ABB · ACS580
The drive has detected a loss of one or more phases in the incoming AC power supply. This condition reduces the drive's power capability and can lead to instability, protective tripping, or damage to internal components if operation continues unregulated.
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De-energize the drive. Measure incoming AC line voltages (L1-L2, L2-L3, L3-L1) at the drive input terminals with a multimeter; expect balanced voltages.
Inspect and verify continuity of all upstream fuses (e.g., R-fuses, Class J fuses) and circuit breaker poles feeding the drive.
Re-torque all input power cable connections at the drive input terminals (e.g., L1, L2, L3) and upstream disconnect switch.
Verify proper operation of any input contactor by measuring voltage across its main contacts when energized.
Check voltage at the immediate upstream distribution panel (e.g., busbar L1, L2, L3) to confirm consistent phase supply.