英文文献CirtcuitBreakersAcircuitbreakerismechanicalswitchingdevicecapableofmaking,andbreakingcurrentsundernormalcircuitconditionsandalsomaking.carringforaspecifiedtime,andmediujminwhichcircuitinterruptionisperformedmaybedesignatedbyasuitableprefix,forexample,air-blastcircuitbreaker,oilcircuitbreaker.Thecircuitbreakerscurrentlyinusecanbedlassifiedintothefollowingcategoriesaccordingtothearc-quenchingprinciples:airswetchesoelciryitbreakers,minmum-oilcircuitbreakers,air-blastcircuitbreakers,themageneticaircircuitbreakers,minimum-oilcircuitbreakers,aer-blastcircuitbreakers,thebyvoltage,insulationlevelcurrent,interruptingcapabilities,transientrecoverycoltage,interruptingtiome,andtripdelay.Thenameplateonacircuitbreakerusuallyindicates:１.Themaximumsteady-statecurrentitcancarry,2.Themaximuminterruptingcurrent,3.Themaximumlinevoltage,4.Theinterruptingtimeincycles,Theinterruptingtimeinmaylastform3to8cyclesona60Hzsystem.Tointerrubtlargecurrentsquickly,wehavetoensurerapidcooling.High-speedinterruptionlunitsthedamagetransmissionlinesandequipmentand,equallyimportant,ithelpstomainmainthestabilityofthesystemwheneveracontingencyoccurs.Themainpartsofacircuitbreakerareusually:arc-quenchingchamber(orinterrupterwithmovingandfixedcontacts)operatingmechanismandsupportingstructures.AirSwitches-Withincreasingcurrentsandvoltages,spring-actiondrivingmechanismsweredevelopedtoreducecontactburingbyfaster-openingoperation.Later,maincontactswerefittedwitharcingcontactsofspecialmaterialandshape,whichopendafterandclosedbeforethemaincontacts.Furtherimprovementsoftheairswitchwerethebursh-typecontactwithawipingandcleaningfunction,theinsulatingbarrierleadingtoarcchutes,andblowoutcoilswithexcellentarc-extinguishingproperties.Thesefeatures,aswellasthehorngapcontact,arestillinuseinlowvoltageasanddebreakers.OilCircuitBreakerAround1900,inordertocopewiththenewrequirementfor“interruptingcapacity”,ACswitcheswereimmersedinatankofoil.Isveryeffectiveinquenchingthearcandestablishingtheopen