Power Loss

What does F3 mean?

This fault signals that the DC bus voltage within the drive is experiencing excessive ripple, which usually indicates an unstable or insufficient incoming AC power supply. This can be caused by a complete or partial loss of one or more phases, or a significant imbalance in the supply voltage. Operating with excessive DC bus ripple can stress internal components and lead to erratic drive behavior or component failure if not addressed.

• One or more phases of the incoming AC supply are missing or severely unbalanced (e.g., blown fuse in L1).
• Loose electrical connections at the drive's main power terminals (L1, L2, L3) causing intermittent contact.
• Internal failure of the drive's rectifier bridge or DC link capacitors, leading to poor DC bus smoothing.
• Insufficient sizing of the incoming AC power source (e.g., transformer, wiring) leading to voltage sag under load.
• Momentary power interruption (brownout) or significant voltage dip on the utility supply.

Click steps to track your progress.

1. 1

   Measure incoming AC line voltage at terminals L1, L2, L3 for phase-to-phase and phase-to-ground stability.

2. 2

   Verify the integrity and continuity of all fuses and circuit breakers in the incoming AC supply path.

3. 3

   Inspect and retorque all main power connections at the drive's L1, L2, L3 terminals and the upstream disconnect.

4. 4

   Monitor the DC bus voltage (via drive display or test terminals) for excessive ripple magnitude during operation.

5. 5

   If excessive ripple is present despite stable AC input, prepare to replace the drive due to internal component failure.