毕业设计供配电类英文原文

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1、附录二：英文原文ElectricpowerdistributionAnelectricpowerdistributionsystemisthefinalstageinthedeliveryofelectricpower;itcarrieselectricityfromthetransmissionsystemtoindividualconsumers.Distributionsubstationsconnecttothetransmissionsystemandlowerthetransmissionvoltagetomediumvoltage

2、rangingbetween2kVand35kVwiththeuseoftransformers.Primarydistributionlinescarrythismediumvoltagepowertodistributiontransformerslocatednearthecustomer'spremises.Distributiontransformersagainlowerthevoltagetotheutilizationvoltageofhouseholdappliancesandtypicallyfeedseveralcusto

3、mersthroughsecondarydistributionlinesatthisvoltage.Commercialandresidentialcustomersareconnectedtothesecondarydistributionlinesthroughservicedrops.Customersdemandingamuchlargeramountofpowermaybeconnecteddirectlytotheprimarydistributionlevelorthesubtransmissionlevel.HistoryFu

4、rtherinformation:HistoryofelectricpowertransmissionElectricpowerdistributiononlybecamenecessaryinthe1880swhenelectricitystartedbeinggeneratedatpowerstations.Beforethatelectricitywasusuallygeneratedwhereitwasused.ThefirstpowerdistributionsystemsinstalledinEuropeanandUSciteswe

5、reusedtosupplylighting:arclightingrunningonveryhighvoltage(usuallyhigherthan3000volt)alternatingcurrent(AC)ordirectcurrent(DC),andincandescentlightingrunningonlowvoltage(100volt)directcurrent.Bothweresupplantinggaslightingsystems,witharclightingtakingoverlargearea/streetligh

6、ting,andincandescentlightingreplacinggasforbusinessandresidentiallighting.Duetothehighvoltagesusedinarclighting,asinglegeneratingstationcouldsupplyalongstringoflights,upto7-mile(11km)longcircuits,sincethecapacityofawireisproportionaltothesquareofthecurrenttravelingonit,eachd

7、oublingofthevoltagewouldallowthesamesizecabletotransmitthesameamountofpowerfourtimesthedistance.Directcurrentindoorincandescentlightingsystems(forexamplethefirstEdisonPearlStreetStationinstalledin1882),haddifficultysupplyingcustomersmorethanamileawayduetothelow110voltsystemb

8、eingusedthroughoutthesystem,fromthegeneratorstothefinaluse.TheEdisonDCsyste