YASKAWA S-V Series User Manual page 192

9 Troubleshooting
Problem
Servomotor
Vibrates at
Frequency of
Approx. 200 to
400 Hz
(cont'd)
High Rotation
Speed Overshoot
on Starting and
Stopping
Absolute Encoder
Position
Difference Error
(The position
saved in the host
controller when
the power was
turned OFF is
different from the
position when the
power is next
turned ON.)
9-22
Probable Cause
Incorrect speed loop integral time
constant value (Pn101)
Incorrect moment of inertia ratio
value (Pn103)
Unbalanced servo gains
Speed loop gain value (Pn100) too
high
Position loop gain value (Pn102)
too high
Incorrect speed loop integral time
constant value (Pn101)
Incorrect moment of inertia ratio
value (Pn103)
Noise interference due to improper
encoder cable specifications
Noise interference due to length of
encoder cable
Noise interference due to damaged
encoder cable
Excessive noise interference at 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.
A SERVOPACK fault occurred.
(The pulse count does not change.)
Host controller multi-turn data read-
ing error
Investigative Actions
Check the speed loop integral time
constant (Pn101).
Factory setting: Ti = 20.0 ms
Check the moment of inertia ratio
value (Pn103).
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
Check the speed loop integral time
constant value (Pn101).
Factory setting: Ti = 20.0 ms
Check the moment of inertia ratio
value (Pn103).
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 encoder cable length.
Check if the encoder cable is bent or
if its sheath is damaged.
Check if the encoder cable is bun-
dled with a high-current line or near
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 the error detection section at
the host controller.
Check if the host controller is exe-
cuting data parity checks.
Check noise in the input/output sig-
nal line between the SERVOPACK
and the host controller.
Corrective Actions
Correct the speed loop integral time
constant value (Pn101).
Correct the moment of inertia ratio
value (Pn103).
Execute the advanced autotuning.
Reduce the speed loop gain value
(Pn100).
Reduce the position loop gain value
(Pn102).
Correct the speed loop integral time
constant value (Pn101).
Correct the moment of inertia ratio
value (Pn103).
Use the specified encoder cable.
2
The encoder cable must be no lon-
ger than 20 m.
Replace the encoder cable and cor-
rect 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.
Replace the SERVOPACK.
Correct the error detection section
of the host controller.
Execute a multi-turn data parity
check.
Take measures against noise, and
again execute a multi-turn data par-
ity check.
(cont'd)