CABLE-GLANDS填料函的应用资料课件

CABLEGLANDSAnIntroductiontoDifferentTypesofCableGlands.E&ISectionTrainingCABLEGLANDAPPLICATIONWhatisaCableGland?STANDARDDEFINITION:“Adevicedesignedtopermittheentryofacableintoelectricalequipmentandwhichprovidessealingandretention.Itmayalsoprovideotherfunctionssuchasearthing(orgrounding),bonding,insulation,strainrelief,oracombinationofthese.”Inadditiontotheseacableglandshouldmaintaintheoverallintegrityoftheenclosureintowhichitistobefitted.STEP1:CableGlandSelectionWhatisthebasicconstructionofthecableandhowdowewanttoterminateit?UnarmouredCableswillrequiretheoutersheathsealwithintheglandtonotonlyprovideingressprotectionbutalsoadegreeofretention.STEP1(cont’n.)ArmouredCablesrequireaglandthatfeaturesaclampingmechanismtoterminatethearmourbothmechanicallyandelectrically.Theglandwillusuallyberequiredtoprovideingressprotectionbysealingontheoutersheathandretentionbyclampingthearmour.Typically,armouredcablesfeatureaninnersheaththattheglandmayberequiredtosealon.STEP2:ThecorrectglandsizeTheentrythread(i.e.M20)isnotasoftenperceived,theglandsizebutsimplytheentrythreadsizeandspecification.(also½”NPT)Itisimportanttounderstandthatselectionofthecorrectglandsizeisbasedsolelyoncabledimensions:OuterSheathDiameterSTEP2(cont’n.)Andwhereapplicable:InnerSheathDiameterArmour/BraidThicknessSTEP3:Maintainingtheoverallintegrityoftheinstallation.Inordertomaintaintheoverallintegrityoftheinstallationitisimportanttoconsidertheequipmentintowhichthecableistobeglandedandthesorroundingenvironment.Theareastoconsiderare:CABLEENTRYINGRESSPROTECTIONSTEP3(cont’n.)IMPACTRESISTANCEMATERIALEXTERNALINFLUENCESCERTIFICATIONSTEP3(cont’n.)CableEntry:Entrytypeand/orthreadspecification.ClearanceHoles:Alocknutwillberequiredtofixtheglandsecurelywithinaclearancehole.Theadditionaluseofaserratedwasherwillprovideagreaterleveloffixingsecurity,thisisdefinitelyworthconsideringiftheequipmentisSTEP3(cont’n.)likelytobesubjecttovibrationorseveretemperaturechanges.Taperedthreadsshouldnotbeinstalledintoclearanceholes.ThreadedEntries:Glandscangenerallybesuppliedwithamalethreadtomatchthefemaleentrythread.Ifthisisnotpossible,ThreadAdaptersorSTEP3(cont’n.)Reducerscanbeusedtomatchdissimilarthreads.Ifthewallthicknesswillpermit,theuseofalocknutwillprovideadditionalsecurity.IngressProtection:TheglandselectedshouldmaintaintheIPintegrityoftheenclosure.InordertomaintaintherequiredIPratingthefollowingsealingarrangementshouldbeused:STEP3(cont’n.)ClearanceHoles:Integral‘O’ringsealornylonIPwasherParallelThreadedEntries:Integral‘O’ringseal,IPwasherornon-hardeningthreadsealantTaperThreadedEntries:Non-hardeningthreadsealantSTEP3(cont’n.)IMPACTRESISTANCE:Theglandselectedmustmaintaintheintegrityoftheenclosure.Forhazardouslocationequipment,theminimumimpactresistanceisusually7Nm.SpecialcareshouldbetakenwhenselectingNylonglandsastheseoftenhavereducedimpactcapabilities.STEP3(cont’n.)Material:Theglandshouldbemanufacturedfromamaterialthatissuitableforthesorroundingenvironmentandwillnotreactadverselywiththematerialoftheenclosureintowhichitisinstalled.Inparticular,itshouldbenotedthatBrassthestandardmaterialformetallicSTEP3(cont’n.)glands,canreactadverselywithAluminium,ifmoisturebecomepresentbi-metalliccorrosionmayoccur.WhenusingbrassglandsH2s,SO2andammoniaarethemostproblematicenvironments.Nickel,TinorZincplatingcanbeappliedtobrasstobothminimizetheSTEP3(cont’n.)potentialforbi-metalliccorrosionandprovideadegreeofprotectionfromthesorroundingenvironment.ExternalInfluences–OperatingTemperature:Themetallicbodyoftheglandisgenerallysuitableforoperatingtemperaturesthatglandsareusedat,meaningthatthesealmaterialisgenerallythelimitingfactor.STEP3(cont’n.)Note:Brass,aluminium,carbonsteelsoftenathighertemperatures(200/250deg.C)whilecarbonsteelcanbecomebrittleat-20deg.C.Neoprenesealsaresuitablefrom-20degto+80degandcanbeusedaslowas-60degbutthestructureofthematerialmaybeaffectedadverselyandSTEP3(cont’n.)thiscouldresultinmaterialbreakdown.Siliconsealsaresuitableforextendedoperatingtemperaturesof-60degto+180degandshouldbeusedforlowtemperatureapplicationsasthesealperformancecanbemaintainedthroughoutthelifetimeoftheinstallation.STEP3(cont’n.)Earthing,Bonding,Grounding,ContinuityorInsulation:Theglandmayberequiredtoprovideelectricalfunctionsinconjunctionwithitsbasicfunctionofsealingandretention.Earthtags(lugsforHVapplication)canbeusedtoprovideanelectricalconnectionpointtoearththecablegland,andbySTEP3(cont’n.)extensionthecablearmourorscreenwhereithasbeenterminatedwithinthegland.Careshouldbetakenwheninstallingearthtagsinhazardouslocationsastheyarenotcertifiedforuse.Alternativelyitmaybearequirementtoinsulatetheequipmentenclosurefromthecablearmour.ThemostflexibleandSTEP3(cont’n.)straightforwardwayofachievingthisistofitaninsulatedadaptorbetweentheenclosureandthegland.ExCertification:WhenselectingExcertifiedglandsforuseinHazardousLocationsitisimportanttoensurethattheproductselectednotonlyperformsSTEP3(cont’n.)thetaskrequiredi.e.terminatingthecable,butmustalsomaintaintheintegrityoftheequipmentintowhichitwillbefitted.WhenselectingequipmentforuseinhazardousareastheappropriatenationalorinternationalstandardsorcodesofpracticemustbeconsideredinparticularSTEP3(cont’n.)

