Mains phase loss

What does 4 mean?

A phase is missing on the supply side, or the mains voltage imbalance is excessively high. This message can also indicate a fault within the input rectifier on the frequency converter. Unresolved mains phase loss can lead to severe damage to the frequency converter or connected motor.

• Complete loss of one or more phases in the incoming AC mains supply (e.g., L1, L2, L3).
• Excessive voltage imbalance between incoming phases, exceeding the frequency converter's tolerance (e.g., >3% imbalance).
• Blown fuse or tripped circuit breaker on one or more of the input phases upstream of the frequency converter.
• Internal fault within the frequency converter's input rectifier bridge, causing erroneous phase loss detection.

Click steps to track your progress.

1. 1

   Measure the voltage between all three incoming phases (L1-L2, L2-L3, L3-L1) at the drive's input terminals; confirm all phases are present and balanced within 2%.

2. 2

   Check the continuity and proper rating of all input fuses or verify the status of upstream circuit breakers feeding the frequency converter.

3. 3

   Inspect power wiring connections at the drive's input terminals (L1, L2, L3) for loose connections, corrosion, or signs of overheating.

4. 4

   With power off and discharged, measure the resistance of the input rectifier diodes using a multimeter to detect internal rectifier failure.