泄漏电流(英文演示稿).ppt

HazardBasedSafetyEngineering-Touch(Leakage)Current,2,OverallSessionObjectives:1.TounderstandtherationalefortheTouch(leakage)CurrentTest,instrumentation,connections,testproceduresandlimits2.Tounderstandlimitationsoftestandalternativeapproaches,Touch(Leakage)Current,3,Touch(Leakage)CurrentTopicsDefinitions(UL101,IEC60990)TouchcurrentpathsPhysiologicaleffectsoftouchcurrent(electricshock)Bodyimpedancemodelsand“safe”voltagelimitsTouch(Leakage)CurrentTest,Touchcurrentinstruments(meters)MeasurementcircuitsandproceduresLimits,4,DEFINITIONSLEAKAGECURRENT(UL101-2002):Electriccurrentwhichflowsthroughapersonuponcontact,betweenaccessiblepartsofanapplianceand(1)ground,or(2)otheraccessiblepartsoftheapplianceTOUCHCURRENT(IEC60990):Electriccurrentthroughahumanbodyorananimalbodywhenittouchesoneormoreaccessiblepartsofaninstallationorofequipment.,5,Touch(Leakage)CurrentPaths,Accessiblemetal,Load,Load,ElectricalinsulationSystem,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,?,Touchcurrent,ReturnPath,6,TouchCurrentPaths,Load,Load,Example:Ungrounded2wireCordandPlug-ConnectedAppliances,touchablemetal,ElectricalInsulationSystem,ToElectricalSupply,7,Canopener,Toasteroven,TV,radio,Coffeemaker,iron,blender,Examplesof2-wireNon-GroundedAppliances,8,TouchCurrentPaths,Touchablemetal,Load,Load,Ungrounded2wireappliance,TouchableMetalofGroundedAppliances,ElectricalinsulationSystem,EquipmentGroundingConductor(protectiveearthingconductor),G,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,ReturnPaths-1,9,dishwasher,range,microwave,refrigerator,Examplesof3-wireGroundedAppliances,Canopener,Toasteroven,TV,radio,Coffeemaker,iron,blender,Examplesof2-wireNon-GroundedAppliances,10,ConstructionGrounds,MetallicPipingSystem,Bondingconnectiontowaterpipe,Touchablemetal,Load,Load,Ungrounded2wireappliance,ElectricalinsulationSystem,G,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,ReturnPaths-2,TouchCurrentPaths,11,Sink,ExamplesofConstructionGrounds,Baseboardheating,Examplesof3-wireGroundedAppliances,Examplesof2-wireNon-GroundedAppliances,dishwasher,range,microwave,refrigerator,Canopener,Toasteroven,TV,radio,Coffeemaker,iron,blender,12,TouchCurrentPaths,Ungrounded2wireappliance,Load,Load,Pathwaythroughearth,Touchablemetal,ElectricalinsulationSystem,Soil,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,ReturnPaths-3,13,TouchCurrentPaths,Touchablemetal,Load,Load,ElectricalinsulationSystem,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,Example:Three-WireGroundedCordandPlugConnectedproduct,14,TouchCurrentPaths,15,2-wirereceptacle(normal-oldconstruction),OR,ConnectiontoUngroundedReceptacle,Touchablemetal,Load,ElectricalinsulationSystem,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,Example:Three-WireGroundedCordandPlugConnectedproduct,Opencircuitorhighimpedance(fault),16,TouchCurrentPaths-4,touchablemetal,Load,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,TouchCurrentFromSimultaneouslyTouchablePartsofsameproduct,17,Touch(Leakage)CurrentTopicsDefinitions(UL101,IEC60990)TouchcurrentpathsPhysiologicaleffectsoftouchcurrent(electricshock),18,PhysiologicalEffectsofTouchCurrent(sinusoidal,rms,60Hz),Perception(microamperesto0.5mA),Startlereaction(0.5mA),Muscletetanization(inabilitytoletgo)(5mA),Ventricularfibrillation(50mA),Electricalburns(70mA),V10-001,19,0.5,1,5