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B737NG Electrical power

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Overview of the B737NG Electrical power system

Overview of the B737NG Electrical power system

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B737NG Electrical power B737NG Electrical power Presentation Transcript

  • B 737 NG Ground School. See the aircraft study guide at www.theorycentre.comThe information contained here is for training purposes only. It is of a general nature it isunamended and does not relate to any individual aircraft. The FCOM must be consulted forup to date information on any particular aircraft.
  • B737-800ELECTRICAL POWER SYSTEM.
  • Electrical Power Controls Forward Overhead Panel.
  • Electrical Power Controls Forward Overhead Panel.ELECT Annunciator onSecond row Captains side
  • Electrical Power Controls Forward Overhead Panel. 4 Light coloured panels requiresELECT Annunciator on CAUTIOUS HANDLINGSecond row Captains side FUEL, ELECT, HYD, AIR.
  • INTRODUCTIONPrimary electrical power is provided by two engine integrated drive generators(IDGs) Which are rated at 90 Kva and supply three-phase, 115 volt, 400 cycle alternating current.
  • INTRODUCTIONPrimary electrical power is provided by two engine integrated drive generators(IDGs) Which are rated at 90 Kva and supply three-phase, 115 volt, 400 cycle alternating current.Each IDG supplies its own bus system in normal operation and can also supply essentialand non-essential loads of the opposite side bus system when one IDG is inoperative.Transformer rectifier (TR) units and a battery or batteries/battery charger(s) supplyDC power. (Aircraft may have 1 or 2 Batteries.)The battery also provides backup power for the AC and DC standby system.
  • INTRODUCTIONPrimary electrical power is provided by two engine integrated drive generators(IDGs) Which are rated at 90 Kva and supply three-phase, 115 volt, 400 cycle alternating current.Each IDG supplies its own bus system in normal operation and can also supply essentialand non-essential loads of the opposite side bus system when one IDG is inoperative.Transformer rectifier (TR) units and a battery or batteries/battery charger(s) supplyDC power. (Aircraft may have 1 or 2 Batteries.)The battery also provides backup power for the AC and DC standby system.The APU operates a 90Kva starter/generator and can supply power to both AC transfer busses onthe ground or in flight up to 41,000 feet.
  • INTRODUCTIONPrimary electrical power is provided by two engine integrated drive generators(IDGs) Which are rated at 90 Kva and supply three-phase, 115 volt, 400 cycle alternating current.Each IDG supplies its own bus system in normal operation and can also supply essentialand non-essential loads of the opposite side bus system when one IDG is inoperative.Transformer rectifier (TR) units and a battery or batteries/battery charger(s) supplyDC power. (Aircraft may have 1 or 2 Batteries.)The battery also provides backup power for the AC and DC standby system.The APU operates a 90Kva starter/generator and can supply power to both AC transfer busses onthe ground or in flight up to 41,000 feet. There are two basic principles of operation for the 737 electrical system:1. There is no paralleling of the AC sources of power.No paralleling means that the power sources are never connected together on the same bus.2. The source of power being connected to a transfer bus automatically disconnects an existingsource.This is a break power transfer, which means that the bus is momentarily without power.
  • INTRODUCTIONPrimary electrical power is provided by two engine integrated drive generators(IDGs) Which are rated at 90 Kva and supply three-phase, 115 volt, 400 cycle alternating current.Each IDG supplies its own bus system in normal operation and can also supply essentialand non-essential loads of the opposite side bus system when one IDG is inoperative.Transformer rectifier (TR) units and a battery or batteries/battery charger(s) supplyDC power. (Aircraft may have 1 or 2 Batteries.)The battery also provides backup power for the AC and DC standby system.The APU operates a 90Kva starter/generator and can supply power to both AC transfer busses onthe ground or in flight up to 41,000 feet. There are two basic principles of operation for the 737 electrical system:1. There is no paralleling of the AC sources of power.No paralleling means that the power sources are never connected together on the same bus.2. The source of power being connected to a transfer bus automatically disconnects an existingsource.This is a break power transfer, which means that the bus is momentarily without power.The electrical power system may be categorized into three main divisions:AC power system.DC power system.Standby power system.
  • AC and DC Metering Panel
  • AC and DC Metering PanelBattery Switch.OFF. Removes power fromBattery bus and Switched hotbattery bus if normal powersupplies available.Removes power from theStandby power system whenthe battery is the only sourceof power.
