Designation:D2900–90(Reapproved1997)e1AnAmericanNationalStandardStandardTestMethodforAcceleratedLifeTestofElectricalGradeMagnesiumOxideasUsedinSheathed-TypeElectricHeatingElements1ThisstandardisissuedunderthefixeddesignationD2900;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.e1NOTE—Section13wasaddededitoriallyinOctober1997.1.Scope1.1Thistestmethodcoverstheacceleratedlifetestingofelectricalgrademagnesiumoxide(MgO)underconditionsinvolvingthermalcyclingtoanelevatedtemperature.Thetestdeterminesboththerateatwhichelectricalinsulationimped-ance(Note1)ortestcurrentthroughtheinsulationchangeswithtimeandthetimespanresultingincompletefailureofatestcellincorporatingthesampleundertest.NOTE1—Attesttemperatures,capacitiveandinductivereactancearenegligible,andthereforeimpedancevaluesareconsideredessentiallyresistive.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.Forspecificsafetyprecaution,see9.4.1.1.3Thevaluesstatedinacceptablemetricunitsaretoberegardedasthestandard.2.ReferencedDocuments2.1ASTMStandards:B344SpecificationforDrawnorRolledNickel-ChromiumandNickel-Chromium-IronAlloysforElectricalHeatingElements2D2755TestMethodofSamplingandReductiontoTestWeightofElectricalGradeMagnesiumOxide33.SummaryofTestMethod3.1Thespecimenofmagnesiumoxideisloadedintoatestcell,whichisformedintoanoperativeheaterofspecificconstruction.Thetestcellisthermallycycledbyinternalheatingunderconditionsdesignedtoacceleratedeteriorationandpromotefailureinaperiodofseveralmonths.Electricalresistanceoftheinsulationismeasuredperiodically.Thetotallengthoftimethetestcelloperatesbeforefailureoccursisrecordedasitsli...
