ACS800 line side Earth fault
1) check to make sure the motor is properly grounded to the drive. Not grounded to the frame and assuming this is an acceptable ground path.
2) Make sure that only set of motor leads are in the conduit between drive and motor. If there are two sets of drive motor leads, the drive will detect the PWM output from the other drive and posting a false-positive (usually this is unlikely)
3) Check the output voltage/current going to the motor. Voltage and current should be similar (i.e. 460, 461, 462 VAC) no more than a couple volts. Current should be similar (i.e. 60, 59, 61 Amps). This measurement must be done at 60 Hz, as this is the frequency that the multi-meters require for an accurate measurement. Frequencies below 58 Hz may not be accurate.
4) Measure the current on the ground wire. Typically this will be at or near zero. There will always be current flowing on this wire!
5) Depending on wire size, put the clamp on meter around all three motor leads at the same time. This should add up to ZERO or very, very close. If not, than that is the amount of current flowing somewhere unwanted.
6) Megger the motor. Should >100 Mega Ohms at 1000 VDC.
7) Megger the motor and the wires going to the motor --- same result at 6)
8) drive will usually trip when current is approximately 50% of drive rated current.