Motor phase V missing

What does ALARM 31 mean?

The motor phase V connection between the frequency converter and the motor is missing or interrupted. This prevents proper motor operation and can lead to damage if ignored.

• Loose or disconnected conductor at the drive output terminal V.
• Loose or disconnected conductor at the motor terminal V.
• Break or high resistance in the motor cable's V phase conductor.
• Faulty contactor or circuit breaker in the motor output circuit (if present) for phase V.
• Failure of the drive's output power stage (e.g., IGBT) specifically for phase V.

Click steps to track your progress.

1. 1

   Power off the drive and disconnect input power. Visually inspect and tighten connections for the V-phase motor cable at both the drive's V output terminal and the motor's V terminal.

2. 2

   Measure the resistance of the V-phase motor cable conductor from the drive end to the motor end to check for continuity (expect < 1 Ohm).

3. 3

   With motor cables disconnected from the drive, measure the resistance between motor terminals V-U, V-W, and U-W. All three values should be balanced and low.

4. 4

   Check for any external fusing or contactors in the V-phase motor circuit for continuity and proper operation.

5. 5

   If cable and motor are verified good, the fault indicates a potential internal drive hardware issue with the V-phase output.