ATV320 PHF fault under load, what to check first?
My Altivar ATV320 drive just tripped on a PHF fault while running a conveyor under load. It was working fine, then suddenly stopped. What should I check first?
A PHF fault on a Schneider Altivar ATV320 drive indicates an input phase loss, meaning one supply phase is missing or the drive is incorrectly supplied. This protection only activates when the drive is under load. It's distinct from output phase loss (OPF1/OPF2) or losing multiple input phases, which might trigger a USF fault.
Likely causes and checks
1Blown fuse or open phase
- Points to it
- This is the most common cause, especially if the fault appeared suddenly. A fuse on one of the input phases may have blown, or there's an open circuit in the supply line.
- Check
- Lock out the power and measure all three input phases at the drive terminals. Also, check the fuses for continuity.
2Drive incorrectly supplied
- Points to it
- If this is a new installation or a 3-phase drive is being fed from a single-phase supply, the drive might be incorrectly configured for its power source.
- Check
- Confirm that the supply voltage and phase configuration (e.g., 3-phase) match the drive's specifications and reference. A 3-phase drive requires a 3-phase supply.
3Loose input connection
- Points to it
- Intermittent PHF faults, especially under load, can be caused by a loose connection at the drive's input terminals or within the contactor.
- Check
- Lock out the power and physically check the tightness of all input terminal connections on the drive and inspect the contactor contacts for good connection.
4Unbalanced load or supply
- Points to it
- While all phases might be present, significant imbalance in voltage or current between phases under load can sometimes trigger a PHF fault.
- Check
- Measure the phase voltages and currents at the drive input while it is operating under load to identify any significant imbalances.
Next check: Start by locking out the power and checking for a blown fuse or an open phase by measuring the voltage across all three input phases at the drive.
Related questions
Describe the fault or upload a photo, and InduQT checks it against the manufacturer manuals. Share the result here when it helps someone else.