Designation:D3284−05(Reapproved2011)StandardPracticeforCombustibleGasesintheGasSpaceofElectricalApparatusUsingPortableMeters1ThisstandardisissuedunderthefixeddesignationD3284;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisfieldpracticecoversthedetectionandestimationofcombustiblegasesinthegasblanketabovetheoiloringasdetectorrelaysintransformersusingportableinstruments.Itisapplicableonlywithtransformersusingmineraloilasthedielectricfluid.Gasesdissolvedintheoilandnoncombustiblegasesarenotdetermined.Amethodofcalibratingtheinstru-mentswithaknowngasmixtureisincluded.1.2Thispracticeaffordsasemi-quantitativeestimateofthetotalcombustiblegasespresentinagasmixture.Ifamoreaccuratedeterminationofthetotalamountofcombustiblegasesoraquantitativedeterminationoftheindividualcompo-nentsisdesired,usealaboratoryanalyticalmethod,suchasTestMethodD3612.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.Specificprecau-tionarystatementsaregiveninSection7.2.ReferencedDocuments2.1ASTMStandards:2D3612TestMethodforAnalysisofGasesDissolvedinElectricalInsulatingOilbyGasChromatography2.2IEEEStandard:3C57.104GuidefortheInterpretationofGasesGeneratedinOil-ImmersedTransformers3.SummaryofPractice3.1Asampleofgasisdilutedtoafixedratiowithairandintroducedintothemeteratapressureofapproximatelyoneatmosphere.AnycombustiblegasespresentarecatalyticallyoxidizedonthesurfaceofasensorwhichisanelementofaWheatstonebridge.Whencombustiblegasesoxidizeonthesurface,theyincreasethetemperatureoftheelement,whichchangesitsresistanceandupsetsthebalanceofthebridge.3.2Thechangeintheresistanceoftheindicatingelementsin...
