Editing Electric motor (section)

==History==
{{main|History of the electric motor}}

===Early motors===
[[File:Faraday_magnetic_rotation.jpg|thumb|[[Michael Faraday|Faraday's]] electromagnetic experiment, 1821, the first demonstration of the conversion of electrical energy into motion<ref name="Faraday (1822)2">{{cite journal|last=Faraday|first=Michael|year=1822|title=On Some New Electro-Magnetical Motion, and on the Theory of Magnetism|url=https://archive.org/details/quarterlyjournal12jour|journal=Quarterly Journal of Science, Literature and the Arts|publisher=Royal Institution of Great Britain|volume=XII|pages=[https://archive.org/details/quarterlyjournal12jour/page/74 74]–96 (§IX)|access-date=12 February 2013}}</ref>]]

Before modern electromagnetic motors, experimental motors that worked by electrostatic force were investigated. The first electric motors were simple [[Electrostatic motor|electrostatic devices]] described in experiments by Scottish monk [[Andrew Gordon (Benedictine)|Andrew Gordon]] and American experimenter [[Benjamin Franklin]] in the 1740s.<ref name="Gordon2">Tom McInally, The Sixth Scottish University. The Scots Colleges Abroad: 1575 to 1799 (Brill, Leiden, 2012) p. 115</ref><ref>Oleg D. Jefimenko (1973). ''Electrostatic Motors, Their History, Types, and Principles of Operation'', Electret Scientific Company. pp. 22–45</ref> The theoretical principle behind them, [[Coulomb's law]], was discovered but not published, by [[Henry Cavendish]] in 1771. This law was discovered independently by [[Charles-Augustin de Coulomb]] in 1785, who published it so that it is now known by his name.<ref>{{Cite journal|last=Guarnieri|first=M.|year=2014|title=Electricity in the age of Enlightenment|journal=IEEE Industrial Electronics Magazine|volume=8|issue=3|pages=60–63|doi=10.1109/MIE.2014.2335431|s2cid=34246664}}</ref> Due to the difficulty of generating the high voltages they required, electrostatic motors were never used for practical purposes.

The invention of the electrochemical battery by [[Alessandro Volta]] in 1799<ref>{{Cite journal|last=Guarnieri|first=M.|year=2014|title=The Big Jump from the Legs of a Frog|journal=IEEE Industrial Electronics Magazine|volume=8|issue=4|pages=59–61+69|doi=10.1109/MIE.2014.2361237|s2cid=39105914}}</ref> made the production of persistent electric currents possible. [[Hans Christian Ørsted]] discovered in 1820 that an electric current creates a magnetic field, which can exert a force on a magnet. It only took a few weeks for [[André-Marie Ampère]] to develop the first formulation of the electromagnetic interaction and present the [[Ampère's force law]], that described the production of mechanical force by the interaction of an electric current and a magnetic field.<ref name="dcmachine2">{{Cite journal|last=Guarnieri|first=M.|year=2018|title=Revolving and Evolving – Early dc Machines|journal=IEEE Industrial Electronics Magazine|volume=12|issue=3|pages=38–43|doi=10.1109/MIE.2018.2856546|hdl-access=free|s2cid=52899118|hdl=11577/3282911}}</ref>

[[Michael Faraday]] gave the first demonstration of the effect with a rotary motion on 3 September 1821 in the basement of the [[Royal Institution]].<ref name="Electric Motion">{{cite news |title=The birth of electric motion |url=https://www.rigb.org/explore-science/explore/blog/birth-electric-motion |access-date=19 July 2022 |work=Royal Institution}}</ref> A free-hanging wire was dipped into a pool of mercury, on which a [[Permanent magnet|permanent magnet (PM)]] was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire.<ref name="SparkMuseum (Motor)2">{{cite conference|title=The Development of the Electric Motor|url=http://www.sparkmuseum.com/MOTORS.HTM|publisher=SparkMuseum|archive-url=https://web.archive.org/web/20130306085840/http://www.sparkmuseum.com/MOTORS.HTM|archive-date=6 March 2013|access-date=12 February 2013|book-title=Early Electric Motors|url-status=live}}</ref> Faraday published the results of his discovery in the ''[[Quarterly Journal of Science]]'', and sent copies of his paper along with pocket-sized models of his device to colleagues around the world so they could also witness the phenomenon of electromagnetic rotations.<ref name="Electric Motion"/> This motor is often demonstrated in physics experiments, substituting [[brine]] for (toxic) mercury. [[Barlow's wheel]] was an early refinement to this Faraday demonstration, although these and similar [[homopolar motor]]s remained unsuited to practical application until late in the century.
[[File:Jedlik_motor.jpg|thumb|[[Ányos Jedlik|Jedlik]]'s "electromagnetic self-rotor", 1827 (Museum of Applied Arts, Budapest). The historic motor still works perfectly today.<ref name="TravelHungary (Dynamo)2">{{cite web|title=The first dinamo?|url=http://www.traveltohungary.com/english/articles/article.php?id=136|url-status=live|archive-url=https://web.archive.org/web/20130720005001/http://www.traveltohungary.com/english/articles/article.php?id=136|archive-date=20 July 2013|access-date=12 February 2013|publisher=travelhungary.com}}</ref>]]

