航空电理论航空英文培训课件

1 Electricity 101 AirlineTransitionCourse 2 LessonObjectives DevelopabasicunderstandingofphysicsrelatedtoElectricalsystemsLookatspecificelectricalcomponentsLearnthebasicoperationofelectricalsystems 3 ElectricalTheory 4 ElectricalPhysics Electricity theflowofelectronsWhat sanelectron AverysmallparticlethatorbitsthenucleusofanatomWhenoneelectronispassedfromoneatomtoanotherelectricityisproduced 5 WhydoElectronsFlow Abalancedatomhasthreeparts Neutrons NochargeProtons PositivelychargedElectrons NegativelychargedIonspullelectronsoffoftheatomsandleavesthemwithmoreprotonsthanelectrons Theatomnowholdsapositivechargebecauseoftheunbalanceofelectronsandprotons Moreprotons positivelychargedparticles resultsinapositivecharge 6 MoreElectricalKnowledge Conductors HoldtheirelectronslooselytoallowtheexchangeofelectronsmoreeasilyInsulators Holdtheirelectronsmoretightlysoelectronscan tflowaseasily 7 MoreElectricalKnowledge Electromotiveforce TheforcethatcauseselectronstoflowAgroupofpositivelychargedparticleswouldflowelectronstowardagroupofnegativelychargedparticlesUsuallymeasuredinVoltsElectronFlow Frompositivetonegative AreaofExcessElectrons NegativeCharge AreaofElectronDeficiency PositivelyCharged 8 ElectricalMeasurement Quantity thecoulomb culom isthebasicunitofelectronflow 1coulomb6 28x1018That s6 280 000 000 000 000 000electronsFlow 1coulombpersecond oneAmperePressure pressurerequiredtoforceoneampofflowthroughoneohmofresistance thepotentialelectromotiveforce 1Volt 9 ElectricalMeasurement Resistance oppositiontocurrentflow theamountofforcetoallowapressureof1volttoforceaflowof1amp OhmsPower 1ampofflowunderofpressureofonevolt 1Watt 10 Magnetism Magnet isabodythathasthepropertyofattractingironandproducingmagneticfieldsexternaltoitself Linesofmagneticforce orFLUX leavethemagnet snorthpole atrightanglestoitssurface andreenterthemagnet ssouthpoleinthesamemanor Ex theEarth 11 Electromagnets Conductivematerialholdingelectricalcurrentwillproduceaninvisiblemagneticfieldaroundthematerial Whenelectricityissentthroughacoilthatisrappedaroundaconductor theconductor corebecomesmagnetized 12 Relays Solenoids 13 RelaysFixedcoreElectricityisappliedandmagnetismdrawsacircuitopenorclosed Usedforvoltageregulators Solenoids MovablecoreElectricityisappliedtothecoilwhichdrawsthecoreinward closingoropeningacircuit RelaysandSolenoidsareusedwhenitisnecessarytocontrolswitcheswhichcarrylargeamountsofpowerfromasmallswitch Ex Startermotor Battery orAvionicsmasterAsmallamountofelectricityisruntotheactualswitch whenturnedonthiselectricityenergizesanelectromagnet 14 Solenoids MovablecoreElectricityisappliedtothecoilwhichdrawsthecoreinward closingoropeningacircuit 15 Solenoids MovablecoreElectricityisappliedtothecoilwhichdrawsthecoreinward closingoropeningacircuit 16 Solenoids MovablecoreElectricityisappliedtothecoilwhichdrawsthecoreinward closingoropeningacircuit 17 Solenoids MovablecoreElectricityisappliedtothecoilwhichdrawsthecoreinward closingoropeningacircuit 18 ACvs DC AlternatingCurrent continuallychangesitsvaluesofvoltageandcurrentwhileperiodicallyreversesitsdirectionofflowEasiertodeveloplargequantitiesofpowerCurrent Amps andvoltagecanbeconvertedeasilyEx Thecurrentflowingthroughaconductorcreatesheat andthereforedeterminesthesizeoftheconductor Wecantradesomecurrentforvoltageandstillachievethesameworkremember W VxAThat swhywehavehightensionpowerlineswith15 000Volts thentheelectricityisbroughtdownto115Voltsrightbeforeitentersourhouse 