关于爬电距离和空气间隙的标准

,Clause29Clearances,Creepagedistancesandsolidinsulation爬电距离、电气间隙和绝缘穿通距离(Table1),Minimumclearance(Table2),Howtofindtheminimumclearance,HouseholdapplianceareinovervoltagecategoryIISelecttheratedvoltageUsingthetable1tofindouttheratedimpulsevoltageAccordingtotable2,theminimumclearancecouldbefoundbyratedimpulsevoltage,Theclearancesoffourinsulationtypes:BasicinsulationSupplementaryinsulationReinforcedinsulationFunctionalinsulation,Theclearanceofbasicinsulation,Example1:WaterkettleRating:220240V50Hz25003000W,220240V,UsingcategoryII,Theratedimpulsevoltagewas2500V,29.1.1clearancesofbasicinsulation,Theminimumclearancesofbasicinsulationwas1.5mm,Specialcomponentsforbasicinsulation,Theterminalsoftubularsheathedheatingelementscounted1mm,ifthemicroenvironmentispollutiondegree1.,1mm,Tubularsheathedheatingelement,Pollutiondegree1,29.1.2clearanceofsupplementinsulation,Theminimumclearanceissameasthebasicinsulation,Thedistancebetweenenclosureandinternalwire,29.1.3clearanceofreinforcedinsulation,Thereinforcedinsulationusingthenextstepforratedimpulsevoltage.,Betweenterminalandplasticenclosure,29.1.4clearanceoffunctionalinsulation,Betweenterminals,Thefunctionalinsulationisbetweenlivepartsofdifferentpotential,PTCHeatingelement,Hairstraighter,PTCheater,Hairstraighterassembly,DifferenttypesofPTCHeatingelements,InternalconstructionofPTCheatingelement,TheclearancebetweensurfacesofPTCheatingelementsmaybereducedto1mm,Theclearance=1mm,Kaptonfilm,PTCheatingplate,Electrodeplate,29.2creepagedistances,Step1(Tofindoutthepollutiondegree)Pollutiondegree2appliesunlessPrecautionshavebeentakentoprotecttheinsulation,inwhichcasepollution1appliesTheinsulationissubjectedtoconductivepollution,inwhichcasepollutiondegree3appliesNote:Thepollutiondegreeshouldneedrefertopart2.,Pollutiondegreeclassification,Trackingindex(CTI)valuesMaterialgroupI:600=CTIMaterialgroupII:400=CTIMaterialgroupIIIa:175=CTI400MaterialgroupIIIb:100=CTI125and=250,Thecreepageofbasicinsulation,Minimumcreepagedistancesforfunctionalinsulation,SummaryofMinimumcreepagedistances,29.2.1creepageforbasicinsulationLacqueredconductorsofwindings,1.5mm,Creepagedistanceofwindingneednotbegreaterthantheassociatedclearancespecifiedintable16,Clause29.2.2,Asperclause29.2.2,thecreepagedistanceofsupplementaryinsulationshallnotlessthanand2.5mm.Theinternalwireofmicro-switchwasnotsecurelyfixedthatitwaspossibletobetouchedbytestfingerwith2Nforce.Thecreepagedistanceweremeasuredas0mm,Internalwireshallbeaccess,Clause29.2.3,Thecreepagedistancesofreinforcedinsulationshallnotlessthan8mm.Asresult,thecreepagedistancewasmeasured7.5mmbetweenleadsofneonlampandthelampcoverjoint.,Leadsofneonlamp,Lens,Enclosure,Leonlampleads,2mm,3mm,2.5m,Thecreepagedistances=2.5+2+3=7.5mm,29.2.4creepagedistancesoffunctionalinsulation,1.5mm,Clause29.2.4,PCBTrack,AB,BA,BA,29.2.4creepagedistanceforfunctioninsulation,Creepagedistancesmaybereducediftheappliancecomplieswithclause19withthefunctionalinsulationshort-circuited.Forexample:Electroniccomponent,Electroniccomponent,Thetransistorleadslimitationofcreepagedistance,LivePart,Supplementaryinsulation(1mm),Basicinsulation,29.3.1Materialthicknessrequirementforsupplementaryinsulation(1),SupplementaryInsulation,LivePart,Reinforcedinsulation(2mm),29.3.1Materialthicknessrequirementforreinforcedinsulation(1),ReinforcedInsulation,LivePart,1stlayerinsulation,2ndlayerinsulation,Eachofthelayersshouldwithstandstheelectricstrengthtestforsupplementaryinsulation,29.3.2Materialrequirementforsupplementaryinsulation(2),Basicinsulation,29.3.2Materialrequirementforreinforcedinsulation(2),LivePart,1stlayerinsulation,2ndlayerinsulation,3rdlayerinsulation,Anytwolayerstogethershouldwithstandstheelectricstrengthtestforreinforcedinsulation,=1mm,Case2,Clearance,Creepagedistance,1mm,Case3,C