[[File:An_electric_motor_presented_to_Kelvin_by_James_Joule_in_1842,_Hunterian_Museum,_Glasgow.jpg|thumb|An electric motor presented to [[Lord Kelvin|Kelvin]] by [[James Joule]] in 1842, Hunterian Museum, Glasgow]]
In 1827, [[Hungary|Hungarian]] [[physicist]] [[Ányos Jedlik]] started experimenting with [[electromagnetic coil]]s. After Jedlik solved the technical problems of continuous rotation with the invention of the [[Commutator (electric)|commutator]], he called his early devices "electromagnetic self-rotors". Although they were used only for teaching, in 1828 Jedlik demonstrated the first device to contain the three main components of practical [[Direct current|DC]] motors: the [[stator]], [[Rotor (electric)|rotor]] and commutator. The device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced solely by the currents flowing through their windings.<ref name="Guillemin (1891)2">{{cite book|last=Guillemin|first=Amédée|url={{google books |plainurl=y |id=QznSAAAAMAAJ}}|title='Le Magnétisme et l'Électricitée'|publisher=Macmillan and Co.|others=trans., ed. & rev. from the French by Sylvanus P. Thompson|year=1891|trans-title=Electricity and Magnetism|archive-url=https://web.archive.org/web/20180104232726/https://books.google.com/books?id=QznSAAAAMAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0|archive-date=2018-01-04|url-status=live}}</ref><ref name="Nature2">{{cite journal|last=Heller|first=Augustus|date=April 1896|title=Anianus Jedlik|journal=[[Nature (journal)|Nature]]|publisher=Norman Lockyer|volume=53|issue=1379|pages=516–517|bibcode=1896Natur..53..516H|doi=10.1038/053516a0|doi-access=free}}</ref><ref name="Blundel (2012)2">{{cite book|last=Blundel|first=Stephen J.|title=Magnetism A Very Short Introduction.|publisher=Oxford University Press|year=2012|isbn=978-0-19-960120-2|page=36}}</ref><ref name="Thein (2009)2">{{cite web|last=Thein|first=M.|title=Elektrische Maschinen in Kraftfahrzeugen|trans-title=Electric Machines in Motor Vehicles|url=http://www.fh-zwickau.de/mbk/kfz_ee/praesentationen/Elma-Gndl-Generator%20-%20Druckversion.pdf|archive-url=https://web.archive.org/web/20130914192636/http://www.fh-zwickau.de/mbk/kfz_ee/praesentationen/Elma-Gndl-Generator%20-%20Druckversion.pdf|archive-date=14 September 2013|access-date=13 February 2013|language=de}}</ref><ref>{{cite book|title=Elektrisiermaschinen im 18. und 19. Jahrhundert – Ein kleines Lexikon ''("Electrical machinery in the 18th and 19th centuries – a small thesaurus")''|publisher=[[University of Regensburg]]|year=2004|language=de|chapter=Elektrische Chronologie|access-date=August 23, 2010|chapter-url=http://www.uni-regensburg.de/Fakultaeten/phil_Fak_I/Philosophie/Wissenschaftsgeschichte/Termine/E-Maschinen-Lexikon/Chronologie.htm|archive-url=https://web.archive.org/web/20110609031544/http://www.uni-regensburg.de/Fakultaeten/phil_Fak_I/Philosophie/Wissenschaftsgeschichte/Termine/E-Maschinen-Lexikon/Chronologie.htm|archive-date=June 9, 2011}}</ref><ref>{{cite web|date=June 9, 2010|title=History of Batteries (inter alia)|url=http://www.mpoweruk.com/history.htm|url-status=live|archive-url=https://web.archive.org/web/20110512173049/http://www.mpoweruk.com/history.htm|archive-date=May 12, 2011|access-date=August 23, 2010|publisher=Electropaedia}}</ref><ref name="Electropaedia (home)2">{{cite web|title=Battery and Energy Technologies, Technology and Applications Timeline|url=http://www.mpoweruk.com/timeline.htm|url-status=live|archive-url=https://web.archive.org/web/20130302153035/http://mpoweruk.com/timeline.htm|archive-date=2 March 2013|access-date=13 February 2013}}</ref>

