leakage protector

Classification

Leakagecurrentprotectorscanbeclassifiedaccordingtotheirprotectionfunctions,structuralfeatures,installationmethods,operatingmodes,numberofpolesandlines,actionsensitivity,etc.HerearemainlybasedontheirprotectionfunctionsandThepurposeisclassifiedanddescribed.Generally,itcanbedividedintothreetypes:leakageprotectionrelay,leakageprotectionswitchandleakageprotectionsocket.

1.Leakageprotectionrelayreferstoaleakageprotectiondevicethathasthefunctionofdetectingandjudgingleakagecurrent,butdoesnothavethefunctionofcuttingoffandconnectingthemaincircuit.Theleakageprotectionrelayiscomposedofazero-sequencetransformer,atripunitandauxiliarycontactsforoutputsignals.Itcanbeusedwithhigh-currentautomaticswitchesasthegeneralprotectionofthelow-voltagepowergridortheleakage,groundingorinsulationmonitoringprotectionofthemainroad.

Whenthemaincircuithasleakagecurrent,becausetheauxiliarycontactandthemaincircuitswitch'sseparatereleaseareconnectedinseriestoformacircuit,theauxiliarycontactconnectstotheseparatereleaseanddisconnectstheairswitch,ACcontactor,etc.Makeittripandcutoffthemaincircuit.Theauxiliarycontactcanalsobeconnectedtothesoundandlightsignaldevicetosendoutaleakagealarmsignaltoreflecttheinsulationstatusoftheline.

2.Leakageprotectionswitchmeansnotonlythatitcanconnectordisconnectthemaincircuitlikeothercircuitbreakers,butalsohasthefunctionofdetectingandjudgingleakagecurrent.WhenleakageorinsulationdamageoccursinthemaincircuitWhentheleakageprotectionswitchisaswitchingelementthatcanturnthemaincircuitonoroffaccordingtothejudgmentresult.Itcanbecombinedwithfusesandthermalrelaystoformafullyfunctionallow-voltageswitchingelement.

Atpresent,thistypeofleakageprotectiondeviceisthemostwidelyused.Theleakageprotectionswitchesonthemarketarecommonlyusedinthefollowingcategoriesaccordingtotheirfunctions:

(1)OnlywithleakageprotectionTheelectricalfunctionmustbeusedwithprotectiveelementssuchasfuses,thermalrelays,andovercurrentrelays.

(2)Italsohasanoverloadprotectionfunction.

(3)Italsohasoverloadandshortcircuitprotectionfunctions.

(4)Italsohasashort-circuitprotectionfunction.

(5)Ithasthefunctionsofshortcircuit,overload,leakage,overvoltageandundervoltageatthesametime.

3.Leakageprotectionsocketreferstoapowersocketwithleakagecurrentdetectionandjudgmentandcapableofcuttingofftheloop.Theratedcurrentisgenerallybelow20A,theleakageactioncurrentis6-30mA,andthesensitivityishigh.Itisoftenusedfortheprotectionofhand-heldpowertoolsandmobileelectricalequipment,andcivilplacessuchashomesandschools.

Historicaldevelopment

Sincetheinventionanduseofelectricitybymankind,electricityhasnotonlybroughtalotofconveniencetomankind,butalsobroughtdisastertomankind.Itmayburnoutelectricalappliances,causeafire,orcauseelectricshocks.Ifthereisadevicethatallowspeopletouseelectricitysafely,manyunnecessarylosseswillbeavoided.Therefore,asavarietyofelectricalappliancescameoneafteranother,allkindsofprotectorswerealsoborn.Oneofthemisspecificallydesignedtoprotectpeople,calledaleakageprotector.Leakageprotector,commonlyknownasleakageswitch,isaprotectiveelectricalapplianceusedtopreventpersonalshockandelectricalfirewhenthecircuitorelectricalinsulationisdamagedandashort-circuittogroundoccurs.Itisgenerallyinstalledonthesocketcircuitofeachdistributionboxandthegeneralpowerdistributionoftheentirebuilding.Thepowersupplylineofthebox,thelatterisdedicatedtopreventelectricalfires.

Leakageprotectorshaveexperiencedalongdevelopmentprocessandarenowwidelyusedallovertheworld.

In1930,avoltage-operatedleakageprotectorwasinventedinEuropetopreventelectricalequipmentfromelectricshockaccidentsduetoinsulationdamage.In1960,acurrent-operatedleakageprotectorappeared.Atpresent,thevoltage-operatedleakageprotectorintheworldhasbeeneliminated,andthecurrent-operatedleakageprotectorhasbecomethemainelectricaldeviceforleakageandelectricshockprotection.

In1964,Japanbegantodevelopvoltage-operatedleakageprotectorstopreventelectricshockaccidentsatconstructionsites.In1966,electromagneticcurrent-operatedleakageprotectorswereintroducedfromWestGermany,andintegratedcircuitswereproducedin1976.Theleakageprotector.

TheUnitedStateshasusedcurrent-operatedleakageprotectorssince1967.Duetotheelectricshockaccidentinswimmingpools,thedevelopmentofleakageprotectorswasemphasized,andtheleakageprotectorwithaleakagecurrentof5mAwasrequiredfromthebeginning..

mycountrybegantodevelopvoltage-operatedleakageprotectorsin1966,begantodevelopandproduceelectromagneticleakageprotectorsin1976,anddevelopedandproducedintegratedcircuitleakageprotectorsaround1985.

