PHL Phase Loss (Input) fault in delta drive

PHL Phase Loss (Input) fault in delta drive troubleshooting

Description

PHL indicates that the drive has detected an imbalance or total loss of one of the incoming power phases (R, S, or T). Running on fewer phases stresses the DC bus capacitors and input rectifiers.

Causes

1. Blown Fuse: One of the input fuses on the distribution panel has blown.
2. Loose Wire: A terminal screw on the input breaker or drive input is loose.
3. Grid Issue: The utility supply has dropped a phase.
4. Screw Terminal Corrosion: High resistance on one leg causing voltage drop.

Solution

Verify supply:
1. Measure Voltage: With the drive powered, carefully measure AC voltage between R-S, S-T, and T-R. They should be equal.
2. Check Fuses: Test continuity on all input fuses.
3. Tighten Connections: Ensure all input wiring is secure.
4. Disable Protection (Not Recommended): Some parameters allow disabling input phase loss detection, but this risks destroying the drive rectifiers under load. Only do this for testing.