Development of protection system based on pulsed power switching for high-resistance ground fault of power feeding system of dc electric railway

Because of relatively high short-circuit resistance, most of the ground-fault accidents between power feeders and supporting structures can not be detected by the conventional protection systems at the DC electric railway substations. A novel protection system has been successfully developed which reduces such a short-circuit resistance to the detectable level. The unit device consists of a CR-integrator, a master pulse generator gap, a decoupling gap switch and two main arc-gap switches in a series connection, and installed between the rail and the supporting structures. The largescale field test has demonstrated that these inexpensive protection systems function well and may improve the reliability of the DC railway systems.