Thepromotionandapplicationofleakageprotectorsareinseparablefromtheformulationofstandardsandregulations.The1971editionoftheNationalElectricalCode(NEC)oftheUnitedStatesstipulatesthatsinceJanuary1,1973,residentialandconstructionsitesmustbeequippedwithleakageprotectors.Japan’s"TechnicalStandardsforElectricalEquipment"andtheMinistryofLabor’s"SafetyandHealthRegulations"stipulatethatelectricalequipmentwithaworkingvoltageofmorethan60Vmustbeequippedwithleakageprotectorswhenusedinhumidplaces,andall400Vcircuitsmustbeequippedwithleakageprotectors.

In1981,mycountry'sformerStateConstructionandIndustryAdministration's"DecisiononStrengtheningLaborProtectionWork"stipulatedthatelectricalequipmentonconstructionsitesmustbeequippedwithleakageprotectiondevices.TheGB3787-1983"SafetyTechnicalRegulationsfortheManagement,Use,InspectionandMaintenanceofHand-heldPowerTools"formulatedin1983stipulatesthathand-heldpowertoolsmustuseleakageprotectors.The"SafetyTechnicalCode"stipulatesthatelectricalconstructionmachineryandhand-heldpowertoolsmustbeequippedwithleakageprotectors,andrequiretheimplementationofsecondaryleakageprotectionincludingthemainpowerleakageprotectionintheconstructionsite.

Features

First,whenthepowergridisgrounded,theleakageprotectoroperatesnormally.Inthiskindofnormalaction,duetotheagingofthepowergridandchangesintheclimateenvironment,themajorityoftheactionscausedbythegroundingpointofthepowergrid,andtheactionscausedbythepersonalelectricshockareveryfew.Itisconceivablethatthenormaluseofelectricityisthefirstdemandofpeople.Inordertopreventtheextremelylowprobabilityofpersonalelectricshockfromcausingfrequentpoweroutages,affectingnormalproductionandlifewillcertainlycausepeople'stroubles.

Second,thepowergridhasnotbeengrounded,buttheleakageprotectormaymalfunctioninthefollowingsituations:

1,becausetheleakageprotectoristriggeredbyasignal,thenOtherelectromagneticinterferencewillalsogenerateasignaltotriggertheactionoftheleakageprotector,causingamalfunction.

2,whenthepowerswitchisclosedandpowerissent,animpactsignalwillbegeneratedandtheleakageprotectorwillmalfunction.

3,thesumofmulti-branchleakagecancauseleapfrogandmisoperation.

4.Repeatedgroundingoftheneutralwiremaycausethestringcurrenttomalfunction.

Itcanbeseenthat,becauseofthepossibilityofmalfunctionoftheleakageprotectortechnically,thefrequencyproblemoftheleakageprotectorwillbecomemoreseriousandmorecomplicated.

Analyzedfromthetechnicalprinciple,theleakageprotectoralsohasatechnicalmisunderstandingthatmaycauserefusaltomove.

1.Whentheneutrallineisrepeatedlygrounded,itwillcausetheleakageprotectortoshuntandrefusetomove,andtherepeatedgroundingpointoftheneutrallineisdifficulttofind.

2,whenthepowersupplylacksphase,andthemissingphasehappenstobetheworkingpowersupplyoftheleakageprotector,itwillrefusetomove.

Fromtheaboveanalysis,itcanbeseenthatthefrequentoperationandrefusaloftheleakageprotectorinactualusearenotonlyduetotheobjectiveenvironmentandmanagement,butalsothetechnicalmisunderstandingoftheleakageprotectoritself.Inparticular,theuseofleakageprotectorsrequiresthattheneutralpointofthepowergridmustbegrounded,andmostofthetechnicalmisunderstandingsoftheleakageprotectorarerelatedtotheneutralpointgroundingofthepowergrid.Thesupportissubjectedtophasevoltagealltheyearround,sothesupportisbrokendown,formingagroundingpointofthepowergrid,causingleakageandcausingfrequentoperationoftheleakageprotector.

Secondly,becausetheneutralpointisgrounded,whenthephaselineisoccasionallygrounded,alargeleakagecurrentwillbegeneratedimmediately,whichwillnotonlyincreasetheelectricalloss,causefire,butalsoincreasethefrequencyoftheleakageprotector.move.

Thirdly,becausetheneutralpointisgrounded,whenapersongetsanelectricshock,itwillimmediatelyproducealargeelectricshockcurrent,whichisverythreateningtohumanlife.Evenifthereisaleakageprotector,itwillbeshockedfirstandthenactuateProtection,iftheactionissloworfails,theconsequenceswillbemoreserious.

Fourth,becausetheneutralpointisgrounded,thedistributedcapacitanceofthegridtothegroundisconnectedintheloop,whichwillincreasetheinrushcurrenttothegroundwhentheswitchisclosedandcausemalfunction.

Fifth,sincetheneutralpointhasbeengrounded,itisdifficulttofindrepeatedgroundingoftheneutralline.Repeatedgroundingoftheneutrallinewillcausetheleakageprotectortoshuntandrejecttheactionandcausetheseriesflowtomalfunction.

Itcanbeseenthattherearetechnicalerrorsintheleakageprotector,andthesetechnicalerrorsarecloselyrelatedtothegroundingofthecentralpointofthepowergrid.Whenusingtheleakageprotector,thecentralpointofthepowergridmustbegrounded.Itisimpossibletosolvetheproblemoffrequentmovementandrefusalwithinthetechnicalthinkingofthedevice.

Twopointsneedtobepointedoutinparticular:

1.Whenahumanbodysingle-phaseelectricshockaccidentoccurs(thiskindofaccidenthasthehighestprobabilityofelectricshockaccidents),thatis,ontheloadsideoftheleakageprotectorItcanplayaverygoodprotectiverolewhenittouchesaphasewire(livewire).Ifthehumanbodyisinsulatedfromtheground,whenittouchesaphaselineandaneutrallineatthistime,theleakageprotectorcannotplayaprotectiverole.

