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Dual electrification is a system whereby a
Dual electrification is a system whereby a railway
Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a p ...
line is supplied power both via overhead catenary
An overhead line or overhead wire is an electrical cable that is used to transmit electrical energy to electric locomotives, trolleybuses or trams. It is known variously as:
* Overhead catenary
* Overhead contact system (OCS)
* Overhead equipm ...
and a third rail
A third rail, also known as a live rail, electric rail or conductor rail, is a method of providing electric power to a railway locomotive or train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway ...
. This is done to enable trains that use either system of power to share the same railway line, for example in the case of mainline and suburban trains (as used at Hamburg
Hamburg (, ; nds, label=Hamburg German, Low Saxon, Hamborg ), officially the Free and Hanseatic City of Hamburg (german: Freie und Hansestadt Hamburg; nds, label=Low Saxon, Friee un Hansestadt Hamborg),. is the List of cities in Germany by popul ...
S-Bahn
The S-Bahn is the name of hybrid urban-suburban rail systems serving a metropolitan region in German-speaking countries. Some of the larger S-Bahn systems provide service similar to rapid transit systems, while smaller ones often resemble c ...
between 1940 and 1955).
Examples
* London, UK **North London Line
The North London line (NLL) is a railway line which passes through the inner suburbs of west, north-west, north, and east London, England between Richmond in the south-west and Stratford in the east, avoiding central London. Its route is a ro ...
changeover at Acton Central
Acton Central railway station is on the North London line, between and , in Travelcard Zone 3. It is also where trains change power supply from overhead line equipment (25 kV AC railway electrification, 25 kV AC) to third rail (750 Volt, V Di ...
.
**Northern City Line
The Northern City Line is a commuter railway line in England, which runs from Moorgate station to Finsbury Park in London with services running beyond. It is part of the Great Northern Route services, and operates as the south-eastern branch ...
changeover at Drayton Park.
** Thameslink route changeover at City Thameslink (northbound) and Farringdon (southbound).
** West London line changeover between Willesden Junction
Willesden Junction is a railway station in Harlesden, north-west London, UK. It is served by both London Overground and London Underground services.
History
The station developed on three contiguous sites: the West Coast Main Line (WCML) st ...
and Shepherd's Bush
Shepherd's Bush is a district of West London, England, within the London Borough of Hammersmith and Fulham west of Charing Cross, and identified as a major metropolitan centre in the London Plan.
Although primarily residential in character ...
.
* New York, NY
** Penn Station Pennsylvania Station is a name applied by the Pennsylvania Railroad to several of its grand passenger terminals.
Pennsylvania Station or Penn Station may also refer to
Current train stations
* Baltimore Penn Station
* Pennsylvania Station (Cinc ...
** East River Tunnels
** North River Tunnels
The North River Tunnels are a pair of rail tunnels that carry Amtrak and New Jersey Transit passenger lines under the Hudson River between Weehawken, New Jersey, and Pennsylvania Station in Manhattan, New York City, New York. Built between 1904 ...
* Athens, GR
** Line 3 of Athens Metro
The Athens Metro ( el, Μετρό Αθήνας, Metro Athinas, translit-std=iso) is a rapid-transit system in Greece which serves the Athens urban area and parts of East Attica. Line 1 opened as a conventional steam railway in 1869 and electrif ...
uses third rail for underground part and overhead power supply on surface for access to/from Airport
An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surfa ...
.
Variations
Both systems live
The system is usually used only in exceptional cases as it can lead to problems caused by the interaction of the electric circuits; for example, where one system is powered withdirect current
Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or ev ...
and another by alternating current
Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in whic ...
(AC), premagnetisation of the substation transformers of the AC system can occur.
One system live
A similar arrangement to dual electrification is one in which both means of powering atrain
In rail transport, a train (from Old French , from Latin , "to pull, to draw") is a series of connected vehicles that run along a railway track and transport people or freight. Trains are typically pulled or pushed by locomotives (often ...
are present, but not live simultaneously. Such arrangements can be found in frontier stations and in sections of railway used for running tests.
See also
*Multi-system (rail)
A multi-system locomotive, also known as a multi-system electric locomotive, multi-system electric multiple unit, or multi-system train, is an electric locomotive which can operate using more than one railway electrification system. Multi-system ...
References