page_title: Electric locomotive
section_title: Alternating current
hierarchical_section_title: Electric locomotive / History / Alternating current
caption_attribution_description: English: A prototype of a Ganz AC electric locomotive in Valtellina , Italy, 1901
context_page_description: An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor.
  Electric locomotives with on-board fueled prime movers, such as diesel engines or gas turbines, are classed as diesel-electric or gas turbine-electric and not as electric locomotives, because the electric generator/motor combination serves only as a power transmission system.
  Electric locomotives benefit from the high efficiency of electric motors, often above 90%. Additional efficiency can be gained from regenerative braking, which allows kinetic energy to be recovered during braking to put power back on the line. Newer electric locomotives use AC motor-inverter drive systems that provide for regenerative braking. Electric locomotives are quiet compared to diesel locomotives since there is no engine and exhaust noise and less mechanical noise. The lack of reciprocating parts means electric locomotives are easier on the track, reducing track maintenance.
context_section_description: The first practical AC electric locomotive was designed by Charles Brown, then working for Oerlikon, Zürich. In 1891, Brown had demonstrated long-distance power transmission, using three-phase AC, between a hydro-electric plant at Lauffen am Neckar and Frankfurt am Main West, a distance of 280 km. Using experience he had gained while working for Jean Heilmann on steam-electric locomotive designs, Brown observed that three-phase motors had a higher power-to-weight ratio than DC motors and, because of the absence of a commutator, were simpler to manufacture and maintain.  However, they were much larger than the DC motors of the time and could not be mounted in underfloor bogies: they could only be carried within locomotive bodies.
  In 1894, Hungarian engineer Kálmán Kandó developed a new type 3-phase asynchronous electric drive motors and generators for electric locomotives. 
  Kandó's early 1894 designs were first applied in a short three-phase AC tramway in Évian-les-Bains (France), which was constructed between 1896 and 1898.
  In 1918, Kandó invented and developed the rotary phase converter, enabling electric locomotives to use three-phase motors whilst supplied via a single overhead wire, carrying the simple industrial frequency (50 Hz) single phase AC of the high voltage national networks.
  In 1896, Oerlikon installed the first commercial example of the system on the Lugano Tramway. Each 30-tonne locomotive had two 110 kW (150 hp) motors run by three-phase 750 V 40 Hz fed from double overhead lines. Three-phase motors run at constant speed and provide regenerative braking, and are well suited to steeply graded routes, and the first main-line three-phase locomotives were supplied by Brown (by then in partnership with Walter Boveri) in 1899 on the 40 km Burgdorf—Thun line, Switzerland. The first implementation of industrial frequency single-phase AC supply for locomotives came from Oerlikon in 1901, using the designs of Hans Behn-Eschenburg and Emil Huber-Stockar; installation on the Seebach-Wettingen line of the Swiss Federal Railways was completed in 1904. The 15 kV, 50 Hz 345 kW (460 hp), 48 tonne locomotives used transformers and rotary converters to power DC traction motors.
  Italian railways were the first in the world to introduce electric traction for the entire length of a mainline rather than just a short stretch. The 106 km Valtellina line was opened on 4 September 1902, designed by Kandó and a team from the Ganz works. The electrical system was three-phase at 3 kV 15 Hz. The voltage was significantly higher than used earlier and it required new designs for electric motors and switching devices. The three-phase two-wire system was used on several railways in Northern Italy and became known as "the Italian system". Kandó was invited in 1905 to undertake the management of Società Italiana Westinghouse and led the development of several Italian electric locomotives. During the period of electrification of the Italian railways, tests were made as to which type of power to use: in some sections there was a 3,600 V ​16 ²⁄₃ Hz three-phase power supply, in others there was 1,500 V DC, 3 kV DC and 10 kV AC 45 Hz supply. After WW2, 3 kV DC power was chosen for the entire Italian railway system.
  A later development of Kandó, working with both the Ganz works and Societa Italiana Westinghouse, was an electro-mechanical converter, allowing the use of three-phase motors from single-phase AC, eliminating the need for two overhead wires. In 1923, the first phase-converter locomotive in Hungary was constructed on the basis of Kandó's designs and serial production began soon after. The first installation, at 16 kV 50 Hz, was in 1932 on the 56 km section of the Hungarian State Railways between Budapest and Komárom. This proved successful and the electrification was extended to Hegyeshalom in 1934.
  In Europe, electrification projects initially focused on mountainous regions for several reasons: coal supplies were difficult, hydroelectric power was readily available, and electric locomotives gave more traction on steeper lines. This was
caption: A prototype of a Ganz AC electric locomotive in Valtellina, Italy, 1901
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