Drives Service & Support > 1336F > Fault Finder

Fault Number: 13
Fault Display: Ground Fault
Fault Name: Ground Fault
Description: A current path to earth ground in excess of 100 amps has been detected at one or more of the drive output terminals. *Note: If ground current exceeds 220% of drive rated current, "Overcurrent Flt" may occur instead of Ground Fault.
Corrective Action: The drives current CT (current transformer) on the DC bus is detecting current of 220% or 100 amps (whichever is less) in reference to ground. It does this by measuring the current going out compared to the current coming into the drive.

Megger motor for shorts. Megger at 1000 volts minimum, readings must be 1 megaohm or greater. If they are less, then the motor should be replaced. Remove the motor cables from the drive, and megger them also. Anything 1 megaohm or lower, and the cables should be replaced. The motor and motor cables can all be meggered at the same time, after they are disconnected from the drive. If a short is detected, they will have to be seperated to determine where the defect exists.

Do NOT megger anything with the motor cables hooked up to the drive. Doing so will damage the output section of the drive. It will not be covered under any warranty if this happens.

If no short is detected, replace drive bus CT (current transformer). B frame drives CT's are on the base driver board, and C frame and larger drives have them seperate.