Editing Electric generator (section)

=== Synchronous generators (alternating current generators) ===
{{Main|Alternator}}
[[File:Ferranti two-phase generator set (Rankin Kennedy, Electrical Installations, Vol III, 1903).jpg|thumb|[[Sebastian Ziani de Ferranti|Ferranti]] [[alternator|alternating current generator]], {{circa|1900}}.]]
Through a series of discoveries, the dynamo was succeeded by many later inventions, especially the AC [[alternator]], which was capable of generating [[alternating current]]. It is commonly known to be the Synchronous Generators (SGs). The synchronous machines are directly connected to the grid and need to be properly synchronized during startup.<ref>{{Cite journal|last=Schaefer|first=Richard C.|date=Jan–Feb 2017|title=Art of Generator Synchronizing|journal=IEEE Transactions on Industry Applications|volume=53|issue=1|pages=751–757|doi=10.1109/tia.2016.2602215|s2cid=15682853|issn=0093-9994}}</ref> Moreover, they are excited with special control to enhance the stability of the power system.<ref>{{Cite journal|last1=Basler|first1=Michael J.|last2=Schaefer|first2=Richard C.|date=2008|title=Understanding Power-System Stability|journal=IEEE Transactions on Industry Applications|volume=44|issue=2|pages=463–474|doi=10.1109/tia.2008.916726|s2cid=62801526|issn=0093-9994}}</ref>

Alternating current generating systems were known in simple forms from [[Michael Faraday]]'s original discovery of the [[Electromagnetic induction|magnetic induction of electric current]]. Faraday himself built an early alternator. His machine was a "rotating rectangle", whose operation was ''heteropolar'': each active conductor passed successively through regions where the magnetic field was in opposite directions.<ref>Thompson, Sylvanus P., ''Dynamo-Electric Machinery''. p. 7</ref>

Large two-phase alternating current generators were built by a British electrician, [[James Edward Henry Gordon|J. E. H. Gordon]], in 1882. The first public demonstration of an "alternator system" was given by [[William Stanley Jr.]], an employee of [[Westinghouse Electric (1886)|Westinghouse Electric]] in 1886.<ref>Blalock, Thomas J., "''[https://web.archive.org/web/20040825140907/http://www.ieee.org/organizations/history_center/stanley.html Alternating Current Electrification, 1886]''". IEEE History Center, IEEE Milestone. (''ed''. first practical demonstration of a dc generator – ac transformer system.)</ref>

{{anchor|Ferranti steam generating plants}}[[Sebastian Ziani de Ferranti]] established ''Ferranti, Thompson and Ince'' in 1882, to market his ''Ferranti-Thompson Alternator'', invented with the help of renowned physicist [[Lord Kelvin]].<ref name=timeline>[http://www.mosi.org.uk/collections/explore-the-collections/ferranti-online/timeline.aspx Ferranti Timeline] {{webarchive |url=https://web.archive.org/web/20151003002335/http://www.mosi.org.uk/collections/explore-the-collections/ferranti-online/timeline.aspx |date=October 3, 2015 }} – ''[[Museum of Science and Industry (Manchester)|Museum of Science and Industry]] (Accessed 22-02-2012)''</ref> His early alternators produced frequencies between 100 and 300 [[hertz|Hz]]. Ferranti went on to design the [[Deptford Power Station]] for the London Electric Supply Corporation in 1887 using an alternating current system. On its completion in 1891, it was the first truly modern power station, supplying high-voltage AC power that was then "stepped down" for consumer use on each street. This basic system remains in use today around the world.

[[File:Murray Alternator with Belt-Driven Exciter.jpg|thumb|200px|A small early 1900s 75 [[kilovolt-ampere|kVA]] direct-driven power station AC alternator, with a separate belt-driven exciter generator.]]
After 1891, [[Polyphase system|polyphase]] alternators were introduced to supply currents of multiple differing phases.<ref>Thompson, Sylvanus P., ''Dynamo-Electric Machinery''. p. 17</ref> Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors.<ref>Thompson, Sylvanus P., ''Dynamo-Electric Machinery''. p. 16</ref>