2.Sincetheroleoftheleakageprotectoristopreventtroublebeforeithappens,itsimportancecannotbereflectedwhenthecircuitisworkingnormally,anditisoftennoteasytoattracteveryone'sattention.Somepeopledonotseriouslyfindthecausewhentheleakageprotectorisactivated,butshort-circuitorremovetheleakageprotector.Thisisextremelydangerousandabsolutelynotallowed.

Mainstructure

Theleakageprotectorhashighsensitivityandrapidactioninresponsetoelectricshockandleakageprotection,whichisincomparabletootherprotectiveappliances,suchasfuses,automaticswitches,etc.of.Automaticswitchesandfusesmustpasstheloadcurrentwhentheyarenormal,andtheiractionprotectionvaluemustbesettoavoidthenormalloadcurrent.Therefore,theirmainfunctionistocutoffthephase-to-phaseshort-circuitfaultofthesystem(someautomaticswitchesalsohaveoverloadprotection)).Theleakageprotectorusestheresidualcurrentreactionandactionofthesystem.Duringnormaloperation,theresidualcurrentofthesystemisalmostzero,soitsactionsettingvaluecanbesettoaverysmallvalue(generallymAlevel).Whentheshelliselectrified,thereisalargeresidualcurrent,andtheleakageprotectorwillreliablyactandcutoffthepowerafterdetectingandprocessingtheresidualcurrent.

Whenelectricalequipmentleaks,itwillpresentanabnormalcurrentorvoltagesignal.Theleakageprotectordetectsandprocessesthisabnormalcurrentorvoltagesignaltoprompttheactuatortoact.Wecalltheleakageprotectorthatoperatesaccordingtothefaultcurrentasacurrenttypeleakageprotector,andtheleakageprotectorthatoperatesaccordingtothefaultvoltageiscalledavoltagetypeleakageprotector.Duetothecomplexstructureofthevoltage-typeleakageprotector,thestabilityoftheactioncharacteristicsduetoexternalinterferenceispoor,andthemanufacturingcostishigh,andithasbeenbasicallyeliminated.Theresearchandapplicationofleakageprotectorsathomeandabroadaredominatedbycurrentleakageprotectors.

Current-typeleakageprotectorsuseapartofthezero-sequencecurrentinthecircuit(usuallycalledresidualcurrent)astheactionsignal,andmostlyuseelectroniccomponentsastheintermediatemechanism,withhighsensitivityandcompletefunctions.Protectivedevicesareusedmoreandmorewidely.Thecurrentleakageprotectoriscomposedoffourparts:

1. Detectionelement:Thedetectionelementcanbesaidtobeazero-sequencecurrenttransformer.TheprotectedphaseandneutralwirespassthroughthetoroidalcoretoformtheprimarycoilN1ofthetransformer,andthewindingswoundonthetoroidalcoreformthesecondarycoilN2ofthetransformer.Ifthereisnoleakage,itwillflowthroughatthistime.Thecurrentvectorsumofthephaselineandtheneutrallineisequaltozero,sothecorrespondinginducedelectromotiveforcecannotbegeneratedonN2.Ifleakageoccurs,thesumofthecurrentvectorsofthephaselineandtheneutrallineisnotequaltozero,whichwillcauseaninducedelectromotiveforceonN2,andthissignalwillbesenttotheintermediatelinkforfurtherprocessing.

2. Intermediatelinks:Theintermediatelinksusuallyincludeamplifiers,comparators,andreleases.Whentheintermediatelinksareelectronic,theintermediatelinksalsoneedauxiliarypowersuppliestoprovideelectroniccircuitworkstations.Powerrequired.Thefunctionoftheintermediatelinkistoamplifyandprocesstheleakagesignalfromthezero-sequencetransformer,andoutputittotheactuator.

3. Actuator:Thisstructureisusedtoreceivetheinstructionsignaloftheintermediatelink,implementactions,andautomaticallycutoffthepowersupplyatthefault.

4. Testdevice:Sincetheleakageprotectorisaprotectiondevice,itshouldbecheckedregularlytoseeifitisintactandreliable.Thetestdeviceistosimulatetheleakagepaththroughtheseriesconnectionofthetestbuttonandthecurrent-limitingresistortocheckwhetherthedevicecanoperatenormally.

Workingprinciple

Basicprincipleanalysis

Beforeunderstandingthemainprincipleofelectricshockprotector,itisnecessarytounderstandwhatItwasanelectricshock.Electricshockreferstoinjurycausedbythepassageofelectriccurrentthroughthehumanbody.Whenahumanhandtouchesthewireandformsacurrentloop,thereiscurrentflowingthroughthehumanbody;whenthecurrentislargeenough,itcanbefeltbyhumansandcauseharm.Whenanelectricshockhasoccurred,itisrequiredtocutoffthecurrentintheshortesttime.Forexample,ifthecurrentpassingthroughapersonis50mA,itisrequiredtocutoffthecurrentwithin1second,ifthecurrentis500mApassingthroughthehumanbody,Thenthetimelimitis0.1seconds.

Thefigureisaschematicdiagramofasimpleleakageprotectiondevice.Itcanbeseenfromthefigurethattheleakageprotectiondeviceisinstalledattheentranceofthepowercord,thatis,nearthewatt-hourmeter,andconnectedtotheoutputendofthewatt-hourmeter,thatis,theuserside.Inthefigure,allhouseholdappliancesarereplacedwitharesistorRL,andRNisusedtoreplacethebodyresistanceofthecontactperson.

CTinthefigurestandsfor"currenttransformer".ItusestheprincipleofmutualinductancetomeasureACcurrent,soitiscalled"transformer",whichisactuallyatransformer.ItsprimarycoilistheAClinethatentersthehouse,andthetwowiresaretakenasonewireandcombinedtoformtheprimarycoil.Thesecondarycoilisconnectedtothecoilofthe"reedrelay"SH.

