Portal:Railway electrification
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Introduction
A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electric railways use electric locomotives to haul passengers or freight in separate cars or electric multiple units, passenger cars with their own motors. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches and transformers.
Power is supplied to moving trains with a (nearly) continuous conductor running along the track that usually takes one of two forms: overhead line, suspended from poles or towers along the track or from structure or tunnel ceilings; third rail mounted at track level and contacted by a sliding "pickup shoe". Both overhead wire and third-rail systems usually use the running rails as the return conductor but some systems use a separate fourth rail for this purpose.
Selected general articles
A bow collector is one of the three main devices used on tramcars to transfer electric current from the wires above to the tram below. While once very common in continental Europe, it was replaced by the pantograph or the trolley pole, itself often later replaced by the pantograph. Read more...
London Underground track at Ealing Common on the District line, showing the third and fourth rails beside and between the running rails
The London Underground in England is one of the few networks that uses a four-rail system. The additional rail carries the electrical return that, on third rail and overhead networks, is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at 7002420000000000000♠+420 V DC, and a top-contact fourth rail is located centrally between the running rails at 2997790000000000000♠−210 V DC, which combine to provide a traction voltage of 7002630000000000000♠630 V DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail.
The key advantage of the four-rail system is that neither running rail carries any current. This scheme was introduced because of the problems of return currents, intended to be carried by the earthed (grounded) running rail, flowing through the iron tunnel linings instead. This can cause electrolytic damage and even arcing if the tunnel segments are not electrically bonded together. The problem was exacerbated because the return current also had a tendency to flow through nearby iron pipes forming the water and gas mains. Some of these, particularly Victorian mains that predated London's underground railways, were not constructed to carry currents and had no adequate electrical bonding between pipe segments. The four-rail system solves the problem. Although the supply has an artificially created earth point, this connection is derived by using resistors which ensures that stray earth currents are kept to manageable levels. Power-only rails can be mounted on strongly insulating ceramic chairs to minimise current leak, but this is not possible for running rails which have to be seated on stronger metal chairs to carry the weight of trains. However, elastomeric rubber pads placed between the rails and chairs can now solve part of the problem by insulating the running rails from the current return should there be a leakage through the running rails. Read more...- The stud contact system is a once-obsolete ground-level power supply system for electric trams. Power supply studs were set in the road at intervals and connected to a buried electric cable by switches operated by magnets on the tramcars. Current was collected from the studs by a "skate" or "ski collector" under the tramcar. The system was popular for a while in the early 1900s but soon fell out of favour because of the unreliability of the magnetic switches.
In recent years the concept has made a comeback, to remove overhead supply systems from scenically sensitive areas. Current manufacturing methods and electronic control means such systems are much more reliable. The new tram system in Bordeaux, France has resurrected the system in the form of Alimentation par le sol for aesthetic reasons in the city centre. Read more...
Bogie from an MP 89 Paris Métro rolling stock. The lateral contact shoe is located between the rubber tyres
A few lines of the Paris Métro in France operate on a four-rail power scheme. The trains move on rubber tyres which roll on a pair of narrow roll ways made of steel and, in some places, of concrete. Since the tyres do not conduct the return current, the two guide bars provided outside the running 'roll ways' become, in a sense, a third and fourth rail which each provide 750 V DC, so at least electrically it is a four-rail scheme. Each wheel set of a powered truck carries one traction motor. A side sliding (side running) contact shoe picks up the current from the vertical face of each guide bar. The return of each traction motor, as well as each wagon, is effected by one contact shoe each that slide on top of each one of the running rails. This and all other rubber-tyred metros that have a 1,435 mm (4 ft 8 1⁄2 in) standard gauge track between the roll ways operate in the same manner. Read more...
An electric multiple unit or EMU is a multiple-unit train consisting of self-propelled carriages, using electricity as the motive power. An EMU requires no separate locomotive, as electric traction motors are incorporated within one or a number of the carriages. An EMU is usually formed of two or more semi-permanently coupled carriages, but electrically powered single-unit railcars are also generally classed as EMUs. The great majority of EMUs are passenger trains, but versions also exist for carrying parcels and mail.
EMUs are popular on commuter and suburban rail networks around the world due to their fast acceleration and pollution-free operation. Being quieter than diesel multiple units (DMUs) and locomotive-hauled trains, EMUs can operate later at night and more frequently without disturbing nearby residents. In addition, tunnel design for EMU trains is simpler as no provision is needed for exhausting fumes, although retrofitting existing limited-clearance tunnels to accommodate the extra equipment needed to transmit electric power to the train can be difficult. Read more...- Railway electric traction describes the various types of locomotive and multiple units that are used on electrification systems around the world. Read more...
