电气专业毕业设计外文翻译----电力变压器工作原理

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1、外文资料翻译PowerTransformerPrinciples1.INTRODUCTIONThehigh-voltagetransmissionwasneedforthecaseelectricalpoweristobeprovidedatconsiderabledistancefromageneratingstation.Atsomepointthishighvoltagemustbereduced,becauseultimatelyismustsupplyaload.Thetransforme

2、rmakesitpossibleforvariouspartsofapowersystemtooperateatdifferentvoltagelevels.Inthispaperwediscusspowertransformerprinciplesandapplications.2.TOW-WINDINGTRANSFORMERSAtransformerinitssimplestformconsistsoftwostationarycoilscoupledbyamutualmagneticflux.

3、Thecoilsaresaidtobemutuallycoupledbecausetheylinkacommonflux.Inpowerapplications,laminatedsteelcoretransformers(towhichthispaperisrestricted)areused.Transformersareefficientbecausetherotationallossesnormallyassociatedwithrotatingmachineareabsent,sorela

4、tivelylittlepowerislostwhentransformingpowerfromonevoltageleveltoanother.Typicalefficienciesareintherange92to99%,thehighervaluesapplyingtothelargerpowertransformers.Thecurrentflowinginthecoilconnectedtotheacsourceiscalledtheprimarywindingorsimplythepri

5、mary.Itsetsupthefluxφinthecore,whichvariesperiodicallybothinmagnitudeanddirection.Thefluxlinksthesecondcoil,calledthesecondarywindingorsimplysecondary.Thefluxischanging;therefore,itinducesavoltageinthesecondarybyelectromagneticinductioninaccordancewith

6、Lenz’slaw.Thustheprimaryreceivesitspowerfromthesourcewhilethesecondarysuppliesthispowertotheload.Thisactionisknownastransformeraction.3.TRANSFORMERPRINCIPLESWhenasinusoidalvoltageVpisappliedtotheprimarywiththesecondaryopen-circuited,therewillbenoenergy

7、transfer.TheimpressedvoltagecausesasmallcurrentIθtoflowintheprimarywinding.Thisno-loadcurrenthastwofunctions:(1)itproducesthemagneticfluxinthecore,whichvariessinusoidallybetweenzeroandφm,whereφmisthemaximumvalueofthecoreflux;and(2)itprovidesacomponentt

8、oaccountforthehysteresisandeddycurrentlossesinthecore.Therecombinedlossesarenormallyreferredtoasthecorelosses.Theno-loadcurrentIθisusuallyfewpercentoftheratedfull-loadcurrentofthetransformer(about2to5%).Sinceatno-loadtheprimarywindingac