Lightning overvoltage protection of AC railroad vehicles by polymeric arresters

In order to improve the operational reliability of AC railroad vehicles, ZnO surge arresters are used to protect them against overvoltages. The most serious threat to arresters installed on the roof of an AC railroad vehicle is the lightning overvoltage. When lightning strikes the mast or conductors, the distribution system can be treated as a system of multiple conductors including feeders, messenger wires, contact wires, protective wires and two tracks. The lightning impulse discharge current through the arrester and the absorbed impulse discharging energy by arrester in the actual field operation and the protective effect of arrester were analyzed by EMTP and discussed when lightning strikes the mast or distribution lines. When the arrester Is installed on the roof of a railroad vehicle, the potential difference on the primary side of high voltage transformer inside the vehicle is suppressed below 150 kV under very serious condition