Switching Surge Overvoltages on A Feeding System of A MAGLEV Train

Abstract

This paper investigates switching surge overvoltages due to a section switchgear between coils and a feeding cable, and surge overvoltages due to a ground fault in the feeding cable. The maximum overvoltage due to switchgear closing is about 25kV on the coil and 15kV on the cable sheath. The coil overvoltage becomes greater as a source voltage reaches its peak. The overvoltages due to switchgear breaking is dependent on a breaking current, and reaches 115kV on the coil and 15kV on the cable sheath when the current is 50A. The fault surge overvoltage is about 24kV on the coil which is smaller than the switching overvoltage. On the contrary, the cable sheath overvoltage reach 32kV which is the largest among various overvoltages investigated in the paper, and could result in sheath insulation breakdown. The coil overvoltage due to current breaking by a section switchgear may cause coil insulation breakdown when the breaking current is large. Both the coil and sheath overvoltages can be controlled to less than the insulation level by arresters.