19 WhydoweuseDCthen Afewreasons Wedon trequirelargesumsofelectricitytopowerouraircraftOurinstrumentsoperateonDCPowerisstored thebattery asDC 20 Circuits SeriesandParallel 21 Circuits Series Allelectricitymustflowthroughallactivecomponents Ifonecomponentfailsthentheentireseriesfails 22 Parallel AportionofthecurrentflowsthrougheachcircuitIfabulbburnsoutinaparallelthentheremainingbulbssharethepower Circuits 23 TypesofPowerSources 24 Generators SimpleACGenerators Remember anytimeaconductorismovedinamagneticfield itcutsacrossthelinesoffluxandvoltageisproduced causingacurrentflowAgeneratorspinsaloopinsideamagnet 25 ControllingGeneratorOutput VoltageinageneratorisregulatedbytherateofatwhichthelinesoffluxarecutMorelinesofflux strongermagnet meansmoreoutput inageneratorthiscannotbechanged FasterrpmmeansmoreoutputAvoltageregulatorisusedtopreventgeneratorrunaway useselectromagnetismtoregulateoutputMoreelectromagnetismmeansalargermagneticfieldwhichmeansmorevotage 26 3PhaseGenerator AvariablephasegeneratorrunsmultipleloopsgivingamoreconstantpeakofpowerEx Athreephasegeneratorhasthreeloopsandthepowerpeaksthreetimesmoreoftenthanasinglephase 27 Alternators Nomagnets generateACpowerinitiallyStator Stationarywindingofwires coil Sincethisstatorisstationarywedon tneedtotransfertheloadthroughbrushesThewireswithinthecoilareconnectedasthreewindingsjoinedtogethertoformaY Thisproducesthreephasesofalternatingcurrent 28 Alternators TherotorisattachedtotwoslipringsandusesDCpowertoenergizeitscoil producingmagneticchargeasitisspuninsidetheStatorOncetherotorisenergizeditcontainsitsownN Spoles SlipRings 29 Generatorsvs Alternators GeneratorsTypicallyusedforDCpowerwithoneslipring commutator CanproduceACbyaddingasecondslipring orproduceACbyaddinganinverterSelfexcited thereisamildmagneticfield fromthemagnet whichproducesasmallcharge whenrotatingthatisaddedtothefieldtoproducealargerchargeVoltageisregulatedbyfieldcharge AlternatorsMoreefficientProduces3phase ACcurrentThepowerisproducedbythestator whichisstationaryTherotorisalsoacoilthat whencharged holdsit sownN Spoles needsDCNotselfexcited thereforeaninitialchargemustcomefromsomewhere battery ForDCwemustuseRECTIFIERS 30 ELECTRICALFORMULAS 31 ElectromotiveForce VoltageIntensityofFlow Amperage CurrentResistanceinOhms ThevoltageisequaltotheamperagemultipliedbytheresistanceThecurrentisequaltothevoltagedividedbytheresistanceTheresistanceisequaltothevoltagedividedbythecurrent 32 ElectromotiveForce VoltageIntensityofFlow Amperage CurrentResistanceinOhms ThevoltageisequaltotheamperagemultipliedbytheresistanceThecurrentisequaltothevoltagedividedbytheresistanceTheresistanceisequaltothevoltagedividedbythecurrent 33 ElectromotiveForce VoltageIntensityofFlow Amperage CurrentResistanceinOhms ThevoltageisequaltotheamperagemultipliedbytheresistanceThecurrentisequaltothevoltagedividedbytheresistanceTheresistanceisequaltothevoltagedividedbythecurrent 34 ConfusedYet Justremember Amps FlowOhms ResistanceVolts PressureWatts PowerAnd Watts VoltsxAmps 35 TypesofStorageDevices 36 Batteries AdevicecomposedofoneormorecellsinwhichchemicalenergyisconvertedintoelectricalenergyThechemicalswithinabatteryprovidesanexcessofelectronsatoneendandadeficiencyattheother 37 ModernBatteryChemicalsModernbatteriesuseavarietyofchemicalstopowertheirreactions Typicalbatterychemistriesinclude Zinc carbonbattery Alsoknownasastandardcarbonbattery zinc carbonchemistryisusedinallinexpensiveAA CandDdry cellbatteries