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A railway electrification system supplies
electric power to
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 pre ...
train
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 Passenger train, transport people or Rail freight transport, freight. Trains are typically pul ...
s and
tram
A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport are ...
s without an on-board
prime mover
Prime mover may refer to:
Philosophy
*Unmoved mover, a concept in Aristotle's writings
Engineering
* Prime mover (engine), motor, a machine that converts various other forms of energy (chemical, electrical, fluid pressure/flow, etc) into energy ...
or local fuel supply.
Electric railways use either
electric locomotive
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. Locomotives with on-board fuelled prime movers, such as diesel engines or gas ...
s (hauling passengers or
freight
Cargo consists of bulk goods conveyed by water, air, or land. In economics, freight is cargo that is transported at a freight rate for commercial gain. ''Cargo'' was originally a shipload but now covers all types of freight, including tran ...
in separate cars),
electric multiple unit
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 numbe ...
s (
passenger cars
A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods.
The year 1886 is regarded as ...
with their own motors) or both.
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
In electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmis ...
, but most purchase power from an
electric utility
An electric utility is a company in the electric power industry (often a public utility) that engages in electricity generation and distribution of electricity for sale generally in a regulated market. The electrical utility industry is a major pr ...
. The railway usually provides its own distribution lines, switches, and
transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
s.
Power is supplied to moving trains with a (nearly) continuous
conductor running along the track that usually takes one of two forms: an
overhead line
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 equipmen ...
, suspended from poles or towers along the track or from structure or tunnel ceilings, or 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 ...
mounted at track level and contacted by a sliding "
pickup shoe
Electric current collectors are used by trolleybuses, trams, electric locomotives or EMUs to carry electrical power from overhead lines, electrical third rails, or ground-level power supplies to the electrical equipment of the vehicles. Those for ...
". 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.
In comparison to the principal alternative, the
diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
, electric railways offer substantially better energy efficiency, lower
emissions
Emission may refer to:
Chemical products
* Emission of air pollutants, notably:
**Flue gas, gas exiting to the atmosphere via a flue
** Exhaust gas, flue gas generated by fuel combustion
** Emission of greenhouse gases, which absorb and emit rad ...
, and lower operating costs.
Electric locomotives are also usually quieter, more powerful, and more responsive and reliable than diesels.
They have no local emissions, an important advantage in tunnels and urban areas.
Some electric traction systems provide
regenerative braking
Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...
that turns the train's
kinetic energy
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acc ...
back into electricity and returns it to the supply system to be used by other trains or the general utility grid.
While diesel locomotives burn petroleum products, electricity can be generated from diverse sources, including
renewable energy
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
.
[P. M. Kalla-Bishop, ''Future Railways and Guided Transport'', IPC Transport Press Ltd. 1972, pp. 8-33] Historically concerns of resource independence have played a role in the decision to electrify railway lines. The landlocked
Swiss confederation
). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
which almost completely lacks oil or coal deposits but has plentiful
hydropower
Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to Electricity generation, produce electricity or to power machines. This is achieved by energy transformation, converting the Pot ...
electrified
its network in part in reaction to supply issues during both World Wars.
Disadvantages of electric traction include: high
capital cost
Capital costs are fixed, one-time expenses incurred on the purchase of land, buildings, construction, and equipment used in the production of goods or in the rendering of services. In other words, it is the total cost needed to bring a projec ...
s that may be uneconomic on lightly trafficked routes, a relative lack of flexibility (since electric trains need third rails or overhead wires), and a vulnerability to power interruptions.
[ ]Electro-diesel locomotive
An electro-diesel locomotive (also referred to as a dual-mode or bi-mode locomotive) is a type of locomotive that can be powered either from an electricity supply (like an electric locomotive) or by using the onboard diesel engine (like a diese ...
s and electro-diesel multiple unit
An electro-diesel multiple unit (EDMU) or bi-mode multiple unit (BMU) is a form of a multiple unit that can be powered either by electric power picked up from the overhead lines or third rail (like an electric multiple unit – EMU) or by using ...
s mitigate these problems somewhat as they are capable of running on diesel power during an outage or on non-electrified routes.
Different regions may use different supply voltages and frequencies, complicating through service and requiring greater complexity of locomotive power. There used to be a historical concern for double-stack rail transport
Double-stack rail transport is a form of intermodal freight transport in which railroad cars carry two layers of intermodal containers. Invented in the United States in 1984, it is now being used for nearly seventy percent of United States inter ...
regarding clearances with overhead line
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 equipmen ...
s[ but it is no longer universally true , with both ]Indian Railways
Indian Railways (IR) is a statutory body under the ownership of Ministry of Railways, Government of India that operates India's national railway system. It manages the fourth largest national railway system in the world by size, with a tot ...
and China Railway regularly operating electric double-stack cargo trains under overhead lines.
Railway electrification has constantly increased in the past decades, and as of 2012, electrified tracks account for nearly one-third of total tracks globally.
Classification
Electrification systems are classified by three main parameters:
* Voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
* Current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
** Direct 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 eve ...
(DC)
** 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)
*** Frequency
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
* Contact system
** Overhead line
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 equipmen ...
s (catenary)
** 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 ...
** Fourth rail
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 either electric locomotives (hauling passengers or freight in separate cars), ...
