ABB ACS850 Fault 1 Overcurrent

Fault 1 – Overcurrent in the ABB ACS850 Drive VFD indicates that the output current has exceeded the drive's internal overcurrent trip limit. To protect the inverter power module (IGBTs) and the motor, the drive immediately trips and displays Fault 1 – Overcurrent.

ABB ACS850 Fault 1 Overcurrent


In addition to an actual overload condition, this fault may also be caused by a motor earth fault, incorrect motor wiring, or incorrect drive parameter settings.

Possible Causes

  • Motor overload.
  • Acceleration time is too short.
  • Sudden load increase.
  • Motor or motor cable short circuit.
  • Earth (ground) fault in the motor or motor cable.
  • Incorrect motor wiring or phase sequence.
  • Contactors opening or closing in the motor cable.
  • Incorrect motor nameplate data entered during commissioning.
  • Motor and drive size mismatch.
  • Mechanical jam or locked rotor.
  • Internal IGBT or power module failure (less common).

Solutions

  1. Check the motor load.
  2. Check the acceleration times and increase them if necessary.
  3. Check the motor and motor cable, including correct phase connections.
  4. Verify that there are no contactors opening or closing in the motor cable while the drive is running.
  5. Check that the motor data entered in the drive matches the motor rating plate.
  6. Check for an earth fault in the motor or motor cable by measuring the insulation resistance.
  7. Repair or replace damaged motor cables or the motor if required.
  8. If the fault persists after all external checks, inspect the drive power module.

Additional Information

The ABB ACS850 continuously monitors the motor output current. If the current exceeds the drive's protection limit, the drive trips with Fault 1 – Overcurrent to prevent damage to the inverter and motor.

Besides excessive motor current, common causes include:

  • Short acceleration ramps.
  • Motor cable faults.
  • Ground faults.
  • Incorrect motor data.
  • Mechanical overload.

Unlike a simple overload warning, Fault 1 immediately disables the inverter output to protect the drive.

Common Symptoms

  • Drive displays Fault 1 – Overcurrent.
  • Motor trips during starting or acceleration.
  • Drive stops immediately after a Run command.
  • High output current is displayed.
  • Repeated overcurrent trips.
  • Motor may hum or fail to accelerate.
  • Production stops unexpectedly.
  • Fault returns after reset if the underlying problem remains.

Recommended Troubleshooting Sequence

  1. Verify that the displayed fault is Fault 1 – Overcurrent.
  2. Disconnect power and follow lockout/tagout procedures.
  3. Check the driven machine for overload or mechanical binding.
  4. Increase the acceleration time if required.
  5. Inspect the motor cable for short circuits or damage.
  6. Verify the motor wiring and phase connections.
  7. Confirm that the motor data matches the motor nameplate.
  8. Measure the insulation resistance of the motor and motor cable.
  9. Ensure there are no contactors switching the motor cable while the drive is operating.
  10. Reset the fault and verify normal drive operation.

Fault 1 Overcurrent Check Table

Check PointAction
Motor loadCheck for overload or mechanical jam
Acceleration timeIncrease if too short
Motor cableInspect for short circuit or damage
Motor wiringVerify correct phase connections
Motor dataCompare with motor rating plate
Earth faultMeasure motor and cable insulation resistance
Motor contactorsEnsure they do not switch during operation
Drive output currentVerify normal current after repair
Power moduleInspect if the fault persists
Drive operationConfirm normal operation after reset

Preventive Maintenance Tips

  • Use acceleration times suitable for the application.
  • Periodically inspect motor cables for insulation damage.
  • Measure motor insulation resistance during scheduled maintenance.
  • Verify motor nameplate parameters after commissioning.
  • Do not install contactors between the drive and motor unless specifically designed for the application.
  • Tighten all motor and power terminals regularly.
  • Keep the drive cooling system clean and ensure adequate airflow.
  • Avoid sudden load changes that can produce high inrush current.
  • Record recurring Fault 1 – Overcurrent events to identify developing mechanical or electrical issues.
  • Follow ABB preventive maintenance recommendations for the ACS850 Drive VFD.

Proper inspection of the motor load, acceleration settings, motor cable, motor wiring, motor data, and earth insulation will help prevent recurring Fault 1 – Overcurrent in ABB ACS850 Drive VFDs, ensuring reliable operation, protection of the inverter power module, and long-term motor performance.

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