Phase fault

What does LU1 mean?

This fault indicates an issue with one or more phases of the incoming mains power supply, such as a phase loss, imbalance, or incorrect phase sequence. By default, this critical condition triggers a full TRIP, inhibiting all ignition pulses and resetting the Ready signal to protect the drive and motor from operating under compromised power conditions, which could lead to damage. It requires manual reset.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Inspect power wiring: Examine all power connections from the mains input to the drive for loose terminals or damaged cables.

2. 4

   Check upstream circuit breakers/fuses: Ensure all protective devices for the power supply are closed and not tripped.

3. 5

   Measure phase current: If possible, measure current on each phase to detect significant imbalances.