** Ground-level power supply
Ground-level power supply, also known as surface current collection or, in French, ''alimentation par le sol'' ("feeding via the ground"), is a concept and group of technologies whereby electric vehicles collect electric power at ground level fro ...
Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotive
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. Locomotives with on-board fuelled prime movers, such as diesel engines or gas ...
s can switch to different supply voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
s to allow flexibility in operation.
Standardised voltages
Six of the most commonly used voltages have been selected for European and international standardisation. Some of these are independent of the contact system used, so that, for example, 750VDC may be used with either third rail or overhead lines.
There are many other voltage systems used for railway electrification systems around the world, and the list of railway electrification systems
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.
Many modern trams and trains ...
covers both standard voltage and non-standard voltage systems.
The permissible range of voltages allowed for the standardised voltages is as stated in standards BSEN50163 and IEC60850. These take into account the number of trains drawing current and their distance from the substation.
Direct current
Overhead systems
1,500V DC is used in Japan, Indonesia, Hong Kong (parts), Ireland, Australia (parts), France (also using , New Zealand (Wellington
Wellington ( mi, Te Whanganui-a-Tara or ) is the capital city of New Zealand. It is located at the south-western tip of the North Island, between Cook Strait and the Remutaka Range. Wellington is the second-largest city in New Zealand by me ...
), Singapore (on the North East MRT Line), the United States (Chicago
(''City in a Garden''); I Will
, image_map =
, map_caption = Interactive Map of Chicago
, coordinates =
, coordinates_footnotes =
, subdivision_type = Country
, subdivision_name ...
area on the Metra Electric
The Metra Electric District is an electrified commuter rail line owned and operated by Metra which connects Millennium Station (formerly Randolph Street Station), in downtown Chicago, with the city's southern suburbs. As of 2018, it is the fift ...
district and the South Shore Line
The South Shore Line is an electrically powered interurban commuter rail line operated by the Northern Indiana Commuter Transportation District (NICTD) between Millennium Station in downtown Chicago and the South Bend International Airport ...
interurban
The Interurban (or radial railway in Europe and Canada) is a type of electric railway, with streetcar-like electric self-propelled rail cars which run within and between cities or towns. They were very prevalent in North America between 1900 ...
line and Link light rail
Link light rail is a light rail rapid transit system serving the Seattle metropolitan area in the U.S. state of Washington. It is managed by Sound Transit in partnership with local transit providers, and consists of two non-connected lines: ...
in Seattle
Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...
, Washington). In Slovakia, there are two narrow-gauge lines in the High Tatras (one a cog railway
A rack railway (also rack-and-pinion railway, cog railway, or cogwheel railway) is a steep grade railway with a toothed rack and pinion, rack rail, usually between the running Track (rail transport)#Rail, rails. The trains are fitted with one or ...
). In the Netherlands it is used on the main system, alongside 25kV on the HSL-Zuid
The HSL-Zuid ( nl, Hogesnelheidslijn Zuid, en, High-speed Line South), is a 125 kilometre-long (78 miles) Dutch high-speed railway line running between the Amsterdam metropolitan area and the Belgian border, with a branch to Breda, North ...
and Betuwelijn
The Betuweroute is a double track freight railway between Rotterdam and Germany. is the official name, after the Betuwe area through which the route passes. The line is popularly called Betuwelijn, after an older track in the same region. Th ...
, and 3,000V south of Maastricht
Maastricht ( , , ; li, Mestreech ; french: Maestricht ; es, Mastrique ) is a city and a municipality in the southeastern Netherlands. It is the capital and largest city of the province of Limburg. Maastricht is located on both sides of the ...
. In Portugal, it is used in the Cascais Line
The Cascais Line ( pt, Linha de Cascais) is a Portuguese railway line which connects the municipalities of Lisbon, Oeiras, and Cascais. The line starts in Lisbon, at Cais do Sodré and ends in Cascais. On the Lisbon urban trains' diagra ...
and in Denmark on the suburban S-train
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 ...
system (1650V DC).
In the United Kingdom, 1,500VDC was used in 1954 for the Woodhead trans-Pennine route (now closed); the system used regenerative braking
Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...
, allowing for transfer of energy between climbing and descending trains on the steep approaches to the tunnel. The system was also used for suburban electrification in East London and Manchester
Manchester () is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The t ...
, now converted to 25kVAC. It is now only used for the Tyne and Wear Metro
The Tyne and Wear Metro is an overground and underground light rail rapid transit system serving Newcastle upon Tyne, Gateshead, North Tyneside, South Tyneside, and the City of Sunderland (together forming Tyne and Wear). The network opened in ...
. In India, 1,500V DC was the first electrification system launched in 1925 in Mumbai area. Between 2012 and 2016, the electrification was converted to 25kV 50Hz, which is the countrywide system.
3kV DC is used in Belgium, Italy, Spain, Poland, Slovakia, Slovenia, South Africa, Chile, the northern portion of the Czech Republic, the former republics of the Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
, and in the Netherlands on a few kilometers between Maastricht and Belgium. It was formerly used by the Milwaukee Road
The Chicago, Milwaukee, St. Paul and Pacific Railroad (CMStP&P), often referred to as the "Milwaukee Road" , was a Class I railroad that operated in the Midwestern United States, Midwest and Pacific Northwest, Northwest of the United States fr ...
from Harlowton, Montana
Harlowton is a city in and the county seat of Wheatland County, Montana, United States. The population was 955 at the 2020 census.
