YASKAWA S-V Series User Manual page 191

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