A
traction power network is an electricity grid for the supply of
electrified railroadElectric train may refer to:* Electric multiple unit* Electric locomotive...
s. The installation of separate traction power network generally is only done if the railway in question uses
alternating currentIn alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again...
with a frequency lower than that of the national grid, such as in
GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
,
AustriaAustria , officially the Republic of Austria , is a landlocked country of roughly 8.3 million people in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west...
and
SwitzerlandSwitzerland , officially the Swiss Confederation , is a federal republic consisting of 26 states named cantons, with Bern as the seat of the federal authorities...
.
Alternatively, the three-phase alternating current of the power grid can be converted in
substationsA traction current converter plant 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, streetcars, and/or trolleybuses with traction...
by rotary transformers or static inverters into the voltage and type of current required by the trains.
A
traction power network is an electricity grid for the supply of
electrified railroadElectric train may refer to:* Electric multiple unit* Electric locomotive...
s. The installation of separate traction power network generally is only done if the railway in question uses
alternating currentIn alternating current the movement of electric charge periodically reverses direction. An electric charge would for instance move forward, then backward, then forward, then backward, over and over again...
with a frequency lower than that of the national grid, such as in
GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
,
AustriaAustria , officially the Republic of Austria , is a landlocked country of roughly 8.3 million people in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west...
and
SwitzerlandSwitzerland , officially the Swiss Confederation , is a federal republic consisting of 26 states named cantons, with Bern as the seat of the federal authorities...
.
Alternatively, the three-phase alternating current of the power grid can be converted in
substationsA traction current converter plant 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, streetcars, and/or trolleybuses with traction...
by rotary transformers or static inverters into the voltage and type of current required by the trains. For railways which run on
direct currentDirect current is the undirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also be through...
, this method is always used, as well as for railways which run on single phase AC current of decreased frequency, as in
Mecklenburg-Western PomeraniaMecklenburg-Vorpommern is a federal state in northern Germany. The capital city is Schwerin. The state was formed through the merger of the historic regions of Mecklenburg and Vorpommern after World War II, dissolved in 1952 and recreated prior to the German reunification in 1990.Due to its lengthy...
,
Saxony-AnhaltSaxony-Anhalt is one of the sixteen Bundesländer that make up the Federal Republic of Germany. It has an area of , and a population of 2.45 million...
,
NorwayNorway , officially the Kingdom of Norway, is a country in Northern Europe occupying the western portion of the Scandinavian Peninsula, as well as Jan Mayen and the Arctic archipelago of Svalbard under the Spitsbergen Treaty...
and
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
. In these areas there are no
traction current networks.
History
Separate power for traction apart from industrial power always has historic roots. There is no reason today to apply different frequencies or current types than for transmission and for industrial usage. However, the advantage with DC current traction was the easier transmission with single copper wires to the feeder points. The advantage with AC current traction is the easier transmission over long distances to the feeder points. Beyond these parameters and securing former investment no evidence exists to stay with different current schemes in networks.
Applications
Dedicated traction current lines are used when railways are supplied with low frequency alternating current. The traction current supply line is connected to substations along the line of the railway and is usually run separately from the overhead catenary wire from which the locomotives are fed.
In countries in which the electric trains run with direct current or with single phase AC current with the frequency of the general power grid, the required conversion of the current is performed in the substations, so again no traction current lines are required.
Traction current supply lines are not usually laid parallel to the railway line, in order to allow a shorter line length and to avoid unnecessary influences to the electrical system near the railway line; this also is applied to the current supply of some rapid-transit railways operating with alternating current in Germany.
It is also possible to lay out the traction current supply on special cross beams right on the overhead wire pylons above the catenary wire. Because the overhead line pylons have a smaller cross section than traction current supply masts the cross beams cannot be too wide, so the standard arrangement of four conductor cables in one level cannot be used. In this case a two-level arrangement is used, or with two electric circuits for double-railed lines the overhead line pylons for both directions are equipped with cross beams for their own traction current system of two conductor cables each.