Description
The city was once the eastern terminus of electric operations (1914–74) for the "Pacific Extension ...
, to Seattle, across the Continental Divide and including extensive branch and loop lines in Montana, and by the Delaware, Lackawanna and Western Railroad (now New Jersey Transit
New Jersey Transit Corporation, branded as NJ Transit, and often shortened to NJT, is a state-owned public transportation system that serves the U.S. state of New Jersey, along with portions of New York State and Pennsylvania. It operates bu ...
, converted to 25kVAC) in the United States, and the Kolkata suburban railway (Bardhaman Main Line) in India, before it was converted to 25kV 50Hz.
DC voltages between 600V and 800V are used by most tram
A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport are ...
ways, trolleybus
A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tramin the 1910s and 1920sJoyce, J.; King, J. S.; and Newman, A. G. (1986). ''British Trolleybus Systems'', pp. 9, 12. London: Ian Allan Publishing. .or trol ...
networks and underground
Underground most commonly refers to:
* Subterranea (geography), the regions beneath the surface of the Earth
Underground may also refer to:
Places
* The Underground (Boston), a music club in the Allston neighborhood of Boston
* The Underground ...
(subway) systems as the traction motors accept this voltage without the weight of an on-board transformer.
Medium-voltage DC
Increasing availability of high-voltage semiconductors may allow the use of higher and more efficient DC voltages that heretofore have only been practical with AC.
The use of medium-voltage DC electrification (MVDC) would solve some of the issues associated with standard-frequency AC electrification systems, especially possible supply grid load imbalance and the phase separation between the electrified sections powered from different phases, whereas high voltage would make the transmission more efficient. UIC conducted a case study for the conversion of the Bordeaux-Hendaye railway line (France), currently electrified at 1.5kV DC, to 9kV DC and found that the conversion would allow to use less bulky overhead wires (saving €20 million per 100route-km) and lower the losses (saving 2GWh per year per 100route-km; equalling about €150,000 p.a.). The line chosen is one of the lines, totalling 6000km, that are in need of renewal.
In the 1960s the Soviets experimented with boosting the overhead voltage from 3 to 6kV. DC rolling stock was equipped with ignitron
An ignitron is a type of gas-filled tube used as a controlled rectifier and dating from the 1930s. Invented by Joseph Slepian while employed by Westinghouse, Westinghouse was the original manufacturer and owned trademark rights to the name "Ignit ...
-based converters to lower the supply voltage to 3kV. The converters turned out to be unreliable and the experiment was curtailed. In 1970 experimental works on system proved a.o. that the equivalent loss levels for a system could be achieved with DC voltage between 11 and 16kV. In the 1980s and 1990s experimental system was being tested on the October Railway
Oktyabrskaya Railway or October Railway (russian: Октябрьская железная дорога) is the subsidiary of RZD, servicing railway lines in the north-west of Russia. It stretches from Moscow's Leningradsky Rail Terminal, Leningrad ...
near Leningrad (now Petersburg). The experiments ended in 1995 due to the end of funding.
Third rail
Most electrification systems use overhead wires, but third rail is an option up to 1,500V. Third rail systems almost exclusively use DC distribution. The use of AC is usually not feasible due to the dimensions of a third rail being physically very large compared with the skin depth
Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases exponentially with greater depths in the co ...
that AC penetrates to in a steel rail. This effect makes the resistance per unit length unacceptably high compared with the use of DC. Third rail is more compact than overhead wires and can be used in smaller-diameter tunnels, an important factor for subway systems.
Fourth rail
The London Underground
The London Underground (also known simply as the Underground or by its nickname the Tube) is a rapid transit system serving Greater London and some parts of the adjacent ceremonial counties of England, counties of Buckinghamshire, Essex and He ...
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 , and a top-contact fourth rail is located centrally between the running rails at , which combine to provide a traction voltage of . The same system was used for Milan
Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
's earliest underground line, Milan Metro
The Milan Metro ( it, Metropolitana di Milano) is the rapid transit system serving Milan, Italy, operated by Azienda Trasporti Milanesi. The network consists of 5 lines, identified by different numbers and colours, with a total network length ...
'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.
The Expo
An expo is a trade exposition. It may also refer to:
Events and venues
* World's fair, a large international public exposition
* Singapore Expo, convention and exposition venue
** Expo Axis, one of the world's largest membrane roofs, constructe ...
and Millennium Line
The Millennium Line is the second line of the SkyTrain rapid transit system in the Metro Vancouver region of British Columbia, Canada. The line is owned and operated by BC Rapid Transit Company, a subsidiary of TransLink, and links the cities ...
of the Vancouver SkyTrain
SkyTrain is the medium-capacity rapid transit system in the Metro Vancouver Regional District, serving Vancouver, British Columbia, Canada. SkyTrain has of track and uses fully automated trains on grade-separated tracks running on underground ...
use side contact fourth-rail systems for their 650V DC supply. Both are located to the side of the train as the space between the running rails is occupied by an aluminum plate, as part of stator of the linear induction propulsion system used on the Innovia ART system. While part of the SkyTrain network, the Canada Line
The Canada Line is a rapid transit line in Metro Vancouver, British Columbia, Canada, that is part of the SkyTrain system. The line is owned by TransLink and InTransitBC and is operated by ProTrans BC. Coloured turquoise on route maps, it op ...
does not use this system and instead uses more traditional motors attached to the wheels and third rail electrification.
