OC1
Overcurrent
The inverter turns off its output when the output current of the inverter flows more than the inverter rated current.
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Cause:
- Accel/Decel time is too short compared to the GD² of the load.
- Load is greater than the inverter rating.
- Inverter output is issued when the motor is free running.
- Output short circuit or ground fault has occurred.
- Mechanical brake of the motor is operating too fast.
Remedy:
- Increase the Accel/Decel time.
- Replace the inverter with appropriate capacity.
- Resume operation after stopping the motor or use H22 (Speed search).
- Check output wiring.
- Check the mechanical brake.
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OC2
Overcurrent 2
When IGBT’s Arm is short and output short occurs, the inverter turns off its output.
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Cause:
- Short occurs between up and down of IGBT.
- Inverter output short occurs.
- Accel/Decel time is very fast comparing with GD².
Remedy:
- Check the IGBT.
- Check output wiring.
- Increase the Accel/Decel time.
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GFT
Ground fault current
The inverter turns off its output when a ground fault occurs and the ground fault current is more than the internal setting value.
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Cause:
- Ground fault has occurred at the output wiring of the inverter.
- The insulation of the motor is damaged due to heat.
Remedy:
- Check the wiring of the output terminal.
- Replace the motor.
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IOL
Inverter Overload
The inverter turns off its output when the output current of the inverter flows more than the rated level (150% for 1 minute).
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Cause:
- Load is greater than the inverter rating.
- Torque boost scale is set too large.
Remedy:
- Upgrade the capacity of motor and inverter or reduce the load weight.
- Reduce torque boost scale.
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OLT
Overload trip
The inverter turns off its output if the output current flows at 150% of rated current for more than the current limit time.
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Cause:
- Load is greater than the inverter rating (Prolonged).
Remedy:
- Upgrade the capacity of motor and inverter or reduce the load weight.
- Check motor sizing vs application.
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OHT
Inverter overheat
The inverter turns off its output if the heat sink overheats due to a damaged cooling fan or an alien substance.
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Cause:
- Cooling system has faults.
- An old cooling fan is not replaced with a new one.
- Ambient temperature is too high.
Remedy:
- Check for alien substances clogged in the heat sink.
- Replace the old cooling fan with a new one.
- Keep ambient temperature under 50°C.
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POT
Output Phase loss
The inverter turns off its output when one or more of the output (U, V, W) phases are open.
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Cause:
- Faulty contact of magnetic switch at output.
- Faulty output wiring.
Remedy:
- Make connection of magnetic switch at output of the inverter securely.
- Check output wiring.
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FAn
Cooling fan fault
Displayed when a fault condition occurs in the inverter cooling fan.
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Cause:
- An alien substance is clogged in a ventilating slot.
- Inverter has been in use without changing a cooling fan.
Remedy:
- Check the ventilating slot and remove the clogged substances.
- Replace the cooling fan.
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OVT
Over voltage
DC voltage increases higher than 400V during deceleration or due to surge voltage.
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Cause:
- Decel time is too short compared to the GD² of the load.
- Regenerative load is at the inverter output.
- Line voltage is too high.
Remedy:
- Increase the Decel time.
- Use Dynamic Brake Unit.
- Check whether line voltage exceeds its rating.
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LVT
Low voltage
The inverter turns off its output if the DC voltage is below 180V.
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Cause:
- Line voltage is low.
- Load larger than line capacity is connected to line (e.g., welding machine, large motor).
- Faulty magnetic switch at the input side.
Remedy:
- Check whether line voltage is below its rating.
- Check the incoming AC line. Adjust the line capacity corresponding to the load.
- Change magnetic switch.
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ETH
Electronic Thermal
The internal electronic thermal determines motor overheating.
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Cause:
- Motor has overheated.
- Load is greater than inverter rating.
- ETH level is set too low.
- Inverter capacity is incorrectly selected.
- Inverter has been operated at low speed for too long.
Remedy:
- Reduce load weight and operating duty.
- Change inverter with higher capacity.
- Adjust ETH level to an appropriate level.
- Select correct inverter capacity.
- Install a cooling fan with a separate power supply.
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EtA
External fault A contact input
Inverter turns off output when external fault signal A (Normal Open) is received.
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Cause:
- The terminal set to “18 (External fault-A)” in I20-I24 in I/O group is ON.
Remedy:
- Eliminate the cause of fault at circuit connected to external fault terminal.
- Check cause of external fault input.
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EtB
External fault B contact input
Inverter turns off output when external fault signal B (Normal Close) is received.
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Cause:
- The terminal set to “19 (External fault-B)” in I20-I24 in I/O group is ON.
Remedy:
- Eliminate the cause of fault at circuit connected to external fault terminal.
- Check cause of external fault input.
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_ _ L
Operating method lost
Frequency command lost when set via Analog input or Communication.
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Cause:
- No frequency command is applied to V1 and I.
Remedy:
- Check the wiring of V1 and I and frequency reference level.
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rErr
Remote keypad communication error
Inverter and remote keypad do not communicate with each other.
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Cause:
- Communication error between inverter keypad and remote keypad.
Remedy:
- Check for connection of communication line and connector.
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nbr
Brake control error
Rating current flows below set value during break control.
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Cause:
- Brake open current does not flow anymore.
Remedy:
- Check the Motor Capacity & Wiring.
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EEP / HWT / Err / COM / ntc
System/Hardware Errors
EEP: Parameter save error
HWT: Hardware fault
Err: Communication error
COM: Keypad error
ntc: NTC open
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Cause:
- Internal hardware damage, memory failure, or communication circuitry failure.
Remedy:
- Contact your local LSIS sales representative.
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