美標標準固體絕緣材料電壓擊穿的實驗方法

ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施StandardTestMethodforDielectricBreakdownVoltageandDielectricStrengthofSolidElectricalInsulatingMaterialsatCommercialPowerFrequencies固體電絕緣材料在工業(yè)用電頻率下旳電壓擊穿和介電強度旳實驗措施1.Scope*1.1Thistestmethodcoversproceduresforthedeterminationofdielectricstrengthofsolidinsulatingmaterialsatcommercialpowerfrequencies,underspecifiedconditions.2,31.2Unlessotherwisespecified,thetestsshallbemadeat60Hz.However,thistestmethodissuitableforuseatanyfrequencyfrom25to800Hz.Atfrequenciesabove800Hz,dielectricheatingisapotentialproblem.1.3ThistestmethodisintendedtobeusedinconjunctionwithanyASTMstandardorotherdocumentthatreferstothistestmethod.Referencestothisdocumentneedtospecifytheparticularoptionstobeused(see5.5).1.4Itissuitableforuseatvarioustemperatures,andinanysuitablegaseousorliquidsurroundingmedium.1.5Thistestmethodisnotintendedformeasuringthedielectricstrengthofmaterialsthatarefluidundertheconditionsoftest.1.6Thistestmethodisnotintendedforuseindeterminingintrinsicdielectricstrength,direct-voltagedielectricstrength,orthermalfailureunderelectricalstress(seeTestMethodD3151).1.7Thistestmethodismostcommonlyusedtodeterminethedielectricbreakdownvoltagethroughthethicknessofatestspecimen(puncture).Itisalsosuitableforusetodeterminedielectricbreakdownvoltagealongtheinterfacebetweenasolidspecimenandagaseousorliquidsurroundingmedium(flashover).WiththeadditionofinstructionsmodifyingSection12,thistestmethodisalsosuitableforuseforprooftesting.1.8ThistestmethodissimilartoIECPublication243-1.AllproceduresinthismethodareincludedinIEC243-1.DifferencesbetweenthismethodandIEC243-1arelargelyeditorial.1.9Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.SpecifichazardstatementsaregiveninSection7.Alsosee6.4.1.ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(三)3.1Definitions:3.1.1dielectricbreakdownvoltage(electricbreakdownvoltage),n—thepotentialdifferenceatwhichdielectricfailureoccursunderprescribedconditionsinanelectricalinsulatingmateriallocatedbetweentwoelectrodes.(SeealsoAppendixX1.)Discussion—Thetermdielectricbreakdownvoltageissometimesshortenedto“breakdownvoltage.”3.1.2dielectricfailure(undertest),n—aneventthatisevidencedbyanincreaseinconductanceinthedielectricundertestlimitingtheelectricfieldthatcanbesustained.

3.1.3dielectricstrength,n—thevoltagegradientatwhichdielectricfailureoftheinsulatingmaterialoccursunderspecificconditionsoftest.

