YASKAWA SGDV User Manual page 280

Problem Probable Cause
Unbalanced servo gains
Speed loop gain value (Pn100) too
high.
Servomotor
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)
Unbalanced servo gains
Speed loop gain value (Pn100) too
high
High Motor Speed
Position loop gain value (Pn102)
Overshoot on
too high
Starting and
Stopping
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.
Absolute Encoder
Position
FG potential varies because of
Difference Error
influence of machines such as weld-
(The position
ers at the servomotor.
saved in the host
controller when
SERVOPACK pulse counting error
the power was
due to noise interference
turned OFF is
different from the
position when the
Excessive vibration and shock to
power was next
the encoder
turned ON.)
An encoder fault occurred.
A SERVOPACK fault occurred.
(The pulse count does not change.)
Host controller multiturn data read-
ing error
9.3 Troubleshooting Malfunction Based on Operation and Conditions of the Servomotor
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)
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