Ground Fault

What does GF mean?

The Drive output grounding current has exceeded 50% of the Drive's rated output current. This indicates a motor lead shorted to ground or a defective DCCT (Direct Current Current Transformer), posing risks of electrical shock, equipment damage, or fire.

• Insulation breakdown or short circuit between a motor phase winding (U, V, or W) and the motor frame or ground.
• Physical damage or insulation failure in the motor output cable, causing a short from a conductor to conduit, ground, or drive enclosure.
• Water ingress, condensation, or conductive contamination within the motor terminal box or the drive's output terminals (U, V, W).
• Failure of the internal DCCT (Direct Current Current Transformer) or current sensing circuitry within the drive.
• Incorrectly installed or damaged output filter (e.g., dV/dT filter, sine wave filter) causing excessive leakage current to ground.

Click steps to track your progress.

1. 1

   Disconnect the motor leads (U, V, W) from the drive's output terminals and perform an insulation resistance test (megohm test) on each motor phase to ground.

2. 2

   Visually inspect the motor output cables for physical damage, chafing, or signs of moisture ingress, especially at cable glands and connections.

3. 3

   Measure the resistance between each output terminal (U, V, W) and the ground terminal (E/PE) at the drive with power off; any reading near 0 ohms indicates a direct short.

4. 4

   If the motor and cables test clear, temporarily remove any output filters or reactors and re-test the drive with a short cable to a known-good test motor, if possible.

5. 5

   Ensure the motor frame and the drive enclosure are correctly and securely connected to the main protective earth (PE) bus.

6. 6

   Verify that output cable shielding is properly terminated to the drive's ground terminal and the motor frame, where applicable.