In densely populated areas there are pylons, which carry circuits for both traction current and for three-phase alternating current for general power. Such lines are found where right of ways are rare. In particular the parallel route of 110 kV and 220 kV three-phase AC is common. The use of 380 kV-power lines on the same pylon requires 220 kV insulators for the traction current line, because in case the 380 kV line fails,
voltage spikeIn electrical engineering, spikes are fast, short duration electrical transients in voltage , current , or transferred energy in an electrical circuit....
s can occur along the traction current line, which the 110 kV insulators cannot handle.
As a rule traction current lines use single conductors, however for the supply of railways with high traffic and in particular for the supply of high speed railway lines, two bundle conductors are used.
Austria
The
MariazellerThe Mariazellerbahn is an electrically operated narrow-gauge railway of the Österreichische Bundesbahnen with a track gauge of which connects the Lower Austrian capital Sankt Pölten with the Styrian pilgrimage centre of Mariazell....
railway in
Lower AustriaLower Austria is the northeast state of the nine states or Bundesländer in Austria. The capital of Lower Austria since 1986 is Sankt Pölten , but formerly, the capital of Lower Austria was Vienna, even though Vienna is not properly part of Lower Austria...
operates on single phase AC at a 25
HzThe hertz is a unit of frequency. It is defined as the number of complete cycles per second. It is the basic unit of frequency in the International System of Units , and is used worldwide in both general-purpose and scientific contexts...
utility frequencyThe line frequency or mains frequency is the frequency at which alternating current is transmitted from a power plant to the end user. In most parts of the world this is 50 Hz, although in the Americas it is typically 60 Hz...
. The railway has its own traction current lines with an operating voltage of 27 kV. These lines are mounted on the pylons of the overhead wire over the catenary wire.
Germany
In
GermanyGermany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
single conductors are usually used for traction current lines, but for the
ICEThe Intercity-Express — in Austria, Denmark and Switzerland: InterCityExpress ; abbreviation: ICE — is a system of high-speed trains predominantly running in Germany and neighbouring countries. It is the highest service category offered by DB Fernverkehr and is the flagship of Deutsche Bahn...
train, two bundle conductors are used. The traction current supply lines from the nuclear power station
NeckarwestheimNeckarwestheim is a municipality with 3524 inhabitants in the Heilbronn district, Baden-Württemberg, in south-west Germany. It is located on the Neckar river and is well-known as the location of a nuclear power station.-Geographical position:...
to the traction current switching station at
NeckarwestheimNeckarwestheim is a municipality with 3524 inhabitants in the Heilbronn district, Baden-Württemberg, in south-west Germany. It is located on the Neckar river and is well-known as the location of a nuclear power station.-Geographical position:...
and from there to the central
substationSubstation can refer to:*Electrical substation*A police substation *The Substation, a Singaporean contemporary arts centre...
in
StuttgartStuttgart is the capital of the state of Baden-Württemberg in southern Germany. The sixth-largest city in Germany, Stuttgart has a population of 600,038 while the metropolitan area has a population of 5.3 million ....
, Zazenhausen are implemented as a four-bundle conductor circuit.
Scandinavia
In
SwedenSweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe...
,
NorwayNorway , officially the Kingdom of Norway, is a country in Northern Europe occupying the western portion of the Scandinavian Peninsula, as well as Jan Mayen and the Arctic archipelago of Svalbard under the Spitsbergen Treaty...
and some areas of the former
German Democratic RepublicThe German Democratic Republic was a Communist state that originated from the Soviet Zone of occupied Germany and the Soviet sector of occupied Berlin...
three phase AC-currentThree-phase electric power is a common method of alternating-current electric power transmission. It is a type of polyphase system, and is the most common method used by electric power distribution grids worldwide to distribute power. It is also used to power large motors and other large loads...
is converted into single phase AC current with a frequency of 16.7 cycles per second at the substations. Unlike in Germany, there are no dedicated power plants for railway electricity. All power comes from general electricity suppliers. In these regions there are no traction current lines, except extra lines along the railways to increase supply for heavily used railways. In
DenmarkDenmark is a Scandinavian country in Northern Europe and the senior member of the Kingdom of Denmark. It is the southernmost of the Nordic countries; southwest of Sweden and south of Norway, and it is bordered to the south by Germany. Denmark borders both the Baltic and the North Sea...
and
FinlandFinland , officially the Republic of Finland
, is a Nordic country and democracy situated in the Fennoscandian region of northern Europe. It borders Sweden on the west, Russia on the east, and Norway on the north, while Estonia lies to its south across the Gulf of Finland...