3.1.4electricstrength,n—seedielectricstrength.Discussion—Internationally,“electricstrength”isusedalmostuniversally.3.1.5flashover,n—adisruptiveelectricaldischargeatthesurfaceofelectricalinsulationorinthesurroundingmedium,whichmayormaynotcausepermanentdamagetotheinsulation.3.1.6Fordefinitionsofothertermsrelatingtosolidinsulatingmaterials,refertoTerminologyD1711.ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(四)

4.SummaryofTestMethod4.2Mostcommonly,thetestvoltageisappliedusingsimpletestelectrodesonoppositefacesofspecimens.Theoptionsforthespecimensarethattheybemoldedorcast,orcutfromflatsheetorplate.Otherelectrodeandspecimenconfigurationsarealsosuitableforusetoaccommodatethegeometryofthesamplematerial,ortosimulateaspecificapplicationforwhichthematerialisbeingevaluated.4.1Alternatingvoltageatacommercialpowerfrequency(60Hz,unlessotherwisespecified)isappliedtoatestspecimen.Thevoltageisincreasedfromzeroorfromalevelwellbelowthebreakdownvoltage,inoneofthreeprescribedmethodsofvoltageapplication,untildielectricfailureofthetestspecimenoccurs.5.SignificanceandUse5.1Thedielectricstrengthofanelectricalinsulatingmaterialisapropertyofinterestforanyapplicationwhereanelectricalfieldwillbepresent.Inmanycasesthedielectricstrengthofamaterialwillbethedeterminingfactorinthedesignoftheapparatusinwhichitistobeused.5.2Testsmadeasspecifiedhereinaresuitableforusetoprovidepartoftheinformationneededfordeterminingsuitabilityofamaterialforagivenapplication;andalso,fordetectingchangesordeviationsfromnormalcharacteristicsresultingfromprocessingvariables,agingconditions,orothermanufacturingorenvironmentalsituations.Thistestmethodisusefulforprocesscontrol,acceptanceorresearchtesting.5.3Resultsobtainedbythistestmethodcanseldombeuseddirectlytodeterminethedielectricbehaviorofamaterialinanactualapplication.Inmostcasesitisnecessarythattheseresultsbeevaluatedbycomparisonwithresultsobtainedfromotherfunctionaltestsorfromtestsonothermaterials,orboth,inordertoestimatetheirsignificanceforaparticularmaterial.

5.4ThreemethodsforvoltageapplicationarespecifiedinSection12:MethodA,Short-TimeTest;MethodB,Step-by-StepTest;andMethodC,SlowRate-of-RiseTest.MethodAisthemostcommonly-usedtestforquality-controltests.However,thelonger-timetests,MethodsBandC,whichusuallywillgivelowertestresults,willpotentiallygivemoremeaningfulresultswhendifferentmaterialsarebeingcomparedwitheachother.Ifatestsetwithmotor-drivenvoltagecontrolisavailable,theslowrate-of-risetestissimplerandpreferabletothestep-by-steptest.TheresultsobtainedfromMethodsBandCarecomparabletoeachother.5.5Documentsspecifyingtheuseofthistestmethodshallalsospecify:5.5.1Methodofvoltageapplication,5.5.2Voltagerate-of-rise,ifslowrate-of-risemethodisspecified,5.5.3Specimenselection,preparation,andconditioning,5.5.4Surroundingmediumandtemperatureduringtest,5.5.5Electrodes,5.5.6Whereverpossible,thefailurecriterionofthecurrentsensingelement,and5.5.7Anydesireddeviationsfromtherecommendedproceduresasgiven.5.6Ifanyoftherequirementslistedin5.5aremissingfromthespecifyingdocument,thentherecommendationsfortheseveralvariablesshallbefollowed.5.7Unlesstheitemslistedin5.5arespecified,testsmadewithsuchinadequatereferencetothistestmethodarenotinconformancewiththistestmethod.Iftheitemslistedin5.5arenotcloselycontrolledduringthetest,itispossiblethattheprecisionsstatedin15.2and15.3willnotbeobtained.5.8Variationsinthefailurecriteria(currentsettingandresponsetime)ofthecurrentsensingelementsignificantlyaffectthetestresults.5.9AppendixX1.containsamorecompletediscussionofthesignificanceofdielectricstrengthtests.ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(六)

6.Apparatus

