Cause : DC link overvoltage comes when excessive intermediate circuit DC voltage due to the DC Link voltage has risen above the acceptable limits.

An AE09 fault code in your ABB ACS880 drive indicates a  DC Link overvoltage fault. The DC Link is a vital part of the drive that converts incoming AC voltage to DC voltage for the motor. This fault signifies that the DC Link voltage has risen above the acceptable limits.

Note: This warning can be shown only when the IGBT supply unit is not modulating. Check that parameter 95.1 Supply voltage is set according to the supply voltage in use.