This European Standard applies to the electrical protection system, provided for AC and DC electric traction systems. It: - establishes railway specific protection principles; - describes the railway specific protection system functionality; - specifies minimum functional requirements and informative examples of their application; - establishes limitations of the protection system and the acceptability of residual risks; - specifies principles for conformity assessment. It applies to: - railways; - guided mass transport systems, such as tramways, elevated and underground railways, mountain railways, trolleybus systems, and magnetically levitated systems which use a contact line system. This European Standard may also be applied to electrified road traffic with a contact line, such as truck-trolley systems. This European Standard applies to new electric traction systems and may be applied to changes of existing systems. It does not apply to: - underground mine traction systems; - cranes, transportable platforms and similar transportation equipment on rails, temporary structures (e.g. exhibition structures) in so far as these are not supplied directly or via transformers from the contact line system and are not endangered by the traction power supply system; - suspended cable cars; - funicular railways; - magnetic levitated systems (without a contact line system); - railways with an inductive power supply without contact system; - railways with a buried contact system that is required to be energized only below the train to ensure safety. This European Standard does not cover: - technical requirements for products, e.g. protection devices; - rules for maintenance of protection systems.