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The War of Currents (sometimes, War of the Currents or Battle of Currents) was a series of events surrounding the introduction of competing electric power transmission systems in the late 1880s and early 1890s including commercial competition, a debate over electrical safety, and a media/propaganda campaign that grew out of it, with the main players being the direct current (DC) based Edison Electric Light Company and the alternating current (AC) based Westinghouse Electric Company. It took place during the introduction and rapid expansion of the alternating current standard (already in use and advocated by several US and European companies〔(AC Power History ). Edison Tech Center.〕) and its eventual adoption over the direct current distribution system. Three aspects have been conflated together into the "war": open competition involving large electric companies and their developing systems, a general fear in the public's mind of death by accidental electrocution from high voltage AC leading to a debate over its safety and regulation, and the debate and behind the scene maneuvers associated with the introduction of the electric chair.〔(Maury Klein, The Power Makers: Steam, Electricity, and the Men Who Invented Modern America, Bloomsbury Publishing - 2010, page 259 )〕 The introduction of large scale outdoor arc lighting systems in the late 1870s,〔(John M. Dobson, Bulls, Bears, Boom, and Bust: A Historical Encyclopedia of American Business Concepts, ABC-CLIO - 2007, page 153 )〕 some of them powered by high-voltage alternating current, was followed in 1882 by Thomas Edison's low voltage DC electric distribution "utility" designed for indoor business and residential use as an alternative to gas and oil-based lighting. In 1886 George Westinghouse began building an alternating current system that used a transformer to step up voltage for long-distance transmission and then stepped it back down for indoor lighting, a more efficient and less expensive system that directly competed for the market the Edison system was designed to serve. As many other AC companies joined in and the use of AC spread rapidly, Edison's company made claims in early 1888 that alternating current was hazardous and inferior to the patented direct current system. In the spring of 1888, a media furor arose over a series of deaths caused by pole-mounted high-voltage AC lines in New York City and around the country, attributed to the greed and callousness of the local AC-based lighting companies. In June of that year a New York electrical engineer named Harold P. Brown came to prominence as an opponent of the use of alternating current, claiming the AC-based lighting companies were putting the public at risk using high-voltages and installing it in a slipshod manner. Brown's campaign immediately gained the assistance of Edison and his company, aiding Brown in the public electrocution of animals with AC trying to prove Brown's claim that AC was more dangerous than DC. Historians noted, and documents from the period seem to show, that there grew to be collusion between Edison's company and Brown in their parallel attempts to limit the use of AC: assisting Brown's attempt to push through legislation to control and severely limit AC installations and voltages (to the point of making it an ineffective power delivery system), providing technical assistance in Brown's tests to show AC would be the best current to power the new electric chair, and colluding with Brown and Westinghouse's chief AC rival, the Thomson-Houston Electric Company, to make sure the first electric chair was powered by a Westinghouse AC generator. This was a period of industrial consolidation and by 1890 over a dozen electric companies had merged down to three; Edison (now Edison General Electric), Thomson-Houston, and Westinghouse. By the early 1890s the latter two were generating profits far in advance of the DC-based Edison company. During this period Thomas Edison left the electric power business and the company he founded was beginning to add AC technology to its system. Edison Electric's institutional opposition to alternating current came to an end in 1892 when they merged with what had become their biggest competitor, the Thomson-Houston company, a merger that put the managers of Thomson-Houston in control of the new company, now called General Electric. The merger of the Edison company (along with its strong lighting patents) with Thomson-Houston (and its AC patents) created a company that now controlled three quarters of the US electrical business.〔Mark Essig, Edison and the Electric Chair: A Story of Light and Death, Bloomsbury Publishing USA - 2009, page 268〕〔Robert L. Bradley, Jr., Edison to Enron: Energy Markets and Political Strategies, John Wiley & Sons - 2011, pages 28-29〕 Westinghouse won the bid to supply electrical power for the World's Columbian Exposition in 1893 and would go on that year to win the first contract at Niagara Falls. Their lead in the field quickly diminished with later contracts being split with General Electric. There were several technical factors that drove the adoption of alternating-current over direct-current. The direct-current system generated and distributed electrical power at the same voltage as used by the customer's lamps and motors. This required the use of large, costly distribution wires and forced generating plants to be near the loads. With the development of a practical transformer, alternating-current power could be sent long distances over relatively small wires at a conveniently high voltage, then reduced in voltage to that used by a customer. Alternating-current generating stations could be larger, more efficient, and the distribution wires were relatively less costly. The lower cost of AC power distribution prevailed, though DC systems persisted in some urban areas throughout the 20th century.〔(【引用サイトリンク】url=http://www.coned.com/newsroom/news/pr20071115.asp )〕 While DC power is not used generally for the transmission of energy from power plants into homes as Edison and others intended, it is still common when distances are small. It is used widely in all modern electronic devices such as computers, telephones, and automotive systems. == Background == The war of currents grew out of the development of two lighting systems; arc lighting running on alternating current and incandescent lighting running on direct current.〔Quentin R. Skrabec, The 100 Most Significant Events in American Business: An Encyclopedia, ABC-CLIO - 2012, page 86〕 Both were supplanting gas lighting systems, with arc lighting taking over large area/street lighting, and incandescent lighting replacing gas for business and residential lighting. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「War of Currents」の詳細全文を読む スポンサード リンク
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