第1題Voltagetransformerisinuse,notallowed.()AprimarysideopencircuitBsecondarysideshortcircuitCtertiarysideopencircuitDopencircuitfourside第2題Currenttransformerisinuse,notallowed.()AopencircuitBopencircuitsecondarysideCshortcircuitDopencircuitfourside第3題Short-circuitimpedanceofelectricweldingtransformer()AissmallBislargeCisconstantDandcannotbedetermined第4題Thethree-itemmagneticcircuitbetweenthethree-itemcoretransformeris().AiscorrelatedtoeachotherBisindependentofeachotherCisindependentandiscorrelatedDwhereonlytwophasesarecorrelated第5題Theefficiencyofthetransformerdependsonthesizeof()AironlossandcopperlossandloadBironlossandcopperlossCloadDcopperloss第6題Mainfactorsaffectingtheexternalcharacteristicsofthetransformer(

)Aironloss,copperloss,andloadBironlossandcopperlossCloadDcopperlossandload第7題Whenthetransformerisrunninginno-load,thepowerfactorisgenerallyin()A0.8~1.0B0.1~0.2C0.3~0.6D0.7~0.8第8題Theloadcoefficientofthetransformerrefersto(

)AI2/I2NBI1/I2CI2/I1DI1N/I2N第9題Thecrosssectionoftheironyokeisprovidedwith().ApentagonBouterTCinnerTDrectangle正確答案：BCD第10題Transformerisdividedinto()accordingtothenumberofwindings.Asingle-winding(self-coupling)transformerBdouble-windingtransformerCsix-windingtransformerDmulti-windingtransformer正確答案：ABD第11題Commonfaultsofsmalltransformersare().AcoilleakageBcoilshortcircuittocoreCleadlineendbreakDcoilexplosion正確答案：ABC第12題Technicalparametersofthetransformerare().AratedcapacityBratedvoltageCratedcurrentDshort-circuitcurrent正確答案：ABC第13題Experimentalmethodforthedeterminationofisopolarityis(

).AcontrolvariablemethodBDCmethodCACmethodDtablecheckingmethod正確答案：CB第14題Toensurethequalityofelectricweldingandthestabilityofelectricarccombustion,theelectricweldingtransformershouldmeetthefollowingrequirements().AThereshouldbesufficientarcinductionvoltage(60~75V)Bwhenon-load(i.e.welding),theelectricweldingtransformershallhavetheexternalcharacteristicsofrapidpressurereduction,andtheoutputvoltagewithratedload(arcbetweenweldingclampandworkpiece,andstablecombustion)isabout30V.CInshortcircuit(whentheelectrodecollideswiththeworkpiece),theshortcircuitcurrentI2shouldnotbetoolargetoavoiddamagetotheweldingmachine.DInordertoadapttodifferentweldingpartsanddifferentspecificationsofweldingrod,thesizeoftheweldingcurrentisrequiredtobeuniformandadjustableinanycase正確答案：ABC第15題Theoutputvoltageofthegeneratorisgenerallya().A3.15kVB6.3kVC10.5kVD16.75kV正確答案：ABC第16題Thebasicprincipleofthetransformeristheelectromagneticinduction第17題Undertheconditionofacertainmagneticfluxpotential,onlychangetheratioofthenumberofthesecondarywindingtoachievethepurposeofchangingtheoutputvoltageofthesecondarywinding.第18題Thereisonlymagneticcouplingbetweentheprimaryandsecondarywindings,andnoelectricdirectconnection第19題Whenusingthetransformer,itmustbenotedthat:becausethesecondarywindingcurrentofthevoltagetransformerisverylarge,soneverallowopencircuit;theprimarywindingturnsofthecurrenttransformerisverysmall,andtheturnsofthesecondarywindingismore,whichwillproduceahighinducedelectromotiveforceinthesecondarywinding,sothesecondarywindingofthecurrenttransformerdoesnotallowshortcircuit.第20題Themainprincipleofthecurrenttransformeristhataccordingtotheconvertereffectofthetransformer,inordertoreducethecurrent,N1<N2isrequired,andtheratedcurrentofthesecondarysideisgenerallystipulatedas10A.第1題Whenthethree-phaseasynchronousmotoradoptsstar-trianglevoltagestarting,itsstartingcurrentis()timesofthefullvoltagestartingcurrent.A1/2B1/3C1/4D1/5第2題Theratedpoweroftheasynchronousmotoris()power.AinputactivepowerBinputapparentpowerCelectromagneticpowerDthemechanicalpoweroutputbytherotorshaft第3題Inthemotorstate,theactualspeedoftheasynchronousmotor()issynchronousspeed.AlessthanBgreaterthanCequalDuncertain第4題ThemaximumallowableworkingtemperatureofGradeEinsulatingmaterialis:()A90°CB105°CC120°CD130°C第5題Theinstantaneousrotationrateofthethree-phaseasynchronousmotoris()An=0,s=1Bn=1,s=0Cn=1,s=1Dn=0,s=0第6題Inthefollowingspeedregulation,thegradedspeedregulationis:()AfrequencyconversionspeedregulationBvariablestagespeedregulationCchangethetransitionratespeedregulationDsteplessspeedregulation第7題Three-phasesynchronousmotorissuitablefor()AdonotrequirespeedadjustmentoccasionsBconstantspeedoccasionsCstartfrequentoccasionsDsmoothspeedadjustmentoccasions第8題Inordertochangethesteeringofthethree-phaseACasynchronousmotor,aslongastheoriginalphasesequenceA-B-Cischangedto:()AB-C-ABA-C-BCC-A-BDA-B-C第9題Themainandsecondarywindingsofthesingle-phaseasynchronousmotorshouldbedifferentinthespaceposition()A120°B180°C60°D90°第10題Athree-phasefour-poleasynchronousmotorwithratedrotationrateis0.04.Ifthepowerfrequencyis50Hz,thespeedofthemotoris().A1450r/minB1440r/minC960r/minD950r/min第11題Thecommonbrakingmethodsusedforthethree-phaseasynchronousmotorare().ApowergenerationBenergyconsumptionCelectricalDmachinery正確答案：CD第12題Thedebuggingmethodsofratcagethree-phaseACasynchronousmotorare()AvariablevoltagespeedregulationBvariablepolespeedregulationCfrequencyconversionspeedregulationDvariableratespeedregulation正確答案：CDB第13題Thecommonlyusedmouse-cagethree-phaseACsynchronousstartingmethodsare(

).AdirectstartBY-Δstep-downstartCautotransformerstep-downstartDseriesresistancestart正確答案：BC第14題Thestructureofthethree-phaseasynchronousmotorincludes()AstatorBairgapCrotorDmachineseat正確答案：ABC第15題Itcanbeviewedonthenameplateofthree-phasesynchronousmotor()ARatedpowerBratedvoltageCratedcurrentDratedspeed正確答案：ABCD第16題Inthethree-phaseasynchronousACmotor,themorethepolarlogarithmic,thehigherthemotorspeed.第17題TurnrateSisanimportantparametertoanalyzetheoperationperformanceoftheasynchronousmotor.Whenthefasterthemotorspeedis,thecorrespondingturnrateislarger.第18題Therotorrotationdirectionofthethree-phaseasynchronousmotoristhesameasthatofthestatorrotatingmagneticfield.第19題Thenameplateofthethree-phaseratcageasynchronousmotorindicates:"ratedvoltage380/220V,wiringY/△".Whenthepowersupplyvoltageis380V,thethree-phaseasynchronousmotorcanbestartedwithY-△step-down.第20題Single-phaseasynchronousmotorgenerallyadoptsstep-downandvariablepolefordebugging.Chapter3Testing第1題IntheDCmotor,thecurrentisDCwith(