Theelectrodesarezincandcarbon withanacidicpastebetweenthemthatservesastheelectrolyte Alkalinebattery UsedincommonDuracellandEnergizerbatteries theelectrodesarezincandmanganese oxide withanalkalineelectrolyte Lithiumphotobattery Lithium lithium iodideandlead iodideareusedincamerasbecauseoftheirabilitytosupplypowersurges Lead acidbattery Usedinautomobiles theelectrodesaremadeofleadandlead oxidewithastrongacidicelectrolyte rechargeable Nickel cadmiumbattery Theelectrodesarenickel hydroxideandcadmium withpotassium hydroxideastheelectrolyte rechargeable 38 Nickel metalhydridebattery Thisbatteryisrapidlyreplacingnickel cadmiumbecauseitdoesnotsufferfromthememoryeffectthatnickel cadmiumsdo rechargeable Lithium ionbattery Withaverygoodpower to weightratio thisisoftenfoundinhigh endlaptopcomputersandcellphones rechargeable Zinc airbattery Thisbatteryislightweightandrechargeable Zinc mercuryoxidebattery Thisisoftenusedinhearing aids Silver zincbattery Thisisusedinaeronauticalapplicationsbecausethepower to weightratioisgood Metal chloridebattery Thisisusedinelectricvehicles ModernBatteryChemicals Cont d 39 Batteries cont Lead acidBatteries MostcommonlyusedonGAapplicationsFilledwithleadplatesundereachelectrodeAnelectrolyteofsulfuricacidandwatercoverstheplates acidic usebakingsodatoneutralize TheCapacityofthebatteryismeasuredbyitsabilitytoproduceagivenamountofcurrentforaspecifictime ampere hours1ampere hourmeansthebatterycansupply1amperefor1hourWehave35amp hourbatteriesifweuseonly10ampshowmanyhourswillourbatterylast 40 Batteries cont Ratedcapacity indicatesthebatteriesabilitytoperformwhenitisnewandistypicallyeffectedby BatteryTemp coldertempsdecreaseperformanceBatteryCharge AbatterythatisnotfullychargedwillnotperformaswellBatteryCondition Affectedbyage servicehistory anyexcessg forcesorhardlandings 41 Batteries cont ComponentsLeadAcid 42 Batteries Nickel cadmiumBatteries canaccepthighchargeratesanddischargeatequallyhighrateswithoutvoltagedrop unlikeleadacidbatteries Eachcellisanindividualunit12voltbatteriesuse9or10cellslinkedinseries while24voltuse18or20cellsQuickreviewonseriesvs parallelconnectionsAnelectrolyteofpotassiumhydroxideandwatercoverstheplates astrongbase usevinegartoneutralize 43 Batteries cont Nickel CadmiumbatteriesproblemsHeat ThistypeofbatteryrequiresoneofthreetypesofwarningsystemstowarntheflightcrewofimpendingproblemsTemp Monitoringdeviceofthecentralintercell usually140 160degreesF andsomethingmustbedone Current Basedontheideathatathermalproblemcannotexistunlessthereischargingcurrent ThepilotiswarnedwhenthiscurrentbecomesexcessiveVoltage Ifallthecellsarebalancedvoltagewisethennoproblemsmayexist 44 Batteries cont Nickel CadmiumbatteriesproblemsHeat ThermalRunawayslookslikethis 45 Batteries cont NiCadBatteryConstruction NiCadCell NiCadBattery 46 AircraftElectricalSystems 47 AircraftElectricalSystems Thesource Usuallya12or24VoltDCsystem inourairplanes MostsystemswillbenegativegroundThenegativeterminalwillbegroundedtotheframeoftheairplaneThisallowsustorunonewiretothecomponentthatwedesiretooperateandusetheframeasthesecond 48 AircraftElectricalSystems MostsystemswillbenegativegroundThenegativeterminalwillbegroundedtotheframeoftheairplane 49 Buses Abus barisaphysicallyconvenientplacetobringallourwirestogether neatlyandsafelyMaybemorethanonebusinanaircraftEx CRJhasaround15buses 50 ProtectiveDevices 51 ProtectiveDevices Fuses Madeofalowmeltingpointalloy incasedinaglasstubeWhentomuchcurrentflowsthrough