The protection of DC railway traction power supply systems against direct lightning strike

The paper presents study on surge arresters used for protection of DC railway traction system. The properties of horn spark gaps and varistors are compared. There are serious doubts regarding to the uncritical use of only the varistor arresters to protect the overhead contact line due to their low withstand to partial lightning currents. A discussion on required withstand to lightning current is conducted. Advantages and disadvantages of application of specific type arresters used in Poland for different traction systems have been presented.