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1、设计巴巴工作室www.88doc88.comTheTransformeronload﹠IntroductiontoDCMachinesTheTransformeronloadIthasbeenshownthataprimaryinputvoltagecanbetransformedtoanydesiredopen-circuitsecondaryvoltagebyasuitablechoiceofturnsratio.isavailableforcirculatingaloadcurrentimpedance.Forthemome
2、nt,alaggingpowerfactorwillbeconsidered.Thesecondarycurrentandtheresultingampere-turnswillchangetheflux,tendingtodemagnetizethecore,reduceandwithit.Becausetheprimaryleakageimpedancedropissolow,asmallalterationtowillcauseanappreciableincreaseofprimarycurrentfromtoanewva
3、lueofequalto.Theextraprimarycurrentandampere-turnsnearlycancelthewholeofthesecondaryampere-turns.Thisbeingso,themutualfluxsuffersonlyaslightmodificationandrequirespracticallythesamenetampere-turnsasonnoload.Thetotalprimaryampere-turnsareincreasedbyanamountnecessaryton
4、eutralizethesameamountofsecondaryampere-turns.Inthevectorequation,;alternatively,.Atfullload,thecurrentisonlyabout5%ofthefull-loadcurrentandsoisnearlyequalto.Becauseinmindthat,theinputkVAwhichisapproximatelyisalsoapproximatelyequaltotheoutputkVA,.Thephysicalcurrenthas
5、increased,andwithintheprimaryleakagefluxtowhichitisproportional.Thetotalfluxlinkingtheprimary,,isshownunchangedbecausethetotalbacke.m.f.,（）isstillequalandoppositeto.However,therehasbeenaredistributionoffluxandthemutualcomponenthasfallenduetotheincreaseofwith.Althought
6、hechangeissmall,thesecondarydemandcouldnotbemetwithoutamutualfluxande.m.f.alterationtopermitprimarycurrenttochange.Thenetfluxlinkingthesecondarywindinghasbeenfurtherreducedbytheestablishmentofsecondaryleakagefluxdueto,andthisopposes.Althoughand设计巴巴工作室www.88doc88.comar
7、eindicatedseparately,theycombinetooneresultantinthecorewhichwillbedownwardsattheinstantshown.Thusthesecondaryterminalvoltageisreducedtowhichcanbeconsideredintwocomponents,i.e.orvectorially.Asfortheprimary,isresponsibleforasubstantiallyconstantsecondaryleakageinductanc
8、e.Itwillbenoticedthattheprimaryleakagefluxisresponsibleforpartofthechangeinthesecondaryterminalvoltageduetoitseffectsonthemu
