(2.6.1)-12高壓熔斷器及運行

ElectricalEquipmentandOperation1ContentsTheRoleoftheFuseTheStructureandWorkingPrincipleoftheFuseTypesofFuseONOperationandMaintenanceoftheFuseThefuseisthefirstadoptedandalsothesimplestkindofprotectionforelectricalappliances.Itisusedinseriesinthecircuit.Whenanoverloadcurrentorashort-circuitcurrentpassesthroughthecircuit,theheatgeneratedbythemeltisusedtofuseitselfandcutoffthecircuittoachievethepurposeofprotectingotherelectricalequipment.Witharcextinguishingability(specialarcextinguishingmaterial,suchasgas-producingfibertube,quartzsand)TheRoleoftheFuseSF63TheRoleoftheFuseSF64Characteristics:simplestructure,smallsize,smallquality,lowprice,convenientmaintenance,andflexibleuse.Inthepowertransmissionanddistributionsystem,high-voltagefusesarewidelyusedforshort-circuitandoverloadprotectionofelectricalequipmentsuchashigh-voltagetransmissionanddistributionlines,powertransformers,voltagetransformers,andpowercapacitorsforsmallandlessimportantloads.5TheStructureandWorkingPrincipleoftheFuseSF65Thefuseismainlycomposedofametalmelt,acontactdevicethatconnectsthemelt,andashell.Metalmeltisthemaincomponentofthefuse.Themeltmaterialgenerallyincludescopper(1080°C),silver(960°C),zinc(420°C),lead(327°C)andlead-tinalloy(200°C).Whenthemeltisinnormaloperation,ifonlyaloadcurrentofnotgreaterthantheratedcurrentvalueofthemeltpassesthrough,itsnormalheatingtemperaturewillnotcausethemelttofuse.Whenoverloadcurrentorshort-circuitcurrentpassesthroughthemelt,themeltmeltsanddisconnectsduetoresistanceheating.Fig.13-2High-voltageCurrent-limitingFuse1—Porcelaincore2—Fuse3—Quartzsand4—Porcelaintube5—Tinball66TheStructureandWorkingPrincipleoftheFuseSF66Thelead-tinalloyandzincmelthaslowmeltingtemperatureandsmallconductivity,therefore,ithasalargercross-sectionalareaandlowarcextinguishingability.Itismainlyusedinlow-voltagefusesbelow1000V;High-voltagefusesrequirealargebreakingcurrentcapability.Becausecopperandsilverhavelowelectricalresistivityandlargethermalconductivity,thecross-sectionalareaofcopperorsilvermeltissmall,andlessmetalvaporisgeneratedduringfusing,whichiseasytoextinguishthearc.FastfuseSpiralTubular

(withpacking)Tubular(withoutpacking)Plug-inTheStructureandWorkingPrincipleoftheFuseAmpere-secondCharacteristicsoftheFuseThetime-currentcharacteristicofahigh-voltagefuseiscalledtheampere-secondcharacteristicofthefuse,andisalsocalledtheprotectioncharacteristicofthefuse.Itisusedtoindicatetherelationshipbetweenthemeltingtimeofthemeltandthecurrentflowingthroughthemelt.Thegreaterthecurrentthroughthemelt,theshorterthemeltingtime.Whenthecurrentisreducedtotheminimummeltingcurrent(Imin),themeltingtimeisinfinite.Themeltofeachspecificationhasanampere-secondcharacteristiccurve,whichisgivenbythemanufacturer.Theampere-secondcharacteristicisanimportantcharacteristicofafuse.Whenusingselectiveprotection,theampere-secondcharacteristicmustbeconsidered.

MeltratedcurrentCurrentthroughthefuseFusingtime8TheStructureandWorkingPrincipleoftheFuseAmpere-secondCharacteristicsoftheFuseSelectthemeltaccordingtotheprotectioncharacteristicstoobtaintheselectivityoffuseaction.Theso-calledselectivityreferstotheprotectionofequipmentineachcircuitwhenseverallevelsoffusesareusedinseriesinthepowergrid.Ifacertainequipmentisoverloadedorshort-circuited,thefusethatprotectstheequipment(thenearesttotheequipment)willbemeltandcutoffthecircuit,thatisselectivefusing;ifthefusethatprotectstheequipmentdoesnotblow,buttheupper-levelfuseblowsorthecircuitbreakertrips,itisanon-selectivefusing.Theoccurrenceofnon-selectivefusingoccurswillexpandpoweroutagerangeandcauseunduelosses.

Whenthefuseisusedinseries,thedifferenceofratedcurrentlevelsofthemeltcannotbetoosmall.Ingeneral,ifthemeltsareofthesamematerial,theratedcurrentofthemeltoftheupperlevelis2to4timesthatofthemeltofthelowerlevel.Asshowninthefigure,themaincircuituses20Ameltandthebranchcircuituses5Amelt.Whenashort-circuitoccursatpointA,theshort-circuitcurrentis200A.Atthistime,themeltingtimeofmelt1is0.35s,andthemeltingtimeofmelt2is0.025s.Obviously,melt2breaksfirst,ensuringselectiveremovalofthefault.Configurationofthefusesinthedistributionline99

TypesofHigh-voltageFuses1.High-voltagefusesfallintoindoorandoutdoortypesaccordingtotheuseenvironment.TherearemainlyRNseriesindoorfuses,RWseriesoutdoordrop-outfusesandpillarfuses,andBRWtypehigh-voltagefusesfortheprotectionofsingleshuntcapacitors.

