局部放电老化机理

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1、Reviewoflecture4TheBasicParametersTheIntegratedQuantitiesTheInceptionandDistinctionVoltagesWaveformCharacteristicsofDischargesContents:BasicParameters1IntegratedQuantitiesuiandueReviewoflecture4Foroil-impregnatedpaper,ui>ue2Estimationofuiforseveraltypicalinternaldischar

2、ges:Reviewoflecture4adielectricwithaflatcavityadielectricwithasphericalcavitytheflatcavityinacylindrical3Reviewoflecture4WaveformCharacteristicsofDischargesSurfacedischargeCoronadischargeInternaldischarge4Lecture5DielectricDeteriorationandPDEvaluation5Contents1.Mechanis

3、msofDielectricAgingbyPD2.ProcessofDielectricAgingbyPD3.TheInfluenceFactorsonAgingRate4.PDEvaluationApproaches局部放电老化机理局部放电老化过程影响老化的因素局部放电评估方法61.MechanismsofDielectricAgingbyPDElectricalagingisatypeofdielectricdeteriorationunderthelong-termelectricalfieldandduetothefactof

4、partialdischarges.电老化：在电场长期作用之下因局部放电而造成的绝缘性能劣化。(1)Bombardmentofchargedparticle带电质点轰击(2)ThermalEffect热效应(3)ResultantofReaction反应生成物(4)RadiationEffect辐射效应(5)MechanicalEffect机械效应Brokethechemicalbondanddamagemolecularstructureofinsulationmaterial.Hightemperatureofdischargep

5、ointacceleratesthermaldamagetomaterialsresultants,suchasozone,moisture,nitricacid,oxalicacid,erodematerials.visiblelight,ultravioletradiation,X-radial,γ-radialembrittlematerials.Successiveblastingdischargesresultinhighgaspressureandcrackthematerials72.ProcessofDielectri

6、cAgingbyPD2.1Damageofinternaldischargetopolymer内部放电对聚合物的破坏(1)SurfaceErosionAuniformsurfaceerosion,whichmaybecausedbybombardmentofparticle,thermaldegradation,radiationandtrappedelectronsbelowsurface,etc.Deeppitsareformedandcarbonized.Dischargesbecomeconcentrated,somedeep

7、pitsareformed,thedischargesfurtherconcentrateandsometimescarbonizationofthepitsoccurs.在放电的各种效应作用下，逐步腐蚀气隙表面InnitrogengasInair放电集中的地方，形成一些深坑；放电进一步集中，并造成一些深坑碳化表面腐蚀82.ProcessofDielectricAgingbyPD(2)Propagationofelectricaltree树枝放电的发展Thedielectricbreaksdownoveradistanceofsome

8、microns.Thestressatthetopofthepitapproachesthebreakdownstrengthoveradistanceofsomemicronsowingtothefieldconcen