Overhead Contact Line

The overhead contact line, also called traction current line, contact wire or catenary, is a special wire that supplies trains, electric buses and streetcars with electricity. It is located above the track, fixed by poles, and is connected to the electric traction units by a pantograph or current collector, so that an electric circuit is closed via the rails. If there are no rails, as in the case of an electric bus, for example, a multipole overhead line is required.

To ensure that the vehicles are supplied with sufficient power, substations are installed at various intervals to convert the power from the public high-voltage power grid into traction current. This is done with the help of transformers. The current is then fed in via the overhead line. For AC railroads, there is a substation every 60-80 km, while for DC railroads, due to the lower voltage, there is a substation every 25 km.