Editing Electric motor (section)

===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>