Rubber-tyred systems
A few lines of the Paris Métro
The Paris Métro (french: Métro de Paris ; short for Métropolitain ) is a rapid transit system in the Paris metropolitan area, France. A symbol of the Paris, city, it is known for its density within the capital's territorial limits, uniform ar ...
in France operate on a four-rail power system. The trains move on rubber tyres which roll on a pair of narrow roll way
A roll way or running pad is the pad placed on a concrete slab or on the ties on the outside of the conventional track along both running rails of a rubber-tyred metro or along the unconventional track of a tram. The rubber-tyred wheels roll d ...
s made of steel and, in some places, of concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
. Since the tyres do not conduct the return current, the two guide bar
The rubber-tyred metro systems that incorporate track have angle irons as guide bars, or guiding bars, outside of the two roll ways. The Busan Subway Line 4, that lacks a rail track, has I-beams installed as guide bars. The flanges are vertic ...
s provided outside the running 'roll way
A roll way or running pad is the pad placed on a concrete slab or on the ties on the outside of the conventional track along both running rails of a rubber-tyred metro or along the unconventional track of a tram. The rubber-tyred wheels roll d ...
s' become, in a sense, a third and fourth rail which each provide , so at least electrically it is a four-rail system. Each wheel set
A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the key components of the wheel and axle which is one of the six simple machines. Wheels, in conjunction with axles, allow heavy objects to be ...
of a powered bogie carries one traction motor
A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric or hydrogen vehicles, elevators or electric multiple unit.
Traction motors are used in electrically powered rail vehicles ( electric multiple ...
. A side sliding (side running) contact shoe
Electric current collectors are used by trolleybuses, trams, electric locomotives or EMUs to carry electrical power from overhead lines, electrical third rails, or ground-level power supplies to the electrical equipment of the vehicles. Those for ...
picks up the current from the vertical face of each guide bar. The return of each traction motor, as well as each wagon
A wagon or waggon is a heavy four-wheeled vehicle pulled by draught animals or on occasion by humans, used for transporting goods, commodities, agricultural materials, supplies and sometimes people.
Wagons are immediately distinguished from ...
, 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 track between the roll way
A roll way or running pad is the pad placed on a concrete slab or on the ties on the outside of the conventional track along both running rails of a rubber-tyred metro or along the unconventional track of a tram. The rubber-tyred wheels roll d ...
s operate in the same manner.
Alternating current
Railways and electrical utilities use AC as opposed to DC for the same reason: to use transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
s, which require AC, to produce higher voltages.
The higher the voltage, the lower the current for the same power because Power = Current x voltage and power loss is proportional to the current squared. The lower current reduces line loss, thus allowing higher power to be delivered.
As alternating current is used with high voltages, this method of electrification is only used on overhead line
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 equipmen ...
s, never on third rails for safety reasons. Inside the locomotive, a transformer steps the voltage down for use by the traction motors and auxiliary loads.
An early advantage of AC is that the power-wasting resistors used in DC locomotives for speed control were not needed in an AC locomotive: multiple taps on the transformer
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...
can supply a range of voltages.
Separate low-voltage transformer windings supply lighting and the motors driving auxiliary machinery.
More recently, the development of very high power semiconductors has caused the classic DC motor to be largely replaced with the three-phase induction motor fed by a variable frequency drive
A variable-frequency drive (VFD) is a type of motor drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and, depending on topology, to control associated voltage or current variat ...
, a special inverter
A power inverter, inverter or invertor is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the opp ...
that varies both frequency and voltage to control motor speed.
These drives can run equally well on DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operation.
Low-frequency alternating current
Five European countries Germany, Austria, Switzerland, Norway and Sweden have standardized on 15kV Hz (the 50Hz mains frequency divided by three) single-phase AC. On 16 October 1995, Germany, Austria and Switzerland changed from Hz to 16.7Hz which is no longer exactly one-third of the grid frequency. This solved overheating problems with the rotary converters used to generate some of this power from the grid supply.
In the US, the New York, New Haven, and Hartford Railroad
The New York, New Haven and Hartford Railroad , commonly known as The Consolidated, or simply as the New Haven, was a railroad that operated in the New England region of the United States from 1872 to December 31, 1968. Founded by the merger of ...
, the Pennsylvania Railroad
The Pennsylvania Railroad (reporting mark PRR), legal name The Pennsylvania Railroad Company also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. It was named ...
and the Philadelphia and Reading Railway
The Reading Company ( ) was a Philadelphia-headquartered railroad that provided passenger and commercial rail transport in eastern Pennsylvania and neighboring states that operated from 1924 until its 1976 acquisition by Conrail.
Commonly called ...
adopted 11kV 25Hz single-phase AC. Parts of the original electrified network still operate at 25Hz, with voltage boosted to 12kV, while others were converted to 12.5 or 25kV 60Hz.
