变压器绝缘故障(国外英文资料)Word文档格式.docx

变压器绝缘故障(国外英文资料)Word文档格式.docx

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servicelifeofthetransformerandthekeytoimprovethereliabilityofpowersupply.

Oilimmersedtransformer,themaininsulationmaterialisagingofinsulatingoilandsolidinsulationpaper,cardboardandwoodandotherso-calledCtransformerinsulation,thematerialisaffectedbyenvironmentalfactorsdecomposition,reduceorlossofinsulationstrength.

1.solidpaperinsulationfailure

Thesolidinsulationpaperisoneofthemainparts,including:

oilimmersedtransformerinsulationinsulationpaper,insulationboard,insulation,insulation,insulationpadrollbanding,itsmaincomponentiscellulose,chemicalexpression（C6H10O6）n,wherenisthedegreeofpolymerization.Ingeneral,thepolymerizationdegreeofnewpaperisabout1300.Whenitdropstoabout250,themechanicalstrengthhasdecreasedbymorethanhalf,andthedegreeofpolymerizationcausedbyextremeAgingleadstotheterminationoflifeof150~200.Whentheinsulationpaperisaging,thepolymerizationdegreeandtensilestrengthwillgraduallydecrease,andwater,COandCO2willbeproduced.Secondly,furfural（furanformaldehyde）willbeproduced.Mostoftheseagingproductsareharmfultoelectricalequipment,whichwillcausebreakdownvoltageandvolumeresistivityofinsulatingpapertodecrease,dielectriclossincrease,tensilestrengthdecrease,andcorrosionofmetalmaterialsinequipmentisveryserious.Solidinsulationhasirreversibleagingproperties,andits

mechanicalandelectricalstrengthcannotbereducedbyaging.Thelifeofthetransformermainlydependsonthelifeofinsulatingmaterials,sothesolidoilimmersedtransformerinsulationmaterials,shouldnotonlyhavegoodpropertiesandmechanicalpropertiesofelectricalinsulation,andtheperformanceoftheMonthsandyearspassby.aftertheoperation,decreasedslowly,namelytheagingcharacteristics.

（1）propertiesofpaperfibermaterials.Theinsulatingpaperfibermaterialisthemaincomponentofinsulationmaterialofoilimmersedtransformer,thepaperfiberisbasicsolidtissueplantcomponents,withthepositivelychargednucleusandaroundthenucleusofanatomofnegativelychargedelectronscomposedofmoleculesatoms,anddifferentmetalconductorinsulationmaterialisalmostnofreeelectrons,conductancethecurrentinsulatormainlyfromminimalionicconductivity.Celluloseconsistingofcarbon,hydrogenandoxygen,suchashydroxylcelluloseduetothepresenceofthemolecularstructure,ithasthepotentialtoformwater,sothatthepaperfibercharacteristicsofwater.Inaddition,thesehydroxylcanbeconsideredtobeavarietyofpolarmolecules（suchasacidandwater）surroundedbythecenter,theythroughhydrogenbonding,destructionofthefiberandfiber:

oftencontainacertainproportion（about7%）oftheimpurities,includingacertainamountofwaterfortheseimpurities,colloidalfibernaturemakesthesewatercannotbecompletelyremoved.Thiswillalsoaffecttheperformanceofpaperfibers.

Thepolarityofthefiberisnotonlyeasytoabsorbmoisture（moisturetostrongpolarmedium）,andwhenthepaperfibersabsorbingwater,theinteractionbetweenhydroxylweak,badsharplyinthemechanicalstrengthoffiberstructureunstableconditions,therefore,

Paperinsulationpartsgenerallyafterdryingorvacuumdrynessprocessingandoilimmersionorinsulatingpaintcanbeusedafterdippingtokeepthefiberwetting.Ensuretheinsulationandhighchemicalstabilityandhighmechanicalstrength.Atthesametime,thepaperissealedbylacquer,whichcanreducethemoistureabsorptionofthepaper,preventtheoxidationofthematerial,andalsofillthegaptoreducetheinfluenceoftheinsulation,thepartialdischargeandtheelectricshock.Butsomethinkthedipafteroilimmersion,theremaybesomepaintwillslowlysolubleinoil,oilpropertiesofthiskindofpaintshouldbeusedtopayattentiontothemolecularcharge.

