Karlsruhe Traction Current Converter Plant

Woburn rail traction substation, Lower Hutt, New Zealand

A traction substation, traction current converter plant, rectifier station or traction power substation (TPSS) is an

electrical substation A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Between the generating station and ...

that converts

electric power Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions o ...

from the form provided by the

electrical power industry Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...

for

public utility A public utility company (usually just utility) is an organization that maintains the infrastructure for a public service (often also providing a service using that infrastructure). Public utilities are subject to forms of public control and r ...

service to an appropriate

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 ...

type and

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 ...

to supply railways, trams (streetcars) or trolleybuses with

traction current 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), ele ...

Conversions

These systems can be used to convert

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 ...

50 Hz or 60 Hz

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) for the supply of AC

railway electrification system 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), ele ...

s at a lower frequency and

single phase In electrical engineering, single-phase electric power (abbreviated 1φ) is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads ...

, as used by many older systems, or to

rectify ''Rectify'' is an American television drama series exploring the life of a man after he is released from prison after nearly 20 years on death row following a wrongful conviction. It was created by Ray McKinnon and is the first original series f ...

AC into

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 even ...

(DC) for those systems (primarily public transit systems) using DC for traction power. The three-phase voltage from the local utility is stepped down and rectified in the traction substations to provide the required DC voltage.

Equipment

Rotating

Originally, the conversion equipment usually consisted of one or more motor-generator sets containing three-phase synchronous AC motors and

single-phase AC generator Single-phase generator (also known as single-phase alternator) is an alternating current electrical generator that produces a single, continuously alternating voltage. Single-phase generators can be used to generate power in single-phase electric ...

s, mechanically coupled to a common shaft.

Rotary converter A rotary converter is a type of electrical machine which acts as a mechanical rectifier, inverter or frequency converter. Rotary converters were used to convert alternating current (AC) to direct current (DC), or DC to AC power, before the adven ...

s were also used, especially where the desired output was DC current from an AC source.

Static

In the 1920s, DC was derived using electronic valves (

mercury arc rectifier Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Mercury ...

s). In modern systems, high-voltage DC (

HVDC A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating curren ...

) "back-to-back" stations are used instead of mechanical equipment to convert between different frequencies and phases of AC power and solid-state

thyristor A thyristor () is a solid-state semiconductor device with four layers of alternating P- and N-type materials used for high-power applications. It acts exclusively as a bistable switch (or a latch), conducting when the gate receives a current ...

rectifier systems are used for conversion from AC power to DC traction power.

Location

Traction current converter plants are either decentralized (where one plant directly supplies the

overhead lines 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 ...

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 t ...

of the traction system, with no feed into a traction current distribution network) or centralized (for the supply of the

traction power network 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 done only if the railway in question uses alternating current (AC) with ...

, usually in addition to the direct supply of the overhead lines or third rail). Central traction current converter plants are generally found in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

(primarily in the cities of

Neckarwestheim Neckarwestheim 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, the Neckarwestheim Nuclea ...

Ulm Ulm () is a city in the German state of Baden-Württemberg, situated on the river Danube on the border with Bavaria. The city, which has an estimated population of more than 126,000 (2018), forms an urban district of its own (german: link=no, ...

Nuremberg Nuremberg ( ; german: link=no, Nürnberg ; in the local East Franconian dialect: ''Nämberch'' ) is the second-largest city of the German state of Bavaria after its capital Munich, and its 518,370 (2019) inhabitants make it the 14th-largest ...

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

and

Switzerland ). 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 ...

, while decentralized traction current converter plants are generally found in

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

and the German states of

Mecklenburg-Vorpommern Mecklenburg-Vorpommern (MV; ; nds, Mäkelborg-Vörpommern), also known by its anglicized name Mecklenburg–Western Pomerania, is a state in the north-east of Germany. Of the country's sixteen states, Mecklenburg-Vorpommern ranks 14th in po ...

and

Brandenburg Brandenburg (; nds, Brannenborg; dsb, Bramborska ) is a states of Germany, state in the northeast of Germany bordering the states of Mecklenburg-Vorpommern, Lower Saxony, Saxony-Anhalt, and Saxony, as well as the country of Poland. With an ar ...

as well as parts of

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...

. A

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 ...

provides further detail.

Conversions

Equipment

Rotating

Static

Location

See also