YASKAWA UAK series User Manual page 276

11 Inspection, Maintenance, and Troubleshooting
11.2.3 Troubleshooting of the Servo Drive Alarms
Alarm:
Alarm Name
A.790:
Motor Overheated
(The motor temperature
has exceeded the upper
limit.)
A.791:
Motor Temperature
Detection Error
(The motor thermistor is
either disconnected or is
damaged.)
A.7A0:
Heat Sink in
SERVOPACK
Overheated
(The temperature of the
heat sink in the SERVO-
PACK exceeded 100°C,
or the thermistor in the
SERVOPACK was dis-
connected or damaged.)
A.7AB:
Built-in Fan in
SERVOPACK
Stopped
A.7AC:
Built-in Fan in
Converter Stopped
(The fan inside the
power regeneration con-
verter stopped.)
11-22
Cause
The ambient temperature around
the motor is high.
Acceleration and deceleration
were repeated frequently.
The cable between the SERVO-
PACK and spindle motor is either
disconnected or has a contact
fault.
The thermistor wiring in the spin-
dle motor is disconnected.
The thermistor has failed.
The operating ambient tempera-
ture is too high.
The overload alarm has been
reset by turning OFF the power
too many times.
The installation orientation of the
SERVOPACK is incorrect or the
distance from other equipment is
insufficient.
SERVOPACK failure
The heat sink cooling fan in the
ventilation duct stopped or the
fan in the base mounting unit
stopped.
The fan inside the SERVOPACK
stopped.
The fan inside the power regener-
ation converter stopped.
Investigative Actions
Check the ambient temperature
around the motor.
−
Make sure the wiring is not discon-
nected and no contact fault exists.
−
−
Check the ambient temperature
using a thermometer.
Check the alarm history to see if the
overload alarm of the SERVO-
PACK was reported.
Check the installation conditions of
the SERVOPACK.
−
Make sure that there is no foreign
matter in the fans.
Check for foreign matter or debris
inside the SERVOPACK.
Check for foreign matter or debris
inside the power regeneration con-
verter.
(cont'd)
Corrective Actions
Make sure the ambient temperature
around the motor does not increase.
Make the acceleration/deceleration
of the motor smoother, or change
the operation pattern.
Correct the wiring.
The spindle motor may be faulty.
Replace the spindle motor.
The spindle motor may be faulty.
Replace the spindle motor.
Improve the installation conditions
of the SERVOPACK and reduce the
operating ambient temperature.
Change the method for resetting the
alarm.
Install the SERVOPACK correctly
as specified.
The SERVOPACK may be faulty.
Replace the SERVOPACK.
Remove the foreign matter. Or
replace the fan.
Remove the foreign matter. If the
alarm still occurs, the SERVO-
PACK may be faulty. Replace the
SERVOPACK.
Remove the foreign matter. If the
alarm still occurs, the power regen-
eration converter may be faulty.
Replace the power regeneration
converter.