11  Inspection, Maintenance, and Troubleshooting
11.2.3  Troubleshooting of the Servo Drive Alarms
11-20
A.510:
Overspeed
(The servomotor speed 
exceeds the maximum.)
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.
A reference value exceeding the 
overspeed detection level was 
input.
Check the input value.
Reduce the reference value or adjust 
the gain.
The motor speed exceeded the 
maximum.
Check the servomotor speed wave-
form.
Adjust the servo gain, or reconsider 
the operation conditions.
SERVOPACK failure −
The SERVOPACK may be faulty. 
Replace the SERVOPACK.
A.521: 
Autotuning Alarm
(Vibration was detected 
during one-parameter 
tuning or Easy-FFT.)
Excessive vibration was detected 
in the motor during one-parame-
ter tuning.
Check the speed waveform of the 
motor.
Perform the corrective action for the 
operating procedure for the func-
tion.
A.531: 
Excessive Speed 
Deviation 
(The deviation between 
the speed reference and 
actual motor speed is 
abnormal.)
The motor main circuit cable is 
either incorrectly wired or has a 
contact fault.
Make sure the wiring is correct. Correct the wiring.
A short-circuit or ground fault 
occurred in the motor main cir-
cuit cable.
Check for short-circuits across 
phase U, V, and W of the cable, or 
between the ground and phase U, V, 
or W.
The cable may have short-cir-
cuited. Replace the cable.
The load is heavy (for example, 
the cutting resistance may be 
high).
Check to see if the load friction is 
high and the moment of inertia of 
the load is too high.
Remove the load.
A.540: 
Overspeed (During 
Low-speed Winding) 
(The low-speed winding 
maximum speed was 
exceeded during low-
speed winding.)
The sequence of phase U, V, and 
W motor lines is incorrect.
Check the wiring of the motor and 
of the electromagnetic contactor for 
winding selection.
Correct the motor wiring.
The reference input value 
exceeds the maximum speed of 
the low-speed winding.
Check the input reference.
Reduce the reference value, or  
adjust the gain.
The low-speed winding maxi-
mum rotation speed was 
exceeded during low-speed wind-
ing.
Check the motor speed from the 
motor speed monitor in SigmaWin 
for the Σ-V-SD (MT).
Adjust the gain, or revise the oper-
ating conditions.
SERVOPACK failure −
The SERVOPACK may be faulty. 
Replace the SERVOPACK.
A.690: 
Winding Selection 
Operation Fault 
During the winding selection 
check that is performed when the 
power is turned ON, the electro-
magnetic contactor for winding 
selection 
did not change accord-
ing to the internal command.
Check the wiring of the SERVO-
PACK  a nd  o f  the electromagnetic 
contactor for winding selection.
Correct the wiring of the winding 
selection signal.
Winding selection was not com-
pleted within two seconds of 
receiving the winding selection 
command.
Check the wiring of the electromag-
netic contactor for winding selec-
tion.
Correct the wiring of the electro-
magnetic contactor for winding 
selection.
Chattering occurred in the elec-
tromagnetic contactor for wind-
ing selection when the winding 
selection command was not 
received.
Check the wiring of the electromag-
netic contactor for winding selec-
tion.
Correct the wiring of the electro-
magnetic contactor for winding 
selection, or replace the electromag-
netic contactor for winding selec-
tion.
A.6B0: 
Emergency Stop 
Failure 
(The motor did not stop 
within 10 s after the 
emergency stop signal 
input.)
The set value of the emergency 
stop torque in Pn406 is too small.
−
Correct the emergency stop torque 
setting in Pn406.
(cont’d)
Alarm:
Alarm Name
Cause Investigative Actions Corrective Actions