YASKAWA Sigma-7-Series Product Manual page 127

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