ČSN EN 50502

This European Standard applies to electrical systems on board of vehicles of the type trolley bus, as defined in 3.1, fed with a nominal line voltage (Un) between 600 V d.c. and 750 V d.c. Standard defines the requirements and constructional hints, especially to avoid electrical danger to the public and to staff. Where special requirements are existing for trolley buses, hints are given for mechanical and functional safety as well as for protection against fire. This European Standard covers vehicles intended for public transport of persons. This Standard applies to trolley buses, buses with current rail for guidance in the road surface and guided buses with bipolar roof current collector. This European Standard does not apply to: a) electric driven vehicles with only internal power supply as hybrid vehicles, diesel - electric vehicles, fuel - cell vehicles and battery vehicles, b) vehicles with safe protective bonding as rubber tyred commuter trains, guided buses with supply by a separate current rail, rail guided buses with unipolar roof current collector and c) vehicles operated outside publicly accessible areas as electric driven lorries on motorways. Guidance and current rails are special solutions and at this time are not under standardization like trolley bus current collectors and overhead contact lines (OCL). It refers mainly to earthed networks, but reference is made also to galvanically insulated networks. Annex A is related to detailed design features for trolley buses. Annexes B and C are related to the current collection systems. The detailed scope of these annexes is given in Annex B.