In the UK, the London, Brighton and South Coast Railway
The London, Brighton and South Coast Railway (LB&SCR; known also as the Brighton line, the Brighton Railway or the Brighton) was a railway company in the United Kingdom from 1846 to 1922. Its territory formed a rough triangle, with London at its ...
pioneered overhead electrification of its suburban lines in London, London Bridge
Several bridges named London Bridge have spanned the River Thames between the City of London and Southwark, in central London. The current crossing, which opened to traffic in 1973, is a box girder bridge built from concrete and steel. It r ...
to Victoria
Victoria most commonly refers to:
* Victoria (Australia), a state of the Commonwealth of Australia
* Victoria, British Columbia, provincial capital of British Columbia, Canada
* Victoria (mythology), Roman goddess of Victory
* Victoria, Seychelle ...
being opened to traffic on 1December 1909. Victoria to Crystal Palace
Crystal Palace may refer to:
Places Canada
* Crystal Palace Complex (Dieppe), a former amusement park now a shopping complex in Dieppe, New Brunswick
* Crystal Palace Barracks, London, Ontario
* Crystal Palace (Montreal), an exhibition building ...
via Balham and West Norwood opened in May 1911. Peckham Rye
Peckham Rye is an open space and road in the London Borough of Southwark in London, England. The roughly triangular open space lies to the south of Peckham town centre. It is managed by Southwark Council and consists of two contiguous areas, wit ...
to West Norwood
West Norwood is a largely residential area of south London within the London Borough of Lambeth, located 5.4 miles (8.7 km) south south-east of Charing Cross. The centre of West Norwood sits in a bowl surrounded by hillsides on its east, ...
opened in June 1912. Further extensions were not made owing to the First World War. Two lines opened in 1925 under the Southern Railway serving Coulsdon North and Sutton railway station. The lines were electrified at 6.7kV 25Hz. It was announced in 1926 that all lines were to be converted to DC third rail and the last overhead-powered electric service ran in September 1929.
Standard frequency alternating current
25 kV AC is used at 60Hz on some US lines, in Saudi Arabia, western Japan, South Korea and Taiwan; and at 50Hz in a number of European countries, India, eastern Japan, countries that used to be part of the Soviet Union, on high-speed lines in much of Western Europe (including countries that still run conventional railways under DC but not in countries using 16.7Hz, see above). On "French system" HSLs, the overhead line and a "sleeper" feeder line each carry 25kV in relation to the rails, but in opposite phase so they are at 50kV from each other; autotransformer
An autotransformer is an electrical transformer with only one winding. The " auto" (Greek for "self") prefix refers to the single coil acting alone, not to any kind of automatic mechanism. In an autotransformer, portions of the same winding act a ...
s equalize the tension at regular intervals.
Three-phase alternating current
Various railway electrification systems in the late nineteenth and twentieth centuries utilised three-phase
Three-phase electric power (abbreviated 3φ) is a common type of alternating current used in electricity generation, Electric power transmission, transmission, and Electric power distribution, distribution. It is a type of polyphase system empl ...
, rather than single-phase electric power delivery due to ease of design of both power supply and locomotives. These systems could either use standard network frequency and three power cables, or reduced frequency, which allowed for return-phase line to be third rail, rather than an additional overhead wire.
Comparisons
AC versus DC for mainlines
The majority of modern electrification systems take AC energy from a power grid that is delivered to a locomotive, and within the locomotive, transformed and rectified to a lower DC voltage in preparation for use by traction motors. These motors may either be DC motors which directly use the DC or they may be three-phase AC motors which require further conversion of the DC to variable frequency three-phase AC (using power electronics). Thus both systems are faced with the same task: converting and transporting high-voltage AC from the power grid to low-voltage DC in the locomotive. The difference between AC and DC electrification systems lies in where the AC is converted to DC: at the substation or on the train. Energy efficiency and infrastructure costs determine which of these is used on a network, although this is often fixed due to pre-existing electrification systems.
Both the transmission and conversion of electric energy involve losses: ohmic losses in wires and power electronics, magnetic field losses in transformers and smoothing reactors (inductors). Power conversion for a DC system takes place mainly in a railway substation where large, heavy, and more efficient hardware can be used as compared to an AC system where conversion takes place aboard the locomotive where space is limited and losses are significantly higher. However, the higher voltages used in many AC electrification systems reduce transmission losses over longer distances, allowing for fewer substations or more powerful locomotives to be used. Also, the energy used to blow air to cool transformers, power electronics (including rectifiers), and other conversion hardware must be accounted for.
Standard AC electrification systems use much higher voltages than standard DC systems. One of the advantages of raising the voltage is that, to transmit certain level of power, lower current is necessary (). Lowering the current reduces the ohmic losses and allows for less bulky, lighter overhead line equipment and more spacing between traction substations, while maintaining power capacity of the system. On the other hand, the higher voltage requires larger isolation gaps, requiring some elements of infrastructure to be larger. The standard-frequency AC system may introduce imbalance to the supply grid, requiring careful planning and design (as at each substation power is drawn from two out of three phases). The low-frequency AC system may be powered by separate generation and distribution network or a network of converter substations, adding the expense, also low-frequency transformers, used both at the substations and on the rolling stock, are particularly bulky and heavy. The DC system, apart from being limited as to the maximum power that can be transmitted, also can be responsible for electrochemical corrosion due to stray DC currents.
Electric versus diesel
Energy efficiency
Electric trains need not carry the weight of prime movers, transmission and fuel. This is partly offset by the weight of electrical equipment.
Regenerative braking
Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...
returns power to the electrification system so that it may be used elsewhere, by other trains on the same system or returned to the general power grid. This is especially useful in mountainous areas where heavily loaded trains must descend long grades.