IEC60079-14ElectricalApparatusforExplosiveGasAtmospheresPart14ElectricalInstallationsinHazardousAreas.HazardousLocationRequirements:CableGlandsmustmaintain:TheGasGroup,TemperatureClassificationandMethodofExplosionSTEP3(cont’n.)protection.TheIngressProtection(min.IP54,realisticallyIP66,68)ImpactResistance(min.7Nm)GasGroups:GasGroupI:Atmospherescontainingfiredampfoundinundergroundmine.STEP3(cont’n.)GasGroupII:Allotherpotentiallyexplosiveatmospheres,GroupIIissub-dividedinto3groupsforExdandExiaIIA:TypicalgaspropaneIIB:TypicalgasethyleneIIC:TypicalgasacethyleneorhydrogenSTEP3(cont’n.)ATEXCategories:InEurope,theynowhavetheadditionalrequirementsoftheATEXDirectivetoconsider,stayingspecificallywithproductselectionthisnowaddstherequirementtoselectaglandwithasuitablecategorystatusfortheequipmentandinstallation.Mining(M):CategoryM1,M2STEP3(cont’n.)SurfaceGases(G):Category1G(Zone0),2G(Zone1),3G(Zone2)Dusts(D):Category1D(Zone20),2D(Zone21),3D(Zone22)TemperatureClassification:ToensurethatthesurfacetemperatureoftheequipmentwillnotignitegasesorvapoursinthesorroundingatmosphereSTEP3(cont’n.)theequipmentwillspecifya‘T’ratingbasedonthemaximumsurfacetemperaturethatcanoccurduringitsoperation.Ascableglandsarepassiveanddonotgenerateheat,theyhavenoeffectontheequipments‘T’ratingandthisneednotbeconsideredwhenselectingthegland.STEP3(cont’n.)TheMethodofExplosionProtection:Thecableglandmustbecertifiedtoasuitablemethodofprotection(preferablythesame)andforuseinthesamegasgroupastheequipmentintowhichitwillbefitted.FlameproofExdglandsaresuitableforusewithbothFlameproofandIncreasedSTEP3(cont’n.)SafetyenclosuresastheyhavemettherequirementsofboththestandardforGeneralRequirementswithinhazardousareasandtheadditionalrequirementsoftheFlameproofstandard.IncreasedsafetyExeglandsaresuitableforIncreasedSafetyapplicationsandothermethodsofprotectionwithoutadditionalSTEP3(cont’n.)requirements,butnotFlameproofapplicationsastheyhavemetthestandardforGeneralRequirementswithinhazardousareabutnottheadditionalrequirementsoftheFlameproofstandards.FlameproofApplications:ItisimportanttounderstandthatwhereSTEP3(cont’n.)FlameproofExdglandswithelastomericsealsarerequiredthatthecablesbecomespartofthesealthatpreventsanyexplosionwithintheequipmentescapingtotheoutsideatmosphere.CablesarenotdesignedtowithstandexplosionandcarefulscrutinyoftheirdesignandconstructionmustbeappliedSTEP3(cont’n.)priortoselectingacableglandwithanelastomericFlameproofseal.IfitcannotbedeterminedthatthecablecanwithstandthepotentialexplosionwithintheenclosureaBarriertypecableglandshouldbeselected.BarrierGlands:AbarrierglandisanExdcableglandincorporatingaSTEP3(cont’n.)compoundfilledchambersealingaroundtheindividualcoresofthecabletomaintaintheFlameproofintegrityoftheequipmentintowhichithasbeenfitted.Abarrierglandmustbeusedwherethestandardmethodofglanding(elastomericseals)anExcableentryisconsideredunlikelytomaintaintheintegrityofFlameproofequipmentandSTEP3(cont’n.)containanexplosionwithintheenclosuredueeitherto:Constructionofthecableand/orThemagnitudeofthepotentialexplosionTheCableConstruction:Thefirstquestionsthatmustbeaskedarewithregardtotheconstructionofthecable.STEP3(cont’n.)Isthecablesubstantiallyroundandcompact?Canthecablebedeemedeffectivelyfilled?IftheanswertoanyofthesequestionsisNO,abarrierglandmustbeused.Iftheanswertoall3questionsisYES,STEP3(cont’n.)theapplicationmustthenbeconsideredusingtheselectionchartwithinIEC60079-14.Note:Determiningwheterthecableiseffectivelyfi