Designation:D2304−18StandardTestMethodforThermalEnduranceofRigidElectricalInsulatingMaterials1ThisstandardisissuedunderthefixeddesignationD2304;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethod2providesproceduresforevaluatingthethermalenduranceofrigidelectricalinsulatingmaterials.Dielectricstrength,flexuralstrength,orwaterabsorptionaredeterminedatroomtemperatureafteragingforincreasingperiodsoftimeinairatselected-elevatedtemperatures.Athermal-endurancegraphisplottedusingaselectedendpointateachagingtemperature.Ameansisdescribedfordetermin-ingatemperatureindexbyextrapolationofthethermalendurancegraphtoaselectedtime.1.2Thistestmethodismostapplicabletorigidelectricalinsulationsuchassupports,spacers,voltagebarriers,coilforms,terminalboards,circuitboardsandenclosuresformanytypesofapplicationwhereretentionoftheselectedpropertyafterheatagingisimportant.1.3Whendielectricstrengthisusedastheagingcriterion,itisalsoacceptabletousethistestmethodforsomethinsheet(flexible)materials,whichbecomerigidwiththermalaging,butisnotintendedtoreplaceTestMethodD1830forthosematerialswhichmustretainadegreeofflexibilityinuse.1.4Thistestmethodisnotapplicabletoceramics,glass,orsimilarinorganicmaterials.1.5Thevaluesstatedinmetricunitsaretoberegardedasstandard.Otherunits(inparentheses)areprovidedforinfor-mation.1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.Aspecificwarningstatementisgivenin11.3.4.1.7Thisinternationalstandardwasdevelopedinaccor-dancewithinternationallyrecognizedprinciplesonstandard-izationestablishedintheDecisiononPrinciplesfortheDevelopmentofInt...
