外文翻译冲压模具 冲压模具设计实例100例Word文件下载.docx

外文翻译冲压模具 冲压模具设计实例100例Word文件下载.docx

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外文翻译冲压模具冲压模具设计实例100例@#@外文翻译冲压模具冲压模具设计实例100例@#@ANIMPROVEDINSULARIONSYSTEMFORTHENEWESTGENERATIONOFSTATORWINDINGSOFROTATINGMACHINESSummary:

@#@Inrecentyearstherehasbeenadistincttrendtoutilizemachineswithindirectlycooledstatorwindingsalsoforthehigherratings,uptoabout300MVAwithaircoolingandabout450MVAwithhydrogencooling.Thisimposednewdemandsonthewell-knowndielectricrequirements,asthisisakeyitemwhenlayingoutthemachine.ThisreportdescribesthemodifiedstructureofanimprovedsyntheticresininsulationMatador-Plus.Themostsignificantchangewastheintroductionofpowderedmetaloxydetotheinsulationstructureusedhitherto,whichitenablethethermalsconductivitytobedoubled.Theresultingcharacteristicallychangesaredescribedrelativetobothshortandlongtermbehaviorsoftheinsulationsystem.Basedontheimprovedinsulatingqualitiesitwaspossibletoreoptimizemachinedesigns,whichisfundamentallydemonstrated.Keywords:

@#@Turbo-generator,statorwinding,insulationsystem,indirectconductorcooling,thermalconductivity.1:

@#@IntroductionOverthelastdecadesthedevelopmentofturbo-generatorswithindirectconductorcoolinginthestatorwindinghasledtoeverincreasingratings.Today,machinesarebeingbuiltwiththistechnologyforratingswhich,justafewyearsago,wereonlypossiblewithdirectwaterorhydrogencoolingofthestatorwindingconductors.Air—cooledmachineswithratingsofupto130MVAwerealreadyinserviceby1970.Withthedevelopmentofgasturbineswithlargerunitratingsthereisatrendtodayforair-cooledturbo-generatorswithratingsof300MVA.Hydrogencoolinginturbogeneratorspermittedmuchhigherunitratings.Bytheofthe50’s,machineswithindirectconductorcoolinghadbeenrealizedupto250MVAandtodaythelimitisabove350MVA.Comparedwithdirectconductorcoolingusedonlargergenerators,indirectcoolingofthestatorendinghastheadvantagesthat,barproductionissimpleandlessexpensive,thespaceneededforcoolantflowwithdirectcoolingisavailableforinstancewithwatercooling.Ontheotherhand,indirectcoolingrequiresthattheheatlossesgeneratedintheconductorsatedissipatedviatheinsulationwrappingonthestatorwindingbarswhichisapoorthermalconductor.Dependingonthecaseunderconsideration,thetemperaturedropinvolvedrepresent20…40%ofthetotaltemperaturerise.Besidestheneedtooptimizethecoolingtechniqueonmachineswithindirectconductorcooling,therewasalsothecontinuousrequirementtoimprovetheinsulationsystemwhichhelpedtomakethiscourseindevelopmentpossible.Thechangeinthe60’sfromthermoplasticmica-foliuminsulationsystemwhichhelpedtomakethermoplasticmica-foliuminsulationstoepoxyresinbases\dsyntheticresininsulationledtoconsiderableimprovementinthephysicalandparticularlyinthedielectricpropertiesoftheinsulationmaterial.Afurtherstepinthe70’ssawtheintroductionoftotalimmersionimpregnation,alsoforlargegenerator[4/5].Thenowfurtherimprovedthermalconductivityallowsabetterdissipationofthewindingheatlossesandsoafurtherincreaseintheratingsforindirectcooledmachines.2.Effectoftheimprovedinsulationsystemonmachinedesign2.1CoolingprincipleThelaminatedcoreisbuiltupfromvarnishinsulated,electricalsheetsegments,andissubdividedintopacketsbyradialductspacerswhichformpassagesforthecoolinggasflow.Inoneofthemostcommondesignsthecoreissplitupintodifferentcoolingzoneswherebythecoolinggasisledinthroughaxialtubeslocatedinthestatorhousing.Thegasflowsradicallythroughthecoreductsandabsorbstheironlossesproducedinthecoreandthecopperlossesgeneratedinthestatorbars.Thetotaltemperaturedropduetoconvectionandthermalconduction.Thegasabsorbsotherheatlossesbeforereachingthecoolingsurfacesofthestatorwindingandthereforealreadyhasacertaintemperaturewhichincreasesfurtherafterabsorbingtheironandcopperlosses.Thewindingcopperlossesmustbedissipatedbythermalconductionviatheinsulation.Intheregionsofthecoolingductsheattransferisbyconvectiondirectlytothecoolinggasflowingoverthebarsurfaces.Thelargerportionofthewindinglossesintheactivepartisfirsttransferredtothestatorteethandthendissipatedtothegasflowingthroughthecoolingducts.2.2Exampleofanair-cooledturbo-generatorInatypicalexample,dissipationbyconvectionrepresentsapproximately35%ofthetotaltemperaturerise.Thisportioncouldtheoreticallybereducedbyincreasingthevelocityofthecoolinggas.However,fromacertainflowvelocityheattransfercanhardlybeimprovedupon,andmoreover,inordertoachievehigherflowvelocityofthecoolinggas.However,fromacertainflowvelocityheattran