)AMainpoleexcitationwindingBChangingpolewindingCArmaturewindingelementDArmaturecircuitatbothendsofthebrush第2題InthearmatureelementoftheDCmotor,thepotentialthathindersthecurrentchangeisdefinitely(

)AReactancepotentialBArmaturereactionpotentialCCommutatorpotentialDSyntheticpotential第3題ThemethodtodeterminewhethertheDCmotorisrunninginthegeneratorstateorthemotorstateisincluded()AComparisonofUandEasizesBComparisonofnoandnsizesCJudgebythepositiveandnegativeofPemDJudgebywhetherthearmatureisconnectedtotheDCpowersupply第4題RegardingthefunctionofthetransductoroftheDCmotor,itistruethat(

)AAutomaticchangethecurrentdirectionwhenthecoilplaneisparalleltothemagneticlineBWhenthecoilplaneisparalleltothemagneticsensorplane,changethecoilrotationdirectionautomaticallyCAutomaticchangeofthedirectionofthesensorlinewhenthecoilplaneisparalleltothesensorlineDAutomaticchangethedirectionofcurrentwhenthecoilplaneisperpendiculartotheinductionline第5題Inordertochangetherotationdirectionofthemotor,thefollowingmeasuresthatcanbetakenarecorrect:(

)AChangethesizeofthepowersupplyvoltageBChangethedirectionofthecurrentpassingthroughthecoilCChangethemagnitudeofthecurrentpassingthroughthecoilDAdjustthepositionofthetwomagneticpolesNandS,andadjustthepositiveandnegativepolesofthepowersupply第6題TheDCmotoroperateswithAconstanttorqueload.Ifitsexcitationcurrentisincreased,itselectromagnetictorquewillbe(

)AincreasedBunchangedCdecreasedDuncertain第7題Whentheelectromagnetictorqueofthemotorisgreaterthantheloadtorque,thepowerdraggingsystemisinthe(

)state.AUncertaintyBDecelerationoperationCConstantspeedoperationDAcceleration第8題IntheDCmotor,thecurrentisdchas(

)AmainmagneticpolewindingBreversingpolewindingCrmaturewindingelementDarmaturecircuitatbothendsofthebrush正確答案：AB第9題ThecommonlyusedelectricalbrakingmethodsforDCmotorare()AenergybrakeBreversebrakeCfeedbackbrakeDlockbrake正確答案：ABC第10題ThecommonlyusedspeedregulationmethodsfortheexcitationDCmotorare()AChangetheloadsizespeedregulationBStep-downspeedregulationCRotorloopstringresistancespeedregulationDToreducethemainmagneticfluxspeedregulation正確答案：BCD第11題ThepotentialandcurrentinthearmatureelementoftheDCmotorarebothDC.第12題ThereversingextremeattentionofDCmotoristoimprovethereversingdirectionofDCmotor.第13題BecausetheDCmotorarmatureistheDCpowersupply,theflowthroughthearmaturewindingelementmustbetheDCcurrent.第14題BecausethecasingoftheDCmotorisapartofthemainmagneticcircuitofthemotor,itismadeofcaststeelinsteadofcastiron.第15題BecausetheinstallationofreversingmagneticpolesisaneffectivemeasuretoimprovethedirectionofDCmotors,allDCmotorsequippedwithreversingmagneticpolescanhaveagoodchangingorientation.第16題TheelectromagnetictorqueoftheDCmotoristhedrivingtorque,so,whenthesteadystateoperation,thelargeelectromagnetictorquecorrespondingtotherotationspeedishigh.第17題HeexcitedDCmotortoreducethepowersupplyvoltagespeedregulationbelongstothewayofbalancebureauspeedregulation,soitcanonlydragtheconstanttorqueloadoperation.第18題ThesizeoftheinducedelectromotiveforceinaDCgeneratormainlydependsonthesizeoftheexternalcircuitload.第19題TheoutputpowerontheDCmotorshaftistheratedpowerofthemotor.Chapter4Testing第1題Forathree-phasesteppingmotorwith40rotor,astepAngleof1.5°shallbepoweredto()AsinglebeatsystemBdoublebeatsystemCsingleanddoublebeatsystemDsubdivisioncircuit第2題RegardingthestepAnglecharacteristicsofthesteppingmotor,itistruethat()Aforeachelectricalpulsesignal,thespatialangleoftherotoriscalledthestepangleBisproportionaltothenumberofrotorteethandinverselyproportionaltothenumberofrunningbeatsCinproportionaltothenumberofrotorteeth,andproportionaltothenumberofrunningbeatsDisproportionaltothenumberofrotorteethandisproportionaltothenumberofrunningbeats第3題ThefunctionrelationshipbetweentheelectromagnetictorqueandtheoutputspeedoftheDCservomotoriscalledits(