6.1.3Thecontrolsonthevariablelow-voltagesourceshallbecapableofvaryingthesupplyvoltageandtheresultanttestvoltagesmoothly,uniformly,andwithoutovershootsortransients,inaccordancewith12.2.Donotallowthepeakvoltagetoexceed1.48timestheindicatedrmstestvoltageunderanycircumstance.Motor-drivencontrolsarepreferableformakingshort-time(see12.2.1)orslow-rate-of-rise(see12.2.3)tests.6.1.4Equipthevoltagesourcewithacircuit-breakingdevicethatwilloperatewithinthreecycles.Thedeviceshalldisconnectthevoltage-sourceequipmentfromthepowerserviceandprotectitfromoverloadasaresultofspecimenbreakdowncausinganoverloadofthetestingapparatus.Ifprolongedcurrentfollowsbreakdownitwillresultinunnecessaryburningofthetestspecimens,pittingoftheelectrodes,andcontaminationofanyliquidsurroundingmedium.6.1.5Itisimportantforthecircuit-breakingdevicetohaveanadjustablecurrent-sensingelementinthestep-uptransformersecondary,toallowforadjustmentconsistentwiththespecimencharacteristicsandarrangedtosensespecimencurrent.Setthesensingelementtorespondtoacurrentthatisindicativeofspecimenbreakdownasdefinedin.6Thecurrentsettingislikelytohaveasignificanteffectonthetestresults.Makethesettinghighenoughthattransients,suchaspartialdischarges,willnottripthebreakerbutnotsohighthatexcessiveburningofthespecimen,withresultantelectrodedamage,willoccuronbreakdown.Theoptimumcurrentsettingisnotthesameforallspecimensanddependingupontheintendeduseofthematerialandthepurposeofthetest,itisoftendesirabletomaketestsonagivensampleatmorethanonecurrentsetting.Theelectrodeareaislikelytohaveasignificanteffectuponthechoiceofcurrentsetting.6.1.7Itispossiblethatthespecimencurrent-sensingelementwillbeintheprimaryofthestep-uptransformer.Calibratethecurrent-sensingdialintermsofspecimencurrent.6.1.8Exercisecareinsettingtheresponseofthecurrentcontrol.Ifthecontrolissettoohigh,thecircuitwillnotrespondwhenbreakdownoccurs;ifsettoolow,itispossiblethatitwillrespondtoleakagecurrents,capacitivecurrents,orpartialdischarge(corona)currentsor,whenthesensingelementislocatedintheprimary,tothestep-uptransformermagnetizingcurrent.6.2VoltageMeasurement—Avoltmetermustbeprovidedformeasuringthermstestvoltage.Ifapeak-readingvoltmeterisused,dividethereadingby=2togetrmsvalues.Theoverallerrorofthevoltage-measuringcircuitshallnotexceed5%ofthemeasuredvalue.Inaddition,theresponsetimeofthevoltmetershallbesuchthatitstimelagwillnotbegreaterthan1%offullscaleatanyrate-of-riseused.6.2.1Measurethevoltageusingavoltmeterorpotentialtransformerconnectedtothespecimenelectrodes,ortoaseparatevoltmeterwinding,onthetesttransformer,thatisunaffectedbythestep-uptransformerloading.6.2.2Itisdesirableforthereadingofthemaximumappliedtestvoltagetoberetainedonthevoltmeterafterbreakdownsothatthebreakdownvoltagecanbeaccuratelyreadandrecorded.ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(七)點擊次數(shù)：138發(fā)布時間：-7-1311:01:456.3Electrodes—Foragivenspecimenconfiguration,itispossiblethatthedielectricbreakdownvoltagewillvaryconsiderably,dependinguponthegeometryandplacementofthetestelectrodes.Forthisreasonitisimportantthattheelectrodestobeusedbedescribedwhenspecifyingthistestmethod,andthattheybedescribedinthereport.6.3.1OneoftheelectrodeslistedinTable1shallbespecifiedbythedocumentreferringtothistestmethod.Ifnoelectrodeshavebeenspecified,selectanapplicableonefromTable1,oruseotherelectrodesmutuallyacceptabletothepartiesconcernedwhenthestandardelectrodescannotbeusedduetothenatureorconfigurationofthematerialbeingtested.SeereferencesinAppendixX2forexamplesofsomespecialelectrodes.Inanyeventtheelectrodesmustbedescribedinthereport.6.3.2TheelectrodesofTypes1through4andType6ofTable1shallbeincontactwiththetestspecimenovertheentireflatareaoftheelectrodes.6.3.3ThespecimenstestedusingType7electrodesshallbe

ofsuchsizethatallportionsofthespecimenwillbewithinandnolessthan15mmfromtheedgesoftheelectrodesduringtest.Inmostcases,testsusingType7electrodesaremadewiththeplaneoftheelectrodesurfacesinaverticalposition.Testsmadewithhorizontalelectrodesshallnotbedirectlycomparedwithtestsmadewithverticalelectrodes,particularlywhenthetestsaremadeinaliquidsurroundingmedium.

6.3.6Whenevertheelectrodesaredissimilarinsizeorshape,ensurethattheoneatwhichthelowestconcentrationofstressexists,usuallythelargerinsizeandwiththelargestradius,isatgroundpotential.6.3.7Insomespecialcasesliquidmetalelectrodes,foilelectrodes,metalshot,water,orconductivecoatingelectrodesareused.Itmustberecognizedthatitispossiblethatthesewillgiveresultsdifferingwidelyfromthoseobtainedwithothertypesofelectrodes.6.3.8Becauseoftheeffectoftheelectrodesonthetestresults,itisfrequentlypossibletoobtainadditionalinformationastothedielectricpropertiesofamaterial(oragroupofmaterials)byrunningtestswithmorethanonetypeofelectrode.Thistechniqueisofparticularvalueforresearchtesting.ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(八)點擊次數(shù)：126發(fā)布時間：-7-1915:17:506.3.3ThespecimenstestedusingType7electrodesshallbeofsuchsizethatallportionsofthespecimenwillbewithinandnolessthan15mmfromtheedgesoftheelectrodesduringtest.Inmostcases,testsusingType7electrodesaremadewiththeplaneoftheelectrodesurfacesinaverticalposition.Testsmadewithhorizontalelectrodesshallnotbedirectlycomparedwithtestsmadewithverticalelectrodes,particularlywhenthetestsaremadeinaliquidsurroundingmedium.6.3.4Keeptheelectrodesurfacescleanandsmooth,andfreefromprojectingirregularitiesresultingfromprevioustests.Ifasperitieshavedeveloped,theymustberemoved.6.3.6Whenevertheelectrodesaredissimilarinsizeorshape,ensurethattheoneatwhichthelowestconcentrationofstressexists,usuallythelargerinsizeandwiththelargestradius,isatgroundpotential.6.3.7Insomespecialcasesliquidmetalelectrodes,foilelectrodes,metalshot,water,orconductivecoatingelectrodesareused.Itmustberecognizedthatitispossiblethatthesewillgiveresultsdifferingwidelyfromthoseobtainedwithothertypesofelectrodes.6.3.5Itisimportantthattheoriginalmanufactureandsubsequentresurfacingofelectrodesbedoneinsuchamannerthatthespecifiedshapeandfinishoftheelectrodesandtheiredgesaremaintained.Theflatnessandsurfacefinishoftheelectrodefacesmustbesuchthatthefacesareinclosecontactwiththetestspecimenovertheentireareaoftheelectrodes.Surfacefinishisparticularlyimportantwhentestingverythinmaterialswhicharesubjecttophysicaldamagefromimproperlyfinishedelectrodes.Whenresurfacing,donotchangethetransitionbetweentheelectrodefaceandanyspecifiededgeradius.6.3.8Becauseoftheeffectoftheelectrodesonthetestresults,itisfrequentlypossibletoobtainadditionalinformationastothedielectricpropertiesofamaterial(oragroupofmaterials)byrunningtestswithmorethanonetypeofelectrode.Thistechniqueisofparticularvalueforresearchtesting.ASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(九)6.4SurroundingMedium—Thedocumentcallingforthistestmethodneedstospecifythesurroundingmediumandthetesttemperature.Sinceflashovermustbeavoidedandtheeffectsofpartialdischargespriortobreakdownmimimized,evenforshorttimetests,itisoftenpreferableandsometimesnecessarytomakethetestsininsulatingliquid(see6.4.1).Breakdownvaluesobtainedininsulatingliquidareoftennotcomparablewiththoseobtainedinair.Thenatureoftheinsulatingliquidandthedegreeofprevioususearefactorsinfluencingthetestvalues.Insomecases,testinginairwillrequireexcessivelylargespecimensorcauseheavysurfacedischargesandburningbeforebreakdown.Someelectrodesystemsfortestinginairmakeuseofpressuregasketsaroundtheelectrodestopreventflashover.Thematerialofthegasketsorsealsaroundtheelectrodeshasthepotentialtoinfluencethebreakdownvalues.6.4.1Whentestsaremadeininsulatingoil,anoilbathofadequatesizeshallbeprovided.