VFD-rated motor cable
Price this when overcurrent or overload faults trace to damaged output wiring.
Allen-Bradley PowerFlex 70 Fault Codes
The Allen-Bradley PowerFlex 70 is a mid-range VFD rated 0.37-448 kW. Fault codes display on the HIM (Human Interface Module) as fault numbers. The PowerFlex 70 uses a similar fault structure to the PF700 and PF755 but with its own parameters (accessible via Connected Components Workbench or DriveExplorer).
PowerFlex 70 Fault Code Table
| Code | Fault Description | Common Cause | Action |
|---|---|---|---|
| F2 | Auxiliary input | External fault from TB6 | Check external fault wiring |
| F3 | Power loss | Input power interruption | Check supply voltage |
| F4 | Undervoltage | Low supply voltage | Verify input voltage |
| F5 | Overvoltage | Regenerative energy or voltage spike | Add brake resistor |
| F6 | Motor stall | Motor stalled or overloaded | Check mechanical load |
| F7 | Motor overcurrent | Motor overload or winding fault | Check motor amps and winding |
| F8 | Heatsink overtemperature | High ambient or blocked cooling | Clean fins, check fan |
| F12 | HW overcurrent | Hardware overcurrent (fast) | Check for short circuit |
| F13 | Ground fault | Motor winding or cable ground | Megger test motor |
| F15 | Load loss | Belt broken or load disconnect | Check mechanical connection |
| F23 | Auto tune fault | Motor data entry error | Verify motor nameplate data |
| F25 | Drive overtemperature | Internal temperature high | Check cooling system |
| F33 | Start inhibit | Safety input or logic inhibit | Check digital input wiring |
| F38 | Phase loss | Output phase missing | Check motor connections |
| F63 | Software fault | Parameter or firmware issue | Reset and reload parameters |
| F111 | Internal fault | Hardware fault | Contact Rockwell support |
Most Common PowerFlex 70 Faults
F7 - Motor Overcurrent
Check motor nameplate FLA vs. parameter P032 (motor NP amps). Verify correct motor overload setting. Check motor for single-phasing, winding imbalance, or locked rotor condition. Increase accel time (parameter A051).
F8 - Heatsink Overtemperature
The PowerFlex 70 requires 3-inch clearance on all sides. Clean fins with compressed air - debris accumulates on the cooling fins rapidly in industrial environments. Check internal cooling fan (starts automatically with drive power).
F13 - Ground Fault
Disconnect motor leads at drive output terminals. Megger test each conductor to ground at 1000 VDC. Reading below 1 Mohm indicates a failed cable or motor winding. Also check cable tray for damaged insulation.
F5 - Overvoltage
Pumping applications with fast deceleration cause motor regeneration. Increase deceleration ramp time (parameter A052). If regeneration is unavoidable, add a dynamic braking resistor to the brake resistor terminals.
Parts Commonly Needed
| Part | Notes |
|---|---|
| HIM module | Plug-in display - model 20-HIM-A3 is most common |
| Cooling fan | Match PowerFlex 70 frame size |
| Input fuses | Class J or CC - match ampere rating |
| Brake resistor | Match ohm and watt rating to drive |
Technician Tips
When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.
Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Pro tip: PowerFlex 70 stores fault queue (F01-F08 parameters in the fault log group). Access via HIM: DIAGNOSTICS -> FAULT LOG. Always review the full fault queue - a single event often produces multiple faults in sequence that tell the root cause story.