Reacances研發(fā)培訓(xùn),設(shè)計培訓(xùn)

ReactanceofInductionMachinesFundamentalConceptsL=InstantaneousInductanceofCoil(Henries)e=Instantaneousvalueofvoltageinducedinthecoilbythechangeofcurrent(Volts)di/dt=Instantaneousvalueoftherateofchange ofthecurrentwhichflowsthroughthecoilFaraday’sLawepath=inducedvoltagearoundanenclosedpathE=VectorofElectricFieldaroundthepathdl=Vectorofenclosedpathd/dt=RateofChangeofFluxenclosedbythepathAmoreusefulformofFaraday’slaw:whereIsthesumofallfluxesxlinkingcorrespondingturnsnxofthecoilCombiningEquationsReactanceofaninductivecircuitX=2fL(Ohms)f=freqencyofvoltageacrossinductance(Hz)orAmpere’sCircuitLawH=VectorofMagneticFieldIntensity(Amp/meter)dl=VectoralongthelengthofthepathJ=VectorfieldofcurrentdensityenclosedbypathdA=areaenclosedbythepathToapplyAmpere’sCircuitlaw,considerthesimplemagneticcircuitofatorus

withanon-ferromagneticcoreHr(2r)=NiB=uruoHB=VectorQuantityofMagneticFluxDensity(Tesla)uo=constantrelatingFluxDensitytoFluxIntensityinfreespaceornon-ferrousmaterials=4x10-7(T?m/A)ur=proportionalityconstantforferromagneticmaterials(unit-less)Rearranging:Also:Amp/meterTheintegrationoffluxdensityoveraunitareagivestotalflux.Foratorroid=BAWebersCombiningEquationsforLand,theinductanceofthecoilisshowntobedeterminedentirelybythedimensionsofthecoilandindependentofthecurrentinthewire.ThereactanceofthetorroidisthenForFerromagneticMaterials,avalueofroisreadfromaSaturationCurveEffectofSaturationonInductanceEquivalentCircuitofInductionMotorR1PrimaryresistanceX1LeakagereactanceofprimarywindingXMMagnetizingReactancegh=ResistancepathtoaccountforcorelossX2SecondaryleakagereactanceR2/sResistanceofsquirrelcagewindingThereisnostandardmethodforreactancecalculationsassimplifyingassumptionsaremadeatmanystepsintheircalculation.Theformulastofollowhavemanysimplifyingassumptions(suchasnosaturation)thatIwilltrytopointoutaswegoalong.However,thedependencyofreactancetophysicalparametersisthesameforallcalculationmethods.MagnetizingReactanceXMT=ReactanceFactorD=StatorBoreDiameter(I.D.)L=CoreLengthinInchesKW=StatorWindingFactorKdxKpg=singleairgapinchesKg=Carter’sAirGapCoefficientP=#PolesT=ReactanceFactor=Wheref=frequencym=#ofphasesZ=#statorconductorsinseriesperphaseTheresultantvoltageintheairgapavailabletocreatetherotatingmagneticfieldislessthanthepeakvoltageofthesinewaveatthemotorterminalsBecauseof2factors:Kp:AccountsforthepitchofthewindingKd:AccountsforthedistributionofthewindingToaccountfortheslotopeningsofthestatorandrotorsurface,agapfactorisusedasamultipliertocreatean““effective”airgap.Thisfactoriscalledthe“Carter’sCoefficient””KgKW=Kp?KdTotalLeakageReactanceX1+X2ThePrimaryslotreactanceTheSecondaryslotreactanceThezig-zagreactanceThebelt-leakagereactanceTheCoilEndLeakageReactanceTheperipheralleakageBecauserelativelyfewstatorsorrotorsareskewed,theleakagereactancecausedbyeitheraskewedstatororskewedrotorwillnotbeconsidered.Itissufficienttoknowthatanadditionalleakagereactanceexistsforskewedmotors.Reactance3and4aresometimescombinedandcalledDifferentialLeakageStatorSlotLeakageReactanceT=ReactanceFactorL=LengthofstatorcoreS=#statorSlotsKs=Factortoaccountforcoilsofdifferentphasesbeinginthesameslot1=PermeanceFactorofStatorSlotBasedonslotgeometryForStator:ForRotor:RotorSlotLeakageReactanceXSR=RotorSlotLeakageReactanceReferredtotheStatorT=ReactanceFactorL=LengthofrotorcoreR=#rotorSlotsKw=statorwindingfactor2=PermeanceFactorofrotorslotBasedonslotgeometryRotorLeakageReactanceCont.ThevalueofXSRiseffectedbytheoperatingconditionofthemotor.Thevaluecalculatedisfor“running””conditionswhenrotorfrequencyis1-2Hzandrotorcurrentisrelativelylow.Duringrunningconditions,therotorbarcurrentcanbethoughofasdistributingevenlythroughoutthebar.Duringlockedrotor,therotorfrequencyis60Hzandduetothe““DeepBarEffect”thecurrentcrowdstowardthetopofthebar.ThecurrentcrowdingalongwiththesaturationeffectsofthehighinrushcurrentcausethestartingvalueofXSRtobesignificantlyreduced.DifferentialLeakageBesidesthefundamentalairgapfluxwaveformthereareharmonicwaveformsthataremultiplesofthenumberofpolesandrotateatsub-multiplesofsynchronousspeed.Theseharmonicsinducevoltagesinthewindingsthatproducedthemandthereforeaddtothereactanceofthewinding.Thedifferentialleakageissometimesbrokeintotwocomponents:Thezig-zagandphasebeltleakage.Thefollowingnotationcombinesthebeltleakagewiththezig-zag.XM=MagnetizingReactanceS=#StatorSlotsP=#PolesR+#RotorSlotsKgSCarter’’sairgapcoefficientforthestatorKgRCarter’’sairgapcoefficientfortherotorKSShortPitchCorrectionFactorKWStatorWindingCorrectionFactorCoilendLeakageReactanceStatorRotorAS=MeanstatoroverhangAR=MeanRotorOverhangAS=MeanStatoroverhangL.M.H.T.=LengthofmeanhalfturnstatorcoilL=Statorcorelength=perunitcoilpitch=PolePitchKS=ShortpitchcorrectionfactorPeripheralAirGapLeakageLinesoffluxthatentertheairgapbutdonotlinktherotorbutinsteadflowperipherallybackintothestator.Ifweimagineainductionmotorwiththerotorremoved,allthefluxinthestatorborewillbeofthisairleakagecharacter.D=StatorI.D.g=SingleairgapPeripheralreactanceisnegligibleforinductionmachineswithsmallairgapsbutcanberelevantonhighspeedsynchronousmotorswithverylargeairgaps.Considera4poleinductionmotor,800framewithD=32.75andg=.175:XP/XM=.00091Considera4polesynchronousmotor,800framewithD=33.5andg=1.0:XP/XM=.028SummaryofInductionMotorLeakageReactanceXSS=StatorslotleakagereactanceXRS=RotorslotleakagereactanceXZZ=differentialleakagereactance(Zig-Zag+BeltLeakage)XES=StatorEndWindingLeakageReactanceXES=RotorEndWindingLeakageReactanceX2=XSR+??XZZ+XERX1=XSS+??XZZ+XESLeakageReactanceSummaryContinuedTheLeakagereactancevariesasthesquareofeffectiveconductorsorturnsperphase.Ifthenumberofstatorslotsandthenumberofparallelcircuitsarenotchanged,itvariesasthesquareofthenumberofturnspercoilInOrdertodecreasetheleakagereactancedooneormoreofthefollowing:Decreasethestatorboreorcorelength.IncreasetheairgapIncreasethenumberofstatororrotorslotsDecreaseslotdepthorincreaseslotwidthReduceStatorCoilPitchTheconverseofalloftheaboveistrueEffectofLeakageReactanceOnMotorPerformanceStartingtorqueincreasesasleakagereactance(X1+X2)decreasesMaximumTorqueorBreakdownTorqueincreasesasleakagereactance(X1+X2)decreasesEffectofLeakageReactanceOnMotorPerformanceCont.OccursatvalueofslipsEffectofLeakageReactanceOnMotorPerformanceInrushincreasesasleakagereactance(X1+X2)decreasesQUESTIONSEffectofReactanceonTransientShortCircuitCurrentByDefinition:XD=XM+X1GeneralequationforshortcircuitcurrentWhere’d>>’’’dFort=0;I’’’=E/XD’’Fort>>’’d;I0For’’’d<t<’d;9、靜夜四無鄰鄰，荒居舊業(yè)業(yè)貧。。1月-231月-23Wednesday,January4,202310、雨中黃葉樹樹，燈下白頭頭人。。22:20:0222:20:0222:201/4/202310:20:02PM11、以我獨獨沈久，，愧君相相見頻。。。1月-2322:20:0222:20Jan-2304-Jan-2312、故人人江海海別，，幾度度隔山山川。。。22:20:0222:20:0222:20Wednesday,January4,202313、乍見翻疑夢夢，相悲各問問年。。1月-231月-2322:20:0222:20:02January4,202314、他鄉(xiāng)生白白發(fā)，舊國國見青山。。。04一月月202310:20:02下下午22:20:021月-2315、比比不不了了得得就就不不比比，，得得不不到到的的就就不不要要。。。。。。一月月2310:20下下午午1月月-2322:20January4,202316、行動出成果果，工作出財財富。。2023/1/422:20:0222:20:0204January202317、做前前，能能夠環(huán)環(huán)視四四周；；做時時，你你只能能或者者最好好沿著著以腳腳為起起點的的射線線向前前。。。10:20:02下下午午10:20下下午22:20:021月-239、沒沒有有失失敗敗，，只只有有暫暫時時停停止止成成功功！！。。1月月-231月月-23Wednesday,January4,202310、很多事情努努力了未必有有結(jié)果，但是是不努力卻什什么改變也沒沒有。。22:20:0222:20:0222:201/4/202310:20:02PM11、成成功功就就是是日日復(fù)復(fù)一一日日那那一一點點點點小小小小努努力力的的積積累累。。。。1月月-2322:20:0222:20Jan-2304-Jan-2312、世間間成事事，不不求其其絕對對圓滿滿，留留一份份不足足，可可得無無限完完美。。。22:20:0222:20:0222:20Wednesday,January4,202313、不知香積寺寺，數(shù)里入云云峰。。1月-231月-2322:20:0222:20:02January4,202314、意意志志堅堅強強的的人人能能把把世世界界放放在在手手中中像像泥泥塊塊一一樣樣任任意意揉揉捏捏。。04一一月月202310:20:02下下午午22:20:021月月-2315、楚塞三湘湘接，荊門門九派通。。。。一月2310:20下午1月-2322:20January4,202316、少少年年十十五五二二十十時時，，步步行行奪奪得得胡胡馬馬騎騎。。。。2023/1/422:20:0222:20:0204January202317、空山新新雨后，，天氣晚晚來秋。。。10:20:02下下午10:20下下午22:20: