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1、INDUCTIONMOTORSTARTINGMETHODSAbstractManymethodscanbeusedtostartlargeACinductionmotors.Choicessuchasfullvoltage,reducedvoltageeitherbyautotransformerorWyes-Delta,asoftstarter,orusageofanadjustablespeeddrivecanallhavepotentialadvantagesandtradeoffs.Reducedvoltagestartingcanlowe
2、rthestartingtorqueandhelppreventdamagetotheload.Additionally,powerfactorcorrectioncapacitorscanbeusedtoreducethecurrent,butcaremustbetakentosizethemproperly.Usageofthewrongcapacitorscanleadtosignificantdamage.Choosingtheproperstartingmethodforamotorwillincludeananalysisofthepo
3、wersystemaswellasthestartingloadtoensurethatthemotorisdesignedtodelivertheneededperformancewhileminimizingitscost.Thispaperwillexaminethemostcommonstartingmethodsandtheirrecommendedapplications.I.INTRODUCTIONThereareseveralgeneralmethodsofstartinginductionmotors:fullvoltage,re
4、ducedvoltage,wyes-delta,andpartwindingtypes.Thereducedvoltagetypecanincludesolidstatestarters,adjustablefrequencydrives,andautotransformers.These,alongwiththefullvoltage,oracrossthelinestarting,givethepurchaseralargevarietyofautomotiveswhenitcomestospecifyingthemotortobeusedin
5、agivenapplication.Eachmethodhasitsownbenefits,aswellasperformancetradeoffs.Properselectionwillinvolveathoroughinvestigationofanypowersystemconstraints,theloadtobeacceleratedandtheoverallcostoftheequipment.Inorderfortheloadtobeaccelerated,themotormustgenerategreatertorquethanth
6、eloadrequirement.Ingeneraltherearethreepointsofinterestonthemotor'sspeed-torquecurve.Thefirstislocked-rotortorque(LRT)whichistheminimumtorquewhichthemotorwilldevelopatrestforallangularpositionsoftheroto匚Thesecondispull-uptorque(PUT)whichisdefinedastheminimumtorquedevelopedbyth
7、emotorduringtheperiodofaccelerationfromresttothespeedatwhichbreakdowntorqueoccurs.Thelastisthebreakdowntorque(BDT)whichisdefinedasthemaximumtorquewhichthemotorwilldevelop.Ifanyofthesepointsarebelowtherequiredloadcurve,thenthemotorwillnotstart.Thetimeittakesforthemotortoacceler
8、atetheloadisdependentontheinertiaoftheloadandthemarginbetween
