ACB vs MCCB | Differences between ACB and MCCB

ACB stands for air circuit breaker, MCCB stands for molded case circuit breaker. Both devices protect circuits against excessive currents. (overload and short ... Skiptocontent HomeTechnicalKnowledgeACBvsMCCB Selectionoftheprotectiondevicesoftheelectricalinstallationisfundamentalbothtoreducetheproblemscausedbyabnormalserviceconditions.ACBandMCCBbothareusedforthesafemakingandbreakingofelectricalsystems.Inprinciple,bothservethesamepurpose.Buttherearesomedifferencesbetweenthesetwodevices.Let’shavealook. TableofContents DifferencesbetweenACBandMCCBDefinitionanddutyTrippingcharacteristicsSafetyUsageareasSizeCurrentLocationinthecircuitPriceandmarketsizeMaintenanceArcgenerationDinrailmountingBreakingcapacitiesMagneticonlyprotectionUtilizationcategory DifferencesbetweenACBandMCCB WithMCCB,thecurrent-carryingcapacityandbreakingcapacityhaveincreasedandthereliabilityhasimproved.Becauseoftechnologicalimprovements,theuseofMCCBinlargecapacitycircuitswhereACBswereconventionallyusedhasincreased.MCCBandACBarebothcircuitbreakersforlowvoltagecircuitprotection,butthesehavethefollowingdifferences. Definitionandduty ACBstandsforaircircuitbreaker,MCCBstandsformoldedcasecircuitbreaker.Bothdevicesprotectcircuitsagainstexcessivecurrents.(overloadandshortcircuit)Byusingtheirhandle,theycanisolatetheloadfromthepowersupply.MCCBscanbeequippedwiththermomagneticorelectronicreleasesbutACBscanbeequippedwithelectronicreleases. Trippingcharacteristics MCCB’slong-delaytrippingcharacteristicsaretypicallyfixed,andtheACB’scharacteristicsareadjustable.ThisissotheprotectivecharacteristicsofthegeneratorofatransformercanbeachievedeasilywhenusingtheACBforapowerbreaker.WhenusingMCCBforthesetypesofapplications,theprotectivecharacteristicscanbeattainedeasilybyusinganelectronicMCCBthathasvariablelong-delaytrippingcharacteristics. InstantaneoustrippingcharacteristicsofMCCBarefixedforcompactmodels,adjustableforlargemodels.TheACB’scharacteristicsareadjustable. Safety MCCBscanbeequippedwiththermomagneticorelectronicreleasesbutACBscanbeequippedwithelectronicreleases.ACBsaredonatedwithmoreprotectionfunctionsbyusingtheadvantageofadvancedelectronicreleases. Usageareas MCCBisusedforgeneralwiringprotection.Itisnotsuitableforapplicationsrequiringfrequentswitching.Itstotalbreakingtimeisshort,andtransientenergyissmall,soMCCBissuitableforprotectingwiringandloaddevices. ACBisusedforgeneratorandtransformerprotectioninthemaincircuit.Itsratedshort-timecurrentishigh,soeasytostructureaselectivebreakingsystem. Size ThesizeofanMCCBissmallerthanACB.ComponentswithlowweightandvolumemakelifeeasyforusersofMCCBs. Current ThecurrentratingoftheACBishigherthantheMCCB.MCCBsaregenerallyproducedupto3200A,butACBsareproducedupto6300A. Locationinthecircuit Theshort-timecapacityoftheACBishigh.Itiseasytostructureaselectivebreakingsystemandissuitableforapplicationsasthemaincircuitbreaker.ACBsareusuallyusedontheupstreamsideofthecircuitbutMCCBsareusedonloadsidecontrol.Load-sideswitchingoperationsaremorefrequentthanupstream. Priceandmarketsize ThepriceofMCCBischeaperthanACB.ButthemarketsizeofMCCBislargerthanACB. Maintenance ACBsandMCCBsaresubjectedtohighcurrents;therefore,maintenanceofthemiscriticalforreliableoperation.MCCBhasasimpleandsafestructurethatdoesnotrequiremaintenanceorinspections.However,theACBisdesignedwithmanyupdatedpartsandmustbesufficientlyservicedandinspected.Thus,MCCBisnotsuitableforapplicationsintendedforfrequentshortcircuitinterruption. Arcgeneration Everytimecurrentisinterruptedbyopeningcontacts,thearcisgeneratedowingtocurrentinertia.Sincethearcissignificantlyharmfultothecontactsandinsulatingmaterials,itmustbeimmediatelyextinguished.ACBgeneratesmoreelectricalarcwhenswitching.Becauseitgenerallycarrieslargeamountsofcurrent.ACBandMCCBareequippedwithanarcsuppressionchamber.Ifthereisnopollutioninarcexhaustpartsandnootherabnormality,thebreakercanbere-used. Dinrailmounting SomesmallMCCBscanbemountedondinrail.ItisimpossibletomountanACBonadinrail.BecauseACBsareheavy. Breakingcapacities TheindependentbreakingcapacityofanMCCBissmallcomparedtotheACB,butincorporatingthecascademethodwiththeupstreamMCCBcanincreasethebreakingcapacity. Magneticonlyprotection SometypesofMCCBshaveonlymagneticprotection.ThistypeofACBsisnotavailableonthemarket.ACBshavethermalandmagneticprotection. Utilizationcategory MostACBshaveutilizationcategory“B”butmostMCCBshaveutilizationcategory“A”. ContinueReading Previous:ContactorvsCircuitbreakerNext:Advantagesanddisadvantagesoftransformers LeaveaReplyCancelreplyYouremailaddresswillnotbepublished.Requiredfieldsaremarked*CommentName* Email* Website Savemyname,email,andwebsiteinthisbrowserforthenexttimeIcomment. 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