Designation:D149−20StandardTestMethodforDielectricBreakdownVoltageandDielectricStrengthofSolidElectricalInsulatingMaterialsatCommercialPowerFrequencies1ThisstandardisissuedunderthefixeddesignationD149;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thistestmethodcoversproceduresforthedetermina-tionofdielectricstrengthofsolidinsulatingmaterialsatcommercialpowerfrequencies,underspecifiedconditions.2,31.2Unlessotherwisespecified,thetestsshallbemadeat60Hz.However,thistestmethodissuitableforuseatanyfrequencyfrom25to800Hz.Atfrequenciesabove800Hz,dielectricheatingisapotentialproblem.1.3ThistestmethodisintendedtobeusedinconjunctionwithanyASTMstandardorotherdocumentthatreferstothistestmethod.Referencestothisdocumentneedtospecifytheparticularoptionstobeused(see5.5).1.4Itissuitableforuseatvarioustemperatures,andinanysuitablegaseousorliquidsurroundingmedium.1.5Thistestmethodisnotintendedformeasuringthedielectricstrengthofmaterialsthatarefluidunderthecondi-tionsoftest.1.6Thistestmethodisnotintendedforuseindeterminingintrinsicdielectricstrength,direct-voltagedielectricstrength,orthermalfailureunderelectricalstress(seeTestMethodD3151).1.7Thistestmethodismostcommonlyusedtodeterminethedielectricbreakdownvoltagethroughthethicknessofatestspecimen(puncture).Itisalsosuitableforusetodeterminedielectricbreakdownvoltagealongtheinterfacebetweenasolidspecimenandagaseousorliquidsurroundingmedium(flashover).WiththeadditionofinstructionsmodifyingSec-tion12,thistestmethodisalsosuitableforuseforprooftesting.1.8ThistestmethodissimilartoIECPublication243-1.AllproceduresinthismethodareincludedinIEC243-1.Differ-encesbetweenthismethodandIEC243-1arelargelyeditorial.1.9Thisstandarddoesnotpurporttoaddressallofthes...
