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1、南京工程学院成绩期末考查报告书电气工程专业外语B院（系、部、中心）电力工程学院专业电气工程及其自动化班级学生姓名学号任课教师年月南京Page1.GeneratorsandMotors(发电机和电动机)1.EnglishtestFromreference1ACGeneratorsAnalternating-currentgeneratorisarotatingmachineforconvertingmechanicalenergyintoalternating-currentelectricpow
2、er.Asinthecaseofadegenerator,therotatingpartofthemachineisdrivenbyasourceofrotatingpowerexternaltothemachineitself.Alternating-currentgenerators,alsocalled"alternators”，canbedividedintothreetypesaccordingtothetypeofdriveorprimemoverTherearedirect-con
3、nectedengine-driven(steamorinternalcombustion)acgenerators,water-wheelacgenerators,turbine-drivenacgenerators.DCGeneratorsAdirect-currentgeneratorisarotatingmachineforconvertingmechanicalenergyintodirect-currentelectricpowerAdegeneratorisdrivenbymech
4、anicalmeans,suchasasteamengine,dieselengineorelectricmotorDirect-currentgeneratorsareratedinkilowatts,sizesrangfromafractionofawatttoseveralthousandwatts>Keywords：ACgenerator,DCgeneratorFromreference2Anelectricmotorcanbereservedbyreservingthedirectio
5、nofthecurrentineitheritsarmatureoritsfieldcoils.Ifbothcurrentsarereservedthemotorcontinuestoturninthesamedirection,anditfollowsthatthecommutatormotorsdescribedabovewillworkfromanACsupply.Thereare,however,twospecialkindsofmotorthatcanbeusedwithAConly.
6、Thefirstoftheseiscalledasynchronousmotorbecauseitsynchronizesitself,thatis,itkeepsinstepwiththeACsupply.Themovingpart,calledtherotor,isastraightbarmagnetmountedonaspindlethoroughitscenterbetweenthepolesofanelectromagnet.Whentheelectromagnetisjoinedto
7、anACsupplyitsmagnetismreservesregularlyeachtimethecurrentchangesdirection,anditspolesbecomealternatelyNandS.Thesynchronousmotorisnotself-starting,butiftherotorisspunroundbyhandatthecorrectspeed,itsSpoleisalwaysapproachingtheupperpoleoftheelectromagne
8、twhenthisisaNpole.AndbythesametimeelectromagnetcurrenthaschangedtheupperpoletoaSpole,therotorhasturnedsothattheNpoleisapproaching.Themagneticattractionbetweentheoppositepolesoftherotorandtheelectromagnetpullstherotorroundandkeepsitmoving.Thecurrent,s
