User`s manual

9 Troubleshooting
9-20
Dynamic Brake
Does Not Operate
(cont’d)
Dynamic brake drive circuit fault –
There is a defective component in
the dynamic brake circuit. Replace
the SERVOPACK.
Abnormal Noise
from Servomotor
The servomotor largely vibrated
during execution of tuning-less
function (factory setting).
Check the servomotor speed wave-
form.
Reduce the load so that the moment
of inertia ratio becomes within the
allowable value, or increase the
load level or lower the tuning level
for the tuning-less level setting
(Fn200).
Mounting is not secured.
Check the mounting status of the
servomotor.
Tighten the mounting screws.
Check if there is misalignment of
couplings.
Align the couplings.
Check if there are unbalanced cou-
plings.
Balance the couplings.
Bearings are defective.
Check for noise and vibration
around the bearings.
Replace the servomotor.
Vibration source at the driven
machine
Check for any foreign matter, dam-
age, or deformations on the machin-
ery's movable parts.
Contact the machine manufacturer.
Noise interference due to incorrect
input/output signal cable specifica-
tions
The I/O signal cables must be
tinned annealed copper shielded
twisted-pair or shielded multi-core
twisted-pair cables with a core of
0.12 mm
2
min.
Use the specified I/O signal wires.
Noise interference due to length of
input/output signal cable
Check the length of the input/output
cable.
The input/output cable must be no
longer than 3 m.
Noise interference due to incorrect
encoder cable specifications
The encoder cable must be tinned
annealed copper shielded twisted-
pair or shielded multi-core twisted-
pair cables with a core of 0.12 mm
2
min.
Use the specified encoder cable.
Noise interference due to length of
encoder cable wiring
Check the length of the encoder
cable.
The encoder cable must be no
longer than 20 m.
Noise interference due to damaged
encoder cable
Check if the encoder cable is bent or
if its sheath is damaged.
Replace the encoder cable and mod-
ify the encoder cable layout.
Excessive noise to the encoder
cable
Check if the encoder cable is bun-
dled with high-current line or near a
high-current line.
Correct the encoder cable layout so
that no surge from high-current
lines is applied.
FG potential varies because of
influence of machines such as weld-
ers at the servomotor.
Check if the machines are correctly
grounded.
Ground machines correctly, and
prevent diversion to the FG at the
PG side.
SERVOPACK pulse counting error
due to noise interference
Check if there is noise interference
on the input/output signal line from
the encoder.
Take measures against noise in the
encoder wiring.
Excessive vibration and shock to
the encoder
Check if vibration from the machine
occurred or servomotor installation
is incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
Reduce vibration from the machine,
or secure the servomotor installa-
tion.
An encoder fault occurred. – Replace the servomotor.
Servomotor
Vibrates at
Frequency of
Approx. 200 to
400 Hz
Unbalanced servo gains
Check to see if the servo gains have
been correctly adjusted.
Execute the advanced autotuning.
Speed loop gain value (Pn100) too
high
Check the speed loop gain value
(Pn100).
Factory setting: Kv = 40.0 Hz
Reduce the speed loop gain value
(Pn100).
Position loop gain value (Pn102)
too high
Check the position loop gain value
(Pn102).
Factory setting: Kp = 40.0/s
Reduce the position loop gain value
(Pn102).
(cont’d)
Problem Probable Cause Investigative Actions Corrective Actions