===DC motors===
{{Main|DC motor}}
The first [[Commutator (electric)|commutator]] {{visible anchor|DC electric motor}} capable of turning machinery was invented by English scientist [[William Sturgeon]] in 1832.<ref>{{cite ODNB|last=Gee|first=William|title=Oxford Dictionary of National Biography|year=2004|chapter=Sturgeon, William (1783–1850)|doi=10.1093/ref:odnb/26748}}</ref> Following Sturgeon's work, a commutator-type direct-current electric motor was built by American inventors [[Thomas Davenport (inventor)|Thomas Davenport]] and [[Emily Davenport]],<ref>{{cite book|last1=Vare|first1=Ethlie Ann|title=Patently Female: From AZT to TV Dinners, Stories of Women Inventors and Their Breakthrough Ideas|last2=Ptacek|first2=Greg|date=November 2001|publisher=John Wiley & Sons, Inc|isbn=978-0-471-02334-0|location=Hoboken, NJ|page=28}}</ref> which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools and a printing press.<ref name="Garrison (1998)2">{{cite book|last=Garrison|first=Ervan G.|url={{google books |plainurl=y |id=5mvVElGudyYC}}|title=A History of Engineering and Technology: Artful Methods|publisher=CRC Press|year=1998|isbn=978-0-8493-9810-0|edition=2nd|access-date=May 7, 2009}}</ref> Due to the high cost of [[Battery (electricity)|primary battery power]], the motors were commercially unsuccessful and bankrupted the Davenports. Several inventors followed Sturgeon in the development of DC motors, but all encountered the same battery cost issues. As no [[Electric power distribution|electricity distribution]] system was available at the time, no practical commercial market emerged for these motors.<ref name="Nye (1990)2">{{cite book|last=Nye|first=David E.|url=http://mitpress.mit.edu/books/electrifying-america|title=Electrifying America: Social Meanings of a New Technology|publisher=The MIT Press|year=1990|isbn=978-0-262-64030-5|archive-url=https://web.archive.org/web/20130403044745/http://mitpress.mit.edu/books/electrifying-america|archive-date=2013-04-03|url-status=live}}</ref>

After many other more or less successful attempts with relatively weak rotating and reciprocating apparatus German-Russian [[Moritz von Jacobi]] created the first real useful rotating electric motor in May 1834. It developed remarkable mechanical output power. His motor set a world record, which Jacobi improved four years later in September 1838.<ref>{{cite web|last=Richter|first=Jan|date=7 February 2013|title=Jacobi's Motor|url=https://www.eti.kit.edu/english/1382.php|url-status=live|archive-url=https://web.archive.org/web/20170512221521/http://www.eti.kit.edu/english/1382.php|archive-date=2017-05-12|access-date=14 May 2017|publisher=Elektrotechnischen Instituts. Karlsruhe Institute of Technology}}>.</ref> His second motor was powerful enough to drive an [[electric boat]] with 14 people across a wide river. It was also in 1839–1840 that other developers managed to build motors with similar and then higher performance.

In 1827–1828, Jedlik built a device using similar principles to those used in his electromagnetic self-rotors that was capable of useful work.<ref name="ReferenceA">{{cite book
|title=Electricity and magnetism, translated from the French of Amédée Guillemin
|place=London
|publisher=MacMillan
|year=1891
|editor-last=Thompson
|editor-first=Silvanus P.}}</ref><ref name="Nature">{{cite journal
|journal=[[Nature (journal)|Nature]]
|title=Anianus Jedlik
|first=Augustus |last=Heller
|publisher=Norman Lockyer
|date=April 1896
|volume=53
|issue=1379
|page=516
|url=https://books.google.com/books?id=nWojdmTmch0C&pg=PA516
|access-date=August 23, 2010
|bibcode = 1896Natur..53..516H |doi = 10.1038/053516a0 |doi-access=free
}}</ref><ref name="mpoweruk.com">{{cite web
|url=http://www.mpoweruk.com/timeline.htm
|title=Technology and Applications Timeline
|access-date=August 23, 2010
|date=May 28, 2010
|publisher=Electropaedia
}}</ref><ref>{{cite web
 |url         = http://www.fh-zwickau.de/mbk/kfz_ee/praesentationen/Elma-Gndl-Generator%20-%20Druckversion.pdf
 |access-date  = August 23, 2010
 |date        = March 22, 2009
 |title       = Elektrische Maschinen in Kraftfahrzeugen
 |trans-title = Electrical machinery in motor vehicles
 |last        = Thein
 |first       = M.
 |publisher   = Falkutat der Kraftfahrzeugen
 |location    = Zwickau
 |language    = de
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20130914192636/http://www.fh-zwickau.de/mbk/kfz_ee/praesentationen/Elma-Gndl-Generator%20-%20Druckversion.pdf
 |archive-date = September 14, 2013
 |df          = mdy-all
}}</ref><ref>{{cite book
 |url         = http://www.uni-regensburg.de/Fakultaeten/phil_Fak_I/Philosophie/Wissenschaftsgeschichte/Termine/E-Maschinen-Lexikon/Chronologie.htm
 |title       = Elektrisiermaschinen im 18. und 19. Jahrhundert&nbsp;– Ein kleines Lexikon
 |trans-title = Electrical machinery in the 18th and 19th centuries&nbsp;– a small thesaurus
 |chapter     = Elektrische Chronologie
 |date        = March 31, 2004
 |access-date  = August 23, 2010
 |language    = de
 |publisher   = [[University of Regensburg]]
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20110609031544/http://www.uni-regensburg.de/Fakultaeten/phil_Fak_I/Philosophie/Wissenschaftsgeschichte/Termine/E-Maschinen-Lexikon/Chronologie.htm
 |archive-date = June 9, 2011
 |df          = mdy-all
}}</ref><ref>{{cite web
|url=http://www.mpoweruk.com/history.htm
|title=History of Batteries (and other things)
|access-date=August 23, 2010
|date=June 9, 2010
|publisher=Electropaedia
}}</ref><ref name="Guillemin (1891)2" /><ref name="Electropaedia (home)2" /> He built a model [[electric vehicle]] that same year.<ref name="Hungarianscience (Frankfurt)2">{{cite web|title=Exhibition on the History of Hungarian Science|url=http://www.frankfurt.matav.hu/angol/magytud.htm|url-status=live|archive-url=https://web.archive.org/web/20130826080638/http://www.frankfurt.matav.hu/angol/magytud.htm|archive-date=26 August 2013|access-date=13 February 2013}}</ref>

A major turning point came in 1864, when [[Antonio Pacinotti]] first described the ring armature (although initially conceived in a DC generator, i.e. a dynamo).<ref name="dcmachine2" /> This featured symmetrically grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered practically non-fluctuating current.<ref name="Antonio Pacinotti2">{{cite web|title=Antonio Pacinotti|url=http://ethw.org/Antonio_Pacinotti|url-status=live|archive-url=https://web.archive.org/web/20160305154622/http://ethw.org/Antonio_Pacinotti|archive-date=2016-03-05}}</ref><ref name="Klein2">{{cite web|title=The Power Makers: Steam, Electricity, and the Men Who Invented Modern America|url={{google books |plainurl=y |id=w0o5Ld53wAEC|page=164}}|url-status=live|archive-url=https://web.archive.org/web/20180104232726/https://books.google.com/books?id=w0o5Ld53wAEC&pg=PT164&lpg=PT164&dq=pacinotti+dc+motor&source=bl&ots=s9gxdk7Xb1&sig=6bXaoWnI8s1M1SXb-cQl9KUtzLc&hl=en&sa=X&ved=0ahUKEwi_-u_B75PLAhWBPpQKHTksCO8Q6AEIODAG#v=onepage&q=pacinotti%20dc%20motor&false|archive-date=2018-01-04}}</ref> The first commercially successful DC motors followed the developments by [[Zénobe Gramme]] who, in 1871, reinvented Pacinotti's design and adopted some solutions by [[Werner Siemens]].

A benefit to DC machines came from the discovery of the reversibility of the electric machine, which was announced by Siemens in 1867 and observed by Pacinotti in 1869.<ref name="dcmachine2" /> Gramme accidentally demonstrated it on the occasion of the [[:fr:Hippolyte Fontaine#1873 : l'expérience décisive|1873 Vienna World's Fair]], when he connected two such DC devices up to 2&nbsp;km from each other, using one of them as a generator and the other as motor.<ref name="gamme2">{{cite conference|title=Zénobe Théophile Gramme|url=http://www.invent.org/hall_of_fame/270.html|archive-url=https://web.archive.org/web/20121101131313/http://www.invent.org/hall_of_fame/270.html|archive-date=2012-11-01|access-date=2012-09-19|book-title=Invent Now, Inc. Hall of Fame profile.}}</ref>

The drum rotor was introduced by [[Friedrich von Hefner-Alteneck]] of Siemens & Halske to replace Pacinotti's ring armature in 1872, thus improving the machine efficiency.<ref name="dcmachine2" /> The laminated rotor was introduced by Siemens & Halske the following year, achieving reduced iron losses and increased induced voltages. In 1880, [[Jonas Wenström]] provided the rotor with slots for housing the winding, further increasing the efficiency.

In 1886, [[Frank Julian Sprague]] invented the first practical DC motor, a non-sparking device that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by [[Thomas Edison]]), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided control systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in [[Richmond, Virginia]], the electric elevator and control system in 1892, and the electric subway with independently powered centrally-controlled cars. The latter were first installed in 1892 in Chicago by the [[South Side Elevated Railroad]], where it became popularly known as the "[[Chicago "L"|L]]". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of an [[Air gap (magnetic)|air gap]] between the rotor and stator. Efficient designs have a comparatively small air gap.<ref name="Ganot (1881)2">{{cite book|last=Ganot|first=Adolphe|url=https://archive.org/details/elementarytreati00ganorich|title=Elementary Treatise in Physics|publisher=William Wood and Co.|others=Trans. and ed. from the French by E. Atkinson|year=1881|edition=14th|pages=[https://archive.org/details/elementarytreati00ganorich/page/907 907]–08, sec. 899<!-- Details inconsistent, there's no Fig. 888 {{Page needed|date=February 2013}} -->|author-link1=Adolphe Ganot}}</ref>{{efn|Ganot provides a superb illustration of one such early electric motor designed by Froment.<ref name="Ganot (1881)">
{{cite book
|last=Ganot
|first=Adolphe
|author-link1=Adolphe Ganot
|title=Elementary Treatise in Physics
|url=https://archive.org/details/elementarytreati00ganorich
|others=Trans. and ed. from the French by E. Atkinson
|edition=14th
|pages=[https://archive.org/details/elementarytreati00ganorich/page/907 907]–08, sec. 899<!-- Details inconsistent, there's no Fig. 888 {{Page needed|date=February 2013}} -->
|year=1881
|publisher=William Wood and Co.}}</ref>}} The St. Louis motor, long used in classrooms to illustrate motor principles, is inefficient for the same reason, as well as appearing nothing like a modern motor.<ref>{{cite web|title=Photo of a traditional form of the St. Louis motor|url=https://www.physics.umd.edu/lecdem/services/demos/demosk4/k4-21.gif|archive-url=https://web.archive.org/web/20110411000202/http://www.physics.umd.edu/lecdem/services/demos/demosk4/k4-21.gif|archive-date=2011-04-11}}</ref>

Electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead, every machine could be equipped with its own power source, providing easy control at the point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses (such as washing machines, dishwashers, fans, air conditioners and refrigerators) of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors consume more than half of the electric energy produced in the US.<ref>{{cite web|title=Buying an Energy-Efficient Electric Motor – Fact Sheet|url=http://www1.eere.energy.gov/industry/bestpractices/pdfs/mc-0382.pdf|url-status=live|archive-url=https://web.archive.org/web/20110902144422/http://www1.eere.energy.gov/industry/bestpractices/pdfs/mc-0382.pdf|archive-date=2011-09-02|publisher=USDoE}}</ref>

