Electrical power distribution
Supplying energy to railway trains- Distribution of electricity

Primary electrical energy is supplied by generating stations (hydro, nuclear, gas, wind, solar), which distribute the current to all domestic and industrial customers. The very-high-voltage (VHV) distribution network includes interconnection substations, which in turn supply distribution substations. The railroads are one of these subscribers, and must adapt this voltage using their own substations.

With very few exceptions, the railway system uses two-pole traction units, either DC or single-phase AC.