Suppression of Cable Overvoltage in a High-Speed Electric Multiple Units System

There are two cases that can cause cable overvoltage in a high-speed electric multiple units (EMU) system: one is the seriously rusty rail; the other is pantograph arcing, especially when the train passes through the phase separations. Both cases can endanger the normal operation of the EMU. In this paper, a full analysis is given on the mechanism of the electromagnetic interference, corresponding to the conducted and radiated interference. First, the actual circumstances in which the two kinds of interferences generate are described and the equivalent circuit model is established. Then, the two kinds of interference are analyzed and the induced overvoltage is calculated by means of finite-difference time domain method and piecewise-line technique. Next, based on the analysis mentioned above, a specific transient voltage suppressor (TVS) is proposed to be applied at the terminal of a cable in the train. Finally, the results of theoretical calculation, simulation by Computer Simulation Technology, and measurement are obtained and compared, among which a good agreement is achieved. Thus, the validity of the equivalent circuit model and the suppression effect of the TVS on overvoltage excited by conducted and radiated interference are verified.