of 40
°
C (104
°
F) or lower.
Servomotor surface dirty
Visual check
Clean dust and oil from motor surface.
Overloaded
Run under no load.
Reduce load or replace with larger capacity servomo-
tor.
Table 9.5 Troubleshooting for Malfunction without Alarm Display (Cont’d)
Symptom
Cause
Inspection
Corrective Actions
: Turn OFF the servo system before executing operations.
SIEPS80000025.book 20 ページ ２００４年１０月２５日 月曜日 午前１１時５７分
