11 Inspection, Maintenance, and Troubleshooting
11.2.3 Troubleshooting of the Servo Drive Alarms
11-26
A.BF4:
System Alarm 4
SERVOPACK failure
−
Turn the power supply OFF and
then ON again. If the alarm still
occurs, the SERVOPACK may be
faulty. Replace the SERVOPACK.
A.C10:
Servo Overrun
Detected
(Detected when the ser-
vomotor power is ON.)
The order of phases U, V, and W
in the servomotor wiring is incor-
rect.
Check the servomotor wiring.
Confirm that the servomotor is cor-
rectly wired.
Encoder failure
−
If the alarm still occurs after turning
the power OFF and then ON again,
even though the servomotor is cor-
rectly wired, the servomotor may be
faulty. Replace the servomotor.
SERVOPACK failure
−
Turn the power supply OFF and
then ON again. If the alarm still
occurs, the SERVOPACK may be
faulty. Replace the SERVOPACK.
A.C2A:
Pulse Encoder Phase
C Error/Pulse Error
An error occurred in the feedback
pulse count of the pulse encoder.
Check the signal wiring of the pulse
encoder.
Correct the wiring of the pulse
encoder.
Malfunction caused by noise.
Improve the noise environment,
including the wiring and installa-
tion, and check to see if the alarm
occurs again.
Install the pulse encoder cable away
from the peripheral equipment, or
add a ferrite core.
A.C3A:
Pulse Encoder Phase
A Disconnection
The signal line for phase A of the
pulse encoder is disconnected.
Check the signal wiring of the pulse
encoder.
Correct the wiring of the pulse
encoder.
A.C3B:
Pulse Encoder Phase
B Disconnection
The signal line for phase B of the
pulse encoder is disconnected.
Check the signal wiring of the pulse
encoder.
Correct the wiring of the pulse
encoder.
A.C3C:
Pulse Encoder Phase
C Disconnection
The signal line for phase C of the
pulse encoder is disconnected.
Check the signal wiring of the pulse
encoder.
Correct the wiring of the pulse
encoder.
A.C50:
Phase C Not Detected
A.C50:
Magnetic Pole
Incorrect Detection
The phase C signal of the pulse
encoder is not wired correctly.
Check the signal wiring of the pulse
encoder.
Correct the wiring of the pulse
encoder.
Pulse encoder error
Check the phase C signal of the
pulse encoder.
The pulse encoder may have failed.
Replace the motor.
The parameters are not set cor-
rectly.
Check the encoder specifications
and the feedback signal status.
Set the power torque limit in Pn430
and the regeneration torque limit in
Pn431 correctly.
Noise is entering on the encoder
signal.
Check to see if the FG on the servo-
motor is connected to the FG on the
SERVOPACK and that the FG on
the SERVOPACK is connected to
the FG on the power supply. Also,
make sure that the encoder cable is
shielded properly. Check to see if
the detection command is being
given repeatedly in the same direc-
tion.
Correct the shield on the encoder
cable.
Correct the FG wiring.
An external force was applied to
the motor’s rotor.
−
Reduce the external force to about
10% or less of the motor’s rated
torque.
The resolution of the encoder is
too low.
−
Increase the magnetic pole detec-
tion command speed in Pn493.
A.C51:
Overtravel Detection
at Polarity Detection
An overtravel signal was detected
during magnetic pole detection.
Check the overtravel position.
Move the motor’s stator to a posi-
tion where overtravel will not be
detected.
(cont’d)
Alarm:
Alarm Name
Cause
Investigative Actions
Corrective Actions