- Railway electrification was initially adopted by the New Zealand Railways in New Zealand for long tunnels; the Otira Tunnel, the Lyttelton Rail Tunnel and the two Tawa Tunnels of the Tawa Flat Deviation. Electrification of Wellington suburban services started with the Johnsonville Line and Kapiti Line out of Wellington from the 1930s. Auckland suburban services were electrified in 2014–15. Electrification of long distance services on the North Island Main Trunk (NIMT) dates from 1986, although KiwiRail is now considering diesel operation of the NIMT. New long tunnels e.g. the Rimutaka Tunnel and the Kaimai Tunnel were operated by diesels, and the Otira and Lyttelton Tunnels have converted to diesel operation.
From 1908 to 1953 there was an electrified mine railway from the Stockton mine on the West Coast of the South Island. Read more... - Railroad electrification in the United States began at the turn of the 20th century and comprised many different systems in many different geographical areas, few of which were connected. Despite this situation, these systems shared a small number of common reasons for electrification.
Most of the systems discussed in this article are either no longer electrified, or are now part of the Northeast Corridor and Keystone Corridor systems used by Amtrak and several commuter rail lines. One exception is the Black Mesa and Lake Powell Railroad, an isolated system hauling coal from a mine to a power plant. Most mass transit, streetcar and interurban systems electrified very early—many from the beginning—but are not within the scope of this article. Read more... - In Switzerland, the voltage levels of the traction power grid are 132 kV/66 kV. At Muttenz and Etzwilen, there are transformers for coupling to 110 kV level of the traction power grid of Germany. Read more...
- In Germany, the voltage of traction current grid is 110 kV. In the Northeastern parts of Germany there is no traction current grid, as decentralized converter plants situated at the substations are used. Read more...
- The Central Organisation for Railway Electrification (CORE), headquartered in Allahabad, India, is in charge of railway electrification of the Indian Railways network. The organisation, founded in 1961, is headed by a general manager. Project units operate in Ambala, Bhubaneshwar, Chennai, Bangalore, Secunderabad, Lucknow, Kota, Kolkata, Ahemedabad, Jaipur, Jabalpur and New Jalpaiguri.
CORE headquarters is assisted by electrical, signal and telecommunications (S&T), civil, store, personnel, vigilance and finance departments. Railway-electrification project offices, headed by chief project directors, operate in Ambala, Bhubaneswar, Chennai, Lucknow, Jaipur and Secunderabad, Gorakhpur, Danapur and New Jalpaiguri and Jabalpur. Read more... - SNCF Class B 82500 multi-system electro-diesel multiple unit at Provins
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 trains provide continuous journeys over routes which are electrified using more than one system. Read more...
Overhead line electrification at Great Bentley
Railway electrification in Great Britain began during the late 19th century. A range of voltages has been used, employing both overhead lines and conductor rails; the two most common systems are 25 kV AC using overhead lines and the 750 V DC third rail system used in southeast England and on Merseyrail. In 2006, 40%—3,062 miles (4,928 km) of the British rail network was electrified, and 60% of all rail journeys were by electric traction (both by locomotives and multiple units).
According to Network Rail, 64% of the electrified network uses the 25 kV AC overhead system, and 36% uses the 660/750 V DC third-rail system. Read more...
A traction substation, traction current converter plant or traction power substation (TPSS) is an electrical substation that converts electric power from the form provided by the electrical power industry for public utility service to an appropriate voltage, current type and frequency to supply railways, trams (streetcars) or trolleybuses with traction current. Read more...
Overhead lines on Swiss Federal Railways
An overhead line or overhead wire is used to transmit electrical energy to trams, trolleybuses or trains. It is known variously as:- Overhead contact system (OCS)
- Overhead line equipment (OLE or OHLE)
- Overhead equipment (OHE)
- Overhead wiring (OHW) or overhead lines (OHL)
- Catenary
- Trolley wire
- Traction wire
In this article, the generic term overhead line is used, as used by the International Union of Railways. Read more...
Electrification of Australian railways began with the Melbourne and Sydney suburban lines.
Melbourne suburban lines were electrified from 1919 using 1.5 kV DC. Sydney suburban lines were electrified from 1926 using the same system.