Central station electricity can often be generated with higher efficiency than a mobile engine/generator. While the efficiency of power plant generation and diesel locomotive generation are roughly the same in the nominal regime, diesel motors decrease in efficiency in non-nominal regimes at low power while if an electric power plant needs to generate less power it will shut down its least efficient generators, thereby increasing efficiency. The electric train can save energy (as compared to diesel) by regenerative braking
Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...
and by not needing to consume energy by idling as diesel locomotives do when stopped or coasting. However, electric rolling stock may run cooling blowers when stopped or coasting, thus consuming energy.
Large fossil fuel power station
A fossil fuel power station is a thermal power station which burns a fossil fuel, such as coal or natural gas, to produce electricity. Fossil fuel power stations have machinery to convert the heat energy of combustion into mechanical energy, wh ...
s operate at high efficiency, and can be used for district heating
District heating (also known as heat networks or teleheating) is a system for distributing heat generated in a centralized location through a system of insulated pipes for residential and commercial heating requirements such as space heating a ...
or to produce district cooling, leading to a higher total efficiency. Electricity for electric rail systems can also come from renewable energy
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
, nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...
, or other low-carbon sources, which do not emit pollution or emissions.
Power output
Electric locomotives may easily be constructed with greater power output than most diesel locomotives. For passenger operation it is possible to provide enough power with diesel engines (see e.g. 'ICE TD
The DBAG Class 605, commonly known as the ICE TD is a high-speed diesel multiple unit (DMU) train, formerly in service with Deutsche Bahn and DSB.
History Development
Following the successful inauguration of the Intercity-Express system ...
') but, at higher speeds, this proves costly and impractical. Therefore, almost all high speed train
High-speed rail (HSR) is a type of rail system that runs significantly faster than traditional rail, using an integrated system of specialised rolling stock and dedicated tracks. While there is no single standard that applies worldwide, lines ...
s are electric. The high power of electric locomotives also gives them the ability to pull freight at higher speed over gradients; in mixed traffic conditions this increases capacity when the time between trains can be decreased. The higher power of electric locomotives and an electrification can also be a cheaper alternative to a new and less steep railway if train weights are to be increased on a system.
On the other hand, electrification may not be suitable for lines with low frequency of traffic, because lower running cost of trains may be outweighed by the high cost of the electrification infrastructure. Therefore, most long-distance lines in developing or sparsely populated countries are not electrified due to relatively low frequency of trains.
Network effect
Network effect
In economics, a network effect (also called network externality or demand-side economies of scale) is the phenomenon by which the value or utility a user derives from a good or service depends on the number of users of compatible products. Net ...
s are a large factor with electrification. When converting lines to electric, the connections with other lines must be considered. Some electrifications have subsequently been removed because of the through traffic to non-electrified lines. If through traffic is to have any benefit, time-consuming engine switches must occur to make such connections or expensive dual mode engines must be used. This is mostly an issue for long-distance trips, but many lines come to be dominated by through traffic from long-haul freight trains (usually running coal, ore, or containers to or from ports). In theory, these trains could enjoy dramatic savings through electrification, but it can be too costly to extend electrification to isolated areas, and unless an entire network is electrified, companies often find that they need to continue use of diesel trains even if sections are electrified. The increasing demand for container traffic, which is more efficient when utilizing the double-stack car, also has network effect issues with existing electrifications due to insufficient clearance of overhead electrical lines for these trains, but electrification can be built or modified to have sufficient clearance, at additional cost.
A problem specifically related to electrified lines are gaps in the electrification. Electric vehicles, especially locomotives, lose power when traversing gaps in the supply, such as phase change gaps in overhead systems, and gaps over points in third rail systems. These become a nuisance if the locomotive stops with its collector on a dead gap, in which case there is no power to restart. Power gaps can be overcome by on-board batteries or motor-flywheel-generator systems.
In 2014, progress is being made in the use of large capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
s to power electric vehicles between stations, and so avoid the need for overhead wires between those stations.
Maintenance costs
Maintenance costs of the lines may be increased by electrification, but many systems claim lower costs due to reduced wear-and-tear on the track from lighter rolling stock. There are some additional maintenance costs associated with the electrical equipment around the track, such as power sub-stations and the catenary wire itself, but, if there is sufficient traffic, the reduced track and especially the lower engine maintenance and running costs exceed the costs of this maintenance significantly.
Sparks effect
Newly electrified lines often show a "sparks effect", whereby electrification in passenger rail systems leads to significant jumps in patronage / revenue. The reasons may include electric trains being seen as more modern and attractive to ride, faster, quieter and smoother service,[ and the fact that electrification often goes hand in hand with a general infrastructure and rolling stock overhaul / replacement, which leads to better service quality (in a way that theoretically could also be achieved by doing similar upgrades yet without electrification). Whatever the causes of the sparks effect, it is well established for numerous routes that have electrified over decades.][
]
Double-stack rail transport
Due to the height restriction imposed by the overhead wires, double-stacked container trains have been traditionally difficult and rare to operate under electrified lines. However, this limitation is being overcome by railways in India, China and African countries by laying new tracks with increased catenary height.