50 Hz is used for the main lines (if electrified) and the electricity comes from general suppliers, and much simpler equipment than in Sweden and Norway is needed for conversion.
South Africa
In the Republic of
South AfricaThe Republic of South Africa is a country located at the southern tip of Africa, with a coastline on the Atlantic and Indian Oceans. To the north lie Namibia, Botswana and Zimbabwe, to the east are Mozambique and Swaziland, while Lesotho is an independent country surrounded by South Africa.Modern...
there are extensive AC and DC traction schemes, including 50 kV and 25 kV AC single phase systems. Electrification in Natal was stimulated by the takeover of the South African Railways' system by the Electricity Supply Commission (now
EskomEskom is a South African electricity public utility, established in 1923 as the Electricity Supply Commission by the government of South Africa in terms of the Electricity Act . It was also known by its Afrikaans name Elektrisiteitsvoorsieningskommissie ...
) based on the
ColensoDo you mean:*Battle of Colenso, 1899, during the Second Boer War*Colenso, KwaZulu-Natal, a town in eastern South Africa*John William Colenso , first Anglican bishop of Natal, mathematician, theologian, Biblical scholar and social activist...
power station.
United Kingdom
In the
United KingdomThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
the
British RailBritish Railways , which later traded as British Rail, was the operator of most of the British railway system from the nationalisation of the 'Big Four' British railway companies in 1948 until privatisation in stages from 1994 to 1997...
Southern Region 750 V DC
electrification systemA railway electrification system supplies electrical energy to railway locomotives and multiple units so that they can operate without having an on-board prime mover. There are several different electrification systems in use throughout the world...
is supplied with power from an extensive 33 kV power distribution network.
Areas with traction power networks
- United Kingdom
The United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
- Germany
Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium,...
(except Mecklenburg-Western Pomerania and Saxony-Anhalt), total length 7959 km
- Switzerland
Switzerland , officially the Swiss Confederation , is a federal republic consisting of 26 states named cantons, with Bern as the seat of the federal authorities...
- Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.3 million people in Central Europe. It borders both Germany and the Czech Republic to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the west...
(separate traction power network for the Mariazeller Bahn)
- USA (in New York and Washington DC area for railway lines running with single phase 25 Hz AC, see also 25Hz Power Transmission System
The 25 Hz Power Transmission System is a traction power grid operated by Amtrak for the southern portion of the Northeast Corridor . In addition to serving the NEC, the grid provides power to some rail lines of New Jersey Transit and the Southeastern Pennsylvania Transportation Authority .-...
)
- South Africa
The Republic of South Africa is a country located at the southern tip of Africa, with a coastline on the Atlantic and Indian Oceans. To the north lie Namibia, Botswana and Zimbabwe, to the east are Mozambique and Swaziland, while Lesotho is an independent country surrounded by South Africa.Modern...
- Melbourne
Melbourne is the capital city and most populous city of the State of Victoria, and the second most populous city in Australia. The Melbourne city centre is the anchor of the larger geographical area and statistical division known as the Greater Melbourne metropolitan area – of which Melbourne is...
, AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
(dedicated high voltage transmission wires between former Newport A Power Station and traction substations)
See also
- Third rail
A third rail is a method of providing electric power to a railway train, through a 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...
- Traction current converter plant
A traction current converter plant 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, streetcars, and/or trolleybuses with traction...
- Traction powerstation
A traction powerstation is a power station that produces only traction current, that is, electrical current used for railways, trams, trolleybuses, or other conveyances. Pure traction power stations are rare, and there are many more power stations that generate current for other purposes, such as...