Въведение
Thermalfuseismainlyusedforoverloadprotection.Ifthefuseisproperlyplacedinthecircuit,thefusewillfuseandcutoffthecurrentwhenthecurrentrisestoacertainheightandheatabnormally,whichprotectsthesafeoperationofthecircuit.
Whenacircuitbreaksdownorisabnormal,thecurrentwillcontinuetorise,andtherisingcurrentmaydamagesomeimportantcomponentsinthecircuit,oritmayburnthecircuitorevencauseafire.Ifthefuseiscorrectlyinstalledinthecircuit,thefusewillfuseandcutoffthecurrentwhenthecurrentabnormallyrisestoacertainheightandheat,therebyprotectingthesafeoperationofthecircuit.
Принцип на работа
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.
Продуктови спецификации
1) Серия RH (тип сплав с ниска точка на топене, пластмасова квадратна форма на черупка, 70℃-150℃ номинална работна температура, 1/2/3/5 номинален ток);
2) Серия RF (тип сплав с ниска точка на топене, керамична цилиндрична форма, 70℃-240℃ номинална работна температура, 1/2/3/5/10/15/20/25 Номинален ток);
3) Серия RS (тип сплав с ниска точка на топене, форма на монтажен отвор от керамика/пластмаса, 70℃-280℃ номинална работна температура, 5/10 номинален ток);
4) Серия RY (органичен химичен тип, металоцилиндрична форма, 65 ℃ -300 ℃ номинална работна температура, 10/15/16/20 номинален ток).
Обяснение на термините
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):
Максималният ток, който може да понесе топлинният предпазител.
Ratedvoltage(Ur):
Максималното работно напрежение на термопредпазителя.