Mitsubishi MD-AX520 Drive

Mitsubishi MD-AX520 Drive Fault Codes:

Fault Code and MeaningCause and Remedy
E.OC1

Acceleration time overcurrent
Cause:
The acceleration torque is beyond the drive unit capability; Outputs U, V, and W are in a short circuit or ground fault; The motor restarted during coasting; Or start signal given with only R1/S1 power.



Remedy:

  • Increase the acceleration time.

  • Change the acceleration/deceleration pattern to an S shape.

  • Check the motor winding resistance.

  • Check the connection cables for damage.

  • Restart the motor after a complete stop.

  • Supply main circuit power (R, S, T).
E.OC2

Constant speed time overcurrent
Cause:
Excessive load was applied instantaneously; Outputs U, V, and W resulted in a short circuit or ground fault during constant-speed operation; Drive capacity does not match motor.



Remedy:

  • Check the motor winding resistance.

  • Check the connection cables for damage.

  • Ensure drive unit capacity matches the motor.
E.OC3

Deceleration time overcurrent
Cause:
The deceleration torque is beyond the drive unit capability; Outputs U, V, and W resulted in a short circuit or ground fault during deceleration; Mechanical brake operates too early.



Remedy:

  • Increase the deceleration time.

  • Change the acceleration/deceleration pattern to an S shape.

  • Check the motor winding resistance.

  • Check the connection cables for damage.

  • Delay the brake operation timing.
E.GF

Output side ground fault overcurrent
Cause:
Any of outputs U, V, W is in a ground fault.



Remedy:

  • Check for ground faults in the motor and wiring.
E.OV1

Acceleration time overvoltage
Cause:
Surge compounded with power during acceleration; Regenerative energy handling capability is insufficient.



Remedy:

  • Install a reactor.

  • Fit a surge suppressor to the surge source.

  • Fit the regenerative brake option.
E.OV2

Constant speed time overvoltage
Cause:
Surge compounded with power; Load increased suddenly activating stall prevention; Regenerative energy capability insufficient.



Remedy:

  • Install a reactor.

  • Fit a surge suppressor to the surge source.

  • Fit the regenerative brake option.
E.OV3

Deceleration time overvoltage
Cause:
Deceleration torque beyond drive capability; Regenerative energy capability insufficient; Surge compounded with power during deceleration.



Remedy:

  • Increase the deceleration time.

  • Change acceleration/deceleration pattern to S shape.

  • Fit the regenerative brake option.

  • Install a reactor or surge suppressor.
E.THT

Electronic overcurrent protection (Transistor)
Cause:
The motor and drive unit are operated under overload.



Remedy:

  • Reduce the load.

  • Increase the capacities of the motor and drive unit.
E.THM

Electronic overcurrent protection (Thermal)
Cause:
The motor and drive unit are operated under overload.



Remedy:

  • Reduce the load.

  • Increase the capacities of the motor and drive unit.
E.IPF

Instantaneous power failure
Cause:
An instantaneous power failure occurred (15 to 100ms).



Remedy:

  • Check power supply stability.

  • Reset the alarm.
E.UVT

Undervoltage
Cause:
Large-capacity equipment started nearby; Jumper across terminals P/+-P1 disconnected.



Remedy:

  • Connect the jumper or DC reactor.

  • Check power supply capacity.
E.FIN

Fin overheat
Cause:
Heat sink temperature exceeded permissible value; Cooling fan failed.



Remedy:

  • Check ambient temperature.

  • Replace cooling fan if failed.

  • Clean heat sink fins.
E.OHT

External fault
Cause:
The external relay or equivalent component connected to the terminal assigned to OH signal operated.



Remedy:

  • Check external device/relay triggering the fault.

  • Check wiring of the OH signal terminal.
E.PUE

PU disconnection
Cause:
Connection fault of operation panel/parameter unit; RS-485 communication interrupted; Comm retries exceeded.



Remedy:

  • Check connection of the operation panel.

  • Check RS-485 wiring and parameters (Pr. 75, Pr. 121).
E.RET

Retry excess
Cause:
The number of alarms that occurred exceeded the retry setting.



Remedy:

  • Investigate the root cause of the recurring alarms.

  • Check Retry count parameter (Pr. 67).
E.OLT

Stall stop
Cause:
Motor overload activated stall prevention consecutively; E.OLT output selected in Pr. 156.



Remedy:

  • Reduce the load.

  • Increase capacities of motor and drive unit.

  • Check Pr. 156 setting.
E.LF

Phase failure
Cause:
A phase failure occurred in any of the outputs U, V, W.



Remedy:

  • Check wiring for breaks or loose connections.

  • Check motor windings.
E.P24

P24 Short Circuit
Cause:
The PC terminal output of the control circuit is in a short circuit.



Remedy:

  • Check the wiring connected to the PC terminal.

  • Reset via method other than RES terminal.
E.CTE

Panel power supply
Cause:
The power supply cable of the operation panel or parameter unit is in a short circuit.



Remedy:

  • Check the cable wiring for shorts.
E.OPT

Option fault
Cause:
The plug-in option fitted is other than specified; Power switched on with high power factor converter setting (Pr. 30 = 2).



Remedy:

  • Check the installed option card.

  • Check Parameter 30 setting.
E.CPU / E.6 / E.7

CPU fault
Cause:
The CPU malfunctioned or failed.



Remedy:

  • If the same message reappears after reset, replace the drive unit.
E.PE

Storage device fault
Cause:
The storage device failed.



Remedy:

  • If the same message reappears after reset, replace the drive unit.
E.BE

Brake circuit fault
Cause:
The regenerative brake circuit failed.



Remedy:

  • Immediately switch power off if E.BE reappears.

  • Leaving power on will overheat the brake resistor.

  • Replace drive unit if fault persists.
OL

Overload 1 (Alarm)
Cause:
Acceleration/Constant speed/Deceleration time overcurrent; Stall stop activated.



Remedy:

  • Reduce load.

  • Check Pr. 22 setting.
oL

Overload 2 (Alarm)
Cause:
Main circuit DC voltage more than 390V (Deceleration-time overvoltage).



Remedy:

  • Increase deceleration time.

  • Check regenerative brake capability.
RB

Brake duty (Alarm)
Cause:
More than 85% of the permissible value (Deceleration-time overvoltage).



Remedy:

  • Reduce braking duty cycle.

  • Check brake resistor sizing.
TH

Motor overheat (Alarm)
Cause:
More than 85% of the electronic overcurrent protection level.



Remedy:

  • Reduce motor load.

  • Check cooling.
FN

Fan failure (Alarm)
Cause:
Cooling fan fault; Fin overheat.



Remedy:

  • Replace cooling fan.

  • Clean heatsink.
Err

Operation error
Cause:
Parameter changing during external operation; Value outside range; RES signal remains ON; Connection fault.



Remedy:

  • Perform parameter changes in PU mode.

  • Check valid parameter ranges.

  • Turn off RES signal.

  • Check panel fitting status.
PS

Emergency stop operation
Cause:
STOP/RESET key was pressed during external operation.



Remedy:

  • Reset cannot be made by normal method.

  • Refer to Pr. 75 for reset procedures.
E.rE4

Copy error
Cause:
Parameters were copied to a different model.



Remedy:

  • Ensure source and destination drive models match.