Earth fault 2 (Ground fault)

What does 45 mean?

A ground fault has been detected in the system, meaning current is flowing to earth through an unintended path. This is a critical safety issue that can cause electrical shock, equipment damage, or fire if not immediately addressed.

• Motor winding insulation breakdown to the motor frame (phase-to-ground fault).
• Motor cable insulation failure to ground (e.g., due to chafing, mechanical damage, water ingress).
• Water or conductive debris in the motor terminal box causing a phase-to-ground short.
• Faulty insulation in associated equipment (e.g., reactors, filters) connected to the motor output.
• Damage to the frequency converter's output stage (e.g., IGBT failure to ground).

Click steps to track your progress.

1. 1

   Disconnect main power supply to the frequency converter at the upstream breaker. Verify zero voltage at L1, L2, L3 terminals.

2. 2

   Disconnect the motor cables (U, V, W) from the frequency converter output terminals (T1, T2, T3).

3. 3

   Measure insulation resistance from each motor phase (U, V, W) to motor frame ground using a megohmmeter (e.g., 500VDC or 1000VDC).

4. 4

   Measure insulation resistance from each motor cable conductor (T1, T2, T3) to earth ground (cable shield/conduit) with the motor disconnected.

5. 5

   Visually inspect the motor cable along its entire length for signs of damage to the outer jacket or inner insulation.

6. 6

   If insulation resistance is below acceptable limits (e.g., < 1 Megohm), isolate the faulty component (motor or cable) and replace.