Fig.2-48RN1typeindoorHVfuseFig.2-49RW9outdoorpillartypeHVfuseFig.2-51RW4typedrop-outfuseThedrop-outfuseconsistsoftwoparts:aninsulatingsupportandanopenfusetube.Thefusetubeismadeofsteelpapertube,shellacmulberrypaperandothergas-producingmaterials.Itusessolidgas-producingmaterialstoextinguisharcs.Whenthefuseisblownandanarcisgeneratedinthefusetube,theinnerwallofthefusetubewillgeneratealargeamountofgasundertheactionofthearctoincreasethepressureinthetube.Thegasissprayedoutwardsathighspeedundertheactionofhighpressure,resultinginastrongde-ionizationeffectandthearcisextinguishedatzerocrossing.Whenthefuseisblown,themovablejointwillbereleased,causingtheupperendofthefusetubetoslipofftheuppercontact,andfalldownthroughrotatingaroundtheaxisofthelowercontactbyitsowngravity.(Presentationthroughanimation)Itcanbeusedforthehigh-voltagesidecurrentswitchofoutdoortransformersof315KVAandbelow.Itiswidelyusedinindustrialandminingenterprisesandruralpowersystems.101010TypesofHigh-voltageFuses2.High-voltagefusesfallintodrop-outtypeandpillartypeaccordingtotheirstructuralcharacteristics.

(1)Drop-outfuseFig.2.2010kVoutdoorDrop-outfuse1—Upperstaticcontact;2—Installationoffixedplate;3—Porcelainbottle;4—Lowermovablecontact;5—Lowerstaticcontact;6—Meltingtube;7—Uppermovablecontact11111111TypesofHigh-voltageFuses2.High-voltagefusesfallintodrop-outtypeandpillartypeaccordingtotheirstructuralcharacteristics.

Thefuseiscomposedofaporcelainsleeve,afusetube,arod-shapedpillarinsulator,andaterminalcap.Themeltingtubeisinstalledinaporcelainsleeve,andthemeltisplacedinthemeltingtubefullofquartzsandwiththeroleoflimitingthecurrent.(2)PillarfuseFig.2-52RXW-35current-limitingoutdoorhigh-voltagefuseThecurrent-limitingfuseiswhenashortcircuitoccurs,themeltblowsbeforetheshort-circuitcurrentreachesthemaximumvalue(short-circuitimpulsecurrent),sothatthecurrentisimmediatelyreducedtozero,thatis,thefuseisconsideredtolimitthedevelopmentoftheshort-circuitcurrent.Therefore,thisfusecangreatlyreducethedamageofelectricalequipmentduringshortcircuit.Afterthenon-current-limitingfusemelts,thecurrenthardlydecreasesandcontinuestoreachthemaximumvalue.Thearcisextinguishedafterthecurrentcrosseszeroforthefirsttimeorafterseveralcycles.1-Rodpillarinsulator2-Porcelainmelttube(withspecialmeltandquartzsandinside)3-Copperpipecap

4.6-Connectionterminal5-Fixedhoop1.Operatinganoutdoordrop-outfuse,mustbeperformedbytwopersons(oneforsupervisionandtheotherforoperation)accordingtoregulations,wearinginsulatinggloves,insulatingboots,andusingqualifiedinsulatingrodswithmatchingvoltagelevels.OperationandMaintenanceofHVFuses12132.Whentheoperatorpullsandclosesthedrop-outfuse,hemustdoitcarefullyandnotusebruteforce,otherwiseitwillhaveanexcessiveimpactonthefuseandeasilycausedamagetothefuse.Theprocessofclosingthefuseisslow(start)-fast(whenthemovablecontactisclosetothestaticcontact)-slow(whenthemovablecontactisclosetotheendofclosing);theprocessofpullingthefuseisslow(start)-fast(whenthemovablecontactisclosetothestaticcontact)-slow(whenthemovablecontactisclosetotheendoftheswitch).Fastistopreventelectricalshortcircuitsandburncontactscausedbyelectricarcs,andslowistopreventoperatingshocksfromcausingmechanicaldamagetothefuse.OperationandMaintenanceofHVFuses1314143.Thethree-phaseoperationsequenceofthehighpressuredrop-outfuse:①Whenoperatingpower-off,firstpullthemiddlephase,andthenthetwosidephases.Whenoperatingpower-on,closethetwosidephasesfirst,andthenthemiddlephase.Thereasonwhythemiddlephaseispulledfirstwhenoperatingpower-offismainlybecausethecurrentisrelativelylargewhenthesecond(sidephase)drop-outfuseisoperated.Atthistime,themiddlephasehasbeenopened,andtheothertwodrop-outfusesarerelativelyfarapart,whichcanp