Such installations are in the Western Dedicated Freight Corridor
The Western Dedicated Freight Corridor or Western DFC is a 1,506 km long, under-construction broad gauge freight corridor in India. It will connect Dadri in Uttar Pradesh (near Delhi) with Jawaharlal Nehru Port in Navi Mumbai, Maharashtra. ...
in India where the wire height is at 7.45 metres to accommodate double-stack container trains without the need of well-wagons.
Advantages
* No exposure of passengers to exhaust from the locomotive
* Lower cost of building, running and maintaining locomotives and multiple units
* Higher power-to-weight ratio (no onboard fuel tanks), resulting in
** Fewer locomotives
** Faster acceleration
** Higher practical limit of power
** Higher limit of speed
* Less noise pollution
Noise pollution, also known as environmental noise or sound pollution, is the propagation of noise with ranging impacts on the activity of human or animal life, most of them are harmful to a degree. The source of outdoor noise worldwide is ma ...
(quieter operation)
* Faster acceleration clears lines more quickly to run more trains on the track in urban rail uses
* Reduced power loss at higher altitudes (for ''power loss'' see Diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
)
* Independence of running costs from fluctuating fuel prices
* Service to underground stations where diesel trains cannot operate for safety reasons
* Reduced environmental pollution, especially in highly populated urban areas, even if electricity is produced by fossil fuels
* Easily accommodates kinetic energy brake reclaim using supercapacitors
* More comfortable ride on multiple units as trains have no underfloor diesel engines
* Somewhat higher energy efficiency in part due to regenerative braking
Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...
and less power lost when "idling"
* More flexible primary energy source: can use coal, natural gas, nuclear or renewable energy (hydro, solar, wind) as the primary energy source instead of diesel fuel
* If the entire network is electrified, diesel infrastructure such as fueling stations, maintenance yards and indeed the diesel locomotive fleet can be retired or put to other uses - this is often the business case in favor of electrifying the last few lines in a network where otherwise costs would be too high. Having only one type of motive power also allows greater fleet homogeneity which can also reduce costs.
Disadvantages
* Electrification cost: electrification requires an entire new infrastructure to be built around the existing tracks at a significant cost. Costs are especially high when tunnels, bridges and other obstructions have to be altered for clearance. Another aspect that can raise the cost of electrification are the alterations or upgrades to railway signalling
Railway signalling (), also called railroad signaling (), is a system used to control the movement of railway traffic. Trains move on fixed rails, making them uniquely susceptible to collision. This susceptibility is exacerbated by the enormo ...
needed for new traffic characteristics, and to protect signalling circuitry and track circuits
A track circuit is an electrical device used to prove the absence of a train on rail tracks to signallers and control relevant signals. An alternative to track circuits are axle counters.
Principles and operation
The basic principle behind ...
from interference by traction current. Electrification may require line closures while the new equipment is being installed.
* Appearance: the overhead line structures and cabling can have a significant landscape impact compared with a non-electrified or third rail electrified line that has only occasional signalling equipment above ground level.
* Fragility and vulnerability: overhead electrification systems can suffer severe disruption due to minor mechanical faults or the effects of high winds causing the pantograph
A pantograph (, from their original use for copying writing) is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen. If a line dr ...
of a moving train to become entangled with the catenary
In physics and geometry, a catenary (, ) is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends in a uniform gravitational field.
The catenary curve has a U-like shape, superfici ...
, ripping the wires from their supports. The damage is often not limited to the supply to one track, but extends to those for adjacent tracks as well, causing the entire route to be blocked for a considerable time. Third-rail systems can suffer disruption in cold weather due to ice forming on the conductor rail.
* Theft: the high scrap value of copper and the unguarded, remote installations make overhead cables an attractive target for scrap metal thieves. Attempts at theft of live 25kV cables may end in the thief's death from electrocution. In the UK, cable theft is claimed to be one of the biggest sources of delay and disruption to train services – though this normally relates to signalling cable, which is equally problematic for diesel lines.
* Incompatibility: Diesel trains can run on any track without electricity or with any kind of electricity (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 ...
or overhead line
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 equipmen ...
, DC or AC, and at any voltage or frequency). Not so for electric trains, which can never run on non-electrified lines, and which even on electrified lines can run only on the single, or the few, electrical system(s) for which they are equipped. Even on fully electrified networks, it is usually a good idea to keep a few diesel locomotives for maintenance and repair trains, for instance to repair broken or stolen overhead lines, or to lay new tracks. However, due to ventilation issues, diesel trains may have to be banned from certain tunnels and underground train stations mitigating the advantage of diesel trains somewhat.
* Birds may perch on parts with different charges, and animals may also touch the electrification system. Dead animals attract foxes or other scavengers, bringing risk of collision with trains.
* In most of the world's railway networks, the height clearance of overhead electrical lines is not sufficient for a double-stack container car or other unusually tall loads. To upgrade electrified lines to the correct clearances () to take double-stacked container trains, besides renewing bridges over it, would normally mean need for special pantographs violating standardisation and requiring custom made vehicles.
World electrification
As of 2012, electrified tracks account for nearly one third of total tracks globally.
As of 2018, there were of railways electrified at 25kV, either 50 or 60Hz; electrified at ; electrified at 15kV 16.7 or Hz and electrified at .
The Swiss rail network is the largest fully electrified network in the world and one of only two to achieve this, the other being Armenia
Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ''Ox ...
. China has the largest electrified railway length with just over 70% of the network. A number of countries have zero electrification length.
