ASTM-D257-2007-绝缘材料直流电阻或电导试验方法

Designation:D257–07AnAmericanNationalStandardStandardTestMethodsforDCResistanceorConductanceofInsulatingMaterials1ThisstandardisissuedunderthefixeddesignationD257;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope*1.1Thesetestmethodscoverdirect-currentproceduresforthemeasurementofdcinsulationresistance,volumeresistance,andsurfaceresistance.Fromsuchmeasurementsandthegeometricdimensionsofspecimenandelectrodes,bothvol-umeandsurfaceresistivityofelectricalinsulatingmaterialscanbecalculated,aswellasthecorrespondingconductancesandconductivities.1.2Thesetestmethodsarenotsuitableforuseinmeasuringtheelectricalresistance/conductanceofmoderatelyconductivematerials.UseTestMethodD4496toevaluatesuchmaterials.1.3Thisstandarddescribesseveralgeneralalternativemethodologiesformeasuringresistance(orconductance).SpecificmaterialscanbetestedmostappropriatelybyusingstandardASTMtestmethodsapplicabletothespecificmaterialthatdefinebothvoltagestresslimitsandfiniteelectrificationtimesaswellasspecimenconfigurationandelectrodegeom-etry.Theseindividualspecifictestmethodologieswouldbebetterabletodefinetheprecisionandbiasforthedetermina-tion.1.4Theproceduresappearinthefollowingsections:TestMethodorProcedureSectionCalculation13ChoiceofApparatusandTestMethod7CleaningSolidSpecimens10.1ConditioningofSpecimens11EffectiveAreaofGuardedElectrodeAppendixX2ElectrodeSystems6FactorsAffectingInsulationResistanceorConductanceMeasurementsAppendixX1HumidityControl11.2LiquidSpecimensandCells9.4PrecisionandBias15ProcedurefortheMeasurementofResist-anceorConductance12ReferencedDocuments2Report14Sampling8SignificanceandUse5SpecimenMounting10SummaryofTestMethods4Terminology3TestSpecimensforInsulation,Volume,andSurfaceResistanceorConductanceDetermination9TypicalMeasurementMethodsAppendixX31.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D150TestMethodsforACLossCharacteristicsandPer-mittivity(DielectricConstant)ofSolidElectricalInsula-tionD374TestMethodsforThicknessofSolidElectricalInsu-lationD1169TestMethodforSpecificResistance(Resistivity)ofElectricalInsulatingLiquidsD1711TerminologyRelatingtoElectricalInsulationD4496TestMethodforD-CResistanceorConductanceofModeratelyConductiveMaterialsD5032PracticeforMaintainingConstantRelativeHumid-itybyMeansofAqueousGlycerinSolutionsD6054PracticeforConditioningElectricalInsulatingMa-terialsforTestingE104PracticeforMaintainingConstantRelativeHumiditybyMeansofAqueousSolutions3.Terminology3.1Definitions—ThefollowingdefinitionsaretakenfromTerminologyD1711andapplytothetermsusedinthetextofthisstandard.3.1.1conductance,insulation,n—theratioofthetotalvolumeandsurfacecurrentbetweentwoelectrodes(onorinaspecimen)tothedcvoltageappliedtothetwoelectrodes.3.1.1.1Discussion—Insulationconductanceistherecipro-calofinsulationresistance.1ThesetestmethodsareunderthejurisdictionofASTMCommitteeD09onElectricalandElectronicInsulatingMaterialsandarethedirectresponsibilityofSubcommitteeD09.12onElectricalTests.CurrenteditionapprovedMay15,2007.PublishedJune2007.Originallyapprovedin1925.Lastpreviouseditionapprovedin2005asD257–99(2005).2ForreferencedASTMstandards,visittheASTMwebsite,@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.1*ASummaryofChangessectionappearsattheendofthisstandard.Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.CopyrightbyASTMInt'l(allrightsreserved);MonApr701:06:31EDT2008Downloaded/printedbyDalianUnivofTechnologypursuanttoLicenseAgreement.Nofurtherreproductionsauthorized.—theratioofthecurrentbetweentwoelectrodes(onthesurfaceofaspecimen)tothedcvoltageappliedtotheelectrodes.3.1.2.1Discussion—(Somevolumeconductanceisun-avoidablyincludedintheactualmeasurement.)Surfacecon-ductanceisthereciprocalofsurfaceresistance.3.1.3conductance,volume,n—theratioofthecurrentinthevolumeofaspecimenbetweentwoelectrodes(onorinthespecimen)tothedcvoltageappliedtothetwoelectrodes.3.1.3.1Discussion—Volumeconductanceisthereciprocalofvolumeresistance.3.1.4conductivity,surface,n—thesurfaceconductancemultipliedbythatratioofspecimensurfacedimensions(dis-tancebetweenelectrodesdividedbythewidthofelectrodesdefiningthecurrentpath)whichtransformsthemeasuredconductancetothatobtainediftheelectrodeshadformedtheoppositesidesofasquare.3.1.4.1Discussion—Surfaceconductivityisexpressedinsiemens.Itispopularlyexpressedassiemens/square(thesizeofthesquareisimmaterial).Surfaceconductivityisthe