ElectricalPowerIntroductionPurposeTheelectricalpowermakes,supplies,andcontrolselectricalpower.Thesystemhasautomaticandmanualcontrolfeatures.Built-intestequipment(BITE)andalternatesourceselectionmakethesystemreliableandeasytokeep

Electricalpowerhasthesesubsystems:-Generatordrive-ACgeneration-DCgeneration-Externalpower-ACelectricalloaddistribution..

AbbreviationsandAcronyms

AGCU-APUgenerationcontrolunitAPB-APUbreakerAPS-APUpowerswitchAPU-auxiliarypowerunitAuto-automaticbat-batteryBPCU-buspowercontrolunitBTB-bustiebreakerCSD-constantspeeddriveEP-externalpowerEPC-externalpowercontactorGCB-generatorcontrolbreakerGCU-generatorcontrolunitgen-generatorIDG-integrateddrivegeneratorPDP-powerdistributionpanelpwr-powerSCU-startconverterunitSPCU-standbypowercontrolunitSPU-startpowerunitstdby-standbyTRU-transformerrectifierunitPurposeTheeletricalpowersystermmakesandsuppliesACandDCpowertoairplane.Thesystemhasautomaticandmanualcontrolsandprotection.AstandbyACandDCsystemgivesnormalandemergencypower.ACPowerTheelectricalpowersystemhasfourmainACpowersourcesandonestandbypowersource.ThesearethemainACpowersourcesandtheirsupplycapacity:-Leftintergrateddrivegenerator(IDG1)(90KVA)-Rightintegrateddrivegenerator(IDG2)(90KVA)-APUstarter-generator(90KVAbelow3200feet/9753meter,andgoesdownto66KVAat4100feet/12496meters)-Externalpower(90KVA).TheIDGsandAPUstarter-generatorsupplya3phase,115/200volts(nominal)at400Hz.TheACpowersystemdesignpreventstwosourcestothesameloadatthesametime.Thestaticinvertersuppliesaonephase,115vacoutputtotheACstandbybusDcpowerThreetransformerrectifierunits(TRUS)change115Vacto28dc.TheairplanealsohastheseDCpowerSources:MainbatteryMainbatterychargerAuxiliarybatteryAuxiliarybatterychargerTuebatteriesarethebackupDCsourceifothersourcesdonotoperate.thestandbypowercontrolunit(SPCU)controlsthedistributionofdcpower.StandbypowerWiththelossofnormalpower,thestandbypowersystemsuppliesaminimumof60minuteofACandDCpowertosystemsnecessarytomaintainsafeflight.thebatteriessupplyDCpower.thestaticinverterusesbatterypowertomakeACpower.theSPCUcontrolsthedistributionofACandDCstandbypower.ControlTheseonthep5panelgivemanualcontroloftheelectricalpowersysem:_Electricalmeters,batteryandgalleypowermodule(p5-13)-Generatordriveandstandbypowermodules(p5-5)-Acsystems,generatorandAPUmodules(p5-4)TheswitchesonthesemodulessendsignalstotheLRUsthatcontrolportionsofthesysem.TheLRUsthenenergizeorde-energizerelaysorbeakerstocontrolelectricalpower.Breakersallowpowertothebuses.Abreakerclosestoletpowerthroughit.ThebreakersclosewhenyoucommandtheGCUtocloseit.TheGCUclosesthebreakeronlywhenpowerisgoodandnootherpowersourceisonthebus.TheGCUreceivesbreakerpositionthoughtheBPCU.Thesearethemainbreakers:-Externalpowercontactor(EPC)-APUpowerbreaker(APB)-Generatorcontrolbreaker(GCB)Themodulesonthep5alsoletyoumonitorthestatusoftheelectricalpowersystem.Thepanelshavelightsandanalpha-numericLEDdisplay.

