S.HASE, T.ITO, K.KAWAHARA, S.AOYAGI
Briefly speaking, the rail is a part of feeding circuit and the voltage of the rail is generated the load current and the rail resistance. The rail is connected to the earth through a certain resistance and thereby a voltage is generated between the rail and the earth. This voltage is called "the rail potential". The rail potential has a close relation to the electrolytic erosion in DC electic railway system. The railway engineers have addressed to this problem for a long time. The problem is aggravating by an increased load current, high resistivity between the rail and the earth and development of a new rail fastening device. The rail potential tends to be larger recently. Therefore it is necessary to suppress the rail potential from a view point of the electrolytic eroison and safety in maintenance work. In this paper, we describe how the rail potential owing to raised feeding voltage is reduced by changing the tap of rectifier transformer and report that the effect has been confirmed by its simulation and field test.