Identifying ground fault location in High Resistance Grounded systems using Adjustable Speed Drive

One of the more difficult problems to solve in industrial plant is to locate and eliminate a ground fault in High Resistance Ground (HRG) system. This is because a ground fault conditions in these systems do not draw enough current to reliably trigger fault current sensors in the drive. This paper developed an approach to identify the ground fault location in HRG systems using voltage sensing, rather than current sensing techniques, inside an Adjustable Speed Drive (ASD). The approach consists of a simple analog circuit and digital signal processing technique to detect a fault condition, as well as to identify the fault location, be it on the load motor side, inside the ASD, or AC line side. The use of this ground fault identification method is also extended and discussed for application to multiple drive lineups.