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ID:50322236
大小:2.66 MB
页数:63页
时间:2020-03-08
《Electric Machinery 电机学 英汉双语 教学课件 作者 刘慧娟 英文课件Chapter2-transformer.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Chapter2TRANSFORMERSContents2.1ConstructionandRatingsofTransformers2.2AnalysisofSinglePhaseTransformersinNo-loadCondition2.3OperationofTransformersinLoadedcondition2.4DeterminingparametersofTransformersbyTests2.5VoltageRegulationandEfficiencyofTransformers2.6Three-ph
2、aseTransformers2.7ParallelOperationofTransformers2.8SpecialTransformers2.1ConstructionandRatingsoftransformers2.1.1Constructionoftransformersatransformerisadevicethatchangesacelectricalpoweratonevoltageleveltoacelectricalpoweratanothervoltagelevelofthesamefrequencyba
3、seduponthelawsofelectromagneticinduction.Itconsistsoftwoormorecoilsofwirewrappedaroundacommonferromagneticcore.Thesecoilsareusuallynotdirectlyconnected.Theinteractionbetweenthecoilsisrealizedthroughthecommonmagneticfluxinthecommoncore.Thetransformerwindingconnectedto
4、thepowersourceiscalledtheprimarywinding(inputwindingwithN1turns),andthewindingconnectedtotheloadiscalledthesecondarywinding(outputwindingwithN2turns).Ifthereisathirdwindingonthetransformer,itiscalledthetertiarywinding.Powertransformersareconstructedusingeitherthecore
5、-formconstructionortheshell-formconstruction.Theformeroneconsistsofasimplerectangularlaminatedpieceofsteelwiththetransformerwindingswrappedaroundtwosidesoftherectangle.Thelaterconstructionconsistsofathree-leggedlaminatedcorewiththewindingswrappedaroundthecenterleg.2.
6、1.2RatingsofatransformerRatedvaluesincludingratedkilovolt-amperes(ratedcapacity),ratedvoltage,ratedcurrent,ratedfrequencyandthetransformerper-unitseriesimpedanceareusuallymarkedonthenameplate.Otherinformationsuchasthevoltageratingsofeachtaponthetransformerandthewirin
7、gschematicofthetransformerisalsoshownonthenameplate.Ratedcapacity(SN,kVAorMVA)Ratedvoltage(UN,VorkV)Ratedcurrent(IN,A)RatedFrequency(fN,Hz)2.2AnalysisofaSinglePhaseTransformerinNo-loadcondition2.2.1PhysicalSituationoftransformersinno-loadconditionTheprimarywindingisc
8、onnectedtoanacpowersource.Thesecondarywindingisopen-circuited.Iftheresistoroftheprimarywindingisr1,thevoltagedropwillbe.Theopen-cir
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