Lightning surge analysis in light rail transit using the FDTD method

Light rail transit is constructed in many cities to alleviate the problems of traffic jam and air pollution. Special arrangements are required for the DC light rail to limit leakage current. The diode boxes implemented between rail tracks and fault current return wires (FCRW) are one of them. They are susceptible to damage during lightning strikes. The surge voltages on diode boxes are analyzed and simulated by the FDTD method under different conditions in this paper. Frequency dependent loss of wire conductors and lossy rail tracks are considered. It is found that rising front of return strokes, lightning channel locations and soil conductivity nearby affect the surge voltage significantly.