Several countries have announced plans to electrify all or most of their railway network such as Indian Railways
Indian Railways (IR) is a statutory body under the ownership of Ministry of Railways, Government of India that operates India's national railway system. It manages the fourth largest national railway system in the world by size, with a tot ...
and Israel Railways
Israel Railways Ltd. , dba Israel Railways ( he, רַכֶּבֶת יִשְׂרָאֵל, ''Rakevet Yisra'el''), is the state-owned principal railway company responsible for all inter-city, commuter, and freight rail transport in Israel. Isra ...
.
The Trans-Siberian Railway
The Trans-Siberian Railway (TSR; , , ) connects European Russia to the Russian Far East. Spanning a length of over , it is the longest railway line in the world. It runs from the city of Moscow in the west to the city of Vladivostok in the ea ...
mainly in Russia is completely electrified, making it one of the longest stretches of electrified railways in the world.
See also
* Battery electric multiple unit
A battery electric multiple unit (BEMU), battery electric railcar or accumulator railcar is an electrically driven multiple unit or railcar whose energy is derived from rechargeable batteries driving the traction motors.
Prime advantages of these ...
* Battery locomotive
* Conduit current collection
Conduit current collection is an obsolete system of electric current collection used by some electric tramways, where the power supply was carried in a 'conduit' (a small tunnel) under the roadway. Modern systems fall under the term ground-leve ...
* Current collector
Electric current collectors are used by trolleybuses, trams, electric locomotives or EMUs to carry electrical power from overhead lines, electrical third rails, or ground-level power supplies to the electrical equipment of the vehicles. Those for ...
* Dual electrification
* Electromote
The Electromote was the world's first vehicle run like a trolleybus, which was first presented to the public on April 29, 1882, by its inventor Dr. Ernst Werner von Siemens in Halensee, a suburb of Berlin, Germany.
In 1847, Siemens told his bro ...
* Fifth rail system
* Ground-level power supply
Ground-level power supply, also known as surface current collection or, in French, ''alimentation par le sol'' ("feeding via the ground"), is a concept and group of technologies whereby electric vehicles collect electric power at ground level fro ...
* History of the electric locomotive
* Initial Electrification Experiments NY NH HR
* List of railway electrification systems
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.
Many modern trams and trains ...
* List of tram systems by gauge and electrification
The following is a list of tram/streetcar (including heritage trams/heritage streetcars), or light rail systems with their track length, track gauge, electrification system.
The vast majority of tram systems use . Generally, standard gauge ...
* 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 ...
* Overhead conductor rails
* Railroad electrification in the United States
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 ...
* Stud contact system
* Traction current pylon
A traction current pylon is a railroad pylon carrying at least one circuit for traction current. In Germany, traction current lines with two systems (4 conductor cables) typically have a single level arrangement of the conductor cables. For trac ...
* Traction powerstation
* Traction substation
A traction substation, traction current converter plant, rectifier station 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 ...
References
Further reading
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*
*
*
*
*
*
*
*
Sources
English
*
* Gomez-Exposito A., Mauricio J.M., Maza-Ortega J.M. "VSC-based MVDC Railway Electrification System" IEEE transactions on power delivery, v. 29, no. 1, Feb. 2014 pp.422–431. (suggests 24 kV DC)
(Jane's) Urban Transit Systems
*
*
*
Russian
* Винокуров В.А., Попов Д.А. "Электрические машины железно-дорожного транспорта" (Electrical machinery of railroad transportation), Москва, Транспорт, 1986. , 520 pp.
* Дмитриев, В.А., "Народнохозяйственная эффективность электрификации железных дорог и применения тепловозной тяги" (National economic effectiveness of railway electrification and application of diesel traction), Москва, Транспорт 1976.
* Дробинский В.А., Егунов П.М. "Как устроен и работает тепловоз" (How the diesel locomotive works) 3rd ed. Moscow, Транспорт, 1980.
* Иванова В.Н. (ed.) "Конструкция и динамика тепловозов" (Construction and dynamics of the diesel locomotive). Москва, Транспорт, 1968 (textbook).
* Калинин, В.К. "Электровозы и электропоезда" (Electric locomotives and electric train sets) Москва, Транспорт, 1991
* Мирошниченко, Р.И., "Режимы работы электрифицированных участков" (Regimes of operation of electrified sections f railways
F, or f, is the sixth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''ef'' (pronounced ), and the plural is ''efs''.
His ...
, Москва, Транспорт, 1982.
* Перцовский, Л. М.; "Энергетическая эффективность электрической тяги" (Energy efficiency of electric traction), ''Железнодорожный транспорт'' (magazine), #12, 1974 p.39+
* Плакс, А.В. & Пупынин, В. Н., "Электрические железные дороги" (Electric Railways), Москва "Транспорт" 1993.
* Сидоров Н.И., Сидорожа Н.Н. "Как устроен и работает электровоз" (How the electric locomotive works) Москва, Транспорт, 1988 (5th ed.). 233 pp, . 1980 (4th ed.).
* Хомич А.З. Тупицын О.И., Симсон А.Э. "Экономия топлива и теплотехническая модернизация тепловозов" (Fuel economy and the thermodynamic modernization of diesel locomotives). Москва: Транспорт, 1975. 264 pp.
External links
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{{DEFAULTSORT:Railway electrification system
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