,10,10,20,35,VentricularFibrillation,Let-Go,I=0.954f,0.716,f70Hz,IECThresholdULLimit,EffectsofFrequencyonElectricShockThresholdsandLimitsforContinuousACcurrent,BodyCurrent(rmsmA),Frequency(Hz),2,1.threshold/limit=2mAat0Hz(dc),(seenote3),3.respiratoryarrestobservedindogsat20,30,and40mA,20,CurrentDensity,Duration*,Pathwaythroughbody,V10-015,(skincontactlocation),OtherTouchCurrentVariables,*SeeSpecialSituationsforTouchCurrentMeasurements,Waveshape*,21,Touch(Leakage)CurrentTopicsDefinitions(UL101,IEC60990)TouchcurrentpathsPhysiologicaleffectsoftouchcurrent(electricshock)Bodyimpedancemodelsand“safe”voltagelimits,22,+,_,=sourceopencircuitvoltage,=sourceimpedance,(,=,f,.),+,=,DeterminingTouchCurrent,VoltageSource,23,C,2,FiveComponentBodyImpedanceModel,Impedancerepresentingoneskin-electrodecontact,Internalbodyimpedance(lesstheskin),Impedancerepresentingotherskin-electrodecontact,24,EffectofCurrentPathwayonInternalBodyImpedance,Whatistheinternalbodyimpedance:Handtohand?_ohmsOnehandtobothfeet?_ohmsBothhandstobothfeet?_ohms,CLASSEXERCISE:,25,SimplifiedBodyImpedanceModels,3-componentmodelfordry-moistcontactandlowtouchvoltage,Conservativemodelforlowskinimpedance(e.g.,wetcontact,highvoltages,and/orhighfrequency),0.22Microfarad,1500ohms,500ohms,500ohms,Combinationtwolargeareaskincontacts,Internalbodyimpedance,26,E=IxZ,FrequencyinHertz,10,10,10,100,100,100,1000,1000,1000,10,000,10,000,10,000,BodyCurrentThresholdforLet-Go,AppliedVoltageThresholdForLet-Go,BodyImpedance,Z,I,CombinedEffectsofFrequencyonBodyImpedanceandElectricShockThresholds,FrequencyinHertz,FrequencyinHertz,27,ExamplesofSafeVoltageCriteria(Checkthespecificend-productstandard),15VACrms(100Hz)30VDC,30VACrms(100Hz)60VDC,42.4Vpeak(100Hz)(includingdc),42.4Vpeak(100Hz)60VDC,71Vpeak(0.2sec,singlefaultconditionsfortime0.2sec,Let-goandfibrillation,drylocations(UL,NEC),Let-goandfibrillation,wetlocations,notincludingimmersion(UL,NEC),28,ElectricalInsulation:BasicEquipmentSafeguardAgainstElectricShock,+,_,Vs,Zs,ZB,ZI,IT,Hazardousvoltageandcurrentsource:,VSexceeds“safe”voltageAND,IS=VS/Zsexceeds“safe”availablecurrent,IS,IS=availablesourcecurrent,29,Electricalinsulationmodel,InsulationResistanceTest,Touch(Leakage)CurrentTest,DielectricWithstandTest(Hi-pot),BasicTestsonElectricalInsulation,30,Touch(Leakage)CurrentTopicsDefinitions(UL101,IEC60990)TouchcurrentpathsPhysiologicaleffectsoftouchcurrent(electricshock)Bodyimpedancemodelsand“safe”voltagelimitsTouch(Leakage)CurrentTest,Touchcurrentinstruments(meters),31,Touch(Leakage)CurrentTest,Accessiblemetal,Load,Load,ElectricalinsulationSystem,L,N,G,+,_,UngroundedConductor,GroundedConductor,Grounding(protectiveearthing)Conductor,applieswhensourceexceeds“safe”voltagelevels,representbodyimpedanceasfunctionoffrequency,representphysiologicaleffectasafunctionoffrequency,32,SelectionofMeasurementInstrument,InstrumentSpecifications,ANSIC101-1986-AverageRespondingSystem(ARS)(StillspecifiedinmostULstandards),UL101-2002(ReplacedANSIC101)(SpecifiedinsomeULendproductstandardsandmostharmonizedULstandards),IEC60990-1999,SPECIFICATIONSFORREACTION:,SPECIFICATIONSFORLET-GO:,IEC609901999,SPECIFICATIONSFORELECTRICALBURNS:,IEC60990-1999,UL101-2002,(0.5mArmslimit60Hz),(3.5mArms,5mArmslimits60Hz),(70mArms),33,Ammeter(averageresponding),MeasurementInstrumentSpecificationsforReaction,(ANSIC101-1986),(a)Inputimpedance(Z),(b)Metertypeandlocation,(intendedtocombineeffectoffrequencyonbodyimpedanceandphysiologicalresponse),AverageRespondingSystem(ARS),34,Voltmeter(averageresponding),(d)Circuitfrequencyresponse(0to100kHz),IA,IA=actualcurrenttonetwork,I1=indicatedcurrenttonetwork(=V1/R1rmsforsinusoid),Z=R1parC1,(0-100kHz),Indication(current)=1.11xVM(ave)/1500,I1,=I1=V1/R1(rmsforsinusoid),(c)Meterindication,Max5%errorindicationof0.75mA,MeasurementInstrumentSpecificationsforReaction,(ANSIC101-1986),(a)Inputimpedance(Z),(b)Metertypeandlocation,(combineseffectoffrequencyonbodyimpedanceandphysiologicalresponse),AverageRespondingSystem(ARS),35,SimpsonModel229(ANSIC101-1986),36,R1,C1,Revisedbodyimpedancemodel,Voltmeter,0.22,0.022,u,F,R3,C2,Frequencysensitivenetworkforreaction,(a)Inputimpedance(UL101):,RevisedMeasurementInstrumentforReaction,UL101-1992,IEC60990-1999,Z=V1/I1(20Hz-1MHz),Rmsreading(UL101),Peakreading(IEC60990),(b)Transferimpedance(UL101):,Z=V3/I1,(c)Meterindication(IIndicated):,=V3/R2=V3/500,(weightedmA-IEC60990;MIU-ANSIC101),(d)InputvoltagepermAindication(IEC60990):,V1/IIndicated(mA),37,Frequencysensitivenetworkforreaction,R3,R1,C1,Bodyimpedancemodel,0.22,uF,IEC60990-1999,MeasurementInstrumentforLet-Go,FrequencysensitivenetworkforLet-Go,M,0.0062,0.0091,uF,R4,C2,C3,V3,V1,Voltmeter,Peakreading(IEC60990),(a)Outputvoltagetoinputvoltageratio:,V3/V1(20Hz-1MHz),(c)Inputvoltagepermilliampereindication:,(b)Meterindication(scale):,IIndicated=V3(peak)/500,WeightedmA,V1/Iindicated(mA),38,39,Touch(Leakage)CurrentTopicsDefinitions(UL101,IEC60990)TouchcurrentpathsPhysiologicaleffectsoftouchcurrent(electricshock)Bodyimpedancemodelsand“safe”voltagelimitsTouch(Leakage)CurrentTest,Touchcurrentinstruments(meters)Measurementcircuitsandprocedures,40,MeasurementInstrument,EUT(EquipmentUnderTest),Powerconnections,Touch(Leakage)CurrentTestMeasurementCircuitComponents,Powersupply,Switchingnetwork,MeasurementEquipmentConnections,41,120V,GNDOPEN,A,A,B,B,S2,S1,2-pole,2-wire,ApplicableEUTPlugConfigurations,2-pole,3-wire,PowerSupply,L,N,Polarityreversingswitch,Groundedconductorswitch,Connectiontogroundedsupplyconductor,MeasurementCircuitfor120VoltEquipment,UL101,SwitchingNetwork,42,120V,A,A,B,B,S2,S1,2-pole,2-wire,ApplicableEUTPlugConfigurations,2-pole,3-wire,S3,Optionaltransformer,1%linevoltage,For3-wireapplications,120Vsupply,L,N,G,IEC60990,MeasurementCircuitfor120VoltEquipment,43,GNDOPEN,A,A,B,B,S2,PowerSupply,Polarityreversingswitch,LineSwitch,Connectiontogroundedsupplyconductor,Measurementcircuitfor2-pole208or230-240Voltequipmentsuitableforuseon230-240volttogroundcircuit,ApplicableU.S.EUTPlugConfigurations,2-pole,2-wire,2-pole,3-wire,(U.S.Commercial/Industrial)(European230/400vresidential),44,S1,GNDOPEN,A,A,B,B,S2,Measurementcircuitfor2-pole208and240voltequipmentforconnectiononlyto120voltstogroundcircuits(120/208,120/240),ApplicableU.S.EUTPlugConfigurations,15amp,20amp,20amp,G,15amp,G,2-pole,2-wire,208or240V,120V,120V,2-pole,3-wire,EQUIPMENTUNDERTEST(EUT),Load,L,L,N,Polarityreversingswitch,LineSwitch,Connectiontogroundedsupplyconductor,INSULATINGTABLE,PowerSupply,MEASUREMENTINSTRUMENT,(U.S.Residential),45,EQUIPMENTUNDERTEST(EUT),Load,A,A,B,B,S2,20amp,N,15amp,N,G,N,G,20amp,3-pole,3-wire,3-pole,4-wire,Measurementcircuitforsinglephase,3-pole,208or240VoltEquipment,ApplicableU.S.EUTPlugConfigur