YASKAWA E-V Series User Manual page 277

8 Troubleshooting
Problem
Servomotor
Vibrates at
Frequency of
Approx. 200 to
400 Hz.
High Motor 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 was next
turned ON.)
8-22
Probable Cause
Unbalanced servo gains
Speed loop gain value (Pn100) too
high.
Position loop gain value (Pn102)
too high.
Incorrect speed loop integral time
constant (Pn101)
Incorrect moment of inertia ratio
(Pn103)
Unbalanced servo gains
Speed loop gain value (Pn100) too
high
Position loop gain value (Pn102)
too high
Incorrect speed loop integral time
constant (Pn101)
Incorrect moment of inertia ratio
data (Pn103)
Noise interference due to incorrect
cable specifications of encoder
cable.
Noise interference due to length of
encoder cable.
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.
A SERVOPACK fault occurred.
(The pulse count does not change.)
Host controller multiturn data read-
ing error
Investigative Actions
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).
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).
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 servomotor installation
is incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
−
−
Check the error detection section of
the host controller.
Check if the host controller is exe-
cuting data parity checks.
Check noise in the cable between
the SERVOPACK and the host con-
troller.
Corrective Actions
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).
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).
Use the specified encoder cable.
2
The encoder cable must be no more
than 50 m.
Replace the encoder cable and cor-
rect the cable layout.
Correct the cable layout so that no
surge is applied.
Ground machines correctly, and
prevent diversion to the FG on the
encoder 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 multiturn data parity
check.
Take measures against noise, and
again execute a multiturn data par-
ity check.
(cont'd)