The phasor combination differential protection for Le-Blanc transformers

The main electrical protection of Le-Blanc connection transformers that supply the single-phase power to electric railway in Taiwan is the overcurrent protcction. This paper prcscnts a more complete protective scheme, the differential protection, for Le-Blanc by phasor combination method. The calculation procedure and the good mismatch results of a practical design example using the parameters of a Le-Blanc transformer of Taiwan Railway Bureau(Tairai1) are described in this paper. h addition, using the normal current transformers and electromagnetic type transformer differential relays to completely construct the protective scheme is another merit of this algorithm.