  • AC and DC Metering PanelBattery Switch.OFF. Removes power fromBattery bus and Switched hot ON. Normal guarded position.battery bus if normal power Provides power to the switchedsupplies available. hot battery bus.Removes power from the Allows automatic switching of theStandby power system when standby power system to batterythe battery is the only source with a loss of normal powerof power. supplies.
  • AC and DC Metering PanelDC Amps and Volts showaccording to rotary selectorposition.TR1, TR2 and TR3 shows DCoutput of TRU.AUX BATTERY if two batteriesfitted.TEST for maintenance only.
  • AC and DC Metering Panel AC Volts, Amps and Frequency Hz. According to the rotary selector position. Test for Maintenance only.
  • AC and DC Metering PanelBattery Discharge (BAT DISCHARGE) LightIlluminated (amber) – with BAT switch ON, excessive batterydischarge detected.
  • AC and DC Metering PanelTR UNIT LightIlluminated (amber) –• on the ground – any TR has failed.• in flight –• TR1 failed; or• TR2 and TR3 failed.
  • AC and DC Metering PanelElectrical (ELEC) LightIlluminated (amber) – a fault exists in DC power system orstandby power system.Note: Operates only with airplane on ground.
  • AC and DC Metering PanelCabin Utility switch.Controls power to the ACGalley buses and main buses.OFF. Removes power from.left & right recirculation fansFwd and aft door areaheatersDrain mast heatersLavatory water heatersLogo lightsPotable water compressor115V AC shaver outlets wheninstalled
  • AC and DC Metering Panel IFE/PASS SEAT. OFF – removes electrical power from installed components of the passenger seats, in-flight entertainment systems, and other power systems including: • 115V AC audio entertainment equipment • 115V AC video entertainment equipment • cabin telephone equipment • FAX machine • 28V DC video equipment and passenger seat electronic outlets
  • Generator Drive and Standby Power Panel
  • Generator Drive and Standby Power PanelGenerator Drive (DRIVE) LightsIlluminated (amber) – Integrated drive generator (IDG) low oil pressure caused by one of the following:• IDG failure• engine shutdown• IDG automatic disconnect due to high oil temperature• IDG disconnected through generator drive DISCONNECT switch.Low oil pressure isless than 162 psi.
  • Generator Drive and Standby Power PanelGenerator Drive Disconnect (DISCONNECT) Switches (guarded)Disconnects IDG if electrical power is available and engine start lever is in IDLE.IDG cannot be reconnected in the air.
  • STANDBY POWER SwitchAUTO (guarded position) –• In flight, or on the ground, and AC transfer busses powered:• AC standby bus is powered by AC transfer bus 1• DC standby bus is powered by TR1, TR2 and TR3• In flight, or on the ground, loss of all AC power• AC standby bus is powered by battery through static inverter• DC standby bus is powered by battery• Battery bus is powered by battery.
  • STANDBY POWER SwitchOFF (centre position) –• STANDBY PWR OFF light illuminates• AC standby bus, static inverter, and DC standby bus are not powered.
  • STANDBY POWER SwitchBAT (unguarded position) –• AC standby bus is powered by battery through static inverter• DC standby bus and battery bus are powered directly by battery.
  • STANDBY Power Off (PWR OFF) LightIlluminated (amber) – one or more of the following busses are unpowered:• AC standby bus• DC standby bus• battery bus.
  • Ground Power Panel and Bus Switching PanelGround Power Available (GRD POWER AVAILABLE) LightIlluminated (blue) – ground power is connected and meets airplane power quality standards.If the Ground power does not Meet Voltage andFrequency requirements the blue light will not illuminate.
  • Ground Power Panel and Bus Switching PanelGround Power (GRD PWR) SwitchThree position switch, spring–loaded to neutralOFF – disconnects ground power from AC transfer busses.ON – if momentarily moved to ON position and groundpower is available:• removes previously connected power from AC transferbusses• connects ground power to AC transfer busses if powerquality is correct.
  • Ground Power Panel and Bus Switching PanelTRANSFER BUS OFF LightsIlluminated (amber) – related transfer bus is not powered.
  • Ground Power Panel and Bus Switching PanelSOURCE OFF LightsIlluminated (amber) – no source has been manuallyselected to power the related transfer bus, or themanually selected source has been disconnected• if a source has been selected to power the oppositetransfer bus, both transfer busses are powered.
