Single phase fault detection technique based on transient current and its application in non-solid grounded network

Very low fault currents and unstable fault conditions make single phase to ground fault detection in non-solid grounded networks very difficult. Many fault detection techniques have been developed and proved unsatisfactory in practical application. A new single phase fault detection and faulty feeder selection method using transient zero sequence current is presented and evaluated in this paper. A fault detection and recording device is developed and installed in a substation. Recorded fault data proved the proposed technique. It should be pointed out that using the transient zero sequence component to detect single phase faults is not a brand new concept. But this technique was not practical until cost effective microelectronics based high speed transient signal acquisition circuits were available. Therefore success of the proposed fault detection method is due to the development of modern electronic techniques.