Theso-called"reedrelay"istowindacoilontheoutsideofthereedtube.Whenthecoilisenergized,themagneticfieldgeneratedbythecurrentmakesthereedelectrodeinsidethereedtubepullintoconnectExternalcircuit.Afterthecoilisde-energized,thereedisreleasedandtheexternalcircuitisdisconnected.Allinall,thisisasmallrelay.

TheswitchDZintheschematicdiagramisnotanordinaryswitch,itisaswitchwithaspring.Whenapersonovercomesthespringforcetocloseit,aspecialhookmustbeusedtobuckleittoensurethatitison.Thestate;otherwise,itwillbebrokenassoonasyouletgo.

Thereedelectrodeofthereedrelayisconnectedtothe"tripcoil"TQcircuit.Thetrippingcoilisanelectromagnetcoil,whichgeneratesattractiveforcewhenpassingcurrent.ThisattractiveforceisenoughtoreleasethehookmentionedaboveandmakeDZdisconnectimmediately.BecausetheDZisconnectedtothelivewireoftheuser'smainwire,theelectricitywillbecutoffwhenitistripped,andthepersonwhogetsanelectricshockwillbesaved.

However,thereasonwhyaleakageprotectorcanprotectpeopleisthatitmustfirst"consciousness"thatpeopleareelectrocuted.Sohowdoestheleakageprotectorknowthatapersonhasbeenelectrocuted?Itcanbeseenfromthefigurethatifthereisnoelectricshock,thecurrentinthetwowiresfromthepowersupplymustbethesameatalltimes,butinoppositedirections.Therefore,themagneticfluxintheprimarycoiloftheCTcompletelydisappears,andthereisnooutputfromthesecondarycoil.Ifsomeonegetsanelectricshock,itisequivalenttoaresistanceonthelivewire,sothatitcaninterlockandcauseacurrentoutputonthesecondaryside.ThisoutputcanmaketheSH'selectricshockpullandclose,sothatthetrippingcoilisenergized,thehookissuckedoff,andtheDZisswitchedon.Disconnect,thusplayingaprotectiverole.

Itisworthnotingthatoncetripped,evenifthecurrentinthetrippingcoilTQdisappears,itwillnotreconnectDZbyitself.Thepowersupplycannotberestoredbecausenooneclosesit.Theelectricshockerleaves,andwantstouseelectricityagainaftercheckingthattherearenohiddendangers.YouneedtoclosetheDZtore-buckleit,andthepowersupplyisrestored.

Theaboveisthemainprincipleoftheelectricshockprotector,butevenwiththeelectricshockprotector,itcannotbeconsideredasfoolproof.Youshouldstillpayattentiontosafetywhenusingelectricity.

1.Itcanbeseenfromthefigurethatwhenthecircuitisworkingnormally,thecurrenttheoremknowsthatthecurrentflowinginandoutofoneendofthenetworkis0,sothesumofthecurrentontherightsideoftheleakageprotectorshouldbe0,Thatis,I1+I2+I3+IN=0;therefore,theleakageprotectorwillnotwork.Notethattheactualdirectionofthecurrentdependsontheactualcircuit.Inthisexample,thedirectionofINisoppositetoI1,I2,andI3.

2.Whenthedeviceshellleaksandsomeonetouchesit,apartofthecurrentIKwillflowintothegroundthroughthehumanbody,sothatthetotalcurrentontherightsideoftheleakageprotectorisnot0,thatistosayI1+I2+I3+IN≠0,whentheleakagecurrentreachestheoperatingcurrentoftheleakageprotector,theleakageprotectorwillacttoturnoffthepowersupply,thusachievingthepurposeofleakageprotection.

Payattentiontothefollowingtwopoints

1.Theneutrallinepassingthroughtheleakageprotectorshallnotbeusedasaprotectionline.Fromtheabovefigure,itcanbeseenthatwhenaleakagecurrentisgenerated,theleakagecurrentIK1passesthroughtheequipmentshell.Itflowsbacktotheleakageprotector.Atthistime,thesumofthecurrentontherightsideoftheleakageprotectorisstill0,sotheleakageprotectorwillnotoperate,sothepurposeofleakageprotectionisnotachieved.

2.Theworkingneutralwirepassingthroughtheleakageprotectorshallnotbegroundedrepeatedly.Ascanbeseenfromtheabovefigure,ifthegroundingisrepeated,partofthecurrentwillbedissipatedbytheearth,whichwillcausethesumofthecurrentontherightsideoftheleakageprotectorItisnot0,sothattheleakageprotectoristurnedoff,andotherelectricalequipmentcannotbeused.

3.Description:Thisexamplediagramisonlytoexplaintheworkingprincipleoftheleakageprotector.Howtoconnecttheactualleakageprotectorshouldbedeterminedaccordingtothezeroprotectionsystemusedbythesystem.

Switchschematicdiagram

Inthefigure,Lisanelectromagnetcoil,whichcandrivetheknifeswitchK1toopenwhenleakageoccurs.Eachbridgearmusestwo1N4007inseriestoincreasethewithstandvoltage.Theresistancevalues​​ofR3andR4arelarge,sowhenK1isclosed,thecurrentflowingthroughLisverysmall,whichisnotenoughtocauseK1todisconnect.R3andR4arethevoltageequalizingresistorsoftheSCRT1andT2,whichcanreducethewithstandvoltagerequirementsoftheSCR.K2isatestbutton,whichsimulatesleakage.PressthetestbuttonK2,K2isconnected,whichisequivalenttotheleakageoftheexternallivewiretotheground.Inthisway,thevectorsumofthecurrentthroughthethree-phasepowerlineandtheneutrallineofthemagneticringisnotzero.Thereisaninducedvoltageoutputatbothendsofb,andthisvoltageimmediatelytriggersT2toturnon.SinceC2hasacertainvoltageinadvance,afterT2isturnedon,C2isdischargedthroughR6,R5,andT2,sothatavoltageisgeneratedonR5totriggerT1toturnon.AfterT1andT2areturnedon,thecurrentflowingthroughLincreases,whichcausestheelectromagnettoact,andthedriveswitchK1isturnedoff.Thefunctionofthetestbuttonistocheckwhetherthefunctionofthedeviceisintactatanytime.Theprincipleofelectromagnetactioncausedbyelectricequipmentleakageisthesame.R1isavaristor,whichplaysaroleofovervoltageprotection.