)AmechanicalpropertiesBergulatingcharacteristicCtorquefactorDSpeedcharacteristics第4題IntheACservomotor,theelectricAnglebetweenthecontrolwindingandtheexcitationwindingis()A60°B45°C0°D90°第5題TheDCspeedmeasuringgeneratorisoutputwiththespeed()AproportionalACvoltageBinverselyproportionalACvoltageCproportionalDCvoltageDinverseproportionalDCvoltage第6題Operationmodeofthree-phasesteppingmotorincludes(

)Athree-phasesinglethreebeatBthree-phasedoublethreebeatCfour-phasesinglefourbeatDtwo-phasesinglefourbeat正確答案：AB第7題Thereisafour-phaseeight-polereactivesteppingmotor,themotorrotortoothnumberis50,anditsstepdistanceAngleis()A1.8°B3.6°C2.7°D0.9°正確答案：AD第8題Themaintypesoflinearasynchronousmotorsare()AflatBtubeCarcDdisc正確答案：ABCD第9題ThecontrolmodeoftheACservomotorisprovidedwith()AamplitudecontrolBphasecontrolCcapacitorcontrolDresistancecontrol正確答案：ABC第10題Steppermotorcanbedividedinto()accordingtodifferentexcitationmodesAelectromagnetictypeBpermanentmagnettypeCreactivetypeDpermanentmagnetinductiontype正確答案：BCD第11題Thethree-phasereactivesteppingmotorcanincreasetheloadcapacitybyincreasingthenumberofpowerphases.第12題Thetorqueofthesteppingmotordecreasesasthefrequencyincreases.第13題Inprinciple,eachrotatingmotorhasacorrespondinglinearmotor.第14題Theprimaryandsecondarystagesoflinearmotorsaregenerallythesameaslong.第15題FortheACservomotor,changethecontrolvoltagetochangeitsspeedandsteering.第16題TheACservomotorcannotrotatewhenthecontrolvoltageiscancelled.第17題WhentheDCspeedmeasuringgeneratorisused,ifitexceedsthespecifiedmaximumspeedorfallsbelowthespecifiedminimumloadresistance,itwillhaveanimpactonitscontrolaccuracy.第18題Linearmotorisanelectricmachinethatrequiresanintermediateconversiondeviceforlinearmovement.第19題TheDCservomotorisdividedintotwobasicstructures:permanentmagnettypeandelectromagnetictype,amongwhichthepermanentmagnettypeDCservomotorcanberegardedastheexcitationtypeDCmotor.第20題Changethepowerorderofthestatorwindingofthesteppermotor,andcannotcontrolthepositiveandreverseofthemotor.Chapter5Testing第1題Manualswitchofelectricalapplianceis(

).AlowvoltagecircuitbreakeBelectricrelayCcontactorDcombinationswitch第2題Circuitbreakertimeofthemeltand().AtheelectriccurrentisdirectlyproportionalBtheelectriccurrentisinverselyproportionalCthesquareofthecurrentisproportionalDthesquareofthecurrentisinverselyproportional第3題Thecoilsuctioncurrentoftheovercurrentrelayshallbe(

