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1、TheTransformeronload﹠IntroductiontoDCMachinesTheTransformeronloadIthasbeenshownthataprimaryinputvoltagecanbetransformedtoanydesiredopen-circuitsecondaryvoltagebyasuitablechoiceofturnsratio.isavailableforcirculatingaloadcurrentimpedance.Forthemoment,alaggingpowerfactorwillbeconsidered.Thesecondar
2、ycurrentandtheresultingampere-turnswillchangetheflux,tendingtodemagnetizethecore,reduceandwithit.Becausetheprimaryleakageimpedancedropissolow,asmallalterationtowillcauseanappreciableincreaseofprimarycurrentfromtoanewvalueofequalto.Theextraprimarycurrentandampere-turnsnearlycancelthewholeofthesec
3、ondaryampere-turns.Thisbeingso,themutualfluxsuffersonlyaslightmodificationandrequirespracticallythesamenetampere-turnsasonnoload.Thetotalprimaryampere-turnsareincreasedbyanamountnecessarytoneutralizethesameamountofsecondaryampere-turns.Inthevectorequation,;alternatively,.Atfullload,thecurrentiso
4、nlyabout5%ofthefull-loadcurrentandsoisnearlyequalto.Becauseinmindthat,theinputkVAwhichisapproximatelyisalsoapproximatelyequaltotheoutputkVA,.Thephysicalcurrenthasincreased,andwithintheprimaryleakagefluxtowhichitisproportional.Thetotalfluxlinkingtheprimary,,isshownunchangedbecausethetotalbacke.m.
5、f.,（）isstillequalandoppositeto.However,therehasbeenaredistributionoffluxandthemutualcomponenthasfallenduetotheincreaseofwith.Althoughthechangeissmall,thesecondarydemandcouldnotbemetwithoutamutualfluxande.m.f.alterationtopermitprimarycurrenttochange.Thenetfluxlinkingthesecondarywindinghasbeenfurt
6、herreducedbytheestablishmentofsecondaryleakagefluxdueto,andthisopposes.Althoughandareindicatedseparately,theycombinetooneresultantinthecorewhichwillbedownwardsattheinstantshown.Thusthesecondaryterminalvoltageisreducedtowhichcanbeconsideredintwocomponents,i.e.orvectorially.Asfortheprimary,isrespo
7、nsibleforasubstantiallyconstantsecondaryleakageinductance.Itwillbenoticedthattheprimaryleakagefluxisresponsibleforpartofthechangeinthesecondaryterminalvoltageduetoitseffectsonthemutualflux.Thetwoleakagefluxesarecloselyrelate