Later Australian systems used 25 kV AC electrification, which had been introduced in the 1950s in France, and by the 1980s become the international standard. Hence they differed from earlier systems, although as each suburban system is centred on a main city and are not interconnected this is not a problem. Later suburban systems were Brisbane from 1979, Perth from 1992 and Adelaide from 2014. There has also been extensive non-urban electrification in Queensland using 25 kV AC, mainly during the 1980s for coal routes. Read more...
Double FEVE electro-diesel locomotive 1915 at El Berrón (Spain)
An electro-diesel locomotive (also referred to as a dual-mode or bi-mode locomotive) is powered either from an electricity supply (like an electric locomotive) or by using the onboard diesel engine (like a diesel-electric locomotive). For the most part, these locomotives are built to serve regional, niche markets with a very specific purpose. Read more...- Electric railways with third rails, or fourth rails, in tunnels carry collector shoes projecting laterally (sideways), or vertically, from their bogies. The contact shoe may slide on top of the third rail (top running), on the bottom (bottom running) or on the side (side running). The side running contact shoe is used against the guide bars on rubber-tired metros. A vertical contact shoe is used on ground-level power supply systems, stud contact systems and fourth rail systems. A pair of contact shoes was used on underground current collection systems. The contact shoe on a stud contact system is called a ski collector. The ski collector moves vertically to accommodate slight variations in the height of the studs. Contact shoes may also be used on overhead conductor rails, on guide bars or on trolley wires. Most railways use three rails, while the London Underground uses four rails. Read more...
Electric locomotive made in USSR in 1933 (designed in USA by GE)— "Suramsky Soviet", the 14th unit made
While the former Soviet Union got a late (and slow) start with rail electrification in the 1930s it eventually became the world leader in electrification in terms of the volume of traffic under the wires. During its last 30 years the Soviet Union hauled about as much rail freight as all the other countries in the world combined and in the end, over 60% of this was by electric locomotives. Electrification was cost effective due to the very high density of traffic and was at times projected to yield at least a 10% return on electrification investment (to replace diesel traction). By 1990, the electrification was about half 3 kV DC and half 25 kV AC 50 Hz and 70% of rail passenger-km was by electric railways. Read more...- Railway electrification in the Republic of Turkey comprises a 1,490 km (930 mi) long system, separated into three parts which are not connected. Along with these several Turkish cities operate rapid transit and tram system electrified with either overhead wire or third rail.
By 2013, the electrified lines reached to 2416 km. There is also 888 km of electrified high speed train network, which makes 3304 km in total. Read more...
Transposition pylon of power line for single-phase AC traction current (110 kV, 16.7 Hz) near Bartholomä in Germany.
A traction network or traction power network is an electricity grid for the supply of electrified rail networks. The installation of a separate traction network generally is only done if the railway in question uses alternating current (AC) with a frequency lower than that of the national grid, such as in Germany, Austria and Switzerland.
Alternatively, the three-phase alternating current of the power grid can be converted in substations by rotary transformers or static inverters into the voltage and type of current required by the trains. For railways which run on direct current (DC), this method is always used, as well as for railways which run on single-phase AC of decreased frequency, as in Mecklenburg-Western Pomerania, Saxony-Anhalt, Norway and Sweden. In these areas there are no traction current networks. Read more...
Conduit current collection is a system of electric current collection used by electric tramways, where the power supply was carried in a 'conduit' under the roadway. Read more...- This is a list of the power supply systems that are, or have been, used for tramway and railway electrification systems.
Note that the voltages are nominal and vary depending on load and distance from the substation. Read more...
The Thamshavn Line became Norway's first electrified when it opened in 1908.
The Norwegian railway network consists of 2,552 kilometers (1,586 mi) of electrified railway lines, constituting 62% of the Norwegian National Rail Administration's 4,114 kilometers (2,556 mi) of line. In 2008, electric traction accounted for 90% of the passenger kilometers, 93% of the tonne kilometers and 74% of the energy consumption of all trains running in Norway, with the rest being accounted for by diesel traction. Read more...- In Austria, the voltage of traction current grid is 110 kV, except of the lines
Meidling-Hütteldorf, Hütteldorf-Auhof, Hütteldorf-Florisdorf, Florisdorf-Simmering
and Meidling-Simmering, which are operated with 55 kV. Read more...
Ground-level power supply, also known as surface current collection and Alimentation Par le Sol (APS, which literally means feeding via the ground), is a modern method of third-rail electrical pick-up for street trams instead of more common overhead lines, thus it is one of the methods that could allow construction of catenary-free light rail system. It was invented for the Bordeaux tramway (Tramway de Bordeaux), which was constructed from 2000 and opened in 2003. From 2011, the technology has been used as part of other systems around the world, with Reims Tramway, Angers tramway and Dubai Tram all having adopted the technology. Read more...
