YASKAWA SGM7D-30F Product Manual page 210

Problem Possible Cause
The servo gains are not bal-
anced.
The setting of Pn100 (Speed
Loop Gain) is too high.
The setting of Pn102 (Posi-
tion Loop Gain) is too high.
Large Motor
Speed
Overshoot
The setting of Pn101 (Speed
on Starting
Loop Integral Time Con-
and Stop-
stant) is not appropriate.
ping
The setting of Pn103
(Moment of Inertia Ratio or
Mass Ratio) is not appropri-
ate.
The torque reference is satu-
rated.
The force limits (Pn483 and
Pn484) are set to the default
values.
Noise interference occurred
because of incorrect Encoder
Cable specifications.
Absolute
Encoder
Position
Noise interference occurred
Deviation
because the Encoder Cable
Error (The
is too long.
position
that was
Noise interference occurred
saved in the
because the Encoder Cable
host con- is damaged.
troller when
the power
Replace the Encoder Cable
was turned
and correct the cable instal-
OFF is dif-
lation environment.
ferent from
the posi-
There is variation in the FG
tion when
potential because of the
the power
influence of machines on the
was next
Servomotor side, such as a
turned ON.)
welder.
There is a SERVOPACK
pulse counting error due to
noise.
3.3 FT82 SERVOPACK with MECHATROLINK-III Communications References
3.3.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
Confirmation
Check to see if the servo
gains have been cor-
rectly 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%.
Check the Encoder Cable
to see if it satisfies speci-
fications. Use a shielded
twisted-pair wire cable or
a screened twisted-pair
cable with conductors of
at least 0.12 mm
Check the length of the
Encoder Cable.
Check the Encoder Cable
to see if it is pinched or
the sheath is damaged.
Check to see if the
Encoder Cable is bundled
with a high-current line or
installed near a high-cur-
rent line.
Check to see if the
machines are correctly
grounded.
Check to see if there is
noise interference on the
I/O signal line from the
encoder or Serial Con-
verter Unit.
Continued from previous page.
Correction
Perform autotuning
without a host refer-
ence.
Set Pn100 to an appro-
priate value.
Set Pn102 to an appro-
priate value.
Set Pn101 to an appro-
priate value.
Set Pn103 to an appro-
priate value.
Use the mode switch.
Set Pn483 and Pn484
to appropriate values.
Use cables that satisfy
the specifications.
2
.
Rotary Servomotors:
The Encoder Cable
length must be 50 m
max.
Replace the Encoder
Cable and correct the
cable installation envi-
ronment.
Correct the cable lay-
out so that no surge is
applied by high-current
lines.
Properly ground the
machines to separate
them from the FG of
the encoder.
Implement counter-
measures against noise
for the encoder or
Serial Converter Unit
wiring.
Continued on next page.
Reference
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3-141