)thereleasecurrentofthecoil.AgreaterthanBless-thanCequaltoDunidentified第4題ForACcontactors,ahighoperatingfrequencycancause（）.AironheartoverheatingBthecoilisoverheatedCmaincontactpointtooverheatDcontrolthecontactpointforoverheating第5題Accordingtotheprincipleofaction,（）isthemostwidelyusedrelay.AinductiontyperelayBphotoelectrictyperelayCelectromagneticrelayDpiezoelectricrelay第6題Volvoltagerelaycanbedividedinto()accordingtothesuctionvoltagerelativetoitsratedvoltage.AovervoltagerelayBundervoltagerelayCthermalrelayDthezero-voltagerelay正確答案：ABD第7題Whichofthefollowingarethemainorderappliances?AButtonBTravelswitchCUniversaltransferswitchDThermalrelay正確答案：ABC第8題Theairdampingtimerelayismainlycomposedof()AelectromagneticmechanismBfusepieceCworkingcontactDairchamber正確答案：ACD第9題TheratedvoltageratingoftheACcontactorcoilis(

)and380V.A36VB110VC127VD220V正確答案：ABCD第10題Contactwearofthecontactorisgenerallydueto().AcorewearBelectricalwearCcopperringfallingoffDmechanicalwear正確答案：BD第11題Lowvoltageswitchescanbeusedtodirectlycontrolthestart,stopandreversemotorofanycapacity.第12題Thebuttonswitchcanbeusedasalow-voltageswitch,tocompletethemaincircuitthroughmanualoperation.第13題Themainorderapplianceisthecontrolappliancethatsendsoutinstructionsorsignalsintheautomaticcontrolsystem.Becauseitisspeciallyordered,soitiscalledthemainorderofelectricalappliances.第14題Inadditiontotheon-offcircuit,thecontactoralsohastheshortcircuitandoverloadprotectionfunction.第15題ToohighortoolowvoltageoftheACcontactorwillcausethecoiloverheating.第16題Theinputsignaloftheintermediaterelayisthepoweronandpoweroffofthecoil.第17題Theknifeswitchcanbeusedinterchangeablyaslongasthevoltageisthesame.第18題Fusesareusedasshort-circuitprotectionandover-currentprotection.第19題Theactionvoltageofundervoltagerelayandzerovoltagerelayisthesame.第20題Allknifeswitcheshaveshort-circuitprotectiondevices.Chapter6Testing第1題ForcontactorKM1,contactorKM2requires（）AstringthenormallyopencontactsofKM2inthecoilloopofKM1BstringthenormallyclosedcontactsofKM2inthecoilloopofKM1CstringintotheconstantopencontactofKM1inthecoilloopofKM2DstringthenormallyclosedcontactsofKM1inthecoilloopofKM2第2題Thethree-phasecagemotoradoptsstar-trianglestep-downstarting,anduses()connectionmotorinnormaloperation.AdeltaBstarCbothDneitherisgood第3題Inthestar-triangularpressurereductioncircuit,thestarconnectionstartingvoltageisthetriangularconnectionvoltage(

)A1/3B1/2C1/4D1/6第4題Thetwocontactorsintheforwardandreverseoperationofthemotormustrealizeeachother(

)AmemoryBauto-lockCprohibitDinterlocking第5題ChangetherunningdirectionoftheACmotorandtakethewaytoadjustthepowersupply（

）AstatorstringresistanceBadjustthephaseorderofthethreephasesCadjustthephaseorderofthetwophasesDtherotorstringresistance第6題Thecommonelectricalbrakingmethodsofthree-phaseasynchronousmotorare()AseriesbrakingBdynamicbrakingCplugbrakingDantihypertensivebrake正確答案：BC第7題The()existsintheunidirectionalrotationstartcontrolcircuitoftheDCmotor.