Ground Fault

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The ground fault detection circuit monitors output current and activates when one of the inverter output phases is connected to ground, or the grounding current exceeds 50% of the inverter rated current. This condition poses a serious electrical hazard, risks personnel safety, and can damage the inverter and connected motor if not resolved promptly.

• Insulation breakdown in the motor windings (phase-to-ground) due to aging, moisture, or overheating.
• Damaged motor cable insulation allowing a phase conductor to contact the cable tray or machine frame.
• Water ingress or condensation inside the motor terminal box or inverter output section.
• Faulty surge arrestors or EMI filters on the inverter output creating a path to ground.
• Incorrectly wired or damaged output contactor or disconnect switch with a ground fault.

Klicken Sie auf Schritte, um Ihren Fortschritt zu verfolgen.

1. 1

   Disconnect power to the inverter and ensure the DC bus capacitors are discharged (wait 5-10 minutes).

2. 2

   Disconnect motor cables (U, V, W) from the inverter output terminals.

3. 3

   Measure insulation resistance of each motor phase to ground using a megohmmeter (e.g., 1000V DC test voltage).

4. 4

   Measure insulation resistance of the motor cables from the inverter side to the motor side (phase-to-ground).

5. 5

   Check for moisture or foreign conductive material inside the motor terminal box or inverter output compartment.

6. 6

   If the fault clears with the motor disconnected, inspect the motor for internal ground faults and the motor cables for damage.