Allen-Bradley 20F11NE027AA0NNNNN

Common Fault Codes

Fault 2

Auxiliary Input fault. A digital input configured as an auxiliary input has opened, indicating an external fault condition from a connected device.
Check the wiring and status of the device connected to the auxiliary input. Clear the external fault condition, then reset the drive.

Fault 3

Power Loss fault. DC bus voltage dropped below the minimum threshold during operation, typically caused by an input power interruption or severe voltage sag.
Verify input supply voltage is stable and within specification (342-528V AC). Check input fuses, contactors, and supply wiring. Restore power and reset the fault.

Fault 4

Undervoltage fault. DC bus voltage has fallen below the undervoltage trip level during run, indicating low input voltage or a momentary power dip.
Measure input line voltage at the drive terminals. Investigate supply quality issues, transformer tap settings, or excessive load on the supply. Correct the supply and reset.

Fault 5

Overvoltage fault. DC bus voltage has exceeded the overvoltage trip threshold, commonly caused by regenerative energy from a decelerating load or high input line voltage.
Check input line voltage. If caused by regeneration, extend the deceleration ramp time or install a dynamic braking resistor. Reset the drive after correcting the condition.

Fault 7

Motor Overload fault. The drive's electronic overload protection has tripped due to sustained overcurrent to the motor, indicating the motor is operating beyond its rated thermal capacity.
Verify motor nameplate data matches drive parameter settings. Check for mechanical overload on the driven equipment. Allow the motor to cool and reset the fault.

Fault 12

HW Overcurrent fault. Output current has exceeded the hardware overcurrent trip level, which may indicate a short circuit at the output, a ground fault, or a motor winding fault.
Disconnect the motor and check output wiring for short circuits or ground faults. Megger test the motor windings. Replace damaged wiring or motor as required and reset.

Fault 33

Auto Restart Tries fault. The drive has exhausted the configured number of automatic restart attempts following a fault without successfully resuming operation.
Identify and resolve the underlying fault that triggered the restart attempts. Manually reset the drive after correcting the root cause. Review auto-restart parameter settings if needed.

Fault 81

Safe Torque Off (STO) fault. The STO input signal has been removed or is in an unexpected state, causing the drive to disable output to the motor as a safety response.
Verify the STO wiring and that the safety circuit is correctly energized. Check the safety relay or controller providing the STO signal. Reset the drive once the STO input is restored.