Ofcourse,differentqualitypropertiesofdifferentcomponentsoffibermaterialsandthesamecomponentsoffibermaterials,theinfluenceofsizeandperformancearealsodifferent,suchascottonfibercomponentsinthehighest,moststronghempfiber,someimportedinsulationboardbecauseofitsgoodprocessingperformance,significantlybetterthandomesticsomematerialboardetc..Mostinsulationmaterialsfortransformersareinsulatedbyvarioustypesofpaper（e.g.,papertape,cardboard,pressuremoldedpartsofpaperetc.）.Therefore,inthetransformermanufacturingandmaintenance,itisveryimportanttochoosetheinsulatingmaterialofthefiber

material.Thespecialadvantagesoffiberpaperispractical,lowprice,convenientprocessing,thetemperatureisnothighandthemoldingprocessingissimpleandflexible,andlightweight,moderateintensity,easytoabsorbimpregnatedmaterials（suchastransformeroilinsulationpaint,etc.）.

（2）mechanicalstrengthofpaperinsulatingmaterial.Transformeroilpaperinsulationmaterialselectionofthemostimportantfactorsinadditiontothepaperfibercomposition,density,permeabilityanduniformity,includingmechanicalstrengthrequirements,includingtensilestrength,tearstrength,punchingstrengthandtoughness:

1）tensilestrength:

whenthetensilestrengthofthepaperfiberisrequired,themaximumstresscanbetoleratedwithoutbreaking

2）PunchingStrength:

ameasureoftheabilityofapaperfibertowithstandpressurewithoutbreaking.

3）tearingstrength:

theforcerequiredfortearingofpaperfibersconformstothestandard.

4）tenacity:

paperfoldingorcardboardbendingwhentheintensitycanmeetthecorrespondingrequirements.

Thedegreeofpolymerizationcanjudgetomeasurepaperorpaperboardsamplingofsolidinsulation,orbyhighperformanceliquidchromatographyanalysisoffurfural

contentinoilmeasurementtechnology,inordertofacilitatetheanalysisoftransformerinternalfault,whetherinvolvingsolidinsulationorwhethertherearecausedbylowtemperatureoverheatingoflocalcoilinsulationaging,ordeterminetheagingdegreeofsolidinsulation.Intheoperationandmaintenanceofpaperfiberinsulationmaterials,attentionshouldbepaidtocontrollingtheratedloadofthetransformer.Theoperatingenvironment,aircirculationandheatdissipationconditionsshouldbeensuredtopreventexcessivetemperatureriseofthetransformerandlackofoilinthetank.Butalsotopreventoilpollution,deteriorationandothercausesofacceleratedagingofthefiber,anddamagetheinsulationperformanceoftransformers,servicelifeandsafeoperation.

（3）deteriorationofpaperfibermaterial.Itmainlyincludesthreeaspects:

1）fiberbrittlefracture.Whenexcessiveheatingcausesmoisturetoescapefromthefibermaterial,itwillhastentheembrittlementofthefibermaterial.Becauseofthebrittleandflakingofthepaper,theinsulationfailuremayoccurundertheinfluenceofmechanicalvibration,

electricstress,operationwaveandotherelectricalshocks.

2）themechanicalstrengthofthefiberdecreased.Themechanicalstrengthoffibermaterialsdecreasedwithprolongedheatingtime,whenthetransformerfevercausedbyinsulationmoistureredischarge,numericalinsulationresistancemaybecomehigh,butitsmechanicalstrength

willbegreatlyreduced,insulationpaperwillaffecttheshort-circuitcurrentcannotwithstandtheimpactloadormechanicalforce.

3）shrinkageoffibermaterialitself.Fibermaterialshrinksafterembrittlement,whichreducestheclampingforce,maycausecontractionmovement,andcausesthetransformerwindingstoshiftandrubunderelectromagneticvibrationorimpactvoltagetodamagetheinsulation.

2.liquidoilinsulationfault

Oilimmersedtransformerdielectricliquidin1887bytheAmericanscientistThompsoninventedin1892bytheUnitedStates,theGeCorpusedinpowertransformer,thetransformerinsulationoilisliquidinsulation.

Thecharacteristicsofoilimmersedtransformers:

greatlyimproveelectricalinsulatingstrength,theinsulationdistanceshortened,thevolumeofequipmentisreduced;

thegreatlyimpro