===AC motors===
{{Main|AC motor}}
In 1824, French physicist [[François Arago]] formulated the existence of [[rotating magnetic field]]s, termed [[Arago's rotations]], which, by manually turning switches on and off, Walter Baily demonstrated in 1879 as in effect the first primitive [[induction motor]].<ref name="Babbage (1825)2">{{cite journal|last=Babbage|first=C.|author2=Herschel, J.F.W.|date=January 1825|title=Account of the Repetition of M. Arago's Experiments on the Magnetism Manifested by Various Substances during the Act of Rotation|url=https://archive.org/stream/philtrans03806447/03806447#page/n0/mode/2up|journal=Philosophical Transactions of the Royal Society|volume=115|pages=467–96|bibcode=1825RSPT..115..467B|doi=10.1098/rstl.1825.0023|access-date=2 December 2012|doi-access=free}}</ref><ref name="Thompson (1895)2">{{cite book|last=[[Silvanus Phillips Thompson|Thompson]]|first=Silvanus Phillips|url=https://archive.org/stream/polyphaseelectri00thomuoft#page/n5/mode/2up|title=Polyphase Electric Currents and Alternate-Current Motors|publisher=E. & F.N. Spon|year=1895|edition=1st|location=London|page=261|access-date=2 December 2012}}</ref><ref name="Bailey (1879)2">{{Cite journal|last=Baily|first=Walter|date=June 28, 1879|title=A Mode of Producing Arago's Rotation|url={{google books |plainurl=y |id=85AOAAAAIAAJ|page=286}}|url-status=live|journal=Philosophical Magazine|publisher=Taylor & Francis|volume=3|issue=1|pages=115–120|bibcode=1879PPSL....3..115B|doi=10.1088/1478-7814/3/1/318|archive-url=https://web.archive.org/web/20161201152007/https://books.google.com/books?id=85AOAAAAIAAJ&pg=PA286&lpg=PA286|archive-date=December 1, 2016}}</ref><ref name="Vuckovic2">{{cite journal|last=Vučković|first=Vladan|date=November 2006|title=Interpretation of a Discovery|url=http://www.doiserbia.nb.rs/img/doi/1451-4869/2006/1451-48690603202V.pdf|url-status=live|journal=The Serbian Journal of Electrical Engineers|volume=3|issue=2|archive-url=https://web.archive.org/web/20130704153359/http://www.doiserbia.nb.rs/img/doi/1451-4869/2006/1451-48690603202V.pdf|archive-date=4 July 2013|access-date=10 February 2013}}</ref> In the 1880s many inventors were trying to develop workable AC motors<ref name="Jonnes (2004)2">{{Cite book|last=Jonnes|first=Jill|url={{google books |plainurl=y |id=2_58p3Z69bIC|page=162}}|title=Empires of Light: Edison, Tesla, Westinghouse, and the Race to Electrify the World|publisher=Random House|year=2004|page=180|archive-url=https://web.archive.org/web/20161201085428/https://books.google.com/books?id=2_58p3Z69bIC&pg=PT162&lpg=PT162&dq=tesla+%22motors+were+in+the+air%22&source=bl&ots=6T_6E2qmuT&sig=8YDP2sdzVB13V-KtO0xxdm0_Ae4&hl=en&sa=X&ei=lflNUMLUH6Tw0gHLlYCIDA&ved=0CC0Q6AEwAA#v=onepage&q=tesla%20%22motors%20were%20in%20the%20air%22&f=false|archive-date=2016-12-01|url-status=live}}</ref> because AC's advantages in long-distance high-voltage transmission were offset by the inability to operate motors on AC.

The first alternating-current commutatorless induction motor was invented by [[Galileo Ferraris]] in 1885. Ferraris was able to improve his first design by producing more advanced setups in 1886.<ref name="acmachine2">{{Cite journal|last=Guarnieri|first=M.|year=2018|title=The Development of ac Rotary Machines|journal=IEEE Industrial Electronics Magazine|volume=12|issue=4|pages=28–32|doi=10.1109/MIE.2018.2874375|hdl=11577/3286584 |s2cid=56597952}}</ref> In 1888, the ''Royal Academy of Science of Turin'' published Ferraris's research detailing the foundations of motor operation, while concluding at that time that "the apparatus based on that principle could not be of any commercial importance as motor."<ref name="Vuckovic2" /><ref name="Ferraris (1888)2">{{cite journal|last=Ferraris|first=G.|year=1888|title=Atti della Reale Academia delle Science di Torino|journal=Atti della R. Academia delle Science di Torino|volume=XXIII|pages=360–75}}</ref><ref name="TFI (now)2">{{cite web|last=The Case Files: Nikola Tesla|title=Two-Phase Induction Motor|url=http://www.fi.edu/learn/case-files/tesla/motor.html|archive-url=https://web.archive.org/web/20121118121135/http://www.fi.edu/learn/case-files/tesla/motor.html|archive-date=18 November 2012|access-date=2 December 2012|publisher=The Franklin Institute}}</ref>

