Allen Bradley PowerFlex 700 F7 Fault — What It Means
Fault F7 on the Allen Bradley PowerFlex 700 AC drive indicates motor overload — the drive’s electronic overload protection (OL) has detected sustained overcurrent to the motor beyond the programmed FLA rating. The PowerFlex 700’s thermal model accumulates an overload count; when it reaches 100%, F7 trips and the drive shuts down to protect the motor windings from thermal damage.
Common Causes
- Mechanical overload on the driven equipment — A jammed conveyor, failed bearing, or excessive process load forces the motor to draw more current than its FLA rating allows.
- Motor overload parameters set incorrectly — Parameter 33 (Motor NP FLA) must match the motor nameplate amps exactly. A value set too low will cause premature F7 trips under normal load.
- Insufficient cooling on the motor — A motor running hot due to poor ventilation, blocked airflow, or high ambient temperature draws more current as winding resistance increases.
- Ramp times too short — Acceleration time set too fast forces high inrush current on every start, accumulating thermal count quickly.
Step-by-Step Fix {#fix}
- Check for mechanical overload — Inspect the driven equipment for jams, seized bearings, or excessive load. Jog the motor uncoupled from the load. If F7 doesn’t trip uncoupled, the load is the problem.
- Verify motor FLA parameter — Check Parameter 33 (Motor NP FLA) in the PowerFlex 700. It must match the motor nameplate full-load amps exactly. Adjust if incorrect.
- Monitor motor current — Use Parameter 2 (Output Current) during operation to confirm actual amps. If current consistently exceeds motor FLA, the load is oversized for the motor.
- Extend acceleration time — Increase Parameter 140 (Accel Time 1) to reduce inrush current during starts. Also check Parameter 141 (Decel Time 1) for similar issues during braking.
- Reset and restart — Press Stop/Reset on the HIM or toggle the reset input. Confirm motor current stays below FLA on the next run cycle.
Parts Often Needed
| Part | Notes |
|---|---|
| Motor (if windings damaged by sustained OL) | Amazon | Verify winding resistance before replacement |
| Driven equipment bearings | Amazon | Replace if seized bearing was root cause |
When to Call a Pro
If F7 trips under no-load conditions with correct parameters, the drive’s current sensing circuit may have failed. Rockwell Automation authorized service handles internal diagnostics.