  • BUS TRANSFER SwitchAUTO (guarded position) – BTBs operate automatically tomaintain power to AC transfer busses from any operatinggenerator or external power• DC cross tie relay automatically provides normal orisolated operation as required.OFF – isolates AC transfer bus 1 from AC transfer bus 2 if one IDG is supplying power to both AC transfer busses• DC cross tie relay opens to isolate DC bus 1 fromDC bus 2.
  • Generator (GEN) SwitchesThree position switch, spring–loaded to neutral.OFF – disconnects IDG from related AC transfer bus byopening generator circuit breaker.ON – connects IDG to related AC transfer bus bydisconnecting previous power source and closinggenerator circuit breaker,
  • Generator Off Bus (GEN OFF BUS) LightsIlluminated (blue) – IDG is not supplying power to therelated transfer bus.
  • APU Generator Off Bus (GEN OFF BUS) LightIlluminated (blue) – APU is running above 95% RPM it is notin a cool down cycle and not powering a bus.
  • APU Generator (GEN) SwitchesThree position switch, spring–loaded to neutral.OFF –• APU generator powering both AC transfer busses• moving a single APU GEN switch to OFF illuminates relatedSOURCE OFF light. APU continues to power AC transferbusses• subsequently moving the other APU GEN switch to OFFdisconnects APU generator from tie bus and removes APUpower from AC transfer busses• APU generator powering one AC transfer bus; IDGpowering one AC transfer bus moving related APU GENswitch to OFF disconnects APU generator from tie bus andAC transfer bus. IDG powers AC transfer busses.
  • APU Generator (GEN) SwitchesThree position switch, spring–loaded to neutral.ON –• Neither AC transfer bus powered by IDG – moving a singleAPU GEN switch to ON:• connects both AC transfer busses to the APU generator• disconnects external power, if connected• opposite SOURCE OFF light illuminates until the other APUGEN switch is moved to ON.• Both AC transfer busses powered by IDGs – moving an APUGEN switch ON:• powers the related AC transfer bus from the APUgenerator• other AC transfer bus continues to receive power from theIDG.
  • 1. AC Power System.
  • Electrical Power GenerationEngine GeneratorsPrimary power is obtained from two engine Integrated drive generators (IDG). The IDGmaintains a constant generator speed throughout the normal operating range of the engine.An integral electro–mechanical disconnect device provides for complete mechanical isolationof the IDG.
  • Electrical Power GenerationEngine GeneratorsPrimary power is obtained from two engine Integrated drive generators (IDG). The IDGmaintains a constant generator speed throughout the normal operating range of the engine.An integral electro–mechanical disconnect device provides for complete mechanical isolationof the IDG.APU GeneratorThe APU generator can supply power to both AC transfer busses on the ground orin flight. As the only power source, the APU generator can meet electrical powerrequirements for all ground conditions and most flight conditions.
  • External Ground PowerAn external AC power receptacle located near the nose gear wheel well, on thelower right side of the fuselage, allows the use of an external power source. Statuslights on a panel adjacent to the receptacle permit the ground crew to determine ifexternal power is being used. When connected, external power can supply powerto both transfer busses.
  • Ground ServiceFor ground servicing, a ground service switch is on the forward attendant’s panel at door 1L.The switch provides ground power directly to the AC ground service busses forutility outlets, cabin lighting and the battery charger without powering all airplaneelectrical busses. The ground service switch is a momentary push button and isoverridden when both AC transfer busses are powered.
  • Ground ServiceFor ground servicing, a ground service switch is on the forward attendant’s panel at door 1L.The switch provides ground power directly to the AC ground service busses forutility outlets, cabin lighting and the battery charger without powering all airplaneelectrical busses. The ground service switch is a momentary push button and isoverridden when both AC transfer busses are powered.
  • AC Power SystemEach AC power system consists of a transfer bus, a main bus, two galley busses,and a ground service bus. Transfer bus 1 also supplies power to the AC standbybus. If the AC source powering either transfer bus fails or is disconnected, thetransfer bus can be powered by any available source through the tie bus with thebus tie breakers (BTBs).
  • With the airplane on the ground and both generator control switches OFF, or withboth engines shut down, selecting the GRD PWR switch ON connects externalpower to both transfer busses.
  • With the airplane on the ground and both generator control switches OFF, or withboth engines shut down, selecting the GRD PWR switch ON connects externalpower to both transfer busses.Likewise, selecting either APU GEN switch ONconnects APU power to both transfer busses. Whichever source is selected lastpowers both busses. It is not possible to power one transfer bus with externalpower and one transfer bus with APU power.
