Input Phase Loss
Yaskawa · F7 Drive Programming
What does PF mean?
A PF fault indicates that one or more of the input AC phases to the drive has been lost. The drive's detection circuit monitors DC bus current ripple and activates if the difference (ΔV) between maximum and minimum DC bus voltage values reaches or exceeds an internal detection level for 0.5 seconds. This can lead to imbalanced current draw, potential damage to the drive's input rectifier, and motor instability.
Additional Steps
Steps 1–2 are listed in Priority Fix.
- 3
Measure the voltage across all three input phases to ensure a balanced and stable AC supply, both at the drive input and upstream.
- 4
Note that PF detection is typically disabled during a stop command, magnetic contactor OFF, CPU A/D converter fault (CPF5), during deceleration, or when output current is low (≤30% of rated current).