Thecircuitbreakerhassimpleprinciples,fewparts,andeasymaintenance.Whenreplacingparts,payattentiontothereliabilityandparametersofthepartstomeettherequirements.

Installationscope

In1992,thenationalstandardGB13955-1992"InstallationandOperationofEarthLeakageProtectors"issuedbytheStateBureauofTechnicalSupervisionmadeuniformprovisionsfortheinstallationofleakageprotectorsinurbanandruralareasacrossthecountry.

2.1Equipmentandplaceswhereleakageprotectors(leakageswitches)mustbeinstalled

(1)ClassImobileelectricalequipmentandhand-heldpowertools(ClassIelectricalproducts,Thatis,theprotectionagainstelectricshockoftheproductnotonlyreliesonthebasicinsulationoftheequipment,butalsoincludesadditionalsafetyprecautions,suchastheproductshellgrounding);

(2)Installedindamp,highlycorrosiveandotherharshplacesElectricalequipment;

(3)Electricalconstructionmachineryandequipmentonconstructionsites;

(4)Temporaryelectricalequipmentfortemporaryuseofelectricity;

(5))Socketcircuitsinguestroomsofhotels,restaurantsandguesthouses;

(6)Socketcircuitsininstitutions,schools,enterprises,residentialbuildingsandotherbuildings;

(7)Swimmingpools,fountains,Waterlightingequipmentinbaths;

(8)powersupplylinesandequipmentinstalledinthewater;

(9)electricalmedicalequipmentdirectlyincontactwiththehumanbodyinhospitals;

(10)Otherplaceswherealeakageprotectorneedstobeinstalled.

2.2Applicationofalarm-typeleakageprotector

Onceleakageoccursandcutoffthepowersupply,electricalinstallationsorplacesthatwillcauseaccidentsormajoreconomiclossesshouldbeinstalledwithalarm-typeleakageprotectors,Suchas:

(1)Channellightingandemergencylightinginpublicplaces;

(2)Fire-fightingelevatorsandequipmenttoensuresafetyinpublicplaces;

(3)Powersupplyforfire-fightingequipment,suchasfirealarmdevices,fire-fightingwaterpumps,fire-fightingpassagelighting,etc.;

(4)Powersupplyforanti-theftalarm;

(5)Otherspecialequipmentandplaceswherepowerfailureisnotallowed.

Usedifference

Theleakageprotectorisinstalledattheoutletofthebranchcircuit,andtheleakageprotectionsocketisinstalledateachendoftheelectricalappliance,whichisaterminalinstallation.Installationandmaintenancearemoreconvenient.

2,thedifferencewhenleakageoccurs

Whenthelineleakage,becauseitisinstalledattheexitofthebranchline,theterminalfailurewillcausetheentirebranchtobepoweredoffandthereisnoelectricityinthehouse,andleakageProtectthesocket.Whenthereiselectricityleakageinthebranchorline,onlythesinglebranchlineisnotenergized,andtheelectricalappliancecannotwork.

3.Thedifferenceofwiringprotection

Theleakageprotectorhasonlylivelineprotection,whiletheleakageprotectionsockethaslivelineandneutrallineprotection.

4.Thedifferencebetweenleakagecurrentandleakagetriptime:

Leakageprotector:I△n=30mA,actiontime0.1S,leakageprotectionsocket:I△n=6mA,Theactiontimeis0.025S.Leakageprotectionsocket,theratedresidualleakagecurrentissmaller,safer,lessharmfultothehumanbody,andquicktripping.Protecthumanlifeandpropertysafety.

ItsapplicablescopeisAC50HZratedvoltage380V,ratedcurrentto250A.

Theinstallationofaleakageprotectorinthelow-voltagepowerdistributionsystemisoneoftheeffectivemeasurestopreventpersonalelectricshockaccidents,anditisalsoatechnicalmeasuretopreventelectricalfiresandelectricalequipmentdamageaccidentscausedbyelectricalleakage.However,theinstallationofaleakageprotectordoesnotmeanabsolutesafety.Duringoperation,preventionshouldbegivenpriority,andothertechnicalmeasurestopreventelectricshockanddamagetoelectricalequipmentshouldbetakenatthesametime.

Selectionprinciple

Inordertoregulatethecorrectuseofleakageprotectors,thecountryhassuccessivelypromulgatedthe"RegulationsontheSafetySupervisionofLeakageProtectors"(Laoanzi(1999)No.16)and"LeakageAseriesofstandardsandregulationssuchastheinstallationandoperationofprotectors(GB13955-92).

Accordingtothesestandardsandregulations,weshouldfollowthefollowingmainprincipleswhenchoosingaleakageprotector:

1.Whenbuyingaleakageprotector,youshouldbuyaQualifiedmanufacturer'sproducts,andtheproductqualityinspectionisqualified.Iwouldliketoremindeveryonehere:manyoftheleakageprotectorssoldonthemarketaresubstandardproducts.OnOctober28,2002,theGeneralAdministrationofQualitySupervision,InspectionandQuarantineannouncedtheresultsoftherandominspectionoftheproductqualityofleakageprotectors.About20%oftheproductswereunqualified.Themainproblemswere:somecouldnotnormallybreaktheshort-circuitcurrenttoeliminatethefirehazard;somedidnotIthastheprotectiveeffectofpersonalelectricshock;therearesometripswhentheyshouldnotbetripped,whichaffectsthenormaluseofelectricity.

