E.GF Output Side Earth Ground Fault in Mitsubishi FR-A800 Drive

E.GF – Output Side Earth Ground Fault in the Mitsubishi FR-A800 Inverter indicates that the inverter has detected an earth (ground) fault on the output (load) side. When excessive ground fault current flows from the inverter output to earth due to insulation failure or damaged wiring, the inverter immediately shuts off its output to protect the power module (IGBTs), motor, and connected equipment.

E.GF Output Side Earth Ground Fault in Mitsubishi FR-A800 Drive


Possible Causes

  • Earth (ground) fault in the motor windings.
  • Earth fault in the motor connection cable.
  • Damaged motor cable insulation.
  • Moisture inside the motor or terminal box.
  • Damaged motor winding insulation.
  • Motor cable crushed or mechanically damaged.
  • Loose or contaminated motor terminals.
  • Incorrect motor wiring causing leakage to ground.
  • Internal motor failure.

Check Points

  • Check for an earth (ground) fault in the motor.
  • Check the motor connection cable for insulation damage or ground leakage.

Solutions

  1. Inspect the motor for an earth (ground) fault.
  2. Inspect the motor connection cable for insulation damage.
  3. Measure the insulation resistance of the motor and motor cable using a megohmmeter.
  4. Repair or replace the damaged motor cable if necessary.
  5. Repair or replace the motor if the winding insulation has failed.
  6. Remove moisture from the motor or terminal box if present.
  7. Correct any wiring faults and ensure proper grounding.
  8. Reset the fault and verify normal inverter operation.

Additional Information

The FR-A800 continuously monitors leakage current on the inverter output. If an earth fault causes excessive current to flow from the output terminals to ground, the inverter trips with E.GF and immediately disables the output.

Typical causes include:

  • Motor winding insulation failure.
  • Damaged motor cable insulation.
  • Moisture contamination.
  • Mechanical damage to the motor cable.
  • Loose or contaminated motor terminals.

Prompt correction of the ground fault is essential to prevent further damage to the inverter and motor.

Common Symptoms

  • Drive displays E.GF – Output Side Earth Ground Fault.
  • Motor will not start.
  • Inverter trips immediately after a Run command.
  • Fault recurs after reset.
  • Insulation resistance is low.
  • Leakage current to ground is detected.
  • Production stops unexpectedly.

Recommended Troubleshooting Sequence

  1. Verify that the displayed fault is E.GF.
  2. Disconnect power and follow lockout/tagout procedures.
  3. Inspect the motor cable for visible damage.
  4. Measure the insulation resistance of the motor cable.
  5. Measure the insulation resistance of the motor windings.
  6. Inspect the motor terminal box for moisture or contamination.
  7. Repair or replace any faulty cables or motor components.
  8. Reconnect the motor and verify correct wiring.
  9. Reset the fault.
  10. Confirm normal inverter operation.

E.GF Output Side Earth Ground Fault Check Table

Check PointAction
MotorCheck for earth (ground) fault
Motor cableInspect for insulation damage
Insulation resistanceMeasure motor and cable with a megohmmeter
Motor terminalsCheck for moisture or contamination
WiringVerify correct motor connections
Ground leakageLocate and repair the leakage path
Drive operationVerify normal operation after repair

Preventive Maintenance Tips

  • Periodically measure motor insulation resistance.
  • Inspect motor cables for abrasion, cuts, or insulation deterioration.
  • Keep motor terminal boxes clean and dry.
  • Protect cables from mechanical damage.
  • Tighten motor and drive terminals during scheduled maintenance.
  • Prevent moisture from entering the motor and terminal box.
  • Replace damaged cables immediately.
  • Record recurring E.GF faults to identify developing insulation problems.
  • Follow Mitsubishi preventive maintenance recommendations for the FR-A800 inverter.

Proper inspection of the motor, motor connection cable, insulation resistance, and ground leakage path will help prevent recurring E.GF – Output Side Earth Ground Fault faults in Mitsubishi FR-A800 drives, ensuring reliable operation, improved electrical safety, and long-term protection of both the inverter and motor.

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