With the development of power distribution automation system, feeder automation technology in the small current
grounding system single-phase grounding fault location plays an important role. In the neutral arc suppression coil
grounding system, because of the compensation effect of arc suppression coil, the system fault feature is not obvious. This
paper puts forward a method of RL series branch parallel in arc suppression coil, when system single-phase grounding
fault occurs, the series branch switch gets closed and acts on the neutral, that changes the compensation degree of arc suppression
coil to zero sequence current in fault line, the change of zero sequence residual current being the biggest in the
fault section from neutral to fault point. FTU is used to monitor the change in each fault line for fault regional location.