What can cause a Hardware Overcurrent fault ( Fault 12 ) in an AC drive, and what can be done to troubleshoot or prevent this?

Hardware Overcurrent Faults (F12) on AC Drive

 A Hardware (HW) Overcurrent fault indicates that the drive is sourcing current that is 2­times its rating. Therefore the motor is receiving this current as well.

One or more of the following items may cause an AC drive to produce a HW Overcurrent fault:
  • The motor nameplate information is not entered correctly in the drive parameters.
  • The motor is not wired correctly.
  • The motor nameplate current plus the cable charging current may exceed the maximum drive output. Check the length of the leads from the drive to the motor.
  • The drive has not been tuned to the motor.
  • The run signal chatters. Check if the control mode is two-­wire and repair the signal so that it is not intermittent.
  • The drive starts the motor when the load is already spinning. To correct this, turn on the flying start function in the drive.
  • A device such as a contactor or a disconnect switch, wired between the drive and the motor, is changing state (opening/closing) after the drive is running. Make sure that all devices on the output of the drive are closed and stay closed while the drive is running
  • The drive is running multiple motors, but it is not in V/Hz mode.
  • The drive has an internal failure. To test for this, run it when the motor and motor leads are disconnected from the drive's output terminals and watch for a fault to occur. (Be sure to only test this way while the drive runs in open loop mode. Turn off encoder feedback if it is enabled.)
  • There is a short in the motor windings.