Fault Detection for Omron 3G3MV VFD (Fatal Errors)
The Inverter detects the following faults if the Inverter, Inverter or motor burns, or if the internal circuits of the Inverter malfunction. When the Inverter detects a fault, the fault code will be displayed on the Digital Operator, the fault contact output will operate, and the Inverter output will be turned off, allowing the motor to freely rotate until it stops. For some faults, a stopping method can be selected, and the selected stopping method will be used with these faults. If a fault occurs, refer to the table below to determine and correct the cause of the fault. After restarting the Inverter, use one of the following methods to reset the fault. However, if an operating command is entered, the reset signal will be ignored. Therefore, be sure to reset the fault when the operating command is OFF.
• Set the fault reset signal to the ON position. A multi-function input (from n050 to n056) should be set to 5 (Fault Reset).
• Press the STOP/RESET button on the Digital Operator.
• TURN OFF the main circuit power supply and then TURN ON again.

Fault Displays and Procedures
Fault Name and Meaning Possible Causes and Solutions
Overcurrent (OC)
The Inverter output current is higher than or equal to 250% of the rated output current.
• A short circuit or ground fault has occurred in the Inverter output.
→ Check and correct the motor power cable.
• Incorrect V/f setting.
→ Reduce the V/f setting voltage.
• The motor capacity is too large for the Inverter.
→ Reduce the motor capacity to the maximum applicable motor capacity.
• The magnetic contactor on the output side of the Inverter has opened and closed.
→ Reorganize the sequence so that the magnetic contactor does not open and close when there is Inverter current output.
• The output circuit of the Inverter is damaged.
→ Replace the Inverter.

Overvoltage (OV)
The main circuit DC voltage has reached the overvoltage detection level (410 V DC for 200 V Inverters, 820 V DC for 400 V Inverters).
• There is excessive regenerative energy without a brake resistor or Brake Resistor Unit connected.
→ Connect a brake resistor or a Brake Resistor Unit.
→ Increase the deceleration time.
• Regenerative energy has not been processed through a brake resistor or Brake Resistor Unit.
→ Set coasting prevention to 1 (disable) during deceleration (n092).
• The brake resistor or Brake Resistor Unit is not connected properly.
→ Check and correct the wiring.
• The power supply voltage is too high.
→ Reduce the voltage to within specifications.
• There is excessive surge due to excessive regenerative energy during acceleration.
→ Suppress the surge as much as possible.
• The brake transistor is damaged.
→ Replace the Inverter.

Main Circuit Undervoltage (UV1)
The main circuit DC voltage has reached the undervoltage detection level (200 V DC for 3G3MV-A2, 160 V DC for 3G3MV-AB, and 400 V DC for 3G3MV-A4).
• Phase loss when power is supplied to the Inverter, loose power input terminal screws, or power cable disconnected.
→ Check the above and take necessary measures.
• Incorrect power supply voltage.
→ Ensure the power supply voltage is within specifications.
• Momentary power failure occurred.
→ Use the instant power failure compensation (set n081 for Inverter restart after power is restored).
→ Improve the power supply.
• The internal circuits of the Inverter are damaged.
→ Replace the Inverter.

Control Power Supply Undervoltage (UV2)
The control power supply voltage has reached the undervoltage detection level.
• Internal circuit fault.
→ TURN OFF and ON the Inverter.
→ Replace the Inverter if the same fault occurs again.

Overheating of Radiator Fins (OH)
The temperature of the Inverter's radiator fins has reached 110°C ± 10°C.
• Ambient temperature is too high.
→ Ventilate the Inverter or install a cooling unit.
• The load is excessive.
→ Reduce the load.
→ Switch to a higher capacity Inverter.
• Incorrect V/f setting.
→ Reduce the V/f setting voltage.
• Acceleration/deceleration time is too short.
→ Increase the acceleration/deceleration time.
• Ventilation is obstructed.
→ Change the position of the Inverter to meet installation conditions.
• The cooling fan of the Inverter is not working.
→ Replace the cooling fan.


Motor Overload (OL1)
The electrical thermal relay has activated the motor overload protection function.
Calculate the heat dissipation of the motor based on the output current of the Inverter, the nominal motor current (n036), the motor protection characteristics (n037), and the motor protection time setting (n038).
• The load is excessive.
→ Reduce the load.
→ Increase the motor capacity.
• Incorrect V/f setting.
→ Reduce the V/f setting voltage.
• The n013 value for the maximum voltage frequency is low.
→ Check the motor type plate and set n013 to the nominal frequency.
• The acceleration/deceleration time is too short.
→ Increase the acceleration/deceleration time.
• The n036 value for the nominal motor current is incorrect.
→ Check the motor type plate and set n036 to the nominal current.
• The Inverter is driving multiple motors.
→ Disable the motor overload protection function and install an electronic thermal relay for each motor.
The motor overload protection function is disabled by setting n036 to 0.0 or n037 to 2.
• The motor protection time setting in n038 is short.
→ Set n038 to 8 (default value).

Inverter Overload (OL2)
The electronic thermal relay has activated the Inverter overload protection function.
• The load is excessive.
→ Reduce the load.
• Incorrect V/f setting.
→ Reduce the V/f setting voltage.
• The acceleration/deceleration time is too short.
→ Increase the acceleration/deceleration time.
• The Inverter capacity is insufficient.
→ Use a higher capacity Inverter model.

Excessive Torque Detection (OL3)
The current or torque exceeded the value set for the excessive torque detection level in n098 and the excessive torque detection time in n099. A fault is detected when the excessive torque detection function selection in n096 is set to 2 or 4.
• The mechanical system is locked or faulty.
→ Check the mechanical system and correct the cause of the excessive torque.
• The parameter settings were incorrect.
→ Adjust the n098 and n099 parameters according to the mechanical system.
Increase the setting values in n098 and n099.

Low Torque Detection (UL3)
The current or torque was equal to or less than the value set for the low torque detection level in n118 and lasted longer than the time set for the low torque detection time in n119. (This fault is detected when the low torque detection function selection in n117 is set to 2 or 4.)
• There is a fault in the mechanical system (e.g., something causing the load to be very light).
→ Check the mechanical system and correct the cause of the low torque.
• The parameter settings were incorrect.
→ Check the n118 (low torque detection level) and n119 (low torque detection time) settings.
(Decrease the n118 setting or increase the n119 setting.)