Omron R88D-GT series User Manual page 467

Symptom Probable cause
There are problems with
the machine's installation.
There is a problem with the
bearings.
The gain is wrong.
The Speed Feedback Filter
Time Constant (Pn13) is
wrong.
Noise is entering the
Control I/O Cable because
the cable does not meet
specifications.
Noise is entering the Con-
trol I/O Cable because the
cable is longer than the
specified length.
Noise is entering the cable
The Servomotor
because the Encoder
is producing
Cable does not meet
unusual noises or
specifications.
the machine is
Noise is entering the
vibrating.
Encoder Cable because
the cable is longer than the
specified length.
Noise is entering the signal
wires because the Encoder
Cable is stuck or the sheath
is damaged.
Too much noise is entering
the Encoder Cable.
The FG's potential is fluctu-
ating due to devices near
the Servomotor, such as
welding machines.
Errors are being caused by
excessive vibration or
shock on the encoder.
The machine and the
Servomotor are resonating.
Items to check
Check whether the Servomotor's
mounting screws are loose.
Check whether the axes are
misaligned in the mechanical
coupling system.
Check whether the coupling is
unbalanced.
Check for noise or vibration around
the bearings.
---
Check the setting of Pn13.
Check that the cable wire is a
twisted-pair wire or shielded
twisted-pair cable with wires of at
2
least 0.08 mm .
Check the length of the Control I/O
Cable.
Check that the cable wires are
shielded twisted-pair wires that are
2
at least 0.12 mm .
Check the length of the Encoder
Cable.
Check the Encoder Cable for cuts
or other damage.
Separate the Encoder Cables far
from high-current lines or check
whether the lines are too close.
Check for ground problems (loss of
ground or incomplete ground) at
equipment such as welding
machines near the Servomotor.
There are problems with mechani-
cal vibration or motor installation
(such as the mounting surface,
attachment, or axial offset).
Check whether the machine is
resonating.
8-3 Troubleshooting
Countermeasures
Tighten the mounting
screws.
Align the mechanical
couplings.
Adjust the coupling's
balance.
Contact your OMRON
representative.
• Use normal mode
autotuning.
• Adjust the gain manually.
Return the setting to 0
(default) or increase the
setting.
Use Control I/O Cable that
meets specifications.
Shorten the Control I/O
Cable to 3 m or less.
Use Encoder Cable that
meets specifications.
Shorten the Encoder Cable
to less than 50 m.
Correct the Encoder Cable's
pathway to prevent damage.
Install the Encoder Cable
where it won't be subjected
to surges.
Ground the equipment
properly and prevent
currents from flowing to the
encoder FG.
Reduce the mechanical
vibration or correct the
Servomotor's installation.
• Readjust the Torque
Command Filter Time
Constant.
• If there is resonance, set
the Notch Filter 1
Frequency (Pn1D) and
Notch Filter 1 Width
(Pn1E).
8-18
8