Restoring the VF-NC3 VFD from a trip
Do not reset the inverter when tripped because of a failure or error before eliminating the cause. Resetting the tripped inverter before eliminating the problem causes it to trip again.
The inverter can be restored from a trip by any of the following operations:
(1) By turning off the power (Keep the inverter off until the LED turns off.)
Note) See inverter trip hold selection F602 for details.
(2) By means of an external signal (Short circuit across RES and CC on control terminal block → Open): The reset function must be assigned to the input terminal block.
(3) By panel keypad operation
(4) By inputting a trip clear signal from communication

To reset the VF-Nc3 inverter by panel keypad operation, follow these steps.
1. Press the STOP key and make sure that CLr is displayed.
2. Pressing the STOP key again will reset the inverter if the cause of the trip has already been eliminated.
* When any overload function [OL1: inverter overload, OL2: motor overload] is active, the inverter cannot be reset by inputting a reset signal from an external device or by operation panel operation before the virtual cooling time has passed.
Virtual cooling time ... OL1 : about 30 seconds after the occurrence of a trip
OL2 : about 120 seconds after a occurrence of a trip
* In case of a trip due to overheat (OH), the inverter checks the temperature within. Wait until the temperature in the inverter falls sufficiently before resetting the inverter.
* The inverter cannot be reset while the emergency stop signal is being input from the terminal.


The motor runs in the wrong direction.
• Invert the phases of the output terminals U, V and W.
• Invert the forward/reverse run-signal terminals of the external input device.
(See 7.2.1 "Assignment of functions to control terminals".)
• Change the setting of the parameter Fr in the case of panel operation.

The motor runs but its speed does not change normally.
• The load is too heavy. Reduce the load.
• The soft stall function is activated. Disable the soft stall function. (See 5.13.)
• The maximum frequency Fh and the upper limit frequency UL are set too low. Increase the maximum frequency Fh and the upper limit frequency ul.
• The frequency setting signal is too low. Check the signal set value, circuit, cables, etc.
• Check the setting characteristics (point 1 and point 2 settings) of the frequency setting signal parameters.  
• If the motor runs at a low speed, check to see that the stall prevention function is activated because the torque boost amount is too large.
Adjust the torque boost amount (ub) and the acceleration time (ACC).

The motor does not ac-celerate or decelerate smoothly.
• The acceleration time (ACC) or the deceleration time (dEC) is set too short. Increase the acceleration time (ACC) or the deceleration time (dEC).

A too large current flows into the motor.
• The load is too heavy. Reduce the load.
• If the motor runs at a low speed, check whether the torque boost amount is too large.

The motor runs at a higher or lower speed than the specified one.
• The motor has an improper voltage rating. Use a motor with a proper voltage rating.
• The motor terminal voltage is too low.
Check the setting of the base frequency voltage parameter (uLu) .
Replace the cable with a cable larger in diameter.
• The reduction gear ratio, etc., are not set properly. Adjust the reduction gear ratio, etc.
• The output frequency is not set correctly. Check the output frequency range.
• Adjust the base frequency.


VF-Nc3 Parameter settings cannot be changed.
Change the setting of the parameter setting selection prohibited parameter F700 to 0 (enabled) if it is set to 1 or 2 (prohibited).
* For reasons of safety, some parameters cannot be reprogrammed while the inverter is running.

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OC1 0001 Overcurrent during acceleration
• The acceleration time ACC is too short.
• The V/F setting is improper.
• A restart signal is imput to the rotating motor after a momentary stop, etc.
• A special motor (e.g. motor with a small impedance) is used.
• Increase the acceleration time ACC.
• Check the V/F parameter.
• Use F301 (auto-restart) and F302 (ride-through control).
• Adjust the PWM carrier frequency F316.
• Set the carrier frequency control mode selection parameter f316 to 1 (carrier frequency decreased automatically).
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OC2 0002 Overcurrent during deceleration
• The deceleration time DEC is too short.
• Increase the deceleration time DEC.
• Set the carrier frequency control mode selection parameter f316 to 1 (carrier frequency decreased automatically).
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OC3 0003 Overcurrent during constant speed operation
• The load fluctuates abruptly.
• The load is in an abnormal condition.
• Reduce the load fluctuation.
• Check the load (operated machine).
• Set the carrier frequency control mode selection parameter f316 to 1 (carrier frequency decreased automatically).
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OCL 0004 Overcurrent (An overcurrent on the load side at start-up)
• The insulation of the output main circuit or motor is defective.
• The motor has too small impedance.
• Check the cables and wires for defective insulation.
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OCA 0005 Arm overcurrent at start-up
• A main circuit elements is defective.
• Make a service call.
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EPHI  0008 Input phase failure
• A phase failure occured in the input line of the main circuit.
• The capacitor in the main circuit lacks capacitance.
• Check the main circuit input line for phase failure.
• Enable F608 (input phase failure detection).
• Check the capacitor in the main circuit for exhaustion.
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EPHO 0009 Output phase failure
• A phase failure occurred in the output line of the main circuit.
• Check the main circuit output line, motor, etc. for phase failure.
Enable F605 (Output phase failure detection).
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OP1 000A Overvoltage during acceleration
• The input voltage fluctuates abnormally.
(1) The power supply has a capacity of 00kVA or more.
(2) A power factor improvement capacitor is opened or closed.
(3) A system using a thyrister is connected to the same power distribution line.
• A restart signal is input to the rotating motor after a momentary stop, etc.
• Insert a suitable input reactor.
• Use F301 (auto-restart) and F302 (ride-through control).
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OP2 000B Overvoltage during deceleration
• The deceleration time DEC is too short. (Regenerative energy is too large.)
• The input voltage fluctuates abnormally.
(1) The power supply has a capacity of 200kVA or more.
(2) A power factor improvement capacitor is opened and closed.
(3) A system using a thyrister is connected to the same power distribution line.
• Increase the deceleration time DEC.
• Enable F305 (overvoltage limit operation).
• Insert a suitable input reactor.
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OP3 000C Overvoltage during constant-speed operation
• The input voltage fluctuates abnormally.
(1) The power supply has a capacity of 200kVA or more.
(2) A power factor improvement capacitor is opened or closed.
(3) A system using a thyrister is connected to the same power distribution line.
• The motor is in a regenerative state because the load causes the motor to run at a frequency higher than the inverter output frequency.
• Insert a suitable input reactor.
• Install an optional brake module.