Protection of 25 kV electrified railway system

Improving the reliability of an electrified railway operation system requires protection against overvoltage, particularly those of atmospheric origin. The most serious threat to the traction system is lightning when it strikes the mast or conductors. The ZnO arresters are used to protect a system from this phenomenon. In the present investigation the system under study is developed and each element is represented by a model corresponding in EMTP program and some elements are modelled using the models section in ATP EMTP. Protective effect of the surge arrester and discharge current which passes through it is analysed and discussed in case lightning strikes a mast. The simulation results have shown that the surge arrester reduces overvoltage in primary power transformer traction below the basic insulation level, under critical conditions.