2.Thepowersupplyvoltage,workingcurrent,leakagecurrentandoperatingtimeoftheleakageprotectorshouldbedeterminedaccordingtothescopeofprotection,personalequipmentsafetyandenvironmentalrequirements.

3.Whenthepowersupplyadoptsleakageprotectorforhierarchicalprotection,itshouldmeettheselectivityofupperandlowerswitchactions.Generally,theratedleakagecurrentoftheupper-levelleakageprotectorisnotlessthantheratedleakagecurrentofthenext-levelleakageprotector,whichcansensitivelyprotectthesafetyofpeopleandequipment,andcanalsoavoidskippingtripsandreducethescopeofaccidentinspection.

4.Hand-heldpowertools(exceptClassIII),mobilehouseholdappliances(exceptClassIII),othermobileelectromechanicalequipment,andelectricalequipmentwithgreaterriskofelectricshock,Aleakageprotectormustbeinstalled.

5.Electricalequipmentforconstructionsitesandtemporarylinesshouldbeinstalledwithleakageprotectors.Thisisclearlyrequiredinthe"TechnicalCodeforSafetyofTemporaryUseofElectricityatConstructionSites"(JGJ46-88).

6.Thesocketcircuitsinoffices,schools,enterprises,andresidentialbuildings,aswellasthesocketcircuitsinguestroomsofhotels,restaurantsandguesthouses,mustalsobeequippedwithleakageprotectors.

7.Powersupplylinesandequipmentinstalledinthewater,aswellasplaceswithhighhumidity,hightemperature,largemetaloccupancyandothergoodelectricalconductivity,suchasoperationsinmachineryprocessing,metallurgy,textiles,electronics,foodprocessingandotherindustriesPlaces,aswellasboilerrooms,waterpumprooms,canteens,bathrooms,hospitalsandotherplaces,mustbeprotectedbyleakageprotectors.

8.Powerdistributionboxeswithleakageprotectorsshouldbeusedforfixedlineelectricalequipmentandnormalproductionsites.Fortemporaryuseofsmallelectricalequipment,leakageprotectionplugs(seats)orsocketboxeswithleakageprotectionshouldbeused.

9.Whentheleakageprotectorisusedasasupplementaryprotectionfordirectcontactprotection(notastheonlydirectcontactprotection),ahigh-sensitivity,fast-actingleakageprotectorshouldbeselected.

Generalenvironmentchoosetheactioncurrentnottoexceed30mAandtheactiontimetonotexceed0.1s.Thesetwoparametersensurethatifthehumanbodygetsanelectricshock,itwillnotcausethepersonwhoisshockedtoproducepathologicalandphysiologicaldangerouseffects.

Theratedoperatingcurrentoftheleakageprotectorinbathrooms,swimmingpoolsandotherplacesshouldnotexceed10mA.

Inoccasionsthatmaycausesecondaryaccidentsafteranelectricshock,aleakageprotectorwitharatedoperatingcurrentof6mAshouldbeselected.

10.Forelectricalequipmentthatisnotallowedtobepoweredoff,suchaschannellightinginpublicplaces,emergencylighting,powersupplyforfire-fightingequipment,powersupplyforanti-theftalarm,etc.,analarmleakageprotectorshouldbeusedtoswitchonSoundandlightalarmsignalsinformthemanagementpersonneltodealwiththefaultintime.

Technicalparameters

Themainoperatingperformanceparametersare:ratedleakageoperatingcurrent,ratedleakageoperatingtime,andratedleakagenon-operatingcurrent.Otherparametersinclude:powerfrequency,ratedvoltage,ratedcurrent,etc.

①Ratedleakageoperatingcurrent

Underthespecifiedconditions,thecurrentvaluethatcausestheleakageprotectortooperate.Forexample,a30mAprotector,whenthecurrentvaluereaches30mA,theprotectorwillacttodisconnectthepowersupply.

②Ratedleakageactiontime

referstothetimefromwhentheratedleakageactioncurrentissuddenlyappliedtothetimetheprotectioncircuitiscutoff.Forexample,fora30mA×0.1sprotector,thetimefromthecurrentvaluereaching30mAtotheseparationofthemaincontactdoesnotexceed0.1s.

③Ratednon-operatingleakagecurrent

Underthespecifiedconditions,thecurrentvalueofthenon-operatingleakageprotectorshouldgenerallybeone-halfoftheleakageoperatingcurrentvalue.Forexample,aleakageprotectorwithaleakageactioncurrentof30mA,whenthecurrentvaluereaches15mAorless,theprotectorshouldnotoperate.Otherwise,itmaymalfunctionduetotoohighsensitivityandaffectthenormaloperationofelectricalequipment.

④Otherparameterssuchas:powerfrequency,ratedvoltage,ratedcurrent,etc.,whenselectingaleakageprotector,itshouldbecompatiblewiththecircuitandelectricalequipmentused.Theworkingvoltageoftheleakageprotectorshouldadapttotheratedvoltageofthenormalfluctuationrangeofthepowergrid.Ifthefluctuationistoolarge,itwillaffectthenormaloperationoftheprotector,especiallyforelectronicproducts.Whenthepowersupplyvoltageislowerthantheratedworkingvoltageoftheprotector,itwillrefusetooperate.Theratedworkingcurrentoftheleakageprotectorshouldalsobeconsistentwiththeactualcurrentintheloop.Iftheactualworkingcurrentisgreaterthantheratedcurrentoftheprotector,itwillcauseoverloadandcausetheprotectortomalfunction.

