Motor phase U missing

What does ALARM 30 mean?

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

Click steps to track your progress.

1. 1

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

2. 2

   Measure the resistance of the U-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 U-V, U-W, and V-W. All three values should be balanced and low.

4. 4

   Check for any external fusing or contactors in the U-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 U-phase output.