Double electrification

Under a double electrification is defined as the equipment of a railway line with overhead line and busbar, for example, to allow simultaneous usage for long-distance trains and rapid transit or a switch of power-rail pantograph (and vice versa) to enable. The latter was the case for example in the Hamburg S -Bahn 1940-1955.

A double electrification is applied only in exceptional cases, as it can lead to very serious problems with the interaction of circuits. Thus, by the voltage drop along the rail current from the busbar system to the overall management system ( and vice versa) to flow. If one of these systems, a DC and the other an AC system, it may be an undesirable dc bias of the transformers in the substations of the AC system.

Not as a double electrification is referred to overhead line or conductor rails, in which a power can be performed as needed with different current systems. Such systems can be found at border stations and railway test track.

• Traction power technology