Ratedcurrent

Itisveryimportanttoselecttheratedleakagecurrentoftheleakageprotectorcorrectlyandreasonably:ontheonehand,whenanelectricshockoccursortheleakagecurrentexceedstheallowablevalue,theleakageprotectorcanbeselectedGroundaction;ontheotherhand,theleakageprotectorshouldnotoperateundertheactionofnormalleakagecurrenttopreventtheinterruptionofpowersupplyandcauseunnecessaryeconomiclosses.

Theratedleakageoperatingcurrentoftheleakageprotectorshouldmeetthefollowingthreeconditions:

(1)Inordertoensurepersonalsafety,theratedleakageoperatingcurrentshouldnotbegreaterthanthehumansafetycurrentvalue.Itisrecognizedthatnohigherthan30mAisasafecurrentvalueforthehumanbody;

(2)Inordertoensurethereliableoperationofthepowergrid,theratedleakageactioncurrentshouldavoidthenormalleakagecurrentofthelow-voltagepowergrid;

(3)Inordertoensuretheselectivityofmulti-levelprotection,theratedleakagecurrentofthenextlevelshouldbelessthantheratedleakagecurrentofthepreviouslevel,andtheratedleakagecurrentofeachlevelshouldhavealeveldifferenceof112to215times.

Thefirst-levelleakageprotectorisinstalledattheoutletofthelow-voltagesideofthedistributiontransformer.

Thelineofthislevelofprotectionislongandtheleakagecurrentislarge.Theratedleakageactioncurrentshallnotexceed100mAwithoutperfectmulti-levelprotection;whenithasperfectmulti-levelprotection,theleakagecurrentissmall.Forpowergrids,75mAinnon-rainyseasonsand200mAinrainyseasons.Forgridswithlargerleakagecurrents,itis100mAinnon-rainyseasonsand300mAinrainyseasons.

Thesecond-levelleakageprotectorisinstalledattheexitofthebranchcircuit.Theprotectedcircuitisshort,thepowerconsumptionisnotlarge,andtheleakagecurrentissmall.Theratedleakagecurrentoftheleakageprotectorshouldbebetweentheratedleakagecurrentoftheupperandlowerlevelprotectors,generally30～75mA.

Thethird-levelleakageprotectorisusedtoprotectsingleormultipleelectricalequipment.Itisaprotectiveequipmenttodirectlypreventpersonalelectricshock.Thepowerconsumptionoftheprotectedcircuitandequipmentissmall,andtheleakagecurrentissmall,generallynotexceeding10mA.Aleakageprotectorwitharatedoperatingcurrentof30mAandanoperatingtimeoflessthan0.1sshouldbeselected.

Wiringmethod

TNsystemmeansthatthelow-voltageneutralpointofthedistributionnetworkisdirectlygrounded,andtheexposedconductivepartoftheelectricalequipmentisconnectedtothegroundingpointthroughtheprotectivewire.

TNsystemcanbedividedinto:

TN-SsystemTheneutrallineandtheprotectionlineofthewholesystemareseparated.

TN-CsystemTheneutrallineandtheprotectionlineoftheentiresystemareintegrated.

ThefirstpartoftheprotectionlineandtheneutrallineoftheTN-C-Ssystemtrunklineareshared,andthelatterpartisseparate.

Phaseline(EnglishLIVE)Lisgenerallyredorbrown(IECsystem)orblack(ULsystem)

Neutralline(EnglishNEUTRAL)N(neutralline)generalBlue(IECsystem)orwhite(ULsystem)

Earthwire(EnglishEARTH)EGenerallyyelloworyellow-green

Operationandmaintenance

ExceptInadditiontotheconventionalelectricalequipmentinstallationregulations,thefollowingpointsshouldbenoted:

1.Theinstallationoftheleakageprotectorshouldmeettherequirementsofthemanufacturer'sproductmanual.

2.Theleakageprotectorsmarkedonthepowersupplysideandtheloadsidemustnotbeconnectedinreverse.Iftheconnectionisreversed,thetripcoiloftheelectronicleakageprotectorwillnotbecutoffwhenthepoweriscutoff,anditwillbeburntwhenitisenergizedforalongtime.

3.Theoriginalsafetyprotectionmeasuresmustnotberemovedorabandonedwheninstallingtheleakageprotector.Theleakageprotectorcanonlybeusedasanadditionalprotectionmeasureintheelectricalsafetyprotectionsystem.

4.Wheninstallingaleakageprotector,theneutrallineandtheprotectionlinemustbestrictlydistinguished.Whenusingthree-polefour-wireandfour-polefour-wireleakageprotector,theneutrallineshouldbeconnectedtotheleakageprotector.Theneutrallinepassingthroughtheleakageprotectorshallnotbeusedasaprotectionline.

5.Theworkingneutrallinemustnotbegroundedrepeatedlyontheloadsideoftheleakageprotector,otherwisetheleakageprotectorcannotworknormally.

6.Forthebranchcircuitusingtheleakageprotector,itsworkingneutrallinecanonlybeusedastheneutrallineofthiscircuit,anditisforbiddentoconnectwiththeworkingneutrallineofothercircuits,andotherlinesorequipmentcannotbeusedforleakageprotection.Thelinebehindthedeviceortheworkingzerolineoftheequipment.

7.Aftertheinstallationiscompleted,itmustbeinaccordancewiththe"ConstructionQualityAcceptanceSpecificationforBuildingElectricalEngineering(GB50303-2002)3.1.6,thatis,"theleakageprotectorofthepowerandlightingengineeringshouldbesimulatedactiontest"Itisrequiredtotestthecompletedleakageprotectortoensureitssensitivityandreliability.Duringthetest,youcanoperatethetestbuttonthreetimes,openandclosetheloadthreetimes,andconfirmthattheactioniscorrectbeforeitcanbeofficiallyputintouse.

