Study on single-phase earthed faulty feeder selection methods in non-solidly grounded systems

All currently used detection principles of single- phase earthed fault are listed in the paper. The advantages and disadvantages of each selection principle are also summarized. Several conclusions are obtained by synthetically analyzing all the single-phase earthed faulty feeder selection methods: firstly, detection methods using transient signals have better sensitivity than that using steady state signals; secondly, transient signal based detection methods are not only applicable for Peterson coiled systems, but also applicable for intermittent arc earthed faults. Lastly, with the developments of modern microelectronic techniques, the transient signals generated by single-phase earthed faults can be easily recorded and processed by complicated digital algorithm; hence, transient signal based detection methods must be more applicable in the future single-phase earthed faulty feeder selection devices.