5.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
5
Maintenance
5-47
Large Motor
Speed
Overshoot
on Starting
and Stop-
ping
The servo gains are not
balanced.
Check to see if the servo
gains have been correctly
tuned.
Perform autotuning with-
out a host reference.
*
The setting of Pn100
(Speed Loop Gain) is
too high.
Check the setting of Pn100.
The default setting is Kv =
40.0 Hz.
Set Pn100 to an appropri-
ate value.
–
The setting of Pn102
(Position Loop Gain) is
too high.
Check the setting of Pn102.
The default setting is Kp =
40.0/s.
Set Pn102 to an appropri-
ate value.
–
The setting of Pn101
(Speed Loop Integral
Time Constant) is not
appropriate.
Check the setting of Pn101.
The default setting is Ti =
20.0 ms.
Set Pn101 to an appropri-
ate value.
–
The setting of Pn103
(Moment of Inertia
Ratio or Mass Ratio) is
not appropriate.
Check the setting of Pn103.
Set Pn103 to an appropri-
ate value.
–
The torque reference is
saturated.
Check the waveform of the
torque reference.
Use the mode switch.
–
The force limits (Pn483
and Pn484) are set to
the default values.
The default values of the
force limits and Pn483 =
30% and Pn484 = 30%.
Set Pn483 and Pn484 to
appropriate values.
*
Absolute
Encoder
Position
Deviation
Error (The
position
that was
saved in the
host con-
troller when
the power
was turned
OFF is dif-
ferent from
the posi-
tion when
the power
was next
turned ON.)
Noise interference
occurred because of
incorrect Encoder
Cable specifications.
Turn OFF the power supply
to the servo system.
Check the Encoder Cable to
see if it satisfies specifica-
tions. Use a shielded
twisted-pair wire cable or a
screened twisted-pair cable
with conductors of at least
0.12 mm
2
.
Use cables that satisfy the
specifications.
–
Noise interference
occurred because the
Encoder Cable is too
long.
Turn OFF the power supply
to the servo system.
Check the length of the
Encoder Cable.
The Encoder Cable length
must be 50 m max.
–
Noise interference
occurred because the
Encoder Cable is dam-
aged.
Turn OFF the power supply
to the servo system.
Check the Encoder Cable to
see if it is pinched or the
sheath is damaged.
Replace the Encoder
Cable and correct the
cable installation environ-
ment.
–
Replace the Encoder
Cable and correct the
cable installation envi-
ronment.
Turn OFF the power supply
to the servo system.
Check to see if the Encoder
Cable is bundled with a
high-current line or installed
near a high-current line.
Correct the cable layout so
that no surge is applied by
high-current lines.
–
There is variation in the
FG potential because
of the influence of
machines on the Ser-
vomotor side, such as
a welder.
Turn OFF the power supply
to the servo system.
Check to see if the
machines are correctly
grounded.
Properly ground the
machines to separate
them from the FG of the
encoder.
–
There is a SERVOPACK
pulse counting error
due to noise.
Turn OFF the power supply
to the servo system.
Check to see if there is
noise interference on the I/O
signal line from the encoder
or Serial Converter Unit.
Implement countermea-
sures against noise for the
encoder or Serial Con-
verter Unit wiring.
–
Continued on next page.
Continued from previous page.
Problem
Possible Cause
Confirmation
Correction
Reference