OLT
Over Load
Displayed when the motor overload trip is activated and the actual load level exceeds the set level. |
Cause:
- The load is greater than the motor’s rated capacity.
- The set value for the overload trip level (Pr.21) is too low.
Remedy:
- Replace the motor and inverter with models that have increased capacity.
- Increase the set value for the overload trip level.
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ULT
Under Load
Displayed when the motor underload trip is activated and the actual load level is less than the set level. |
Cause:
- There is a motor-load connection problem.
- The set value for underload level (Pr.29, Pr.30) is less than the system’s minimum load.
Remedy:
- Replace the motor and inverter with models with lower capacity.
- Reduce the set value for the underload level.
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OCT
Over Current1
Displayed when inverter output current exceeds 200% of the rated current. |
Cause:
- Acc/Dec time is too short, compared to load inertia (GD2).
- The inverter load is greater than the rated capacity.
- The inverter supplied an output while the motor was idling.
- The mechanical brake of the motor is operating too fast.
- A ground fault has occurred in the inverter output wiring.
- The motor insulation is damaged.
Remedy:
- Increase Acc/Dec time.
- Replace the inverter with a model that has increased capacity.
- Operate the inverter after the motor has stopped or use the speed search function (Cn.60).
- Check the mechanical brake.
- Check the output wiring.
- Replace the motor.
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OVT
Over Voltage
Displayed when internal DC circuit voltage exceeds the specified value. |
Cause:
- Deceleration time is too short for the load inertia (GD2).
- A generative load occurs at the inverter output.
- The input voltage is too high.
- A ground fault has occurred in the inverter output wiring.
- The motor insulation is damaged.
Remedy:
- Increase the deceleration time.
- Use the braking unit.
- Determine if the input voltage is above the specified value.
- Check the output wiring.
- Replace the motor.
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LVT
Low Voltage
Displayed when internal DC circuit voltage is less than the specified value. |
Cause:
- The input voltage is too low.
- A load greater than the power capacity is connected to the system (e.g., a welder, direct motor connection).
- The magnetic contactor connected to the power source has a faulty connection.
Remedy:
- Determine if the input voltage is below the specified value.
- Increase the power capacity.
- Replace the magnetic contactor.
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LV2
Low Voltage 2
Displayed when internal DC circuit voltage is less than the specified value during inverter operation. |
Cause:
- The input voltage has decreased during operation.
- An input open-phase has occurred when input voltage is low.
- The magnetic contactor connected to the power source has a faulty connection.
Remedy:
- Determine if the input voltage is below the specified value.
- Check the input wiring.
- Replace the magnetic contactor.
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GFT
Ground Trip
Displayed when a ground fault trip occurs on the output side of the inverter. |
Cause:
- A ground fault has occurred in the inverter output wiring.
- The motor insulation is damaged.
Remedy:
- Check the output wiring.
- Replace the motor.
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ETH
E-Thermal
Displayed based on inverse time-limit thermal characteristics to prevent motor overheating. |
Cause:
- The motor has overheated.
- The inverter load is greater than the rated capacity.
- The set value for electronic thermal protection is too low.
- The inverter has been operated at low speed for an extended duration.
Remedy:
- Reduce the load or operation frequency.
- Replace the inverter with a model that has increased capacity.
- Set an appropriate electronic thermal prevention (ETH) level.
- Replace the motor with a model that supplies extra power to the cooling fan.
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POT
Out Phase Open
Displayed when a 3-phase inverter output has one or more phases in an open circuit condition. |
Cause:
- The magnetic contactor on the output side has a connection fault.
- The output wiring is faulty.
Remedy:
- Check the magnetic contactor on the output side.
- Check the output wiring.
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IPO
In Phase Open
Displayed when a 3-phase inverter input has one or more phases in an open circuit condition. |
Cause:
- The magnetic contactor on the input side has a connection fault.
- The input wiring is faulty.
- The DC link capacitor needs to be replaced.
Remedy:
- Check the magnetic contactor on the input side.
- Check the input wiring.
- Replace the DC link capacitor (Contact retailer/service center).
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IOLT
Inverter OLT
Displayed when the inverter has been protected from overload and resultant overheating. |
Cause:
- The load is greater than the rated motor capacity.
- The torque boost level is too high.
Remedy:
- Replace the motor and inverter with models that have increased capacity.
- Reduce the torque boost level.
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OHT
Over Heat
Displayed when the temperature of the inverter heat sink exceeds the specified value. |
Cause:
- There is a problem with the cooling system.
- The inverter cooling fan has been operated for an extended period.
- The ambient temperature is too high.
Remedy:
- Determine if a foreign object is obstructing the air inlet, outlet, or vent.
- Replace the cooling fan.
- Keep the ambient temperature below 50°C.
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OC2
Over Current2
Displayed when the DC circuit in the inverter detects a specified level of excessive, short circuit current. |
Cause:
- Output wiring is short-circuited.
- There is a fault with the electronic semiconductor (IGBT).
- A ground fault has occurred in the inverter output wiring.
- The motor insulation is damaged.
Remedy:
- Check the output wiring.
- Do not operate the inverter. Contact the retailer or service center.
- Check the output wiring.
- Replace the motor.
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NTC
NTC Open
Displayed when an error is detected in the temperature sensor of the Insulated Gate Bipolar Transistor (IGBT). |
Cause:
- The ambient temperature is too low.
- There is a fault with the internal temperature sensor.
Remedy:
- Keep the ambient temperature above –10°C.
- Contact the retailer or the LSIS customer service center.
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FAN
Fan Trip
Displayed when an error is detected in the cooling fan. |
Cause:
- A foreign object is obstructing the fan’s air vent.
- The cooling fan needs to be replaced.
Remedy:
- Remove the foreign object from the air inlet or outlet.
- Replace the cooling fan.
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