Thesafeoperationoftheleakageprotectordependsonasetofeffectivemanagementsystemsandmeasures.Inadditiontoregularmaintenance,theoperatingcharacteristicsoftheleakageprotector(includingleakageactionvalueandoperatingtime,leakagenon-operatingcurrentvalue,etc.)shouldbetestedregularly,andthetestrecordsshouldbemade,andthevalueshouldbecomparedwiththeinitialvalueoftheinstallation.Compareandjudgewhetherthereisanychangeinitsquality.

Inuse,usetheleakageprotectorinaccordancewiththerequirementsoftheinstructionmanual,andcheckitonceamonthasrequired,thatis,operatethetestbuttonoftheleakageprotectortocheckwhetheritcannormallydisconnectthepowersupply.Duringtheinspection,itshouldbenotedthatthetimetooperatethetestbuttonshouldnotbetoolong.Generally,itisadvisabletojog,andthenumberoftimesshouldnotbetoomany,soastoavoidburningtheinternalcomponents.

Theleakageprotectortripsduringuse.Ifthecauseoftheswitchactionisnotfoundafterinspection,itisallowedtotestthepoweronce.Ifittripsagain,thecauseshouldbefoundoutandthefaultshouldbefoundout,andthepowershouldnotbecontinuouslyforciblysent.

Oncetheleakageprotectorisdamagedandcannotbeused,itshouldbecheckedorreplacedbyaprofessionalelectricianimmediately.Iftheleakageprotectormalfunctionsorrefusestooperate,thereasonisontheonehandcausedbytheleakageprotectoritself,andontheotherhand,itisfromtheline.Itshouldbecarefullyanalyzedindetail,andtheinternalcomponentsoftheleakageprotectorshouldnotbedisassembledandadjustedprivately.

Instructionsforuse

(1)Theleakageprotectorissuitableforlow-voltagepowerdistributionsystemswheretheneutralpointofthepowersupplyisdirectlygroundedorgroundedthroughresistanceandreactance.Forsystemswheretheneutralpointofthepowersupplyisnotgrounded,leakageprotectorsshouldnotbeused.Becausethelattercannotformaleakageelectricalcircuit,evenifagroundfaultoccursandaratedoperatingcurrentgreaterthanorequaltotheleakageprotectorisgenerated,theprotectorcannotactintimetocutoffthepowercircuit;orrelyonthehumanbodytoconnecttothefaultpointtoformaleakageelectricalcircuit.Thecircuitpromptstheactionoftheleakageprotectorandcutsoffthepowercircuit.However,thisisstillnotsafeforthehumanbody.Obviously,itisnecessarytohavetheconditionsofagroundingdevice.Whenanelectricalequipmentleaksandtheleakagecurrentreachestheoperatingcurrent,itcanimmediatelytripwithin0.1secondsandcutoffthemaincircuitofthepowersupply.

(2)TheworkingneutrallineNoftheleakageprotectorprotectioncircuitmustpassthroughazero-sequencecurrenttransformer.Otherwise,afterswitchingon,therewillbeanunbalancedcurrentthatwillcausetheleakageprotectortomalfunction.

(3)Connectingtothezeroprotectionline(PE)isnotallowedtopassthroughthezerosequencecurrenttransformer.Becausewhentheprotectivecircuit(PE)passesthroughthezerosequencecurrenttransformer,theleakagecurrentpassesthroughthezerosequencecurrenttransformerthroughthePEprotectionline,causingthecurrenttobeoffset,andtheleakagecurrentvaluecannotbedetectedonthetransformer.Intheeventofafault,theleakageprotectorwillnotoperateandfailtoprotect.

(4)Theworkingneutralwireofthecontrolloopcannotbegroundedrepeatedly.Ontheonehand,whengroundingisrepeated,undernormalworkingconditions,partoftheoperatingcurrentreturnstotheneutralpointofthepowersupplythroughrepeatedgrounding,andanunbalancedcurrentwillappearinthecurrenttransformer.Whentheunbalancedcurrentreachesacertainvalue,theleakageprotectorwillmalfunction;ontheotherhand,whentheleakageoccursduetoafault,theleakagecurrentontheprotectionlinemayalsopassthroughtheindividuallineofthecurrenttransformerandreturntotheneutralpointofthepowersupplytooffsetTheleakagecurrentofthetransformerisreduced,andtheprotectorrefusestooperate.

(5)TheworkingneutrallineNandtheprotectionline(PE)behindtheleakageprotectorcannotbecombinedintoone.Ifthetwoarecombinedintoone,whenthereisaleakagefaultorahumanbodyisshocked,theleakagecurrentflowsbackthroughthecurrenttransformer,andtheresultissimilartothesituation(3),causingtheleakageprotectortorefusetooperate.

(6)Thelinesbetweentheprotectedelectricalequipmentandtheleakageprotectorcannottoucheachother.Ifthereisaline-to-linecollisionorazero-linecross-connection,itwillimmediatelydestroythezero-sequencebalancecurrentvalueandcausetheleakageprotectortomalfunction;inaddition,theprotectedelectricalequipmentcanonlybeinstalledinparallelaftertheleakageprotector.Ensurethatitiscorrect,anditisnotallowedtoconnectelectricalequipmenttothewiringoftheexperimentbutton.

Relatedstandards

1,GB14048.2circuitbreaker

2,GB16916.1RCCB

3,GB16917.1RCBO

4,GB20044PRCD

5,GB10963.1MCB

6.GeneralrequirementsforGB6829leakageprotectors