(Warning—Theuseofglasscontainersisnotrecommendedfortestsatvoltagesaboveabout10kV,becausetheenergyreleasedatbreakdownhasthepotentialtobesufficienttoshatterthecontainer.Metalbathsmustbegrounded.)ItisrecommendedthatmineraloilmeetingtherequirementsofSpecificationD3487,TypeIorII,beused.ItshallhaveadielectricbreakdownvoltageasdeterminedbyTestMethodD877ofatleast26kV.Otherdielectricfluidsaresuitableforuseassurroundingmediumsifspecified.Theseinclude,butarenotlimitedto,siliconefluidsandotherliquidsintendedforuseintransformers,circuitbreakers,capacitors,orcables.Thequalityoftheinsulatingoilhasthepotentialtohaveanappreciableeffectuponthetestresults.Inadditiontothedielectricbreakdownvoltage,mentionedabove,particulatecontaminantsareespeciallyimportantwhenverythinspecimens(25μm(1mil)orless)arebeingtested.Dependinguponthenatureoftheoilandthepropertiesofthematerialbeingtested,otherproperties,includingdissolvedgascontent,watercontent,anddissipationfactoroftheoilalsohavethepotentialtoaffecttheresults.Frequentreplacementoftheoil,ortheuseoffiltersandotherreconditioningequipmentisimportanttominimizetheeffectofvariationsofthequalityoftheoilonthetestresults.Breakdownvaluesobtainedusingliquidshavingdifferentelectricalpropertiesareoftennotcomparable.(SeeX1.4.7.)Iftestsaretobemadeatotherthanroomtemperature,thebathmustbeprovidedwithameansforheatingorcoolingtheliquid,andwithameanstoensureuniformtemperature.Smallbathscaninsomecasesbeplacedinanoven(see6.4.2)inordertoprovidetemperaturecontrol.Ifforcedcirculationofthefluidisprovided,caremustbetakentopreventbubblesfrombeingwhippedintothefluid.Thetemperatureshallbemaintainedwithin65°Cofthespecifiedtesttemperatureattheelectrodes,unlessotherwisespecified.Inmanycasesitisspecifiedthatspecimenstobetestedininsulatingoilaretobepreviouslyimpregnatedwiththeoilandnotremovedfromtheoilbeforetesting(seePracticeD2413).Forsuchmaterials,thebathmustbeofsuchdesignthatitwillnotbenecessarytoexposethespecimenstoairbeforetesting.6.4.2Iftestsinairaretobemadeatotherthanambienttemperatureorhumidity,anovenorcontrolledhumiditychambermustbeprovidedforthetests.OvensmeetingtherequirementsofSpecificationD5423andprovidedwithmeansforintroducingthetestvoltagewillbesuitableforusewhenonlytemperatureistobecontrolled.6.4.3Testsingassesotherthanairwillgenerallyrequiretheuseofchambersthatcanbeevacuatedandfilledwiththetestgas,usuallyundersomecontrolledpressure.ThedesignofD149–094suchchamberswillbedeterminedbythenatureofthetestprogramtobeundertakenASTMD149美標原則固體絕緣材料電壓擊穿旳實驗措施(十)6.5TestChamber—Thetestchamberorareainwhichthetestsaretobemadeshallbeofsufficientsizetoholdthetestequipment,andshallbeprovidedwithinterlockstopreventaccidentalcontactwithanyelectricallyenergizedparts.Anumberofdifferentphysicalarrangementsofvoltagesource,measuringequipment,bathsorovens,andelectrodesarepossible,butitisessentialthat(1)allgatesordoorsprovidingaccesstospacesinwhichthereareelectricallyenergizedpartsbeinterlockedtoshutoffthevoltagesourcewhenopened;(2)clearancesaresufficientlylargethatthefieldintheareaoftheelectrodesandspecimenarenotdistortedandthatflashoversandpartialdischarges(corona)donotoccurexceptbetweenthetestelectrodes;and(3)insertionandreplacementofspecimensbetweentestsbeassimpleandconvenientaspossible.Visualobservationoftheelectrodesandtestspecimenduringthetestisfrequentlydesirable.7.Hazards7.1Warning—Itispossiblethatlethalvoltageswillbepresentduringthistest.Itisessentialthatthetestapparatus,andallassociatedequipmentelectricallyconnectedtoit,beproperlydesignedandinstalledforsafeoperation.Solidlygroundallelectricallyconductivepartsthatanypersonmightcomeintocontactwithduringthetest.Providemeansforuseatthecompletionofanytesttogroundanypartswhichfallintoanyofthefollowingcases:(a)wereathighvoltageduringthetest;(b)havethepotentialtoacquireaninducedchargeduringthetest;or(c)havethepotentialtoretainachargeevenafterdisconnectionofthevoltagesource.Thoroughlyinstructalloperatorsintheproperwaytoconducttestssafely.Whenmakinghigh-voltagetests,particularlyincompressedgasorinoil,itispossiblethattheenergyreleasedatbreakdownwillbesufficienttoresultinfire,explosion,orruptureofthetestchamber.Designtestequipment,testchambers,andtestspecimenssoastominimizethepossibilityofsuchoccurrencesandtoeliminatethepossibilityofpersonalinjury.7.2Warning—Ozoneisaphysiologicallyhazardousgasatelevatedconcentrations.TheexposurelimitsaresetbygovernmentalagenciesandareusuallybaseduponrecommendationsmadebytheAmericanConferenceofGovernmentalndustrialHygienists.8Ozoneislikelytobepresentwhenevervoltagesexistwhicharesufficienttocausepartial,orcomplete,dischargesinairorotheratmospheresthatcontainoxygen.Ozonehasadistinctiveodorwhichisinitiallydiscernibleatlowconcentrationsbutsustainedinhalationofozonecancausetemporarylossofsensitivitytothescentofozone.Becauseofthisitisimportanttomeasuretheconcentrationofozoneintheatmosphere,usingcommerciallyavailablemonitoringdevices,whenevertheodorofozoneispersistentlypresentorwhenozonegeneratingconditionscontinue.Useappropriatemeans,suchasexhaustvents,toreduceozoneconcentrationstoacceptablelevelsinworkingareas.8.Sampling8.1Thedetailedsamplingprocedureforthematerialbeingtestedneedstobedefinedinthespecificationforthatmaterial.8.2Samplingproceduresforqualitycontrolpurposesshallprovideforgatheringofsufficientsamplestoestimateboththeaveragequalityandthevariabilityofthelotbeingexamined;andforproperprotectionofthesamplesfromthetimetheyaretakenuntilthepreparationofthetestspecimensinthelaboratoryorothertestareaisbegun.8.3Forthepurposesofmosttestsitisdesirabletotakesamplesfromareasthatarenotimmediatelyadjacenttoobviousdefectsordiscontinuitiesinthematerial.Avoidtheouterfewlayersofrollmaterial,thetopsheetsofapackageofsheets,ormaterialimmediatelynexttoanedgeofasheetorroll,unlessthepresenceorproximityofdefectsordiscontinuitiesisofinterestintheinvestigationofthematerial.8.4Thesampleshallbelargeenoughtopermitmakingasmanyindividualtestsasrequiredfortheparticularmaterial(see12.4).9.TestSpecimens9.1PreparationandHandling:9.1.1Preparespecimens