What is Railway electrification system?
[[Image:Three engines of type Rc4.jpg|thumb|250px|[[Electric locomotive]]s under the wires in [[Sweden]]]] [[Image:Jar Station 10.jpg|thumb|Dual electrification; both overhead wire and third rail for different trains]] A '''railway electrification system''' supplies [[Electricity|electrical energy]] to railway [[locomotive]]s and [[Electric multiple unit|multiple unit]]s so that they can operate without having an on-board [[Prime mover (locomotive)|prime mover]]. Their main advantages are high [[energy efficiency]] and low operating cost. Building their wires and other [[infrastructure]] is expensive, however. ==Power supply== Electricity may be sent to the train in different ways. Different countries use different systems. The most widely used systems are: * [[Alternating current]] from [[overhead lines]] at 15,000 [[volt]]s, 16.7 [[Utility frequency|Hz]] * [[Alternating current]] from [[overhead lines]] at 25,000 volts, 50 Hz * [[Direct current]] from [[overhead lines]] at 1,500 or 3,000 volts * [[Direct current]] from a [[third rail]] at 600 or 750 volts ==Related pages== * [[Electric locomotive]] {{Railway electrification}} [[Category:Rail infrastructure]] [[Category:Rail technologies]] [[Category:Electric railways]] {{transport-stub}}