关于爬电距离和空气间隙的标准.ppt

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 220 240V50Hz2500 3000W 220 240V 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 CTI 400MaterialgroupIIIb 100 CTI 175 Step2 Tofindoutthematerialgroup Trackingindextester Trackingindex CTI values Minimumcreepagedistancesforbasicinsulation Thecreepageofbasicinsulation Example1 WaterkettleRating 220 240V50Hz2500 3000W Pollutiondegree3 refertostandard60335 2 15 Themicroenvironmentispollutiondegree3iftheinsulationcanbepollutedbycondensationfromsteamproducedduringnormaluseofappliance AssumethematerialgroupisIII thetightengrade Workingvoltageisbetween 125and 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 Thetransistorleads limitationofcreepagedistance 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 Case1 Clearance Creepagedistance 1mm Case2 Clearance Creepagedi