Earth (ground) fault

What does ALARM 14 mean?

Current is flowing from the output phases to ground, either in the cable between the frequency converter and the motor, or within the motor itself. This is a severe fault that can cause electrocution, fire, and damage to the frequency converter or motor.

• Insulation breakdown in the motor windings, causing a path for current to flow to the motor frame (ground).
• Damaged or improperly installed motor cable (e.g., crushed, cut, water ingress) leading to insulation failure to ground.
• Water or contamination ingress into the motor terminal box or frequency converter output terminals (U, V, W).
• Incorrectly terminated motor cable shields, or shield damage, allowing phase-to-ground contact.
• Faulty ground detection circuit within the frequency converter.

Click steps to track your progress.

1. 1

   Disconnect the motor cables (U, V, W) from the frequency converter output terminals and measure insulation resistance from each motor phase to ground using a megohmmeter (e.g., 500VDC).

2. 2

   Perform a visual inspection of the motor cable for any signs of damage, crushing, or water ingress along its entire length.

3. 3

   Check the motor terminal box for any signs of moisture, contamination, or loose wiring that could cause a ground fault.

4. 4

   Verify proper grounding of both the motor frame and the frequency converter chassis to the plant's earth ground system.

5. 5

   Isolate the fault by first testing the motor cable separately (disconnected from motor and frequency converter) for insulation resistance to ground.