Troubleshooting Summary

If the inverter and motor do not operate as expected during startup, it may be due to parameter settings, faulty wiring, or other issues. Use the following guide to take appropriate measures. If a fault code is displayed, refer to the Protection and Diagnostic Functions section.
Unable to Set Parameters?

    Display Doesn’t Change with Increment/Decrement Keys:
- Possible Causes:
+ The inverter may be in drive mode; some parameters cannot be changed during operation. Turn off the inverter to adjust settings.
+ “Parameter write enable” may be active through a multi-function input terminal. Enable this input and then set the parameters.
+ Password mismatch: If the password settings (A1-04 and A1-05) differ, parameters cannot be changed. Reset the password.

    OPE01 through OPE11 Displayed:
- The parameter value is incorrect. Refer to the relevant section to correct the error settings.

    CPF00 or CPF01 Displayed:
- This is a Digital Operator communication error; the connection may be faulty. Reinstall the Digital Operator.

Fault Codes and Explanations

    o C – Overcurrent
    Condition: The inverter output current exceeded the overcurrent detection level.
    Possible Causes:
- A short-circuit or ground fault may have occurred at the output.
- The load may be too large, or the acceleration/deceleration time too short.
- The motor used may have a capacity larger than the inverter.
- A magnetic switch may have been activated at the output.
- Solution: Reset the inverter after correcting the cause.

    GF – Ground Fault
    Condition: The ground fault current at the inverter output exceeded approximately 50% of the inverter rated output current.
    Possible Causes:
- A ground fault may have occurred due to motor burn damage, worn insulation, or a damaged cable.
- Solution: Reset the inverter after correcting the cause.

    P U F – Fuse Blown
    Condition: The fuse in the main circuit is blown.
    Possible Causes:
- The output transistor may have failed due to a short-circuit or ground fault at the output. Check for a short-circuit between the U, V, W terminals.
- Solution: Replace the inverter after correcting the cause.

    o U – Main Circuit Overvoltage
    Condition: The main circuit DC voltage exceeded the overvoltage detection level.
    Possible Causes:
- The deceleration time may be too short, resulting in excessive regenerative energy from the motor.
- The power supply voltage may be too high.
- Solution: Increase the deceleration time or connect a Braking Resistor Unit and Braking Unit. Adjust the voltage to within specifications.

    o u 1 – Main Circuit Undervoltage
    Condition: The main circuit DC voltage is below the Undervoltage Detection Level (L2-05).
    Possible Causes:
- The MC stopped responding during inverter operation.
- The applied inverter capacity may be inappropriate.
- Solution: Reset the inverter after correcting the cause.

Fault Codes and Explanations

    o u 2 – Control Power Fault
    Condition: The control power supply voltage dropped.
    Solution:
- Try turning the power supply off and on again.
- If the fault persists, replace the inverter.

    o u 3 – Inrush Prevention Circuit Fault
    Condition: Overheating occurred in the inrush resistor.
    Solution:
- Try turning the power supply off and on again.
- If the fault persists, replace the inverter.

    P F – Main Circuit Voltage Fault
    Condition: The main circuit DC voltage is oscillating unusually (not during regeneration).
    Solution:
- Reset the inverter after correcting the cause.

    L F – Output Open-phase
    Condition: An open-phase occurred at the inverter output.
    Solution:
- Reset the inverter after correcting the cause.
- Check the motor and inverter capacity.

    o H (o H 1) – Cooling Fin Overheating
    Condition: The inverter's cooling fin temperature exceeded the set limit.
    Solution:
- Install a cooling unit.
- Remove the heat source.
- Replace the cooling fan. (Contact your sales representative.)

    Inverter's Cooling Fan Stopped
    Solution: Replace the cooling fan. (Contact your sales representative.)

    o H 3 – Motor Overheating Alarm
    Condition: The motor has overheated, and the inverter may stop or continue operation depending on the setting.
    Solution:
- Check the load size and the acceleration, deceleration, and cycle times.
- Check the V/f characteristics.
- Check the motor temperature input on terminals A1 and A2.

    o H 4 – Motor Overheating Fault
    Condition: The motor has overheated, and the inverter will stop according to the setting.
    Solution:
- Check the load size and the acceleration, deceleration, and cycle times.
- Check the V/f characteristics.
- Check the motor temperature input on terminals A1 and A2.

    o L 1 – Motor Overload
    Condition: The motor overload protection function has operated.
    Solution:
- Check the load size and the acceleration, deceleration, and cycle times.
- Check the V/f characteristics.
- Check the Motor Rated Current (E2-01).

    o L 2 – Inverter Overload
    Condition: The inverter overload protection function has operated.
    Solution:
- Check the load size and the acceleration, deceleration, and cycle times.
- Check the V/f characteristics.
- Replace the inverter with one that has a larger capacity.

    o L 3 – Overtorque Detected 1
    Condition: The current exceeded the setting in L6-02 for longer than the setting in L6-03.
    Solution:
- Ensure that the settings in L6-02 and L6-03 are appropriate.
- Check the mechanical system and correct the cause of the overtorque.

    o L 7 – High-slip Braking OL
    Condition: The output frequency did not change for longer than the time set in N3-04.
    Solution:
- Ensure the load is an inertial load.
- Set the deceleration time that does not produce 0 V to 120 s or less.

Fault Codes and Explanations

    u L 3 – Undertorque Detected 1
    Condition: The current remained below the setting in L6-02 for longer than the setting in L6-03.
    Solution:
- Ensure that the settings in L6-02 and L6-03 are appropriate.
- Check the mechanical system and correct the cause of the undertorque.

    F b L – PI Feedback Reference Lost
    Condition: The PI feedback reference was lost, and the feedback input remained below the set level.
    Solution: No specific solution provided for this condition.

    E F O – External Fault Input
    Condition: An external fault input was received from the Communications Card.
    Solution: Check the Communications Card and signals.

    E F 3 - E F 7 – External Fault (Input Terminal 3 - 7)
    Condition: An “external fault” was input from a multi-function input terminal (S3 to S7).
    Solution:
- Reset the external fault inputs.
- Remove the cause of the external fault.

    o P r – Digital Operator Connection Fault
    Condition: The connection to the Digital Operator was lost during a RUN command.
    Solution: Check the connection to the Digital Operator.

    C E – RS-422A/485 Communications Error
    Condition: Normal reception was not possible for 2 seconds or longer after control data was received.
    Solution: Check the communication devices and signals.