themetalheatsupandmeltsopeningthecircuit OPEN CLOSED 52 ProtectiveDevices Circuitbreakers TheseautomaticallyopenthecircuitifcurrentbecomesexcessiveThebreakerpopsandisabletoberesetIfresetanditpopsagain afaultexistsanditshouldbeleftopenTwotypes Thermal excesscurrentheatsanelementintheswitchthatsnapsitopenMagnetic theflowofelectricityincreasesamagneticfieldthatwillpopthecircuitbreakeropenwhentheflowbecomestomuch 53 MagneticCircuitbreakers Thehotwireinthecircuitconnectstothetwoendsoftheswitch Whentheswitchisflippedtotheonposition electricitycanflowfromthebottomterminal throughtheelectromagnet uptothemovingcontact acrosstothestationarycontactandouttotheupperterminal Theelectricitymagnetizestheelectromagnet Increasingcurrentbooststheelectromagnet smagneticforce anddecreasingcurrentlowersthemagnetism Whenthecurrentjumpstounsafelevels theelectromagnetisstrongenoughtopulldownametalleverconnectedtotheswitchlinkage Theentirelinkageshifts tiltingthemovingcontactawayfromthestationarycontacttobreakthecircuit Theelectricityshutsoff 54 ThermalCircuitbreakers Intheclosedposition theconductivesnapactingdiscwithitscontacts bridgestheterminalcontactstomaintainthecurrent Atpredeterminedoverloads theresistanceheat causedbycurrentpassingthroughthedisc snapsthediscintoreversepositiontoopenthecontactsandbreakthecircuit thecontactshaveopened itremainssountilmanuallyresetbythepushbutton Inresettingtheseunits thepushbuttonmovesinwardonlywhilepushedandalwaysreturnstothesamepositionwhenreleased 55 OnetotheOther Inverters ConvertsDirectCurrenttoAlternatingCurrentRectifiersConvertsAlternatingCurrenttoDirectCurrent 56 SAFETYCONSIDERATIONS 57 SAFETYCONSIDERATIONS 58 Planeveryjobandthinkaboutwhatcouldgowrong Usetherighttoolsforthejob Useprocedures drawings andotherdocumentstodothejob Isolateequipmentfromenergysources Identifytheelectricshockandarcflash aswellasotherhazardsthatmaybepresent Minimizehazardsbyguardingorestablishingapproachlimitations Testeverycircuitandeveryconductoreverytimebeforeyoutouchit Usepersonalprotectiveequipment PPE asalastlineofdefenseincasesomethinggoeswrong WorkplaceElectricalSafetyTips 59 Besureyouareproperlytrainedandqualifiedforthejob Workonelectricalequipmentandconductorsonlywhendeenergized unlessproceduresandsafeguardshavebeenestablishedtoensurezeroexposurefortheworkerandotherpeopleinthearea Lockout tagoutandground whereappropriate beforeworkingonequipment Treatdeenergizedelectricalequipmentandconductorsasenergizeduntillockout tagout test andgroundprocedures whereappropriate areimplemented Wearprotectiveclothingandequipmentanduseinsulatedtoolsinareaswheretherearepossibleelectricalhazards WorkplaceElectricalSafetyTips 60 De energizeandvisiblyguard wherepossible whenevercontactwithuninsulatedoverheadpowerlinesispossible Checkanddoublechecksafetyregulationswhenaladderorpartsofanyvehicleormechanicalequipmentstructurewillbeelevatednearenergizedoverheadpowerlines Callyourlocalelectricutilityforassistance Peoplestandingonthegroundmaybeparticularlyvulnerabletopossibleinjury WorkplaceElectricalSafetyTips 61 Cords Equipment andToolGrounding MakesureallequipmentandextensioncordsbearthemarkofanindependenttestinglaboratorysuchasUL CSA ETLorMETLabs Protectflexiblecordsandcablesfromphysicaldamage Checkcordsforcut broken orcrackedinsulation Keepslackinflexiblecordstopreventtensiononelectricalterminals Makesuretheinsulatingqualitiesofaspliceareequaltoorgreaterthantheoriginalcord Extensioncordsarefortempo