Possible industrial development was envisioned by [[Nikola Tesla]], who invented independently his induction motor in 1887 and obtained a patent in May 1888. In the same year, Tesla presented his paper ''A New System of Alternate Current Motors and Transformers'' to the [[American Institute of Electrical Engineers|AIEE]] that described three patented two-phase four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting [[reluctance motor]], another with a wound rotor forming a self-starting [[induction motor]], and the third a true [[synchronous motor]] with separately excited DC supply to rotor winding. One of the patents Tesla filed in 1887, however, also described a shorted-winding-rotor induction motor. [[George Westinghouse]], who had already acquired rights from Ferraris (US$1,000), promptly bought Tesla's patents (US$60,000 plus US$2.50 per sold hp, paid until 1897),<ref name="acmachine2" /> employed Tesla to develop his motors, and assigned [[Charles F. Scott (engineer)|C.F. Scott]] to help Tesla; however, Tesla left for other pursuits in 1889.<ref name="Alger (1976)2">{{cite journal|last1=Alger|first1=P.L.|last2=Arnold z|first2=R.E.|year=1976|title=The History of Induction Motors in America|journal=Proceedings of the IEEE|volume=64|issue=9|pages=1380–83|doi=10.1109/PROC.1976.10329|s2cid=42191157}}<!--|access-date=1 December 2012--></ref><ref name="Klooster (2009)2">{{Cite book|last=Klooster|first=John W.|url={{google books |plainurl=y |id=WKuG-VIwID8C|page=305}}|title=Icons of Invention: The Makers of the Modern World from Gutenberg to Gates|publisher=ABC-CLIO, LLC|year=2009|isbn=978-0-313-34746-7|page=305|access-date=10 September 2012|archive-url=https://web.archive.org/web/20121112163653/http://books.google.com/books?id=WKuG-VIwID8C&pg=PA305&lpg=PA305&dq=tesla+hired+by+westinghouse&source=bl&ots=KDI0aTz0EK&sig=oct2jnPyWkQ3qvUR-JmstK9F0FI&hl=en&sa=X&ei=jRwxUKK3LtS80QHjxoGYAg&sqi=2&ved=0CEEQ6AEwAw#v=onepage&q=tesla%20hired%20by%20westinghouse&f=false|archive-date=12 November 2012|url-status=live}}</ref><ref name="Day (1996)2">{{cite book|url={{google books |plainurl=y |id=n--ivouMng8C|page=1204}}|title=Biographical Dictionary of the History of Technology|publisher=Routledge|year=1996|isbn=978-0-203-02829-2|editor-last1=Day|editor-first1=Lance|location=London|page=1204|access-date=2 December 2012|editor-last2=McNeil|editor-first2=Ian}}</ref><ref name="Froehlich (1992)2">{{cite book |editor-last=Froehlich |editor-first=Fritz E. |title=The Froehlich/Kent Encyclopedia of Telecommunications |volume=17 – Television Technology to Wire Antennas |editor2=[[Allen Kent]] |publisher=Marcel Dekker |year=1992|isbn=978-0-8247-2902-8 |location=New York|page=36}}</ref> The constant speed AC induction motor was found not to be suitable for street cars,<ref name="Jonnes (2004)2" /> but Westinghouse engineers successfully adapted it to power a mining operation in Telluride, Colorado in 1891.<ref name="Maddox (2003)2">{{Cite book|last=Mattox|first=D. M.|url={{google books |plainurl=y |id=31O4upzTHQwC|page=39}}|title=The Foundations of Vacuum Coating Technology|publisher=Random House|year=2003|isbn=978-0-8155-1495-4|page=39|archive-url=https://web.archive.org/web/20161201151805/https://books.google.com/books?id=31O4upzTHQwC&pg=PA39&dq=In+1891+Telluride+westinghouse+induction+motor&hl=en&sa=X&ei=Qc3PUP-ZA--n0AHah4HwBA&sqi=2&ved=0CFMQ6AEwBA#v=onepage&q=In%201891%20Telluride%20westinghouse%20induction%20motor&f=false|archive-date=2016-12-01|url-status=live}}</ref><ref name="Hughes (1993)2">{{cite book|last=Hughes|first=Thomas Parke|url={{google books |plainurl=y |id=g07Q9M4agp4C|page=117}}|title=Networks of Power: Electrification in Western society, 1880–1930|publisher=Johns Hopkins University Press|year=1983|isbn=978-0-8018-2873-7|page=117|archive-url=https://web.archive.org/web/20161201050558/https://books.google.com/books?id=g07Q9M4agp4C&pg=PA117&dq=Galileo+Ferraris+and+rotating+magnetic+field&hl=en&sa=X&ei=NMp0T_bXL6Gc2AXt7e3ODg&ved=0CDAQ6AEwAA#v=onepage&q=Galileo%20Ferraris%20and%20rotating%20magnetic%20field&f=false|archive-date=2016-12-01|url-status=live}}</ref><ref>{{cite web|title=Timeline of Nikola Tesla|url=http://www.teslasociety.org/timeline.html|archive-url=https://web.archive.org/web/20120508181221/http://www.teslasociety.org/timeline.html|archive-date=8 May 2012|access-date=5 July 2012|publisher=Tesla Society of USA and Canada}}</ref> Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, but these early Westinghouse motors were two-phase motors with wound rotors. [[Benjamin G. Lamme|B.G. Lamme]] later developed a rotating bar winding rotor.<ref name="Alger (1976)2" />

