Characteristics of Railway Electrification
Railway electrification provides traction energy to trains; the energy is typically generated in large-scale commercial generating stations, where the fuel efficiency of generation can be optimised. The electrical energy is conveyed to the trains by transmission lines to the railway, and then distributed within the railway network to the various trains. There is usually an internal energy distribution system and voltage transformation provided by the railway infrastructure manager.
The energy is transferred to moving trains through a continuous or nearly continuous contact conductor. In the case of overhead systems this is usually a contact wire suspended in a catenary wire system to maintain accurate registration of geometrical position. The trains have a pantograph mounted on the roof, which supports conducting strips held in contact with the contact wire by a spring system. Some variants of this system are described later in this article.
In the case of third rail systems, the conductor is a rail supported on the sleepers (ties). Four rail systems are described later in this article.
As compared with diesel traction, the principal alternative system, electrification enables considerably enhanced fuel efficiency even allowing for transmission losses; it enables much higher specific installed power in the traction unit; it substantially reduces maintenance cost and out of service time for the traction units; it enables more responsive control; it avoids discharge of products of combustion in urban areas; and it enables regeneration, when a train is decelerating and the motors act as generators, returning energy to the power line (although this is not widely implemented).
Its disadvantages are the very high first cost of providing the energy distribution system; a corresponding inability to provide a cheap service to lightly trafficked routes; a relative lack of flexibility in the event of route disruption.
Read more about this topic: Railway Electrification System
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