PowerFlex 525 Fault Codes: The Plain-English Reference
The Allen-Bradley PowerFlex 525 reports problems as F-codes on its display. This page is the plain-English version of the common ones: what each code means, what usually causes it in the field, and where to look first. Type in the box to filter the table.
Safety first: drives hold lethal DC bus charge after power-off and can restart machinery when a fault clears. Lockout/tagout, wait the manufacturer's specified discharge time before touching terminals, and have qualified personnel do electrical work. This reference is a quick-orientation aid — always confirm against the official manual for your exact model and firmware.
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| Code | Name | What it means | What to check first |
|---|---|---|---|
| F002 | Auxiliary Input | An external device wired to the auxiliary input opened the circuit | Check the external interlock/device wired to the aux input and its wiring |
| F003 | Power Loss | Incoming line power dipped or a phase dropped while running | Check supply voltage, upstream fuses/breaker, and incoming connections |
| F004 | UnderVoltage | DC bus voltage fell below the minimum limit | Low line voltage or brownout — monitor supply; check for sagging feeds under load |
| F005 | OverVoltage | DC bus voltage exceeded the maximum limit | Often regen from a fast-decelerating load — extend decel time or add a brake resistor; check for line transients |
| F006 | Motor Stalled | Motor could not accelerate — drive hit current limit too long | Mechanical jam or overload; too-short accel time; undersized drive for the load |
| F007 | Motor Overload | Electronic overload (I²t) tripped for the motor | Verify motor OL current parameter matches the nameplate; check for mechanical overload |
| F008 | Heatsink OvrTemp | Drive heatsink exceeded temperature limit | Clean the heatsink/fan, check enclosure ventilation and ambient temperature, verify fan operation |
| F012 | HW OverCurrent | Instantaneous output current exceeded the hardware trip level | Short circuit or ground fault in motor cable/motor; sudden load slam — inspect cable and motor insulation |
| F013 | Ground Fault | Current leakage path to ground detected on the output | Megger the motor and cable; check for moisture in the motor junction box |
| F015 | Load Loss | Output torque fell below the configured load-loss level | Broken belt/coupling or lost load — inspect the mechanical transmission |
| F021 | Output Ph Loss | One output phase to the motor was lost | Check motor leads and connections at drive and motor terminal box |
| F029 | Analog In Loss | The analog speed-reference signal was lost | Broken 4-20 mA/0-10 V wiring or failed transmitter — check the reference source and cable |
| F033 | Auto Rstrt Tries | The drive exhausted its configured automatic restart attempts | Find and fix the underlying recurring fault; the restart counter is telling you it keeps happening |
| F038 | Phase U to Gnd | Ground fault detected on output phase U | Insulation test motor and cable on that phase; check terminations |
| F039 | Phase V to Gnd | Ground fault detected on output phase V | As F038, phase V |
| F040 | Phase W to Gnd | Ground fault detected on output phase W | As F038, phase W |
| F041 | Phase UV Short | Short circuit detected between output phases U and V | Inspect motor cable and motor windings; do not keep resetting into a short |
| F042 | Phase UW Short | Short circuit between phases U and W | As F041 |
| F043 | Phase VW Short | Short circuit between phases V and W | As F041 |
| F048 | Params Defaulted | The drive was commanded to reset parameters to defaults | Expected after a reset — reload or re-enter your application parameters |
| F059 | Safety Open | The Safe Torque Off (STO) safety inputs are open | Check the safety circuit (relay, e-stop chain, jumpers if STO unused) wired to the safety terminals |
| F063 | SW OverCurrent | Output current exceeded the software trip level | Check for mechanical overload, aggressive accel, or incorrect motor data |
| F064 | Drive Overload | Drive I²t overload — running above rating too long | Load exceeds drive rating — check sizing, duty cycle, and cooling |
| F070 | Power Unit | Fault detected in the drive power section | Cycle power; if it persists the power stage has likely failed — drive service/replacement |
| F071 | Net Loss | Communication loss on the embedded EtherNet/IP network | Check network cabling, switch, and the controller connection; review comm loss action settings |
| F081 | Comm Loss | Communication loss on the DSI/serial port | Check serial/keypad wiring and the connected device |
| F094 | Function Loss | The function-loss input opened | Check the device wired to the function-loss terminal |
| F100 | Parameter Chksum | Drive memory checksum error in stored parameters | Reset to defaults (P041) and reprogram; if recurring, the control board memory is suspect |
| F111 | Safety Hardware | Fault in the safety (STO) input hardware | Check safety wiring for miswire/overvoltage; persistent fault means control board service |
| F114 | uC Failure | The drive microcontroller detected an internal failure | Cycle power; persistent F114 is an internal hardware fault — contact Rockwell support/replace the drive |
How to clear a PowerFlex 525 fault
- Read the code first (and note it) — clearing without reading throws away the diagnosis. Recent faults are stored in the drive's fault buffer (viewable via display group parameters or software).
- Fix the cause — most faults on this list return immediately if the underlying condition remains.
- Clear it — press the red Stop/reset key, cycle a digital input configured for fault reset, send a comms reset from the PLC, or cycle power. If the drive restarts automatically, treat that behavior with respect: auto-restart on a machine that can move people or product must be a deliberate, risk-assessed choice.
The three fault families worth recognizing
- Power-quality faults (F003/F004/F005): the drive is telling you about your supply or your decel rate, not about itself. Bus overvoltage on decel is the classic — the motor becomes a generator and the bus absorbs it; lengthen decel or add braking.
- Output faults (F012/F013/F038-F043): the cable and motor are the suspects. Insulation-test before resetting repeatedly — resetting into a real short damages the drive.
- Thermal faults (F007/F008/F064): something is working harder than designed — dirty heatsink, dead fan, hot enclosure, or a load that grew over the years while the drive stayed the same size.
New to drives? Start with what a VFD is and how it works — the fault list makes far more sense once the rectifier/DC-bus/inverter architecture is clear. Setting one up? See the PowerFlex 525 parameters guide.
Frequently asked questions
What does F059 mean on a PowerFlex 525?
F059 "Safety Open" means the Safe Torque Off (STO) safety inputs are open — the drive is being held safe by its safety circuit. Check the e-stop chain, safety relay, or (if STO is unused) the safety-terminal jumpers per the manual.
How do I clear a fault on a PowerFlex 525?
Fix the cause first, then reset: press the red Stop key, pulse a digital input configured for fault reset, send a reset over the network from the PLC, or cycle power. Faults whose cause remains will return immediately.
What causes F005 OverVoltage on a PowerFlex 525?
Usually regeneration: a high-inertia load decelerating too fast pumps energy back into the DC bus. Lengthen decel time (P040) or add a dynamic-brake resistor; also rule out line transients.
Where is the official PowerFlex 525 fault list?
Rockwell Automation publication 520-UM001 (PowerFlex 520-Series Adjustable Frequency AC Drive User Manual), available free from Rockwell\u2019s literature library — always the final authority for your firmware revision.
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