The diamond-shaped, electric-rod pantograph of the Swiss cogwheel locomotive of the Schynige Platte railway in Schynige Platte, built in 1911
A pantograph (or "pan") is an apparatus mounted on the roof of an electric train, tram or electric bus to collect power through contact with an overhead line. It is a common type of current collector. Typically, a single or double wire is used, with the return current running through the track. The term stems from the resemblance of some styles to the mechanical pantographs used for copying handwriting and drawings. Read more...
Railway electrification in Iran describes the past and present electrification systems used to supply traction current to rail transport in Iran with a chronological record of development, a list of lines using each system, and a history and a technical description of each system.
The project is sometimes abbreviated to RAIELEC, in which RAI is the abbreviation of Islamic Republic of Iran Railways (Persian: برقی کردن راه آهن در ایران, abbr: بكرا). Read more...
The New York City Subway is the world's largest single operator rapid transit system by number of stations served, utilizing hundreds of miles of electrified track.
A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply.
Electric railways use electric locomotives to haul passengers or freight in separate cars or electric multiple units, passenger cars with their own motors.
Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches and transformers.
Power is supplied to moving trains with a (nearly) continuous conductor running along the track that usually takes one of two forms: overhead line, suspended from poles or towers along the track or from structure or tunnel ceilings; third rail mounted at track level and contacted by a sliding "pickup shoe". Both overhead wire and third-rail systems usually use the running rails as the return conductor but some systems use a separate fourth rail for this purpose. Read more...
An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor.
Electric locomotives with on-board fueled prime movers, such as diesel engines or gas turbines, are classed as diesel-electric or gas turbine-electric and not as electric locomotives, because the electric generator/motor combination serves only as a power transmission system. Read more...- Railway electrification in Malaysia is a relatively recent development of rail transport in Malaysia. While the first railway in the country dates back to 1885, it was not until 3 August 1995 that the first electrified railway service, KTM Komuter, began operations.
The term "railway electrification" mainly refers to the project to electrify the Keretapi Tanah Melayu's West Coast Line from Padang Besar to Johor Bahru, combined with the duplication of the single-track line and the elimination of level crossings. As of November 2015, the stretch between Padang Besar and Gemas has been completed, with two electrified train services operating on the stretch: the KTM Komuter and the ETS. Read more...
Japan's conventional mainline railway network schematic map showing electrification systems with voltages and frequencies as of 2017. Third-sector railways are included. Shinkansen exclusive-use trackage is not included. Municipal subways and other rapid transit networks are not included. Private railways are not included.
This is a list of Railway Electrification Systems in Japan:
Overhead line power supply, unless otherwise noted. Read more...- Electric railways in Sweden are powered from a single-phase AC supply of 15 kV at 16 2⁄3 Hz, as used in Germany, Austria and Switzerland. Unlike these countries, the 132 kV traction current grid covers only part of the country, approximately north of Stockholm. This grid is fed by frequency converters and has no generation nor transmission lines from Norway, which uses the same traction current system. Formerly, the Porjus Hydroelectric Power Station provided electric power to the traction network. In the future the Älvkarleby Hydroelectric Power Station may be connected to the traction network, as this would increase stability of the power grid of the railway system.
Separate from the 132 kV grid is a 30 kV line connection between Mon and Varp substation north of Gothenburg.
Also the overhead wire system has some differences. It is common, that the pylons for the overhead wire also carry a three phase AC system. In order to reduce counts of substations, the voltage at the substations for the overhead wire is 32 kV at some lines (AT-System). However trains require 16 kV and therefore auto transformers are used, which have a central connection connected with the grounded railway, while the other connections are connected to the 32 kV output. The voltage between this central connection to the phase is 16 kV. The other pole to ground is also 16 kV, but with opposite polarity and runs along the track on the overhead wires until separation section. Other lines are fed directly with 16 kV from the substations. However differential transformers are used for feeding, in order to eliminate jamming signals. Read more...
Trolley pole tipped with a trolley shoe on a Toronto streetcar
A trolley pole is a tapered cylindrical pole of wood or metal, used to transfer electricity from a "live" overhead wire to the control and the electric traction motors of a tram or trolley bus. It is a type of current collector. The use of overhead wire in a system of current collection is reputed to be the 1880 invention of Frank J. Sprague, but the first working trolley pole was developed and demonstrated by Charles Van Depoele, in autumn 1885. Read more...
