Editing Direct current (section)

==History==
{{further|History of electric power transmission}}
[[File:Brush central power station dynamos New York 1881.jpg|400px|thumb|left|Brush Electric Company's central power plant with dynamos generating direct current to power arc lamps for public lighting in New York. Beginning operation in December 1880 at 133 West Twenty-Fifth Street, the high voltages it operated at allowed it to power a {{convert|2|mi|km|adj=on}} long circuit.<ref>{{cite journal|url=http://publications.ohiohistory.org/ohstemplate.cfm?action=detail&Page=0070142.html&StartPage=128&EndPage=144&volume=70&newtitle=Volume%2070%20Page%20128 |volume=70 |page=142 |title=Charles F. Brush and the First Public Electric Street Lighting System in America |author=Mel Gorman |journal=[[Ohio History]] |publisher=[[Kent State University Press]] }}{{dead link|date=April 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>]]

Direct current was produced in 1800 by Italian physicist [[Alessandro Volta]]'s battery, his [[Voltaic pile]].<ref>{{Cite web |url=http://grants.hhp.coe.uh.edu/clayne/HistoryofMC/HistoryMC/VoltaII.htm |title=Alessandro Giuseppe Antonio Anastasio Volta – grants.hhp.coe.uh.edu |access-date=2017-05-29 |archive-url=https://web.archive.org/web/20170828022138/http://grants.hhp.coe.uh.edu/clayne/HistoryofMC/HistoryMC/VoltaII.htm |archive-date=2017-08-28 |url-status=dead }}</ref> The nature of how current flowed was not yet understood. French physicist [[André-Marie Ampère]] conjectured that current travelled in one direction from positive to negative.<ref>{{cite book|first=Jim|last=Breithaupt|title=Physics|publisher=Palgrave Macmillan|year=2010|page=175|isbn=9780230231924}}</ref> When French instrument maker [[Hippolyte Pixii]] built the first [[Dynamo|dynamo electric generator]] in 1832, he found that as the magnet used passed the loops of wire each half turn, it caused the flow of electricity to reverse, generating an [[alternating current]].<ref>{{Cite web |url=http://www.magnet.fsu.edu/education/tutorials/java/pixiimachine/index.html |title=Pixii Machine invented by Hippolyte Pixii, National High Magnetic Field Laboratory |access-date=2008-06-12 |archive-url=https://web.archive.org/web/20080907092008/http://www.magnet.fsu.edu/education/tutorials/java/pixiimachine/index.html |archive-date=2008-09-07 |url-status=dead }}</ref> At Ampère's suggestion, Pixii later added a [[Commutator (electric)|commutator]], a type of "switch" where contacts on the shaft work with "brush" contacts to produce direct current.

The late 1870s and early 1880s saw electricity starting to be generated at [[power stations]]. These were initially set up to power [[arc lamp|arc lighting]] (a popular type of street lighting) running on very high voltage (usually higher than 3,000 volts) direct current or alternating current.<ref>{{cite web| url = http://www.edisontechcenter.org/ArcLamps.html| title = The First Form of Electric Light History of the Carbon Arc Lamp (1800–1980s)}}</ref> This was followed by the widespread use of low voltage direct current for indoor electric lighting in business and homes after inventor [[Thomas Edison]] launched his incandescent bulb based electric "[[Public utility|utility]]" in 1882. Because of the significant advantages of alternating current over direct current in using [[transformer]]s to raise and lower voltages to allow much longer transmission distances, direct current was replaced over the next few decades by alternating current in power delivery. In the mid-1950s, [[high-voltage direct current]] transmission was developed, and is now an option instead of long-distance high voltage alternating current systems. For long distance undersea cables (e.g. between countries, such as [[NorNed]]), this DC option is the only technically feasible option. For applications requiring direct current, such as [[third rail]] power systems, alternating current is distributed to a substation, which utilizes a [[rectifier]] to convert the power to direct current.