Mitsubishi Electronics FR-E720-0.1KSC to 15KSC ユーザーズマニュアル

The electronic thermal relay function for inverter 
element protection has been activated.



Set the acceleration time longer.



Adjust the Pr. 0 Torque boost setting.



Set the Pr. 14 Load pattern selection setting according to the 
load pattern of the using machine.



Reduce the load.



Set the surrounding air temperature to within the 
specifications.

The electronic thermal relay function for motor 
protection has been activated.



Reduce the load.



For a constant-torque motor, set the constant-torque motor in 
Pr. 71 Applied motor.



Set the stall prevention operation level accordingly.

The heatsink has overheated.



Set the surrounding air temperature to within the 
specifications.



Clean the heatsink.



Replace the cooling fan.



One of the three phases on the inverter input side 
has been lost. It may also appear if phase-to-
phase voltage of the three-phase power input has 
become largely unbalanced.



Wire the cables properly.



Repair a break portion in the cable.



Check the Pr. 872 Input phase loss protection selection setting.



Set Pr. 872 Input phase loss protection selection = "0" (without 
input phase loss protection) when three-phase input voltage is 
largely unbalanced.

The output frequency has dropped to 1Hz as a 
result of deceleration due to the excess motor load.

Reduce the load. (Check the Pr. 22 Stall prevention operation level 
setting.)

A fault has occurred in the brake circuit, such as a 
brake transistor breakage.(In this case, the 
inverter must be powered off immediately.)

Replace the inverter.



An earth (ground) fault has occurred on the 
inverter's output side (detected only at a start).

Remedy the ground fault portion.

One of the three phases (U, V, W) on the inverter's 
output side (load side) has been lost during 
inverter operation.



Wire the cables properly.



If the motor capacity is smaller than the inverter capacity, 
choose the inverter and motor capacities that match.



If the motor is coasting, stop the motor, then input a start 
command. Alternatively, use the automatic restart after 
instantaneous power failure/flying start function.



The external thermal relay connected to the OH 
signal has been activated.



Reduce the load and operate less frequently.



Even if the relay contacts are reset automatically, the inverter 
will not restart unless it is reset.

A communication option has been mounted while 
Pr.296 Password lock level = "0 or 100."



To apply the password lock when installing a communication 
option, set Pr.296 Password lock level 

 "0, 100."



If the problem still persists after taking the above measure, 
contact your sales representative.

A communication error has occurred on the 
communication line of the communication option. 



Check the settings of the option functions. 



Connect the built-in option securely.



Check the connections of the communication cables.



Connect terminating resistors correctly. 

A fault, such as a contact fault, has occurred at the 
contactor of the inverter or the plug-in option. The 
setting of the switch on the plug-in option, which is 
for manufacturer setting, has been changed.



Connect the plug-in option securely.



Take measures against noises if there are devices producing 
excess electrical noises around the inverter.
If the situation does not improve after taking the above 
measure, please contact your sales representative.



Set the switch on the plug-in option, which is for manufacturer 
setting, back to the initial setting. (Refer to the Instruction 
Manual of each option.)

Operation of the component where parameters 
are stored (control circuit board) has become 
abnormal.

Please contact your sales representative.
When performing parameter writing frequently for 
communication purposes, set "1" in Pr. 342 Communication 
EEPROM write selection to enable RAM write. Note that powering 
OFF returns the inverter to the status before RAM write.

The control circuit board and the main circuit 
board do not match.

Please contact your sales representative.
(For parts replacement, consult the nearest Mitsubishi FA 
Center.)



A communication error has occurred between 
the PU and the inverter.



The communication interval has exceeded the 
permissible time period during RS-485 
communication via the PU connector.



The number of communication errors has 
exceeded the number of retries.



Connect the parameter unit cable securely.



Check the communication data and communication settings.



Increase the Pr. 122 PU communication check time interval 
setting, or set "9999" (no communication check).



Operation restart within the set number of retries 
has failed.

Eliminate the cause of the error preceding this error indication.