6.1  Alarm Displays
6.1.2  Troubleshooting Alarms
6-16
A.521:
Autotuning Alarm 
(Vibration was 
detected while 
executing the 
custom tuning, 
Easy FFT, or the 
tuning-less func-
tion.)
The Servomotor 
vibrated considerably 
while performing the 
tuning-less function.
Check the waveform of 
the motor speed.
Reduce the load so that 
the moment of inertia ratio 
is within the allowable 
value. Or increase the 
load level or reduce the 
rigidity level in the tuning-
less level settings.
*1
The Servomotor 
vibrated considerably 
while performing cus-
tom tuning or Easy 
FFT.
Check the waveform of 
the motor speed.
Check the operating pro-
cedure of corresponding 
function and implement 
corrections.
*1
A.550:
Maximum Speed 
Setting Error
The setting of Pn385 
(Maximum Motor 
Speed) is greater than 
the maximum speed.
Check the setting of 
Pn385, and the upper 
limits of the maximum 
motor speed setting 
and the encoder output 
resolution setting.
Set Pn385 to a value that 
does not exceed the max-
imum motor speed.
*1
A.710:
Instantaneous 
Overload
A.720:
Continuous 
Overload
The wiring is not cor-
rect or there is a faulty 
contact in the motor 
or encoder wiring.
Check the wiring.
Make sure that the Servo-
motor and encoder are 
correctly wired.
*1
Operation was per-
formed that exceeded 
the overload protec-
tion characteristics.
Check the motor over-
load characteristics and 
Run command.
Reconsider the load and 
operating conditions. Or, 
increase the motor 
capacity.
–
An excessive load 
was applied during 
operation because the 
Servomotor was not 
driven due to 
mechanical problems.
Check the operation 
reference and motor 
speed.
Correct the mechanical 
problem.
–
There is an error in the 
setting of Pn282 (Lin-
ear Encoder Scale 
Pitch).
Check the setting of 
Pn282.
Correct the setting of 
Pn282.
*1
There is an error in the 
setting of Pn080 = 
n.X (Motor 
Phase Sequence 
Selection).
Check the setting of 
Pn080 = n.X.
Set Pn080 = n.X to 
an appropriate value.
*1
A failure occurred in 
the SERVOPACK.
–
The SERVOPACK may be 
faulty. Replace the 
SERVOPACK.
–
A.730 and A.731:
Dynamic Brake 
Overload 
(An excessive 
power consump-
tion by the 
dynamic brake 
was detected.)
The Servomotor was 
rotated by an external 
force.
Check the operation 
status.
Implement measures to 
ensure that the motor will 
not be rotated by an 
external force.
–
When the Servomo-
tor was stopped with 
the dynamic brake, 
the rotational or linear 
kinetic energy 
exceeded the capac-
ity of the dynamic 
brake resistor.
Check the power con-
sumed by the DB resis-
tor to see how 
frequently the DB is 
being used.
Reconsider the following:
• Reduce the Servomotor 
command speed.
• Decrease the moment 
of inertia ratio or mass 
ratio.
• Reduce the frequency of 
stopping with the 
dynamic brake.
–
A failure occurred in 
the SERVOPACK.
–
The SERVOPACK may be 
faulty. Replace the 
SERVOPACK.
–
Continued on next page.
Continued from previous page.
Alarm Number: 
Alarm Name
Possible Cause Confirmation Correction Reference