YASKAWA UAK series User Manual page 297

Problem Probable Cause
Mounting is not secured.
Bearings are defective.
Vibration source at the driven
machine
Noise interference due to incorrect
I/O signal cable specifications
Noise interference due to length of
I/O signal cable
Abnormal Noise Noise interference due to incorrect
from Servomotor encoder cable specifications
Noise interference due to length of
encoder cable
Noise interference due to damaged
encoder cable
Excessive noise to the encoder
cable
The FG potential varies because of
influence from machines on the ser-
vomotor side, such as the welder.
SERVOPACK pulse counting error
due to noise interference
Excessive vibration and shock to
the encoder
Encoder failure
Unbalanced servo gains
Speed loop gain value (Pn100) too
high
Motor Vibrates at
Position loop gain value (Pn102)
Frequency of
too high
Approx. 200 to
400 Hz.
Incorrect speed loop integral time
constant (Pn101)
Incorrect moment of inertia ratio
(Pn103)
11.5 Troubleshooting Malfunction Based on Operation and Conditions of the Motor
Investigative Actions
Check if there are any loose mount-
ing screws.
Check if there is misalignment of
couplings.
Check if there are unbalanced cou-
plings.
Check for noise and vibration
around the bearings.
Check for any foreign matter, dam-
age, or deformations on the machin-
ery's movable parts.
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
min.
Check the length of the I/O signal
cable.
The encoder cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
min.
Check the length of the encoder
cable.
Check if the encoder cable is bent
and the sheath is damaged.
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Check if the machines are correctly
grounded.
Check if there is noise interference
on the I/O signal line from the
encoder.
Check if vibration from the machine
occurred or motor installation is
incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
−
Check to see if the servo gains have
been correctly adjusted.
Check the speed loop gain (Pn100).
Factory setting: Kv = 40.0 Hz
Check the position loop gain
(Pn102).
Factory setting: Kp = 40.0/s
Check the speed loop integral time
constant (Pn101).
Factory setting: Ti = 20.0 ms
Check the moment of inertia ratio
(Pn103).
Corrective Actions
Tighten the mounting screws.
Align the couplings.
Balance the couplings.
Replace the motor.
Contact the machine manufacturer.
Use the specified I/O signal cable.
2
The I/O signal cable length must be
no more than 3 m.
Use the specified encoder cable.
2
The encoder cable must be no more
than 20 m.
Replace the encoder cable and mod-
ify the encoder cable layout.
Correct the encoder cable layout so
that no surge is applied.
Properly ground the machines to
separate from the encoder FG.
Take measures against noise in the
encoder wiring.
Reduce vibration from the machine,
or secure the motor installation.
Replace the motor.
Execute the advanced autotuning.
Reduce the speed loop gain
(Pn100).
Reduce the position loop gain
(Pn102).
Correct the speed loop integral time
constant (Pn101).
Correct the moment of inertia ratio
(Pn103).
(cont'd)
1 1
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