自动化专业英语翻译.doc

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1、发电机和电动机GeneratorsandElectricMotorsPassageAACGeneratorsAnalternating-currentgeneratorisarotatingmachineforconvertingmechanicalenergyintoalternating-currentelectricpower.Asinthecaseofadegenerator,therotatingpartofthemachineisdrivenbyasourceofrotatingpowerexternaltothemachineitself.Al

2、ternating-currentgenerators,alsocalled"alternators,canbedividedintothreetypesaccordingtothetypeofdriveorprimemover.Therearedirect-connectedengine-driven(steamorinternalcombustion)acgenerators,water-wheelacgenerators,turbine-drivenacgenerators.OperationBasically.thealternatoroperat

3、esontheprincipleofgeneratoraction-voltageissetupincoilsofwirewhentheyaremovedinamagneticfieldinsuchawayastocutthemagneticlinesofforce.Thisisthesameprincipleonwhichthedegeneratoroperates.Butthereisabasicdifferencebetweendegeneratorsandalternatorsinaccomplishingtherelativemotionbetwe

4、encoilsandfield.Inadegenerator,themagneticfieldissetupbyplacingelector-magneticfieldpolesaroundtheinsideofthehousingorstator.Coilsareplacedontherotorsothatwhentherotorrotates,thecoilsarecuttingacrossthemagneticlinesofforcesetupbythepolesandvoltageisproducedintherotorcoils.Bytheuseo

5、facommutatorandbrushes,voltageistakenfromtherotor.Inanacgenerator,theelectro-magneticfield-thesourceofthemagneticlinesofforce-isgenerallyplacedontherotorandthecoilsinwhichthevoltageistobegeneratedaremountedaroundtheinsideofthestator.Inthiscase,therotatingfieldsweepsthelinesofmagnet

6、icforceacrossthestationarycoilsandproducesthevoltageinthem.Alternatorswithstationarycoils(orstationaryarmature,asitissometimesdescribed)havedistinctadvantagesoveralternatorswithrotatingcoilsandarethemostcommontype.Ifthegeneratorcoilsareplacedontherotor,twoormoreslipringsmustbeusedf

7、orconductingtheacpowertotheexternalcircuitwhichthegeneratorfeeds.Suchringsareafrequentsourceoftrouble,particularlyatthehighvoltageputoutbystandardalternatorsjfstationarycoilareused,thegeneratedacpowercanbetakendirectlyfromthecoilleadstooutputbusbars.Also.ifthecoilsareontheroto^itis

8、moredifficulttoproperlyins