Introduction
Thermalfuseismainlyusedforoverloadprotection.Ifthefuseisproperlyplacedinthecircuit,thefusewillfuseandcutoffthecurrentwhenthecurrentrisestoacertainheightandheatabnormally,whichprotectsthesafeoperationofthecircuit.
Whenacircuitbreaksdownorisabnormal,thecurrentwillcontinuetorise,andtherisingcurrentmaydamagesomeimportantcomponentsinthecircuit,oritmayburnthecircuitorevencauseafire.Ifthefuseiscorrectlyinstalledinthecircuit,thefusewillfuseandcutoffthecurrentwhenthecurrentabnormallyrisestoacertainheightandheat,therebyprotectingthesafeoperationofthecircuit.
Workingprinciple
Whencurrentflowsthroughtheconductor,theconductorwillgenerateheatduetotheresistanceoftheconductor.Andthecalorificvaluefollowsthisformula:Q=0.24I2RT;whereQisthecalorificvalue,0.24isaconstant,Iisthecurrentflowingthroughtheconductor,Ristheresistanceoftheconductor,andTisthecurrentThetimeflowingthroughtheconductor;accordingtothisformula,itisnotdifficulttoseethesimpleworkingprincipleofthefuse.
Whenthematerialandshapeofthefusearedetermined,itsresistanceRisrelativelydetermined(ifthetemperaturecoefficientofresistanceisnotconsidered).Whencurrentflowsthroughit,itwillheatup,anditsheatwillincreasewiththeincreaseoftime.Thecurrentandresistancedeterminethespeedofheatgeneration.Thestructureofthefuseanditsinstallationstatusdeterminethespeedofheatdissipation.Iftherateofheatgenerationislessthantherateofheatdissipation,thefusewillnotblow.Iftherateofheatgenerationisequaltotherateofheatdissipation,itwillnotfuseforalongtime.Iftherateofheatgenerationisgreaterthantherateofheatdissipation,thenmoreandmoreheatwillbegenerated.Andbecauseithasacertainspecificheatandquality,theincreaseinheatismanifestedintheincreaseintemperature.Whenthetemperaturerisesabovethemeltingpointofthefuse,thefuseblows.
Productspecifications
1)RHseries(lowmeltingpointalloytype,plasticsquareshellshape,70℃-150℃ratedoperatingtemperature,1/2/3/5Aratedcurrent);
2)RFseries(lowmeltingpointalloytype,ceramiccylindricalshape,70℃-240℃ratedoperatingtemperature,1/2/3/5/10/15/20/25Aratedcurrent);
3)RSseries(lowmeltingpointalloytype,ceramic/plasticmountingholeshape,70℃-280℃ratedoperatingtemperature,5/10Aratedcurrent);
4)RYseries(organicchemicaltype,metalcylindricalshape,65℃-300℃ratedoperatingtemperature,10/15/16/20Aratedcurrent).
Explanationofterms
Ratedoperatingtemperature(Tf):
Thetemperaturefuseistestedaccordingtothestandardmethodtochangeitsconductivestatetemperature.AccordingtothesafetystandardsbasedonIEC6091,thethermalfusemustoperatewithintherangeofratedoperatingtemperature+0/-10°C(thetolerancerangespecifiedbytheJapaneseElectricalAppliancesManagementLawis±7°C).
Measuredoperatingtemperature:
Thetemperaturefuseisheatedinthesiliconeoilbathatarateof0.5-1°Cperminute,measuredundertheconditionthatthedetectioncurrentislessthan10mAFusingtemperature.Itistheactualoperatingtemperatureofthethermalfuse.
Holdingtemperature(Th):
Whenthethermalfusepassestheratedcurrent,itcanmaintainthehighesttemperaturefor168hourswithoutchangingitsconductivestate.
Limittemperature(Tm):
Themaximumtemperatureatwhichthethermalfusecanwithstand10minuteswithoutreconnection.
Ratedcurrent(Ir):
Themaximumcurrentthatthethermalfusecancarry.
Ratedvoltage(Ur):
Themaximumoperatingvoltageofthethermalfuse.