Cause : BU earth leakage comes when total earth leakage of inverter modules is excessive. A 2392 fault in ABB ACS880 drive indicates a potential earth fault, which means current is leaking to the ground instead of flowing through the intended path in the motor circuit.

1. Check there are no power factor correction capacitors or surge absorbers in motor cable.
2. Measure insulation resistances of motor cables and motor.