The Thamshavn Line became Norway's first electrified when it opened in 1908.
The Norwegian railway network consists of 2,552 kilometers (1,586 mi) of electrified railway lines, constituting 62% of the Norwegian National Rail Administration's 4,114 kilometers (2,556 mi) of line. The first three mainline systems to be electrified were private ore-hauling lines. The Thamshavn Line opened in 1909, and remained in revenue use until 1973, after which it was converted to a heritage railway. It is the world's oldest remaining alternating-current railway and the only narrow gauge railway in the country to have been electrified. It was followed by Norsk Transport's Rjukan and Tinnoset Lines two years later, and Sydvaranger's Kirkenes–Bjørnevatn Line in 1922. The Norwegian State Railways' (NSB) first electrification was parts of the Drammen Line in 1922 and the ore-hauling Ofoten Line in 1923, which connects to the Iron Ore Line in Sweden. The use of El 1 locomotives on the Drammen Line proved a large cost-saver over steam locomotives, and NSB started electrifying other lines around Oslo; from 1927 to 1930, the remainder of the Drammen Line, and the continuation along the Randsfjorden and Sørlandet Lines to Kongsvinger were converted, along with the first section of the Trunk Line. In 1935, the Hardanger Line became the first section of new NSB track to be electrified. From 1936 to 1940, NSB electrified the Østfold Line as well as more of the Sørland Line and the Bratsberg Line, connecting all electric lines west of Oslo.
During the 1940s, NSB electrified the Sørland Line, although the final section from Egersund to Stavanger was not converted until 1956. In 1957, the Kirkenes–Bjørnevatn Line became the only line to remove the electrification and replace the electric locomotives with diesel power. The 1950s saw the electrification of several regional and commuter lines around Oslo, including the Kongsvinger Line, the Trunk Line and the Dovre Line from Lillestrøm to Hamar, the Vestfold Line and the Eastern Østfold Line. This was largely due to NSB's program to remove all steam locomotives, either by electrification or by dieselization. In the late 1950s and 1960s, several to-be electrified lines were operated with diesel locomotives as an interim solution. The 1960s saw the remaining two steam lines in Southern Norway, the Bergen and Dovre Lines, electrified along with the Gjøvik Line. The Bergen Line was completed in 1964 and the Dovre Line completed in 1970. This finished all the planned electrifications, and the authorities deemed the remaining lines unprofitable to electrify because of low traffic. During the 1990s, a new program was attempted, this time to electrify the entire network, but only the Arendal Line was converted before the program was canceled. However, new lines around Oslo, including the Lieråsen and Oslo Tunnels on the Drammen Line, and the Gardermoen and Asker Lines were electrified at the time they opened. Further plans have been launched, in particular the section of the Nordland Line from Trondheim to Steinkjer, which is part of the Trøndelag Commuter Rail, and the Meråker Line, which connects to the electrified Central Line in Sweden. Read more...
Third rail (top) at Bloor-Yonge Station (Line 1) in Toronto, ON. for the Toronto Transit Commission. Energized at 600 volts DC, the third rail provides electrical power to the power-train, and ancillaries of the subway cars.
A third 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 track. It is used typically in a mass transit or rapid transit system, which has alignments in its own corridors, fully or almost fully segregated from the outside environment. Third rail systems are always supplied from direct current electricity.
The third-rail system of electrification is unrelated to the third rail used in dual gauge railways. Read more...
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Selected images
Double pantograph for three phase electrification on the Jungfraubahn, Switzerland
Workers electrifying parts of the Roca Line in Buenos Aires using 25 kV electrification.
An early rail electrification substation at Dartford in England, UK
Lots Road Power Station in a poster from 1910. This private power station, used by London Underground, gave London trains and trams a power supply independent from the main power network.
Electric locomotives under the Overhead line in Sweden
Close-up view of catenary on Northeast Corridor, United States
London Underground track at Ealing Common on the District line, showing the third and fourth rails beside and between the running rails
An S-series train in its original (1985–2015) livery leaving Lawrence East, bound for McCowan. Note the strip between the running rails.
The New York City Subway is the world's largest single operator rapid transit system by number of stations served, utilizing hundreds of miles of electrified track.
The Royal Border Bridge in England, a protected monument. Adding electric catenary to older structures may be an expensive cost of electrification projects
A bottom-contact third rail on the Amsterdam Metro, Netherlands
Railroad rotary converter at Illinois Railway Museum
Nottingham Express Transit in United Kingdom uses a 750 V DC overhead, in common with most modern tram systems.
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