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1、9576_C04.fmPage167Monday,October17,20059:12AMTransformers167FIGURE4.4Single-phasedistributiontransformer.(PhotocourtesyofABB,Inc.Withpermission.)service.Atransformer’snameplategivesthekVAratings,thevoltageratings,percentimpedance,polarity,weight,connectiondiagra
2、m,andcoolingclass.Figure4.4showsacutawayviewofasingle-phasetransformer.Forasingle-phasetransformersupplyingsingle-phaseservice,theload-fullcurrentinamperesisSkVAI=VkVwhereSkVA=TransformerkVAratingVkV=Line-to-groundvoltageratinginkVCopyright©2006Taylor&FrancisGro
3、up,LLC9576_C04.fmPage168Monday,October17,20059:12AM168ElectricPowerDistributionEquipmentandSystemsTABLE4.5WindingDesignationsforSingle-PhasePrimaryandSecondaryTransformerWindingswithOneWindingNomenclatureExamplesDescriptionE13800EshallindicateawindingofEvoltstha
4、tissuitablefor∆connectiononanEvoltsystem.E/E1Y2400/4160YE/E1YshallindicateawindingofEvoltsthatissuitablefor∆connectiononanEvoltsystemorforYconnectiononanE1voltsystem.E/E1GrdY7200/12470GrdYE/E1GrdYshallindicateawindingofEvoltshavingreducedinsulationthatissuitable
5、for∆connectiononanEvoltsystemorYconnectiononanE1voltsystem,transformer,neutraleffectivelygrounded.E1GrdY/E12470GrdY/7200E1GrdY/EshallindicateawindingofEvoltswith480GrdY/277reducedinsulationattheneutralend.TheneutralendmaybeconnecteddirectlytothetankforYorforsing
6、le-phaseoperationonanE1voltsystem,providedtheneutralendofthewindingiseffectivelygrounded.E1=E3Note:Eisline-to-neutralvoltageofaYwinding,orline-to-linevoltageofa∆winding.Source:IEEEStd.C57.12.00-2000.Copyright2000IEEE.Allrightsreserved.So,asingle-phase50-kVAtrans
7、formerwithahigh-voltagewindingof12470GrdY/7200Vhasafull-loadcurrentof6.94Aontheprimary.Ona240/120-Vsecondary,thefull-loadcurrentacrossthe240-Vwindingis208.3A.Table4.5andTable4.6showthestandardsingle-phasewindingconnec-tionsforprimaryandsecondarywindings.High-vol
8、tagebushingsarelabeledH*,startingwithH1andthenH2andsoforth.Similarly,thelow-voltagebushingsarelabeledX1,X2,X3,andsoon.ThestandardNorthAmericansingle-phasetransformerc
