New concept for the protection against lightning overvoltages and touch voltages

Overvoltages in electrical supply networks of AC and DC railway networks result from the effects of lightning strokes and switching actions and cannot be avoided. Furthermore, the power supply of electrical railways is endangered by direct or nearby lightning. Considering additional the safety aspects for people (touch voltages) in railway systems, one has to deal with three aspects: direct or nearby lightning, induced voltages, and unacceptable voltages due to failures in the system (e.g. breaking of overhead line). Depending on the insulation of the rails against earth, different aspects have to be considered for a general protection concept. A new device, combining protection against overvoltages and touch voltages is introduced.