GeneralTheseACbusesreceivepowerdirectlyfromanACpowersource:--ACtransferbus1--ACtransferbus2--Groundservicebus1--Groundservicebus2SystemlogicautomnticallyremovesloadstopreventanoverloadofanACpowersourceTheseDCbusesreceivepowerdirectlyfromthetransformerrectyfierunits:--DCbus1--DCbus2--Batterybus.Thesebusesreceivepowerdirectlyfromthemainbatteryorthemainbatterycharger:--HOTbatterybus--SwitchedhotbatterybusACtransBusesTheseACSourcessupplypowertotheACtransferbuses:--Externalpower--APUstartergenerator--Integrateddrivegenerators(IDGs)ThesystemdesignmakessurethattwoACpowersourcescannotsupplypowertothesametransferbusatthesametime.However.OneACpowersourcecansupplypowertobothtransferbusesthroughthebustiebreakers.(BTBs).Eachtransferbussuppliespowertothesecomponentsorbuses:Galleys(asmanyas2)MainBusGroundsevicebusTransformerrectifierunit(asmanyas2)GroundServiceBusesEachgroundservicebusreceivespowerinoneofthesetwoways:TheACtransferbusonthatsidehaspowerThegroundserviceswitchontheforwardattendantpanelisintheONpositionandexternalpowerisconnectedtotheairplane.Thetwogroundservicetransferrelayscontroltheselectionofthepowersource.MainBusesandGalleyBusesThemainbusesandthegalleybusesreceivepowerfromtheirrespectiveACtransferbus.Loadshedrelaysremovethepowertothesebuseswhentheirloadsexceedoperatinglimits.thisprotectstheACpowersource.Fromoverload.thebuspowercontrolcontrolstheloadshedfunctionDCBUSESDCbus1usuallyreceiverpowerfromTRU1HoweverthebusreceiverpowerfromTRU2orTRU3throughthebustierelay.ThisrelayisusuallyenergizedDCbus2usuallyreceiverpowerfromTRU2TRU3suppliespowerifTRU2fails.DCbus2mayalsoreceiverpowerfromTRU1throughthebustierelayStandbybusesTheACstandbybususuallyreceivespowerfromACtransferbus1.Thestaticinvertermayalsosupplypowertothisbus.Aremotecontrolcircuitbreakercontrolpowertothestaticinverter

TheDCstandbybususuallyreceivespowerfromDCThehotbatterybusmayalsosupplypowertotheDCstandbybus

BatteryBusesThehotbatterybususuallyreceiverpowerfromthemainbatteryormainbatterychanger.Theauxiliarybatteryandauxiliarybatterychangerconnectsinparallelwiththemainbatteryduringnon-normalconditionstohelpsupplypower.SeetheDCgenerationsectionformoreinformationThebatterybusnormallyreceivespowerfromTRU3.ThebatterybusreceivespowerfromthebatteryifTRU3hasnooutput..Theswitchhotbatterybusreceivespowerfromthehotbatterybuswhenthebatteryswitch(P5panel)isintheONposition.ExternalPowerExternalpowercansupplypowertothesebuses:ACtransferbusesGroundservicebusesExternalpowersuppliespowertoeachACtransferbusthroughtheexternalpowercontactor(EPC)andthenecessarybustiebreaker(BTB).APUPowerTheAPUstarter-generatorsuppliespowertoeachACtransferbusthroughtheAPUbreaker(APB)andthenecessaryBTB.TheAPUcansupplypowertobothACtransferbusesonthegroundorinflight.SeetheACGenerationsectionformoreinformation.(AMMPARTI24-20)IDGPowerTheIDGsarethenormalpowersourcesoftheACtransferbuses.AnIDGsuppliespowerthroughageneratorcontrolbreaker(GCB)BatterychargeEachbatterychargemakessureitsbatterystaysatmaximumcharge.eachbatterychargealsooperatesasaTRUwhennotinthechargemode.Remotecontrolcircuitbreaker（RCCB)ThestandbypowersystemusesaRCCBtocontrolpowerinputtothestaticinverter.ThisRCCBisnorma