Steadfast in his promotion of three-phase development, [[Mikhail Dolivo-Dobrovolsky]] invented the three-phase induction motor in 1889, of both types cage-rotor and wound rotor with a starting rheostat, and the three-limb [[transformer]] in 1890. After an agreement between AEG and [[Maschinenfabrik Oerlikon]], Doliwo-Dobrowolski and [[Charles Eugene Lancelot Brown]] developed larger models, namely a 20-hp squirrel cage and a 100-hp wound rotor with a starting rheostat. These were the first three-phase asynchronous motors suitable for practical operation.<ref name="acmachine2" /> Since 1889, similar developments of three-phase machinery were started Wenström. At the 1891 Frankfurt International Electrotechnical Exhibition, the first long distance three-phase system was successfully presented. It was rated 15 kV and extended over 175&nbsp;km from the Lauffen waterfall on the Neckar river. The Lauffen power station included a 240&nbsp;kW 86 V 40&nbsp;Hz alternator and a step-up transformer while at the exhibition a step-down transformer fed a 100-hp three-phase induction motor that powered an artificial waterfall, representing the transfer of the original power source.<ref name="acmachine2" /> The three-phase induction is now used for the vast majority of commercial applications.<ref>{{cite book|last=Hubbell|first=M.W.|title=The Fundamentals of Nuclear Power Generation Questions & Answers.|publisher=Authorhouse|year=2011|isbn=978-1-4634-2441-1|page=27}}</ref><ref name="IEEE German Ch. (2012)2">{{cite web |website=Verband der Elektrotechnik, Elektronik und Informationstechnik |date=January 2012 |title=150. Geburtstag von Michael von Dolivo-Dobrowolsky |url=http://www.vde.com/de/fg/ETG/Arbeitsgebiete/Geschichte/Aktuelles/Seiten/150JMDD.aspx |archive-url=https://web.archive.org/web/20130225110200/http://www.vde.com/de/fg/ETG/Arbeitsgebiete/Geschichte/Aktuelles/Seiten/150JMDD.aspx|archive-date=25 February 2013|access-date=10 February 2013 |language=de}}</ref> [[Mikhail Dolivo-Dobrovolsky]] claimed that Tesla's motor was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work.<ref name="Dolivo-Dobrowolsky (1891)2">{{cite journal|last=Dolivo-Dobrowolsky|first=M.|year=1891|title=Alternating current|journal=ETZ|volume=12|pages=149, 161}}</ref>

The [[General Electric Company]] began developing three-phase induction motors in 1891.<ref name="Alger (1976)2" /> By 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design, later called the [[squirrel-cage rotor]].<ref name="Alger (1976)2" /> Induction motor improvements flowing from these inventions and innovations were such that a 100-[[horsepower]] induction motor currently has the same mounting dimensions as a 7.5-horsepower motor in 1897.<ref name="Alger (1976)2" />

=== Twenty-first century ===
In 2022, electric motor sales were estimated to be 800 million units, increasing by 10% annually. Electric motors consume ≈50% of the world's electricity.<ref>{{Cite web |last=Gustes-Pinto |first=Paulo |date=2022-03-26 |title=This Axial-Flux Motor With a PCB Stator Is Ripe for an Electrified World |url=https://spectrum.ieee.org/axial-flux |access-date=2022-04-26 |website=IEEE Spectrum |language=en}}</ref> Since the 1980s, the market share of DC motors has declined in favor of AC motors.<ref>{{Cite book |last=Hughes |first=Austin |title=Electric motors and drives: fundamentals, types and applications |last2=Drury |first2=Bill |date=2019 |publisher=Newness |isbn=978-0-08-102615-1 |edition=5th |location=Oxford}}</ref>{{Rp|page=89}}{{clarify|reason=By units, by value, by installed horse power?|date=January 2024}}