  • External power Contactor. Ground power Available and acceptable.
  • External power Contactor. Ground power Available and acceptable. ON selection will remove any other previously selected source
  • One TIE BUS joining both AC Transfer bussesWith 2 Bus Tie Breakers (BTB) controllingconnection between the Transfer busses.
  • Both the APU and External power Supply directly to the Tie Bus.One TIE BUS With 2 BusTie Breakers
  • Both the APU and External power Supply directly to the Tie Bus.Is it possible to useBOTH EXT POWER andthe APU together? One TIE BUS With 2 Bus Tie Breakers
  • Both the APU and External power Supply directly to the Tie Bus. Is it possible to use BOTH EXT POWER and the APU together?The APU and External power both supply the Tie bus.Selection of one removes the other first! One TIE BUS With 2 Bus Tie Breakers
  • Both the APU and External power Supply directly to the Tie Bus. Is it possible to use The APU and External power are BOTH EXT POWER and never paralleled on the Tie Bus. the APU together?The APU and External power both supply the Tie bus.Selection of one removes the other first! One TIE BUS With 2 Bus Tie Breakers
  • The transfer busses can be powered from the engine generators bymomentarily positioning the related generator switch to ON. This closesthe related generator circuit breaker (GCB) and connects the generatorto the transfer bus.
  • Whenever external power or APU is powering both transfer busses, and enginegenerator power is applied to its onside transfer bus, external power or APUcontinues to supply power to the remaining transfer bus.
  • Both Engines are running. APU is powering the aircraft.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. GEN OFF BUS light extinguishes.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. BTB 1 Opens first.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. BTB 1 Opens first. GCB 1 closes.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. BTB 1 Opens first. GCB 1 closes. The APU powers AC bus 2.
  • External power is available.You need passenger cabinlighting.What do you need to do?
  • External power is available. You need passenger cabin lighting. What do you need to do? Ground Service Switch at Door 1LThis connects the Ground service bussesdirectly to Ground power
  • External power is available. You need passenger cabin lighting. What do you need to do? Ground Service Switch at Door 1LWhat important itemnow gets power fromGSB 2?
  • External power is available. You need passenger cabin lighting. What do you need to do? Ground Service Switch at Door 1LWhat important itemnow gets power fromGSB 2?
  • External power is connected and selected ON. This light is illuminated. What does it tell you?
  • External power is connected and selected ON. This light is illuminated. What does it tell you? The APU is running the APU is above 95 percent RPM and not in a cool down cycle. It is Ready to supply power.
  • External power is connected and selected ON. You move the APU Number 2 switch to ON. What happens?
  • External power is connected and selected ON. The Bus power Controller opens the external power contactor and then closes the APU Generator control Breaker. You move the APU Number 2 switch to ON. What happens?
  • External power is connected and selected ON. The Number 1 Transfer bus is now not powered by a manually selected source! The SOURCE OFF light illuminates. The Bus power Controller opens the external power contactor and then closes the APU Generator control Breaker. You move the APU Number 2 switch to ON. What happens?
  • External power is connected and selected ON. The Number 1 Transfer bus is now not powered by a manually selected source! The SOURCE OFF light illuminates. Move the APU Number 1 switch to ON to reset the logic and extinguish the SOURCE OFF light. The Bus power Controller opens the external power contactor and then closes the APU Generator control Breaker. You move the APU Number 2 switch to ON. What happens?
  • External power is still connected. The APU Is powering both Transfer busses. What Do you need to do with Ground Power?
  • External power is still connected. The APU Is powering both Transfer busses. What Do you need to do with Ground Power?ASK the Engineer to Disconnect Ground Power!Connecting APU power removed Ground power automatically from thetransfer busses.
  • Both Engines are running. APU is powering the aircraft.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. What Happens?
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. What Happens? BTB 1 Opens first.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. What Happens? BTB 1 Opens first. GCB 1 closes.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. What Happens? BTB 1 Opens first. GCB 1 closes. The APU powers AC bus 2.
  • Both Engines are running. APU is powering the aircraft. Generator 1 SW to ON. What Happens? BTB 1 Opens first. GCB 1 closes.Remember the aircraft is designed to fly with 2operating generators! Both IDG’s or 1 IDG and the The APU powers AC bus 2.APU generator.
  • AC Power System.
  • AC Power System.Four Power sources
  • AC Power System.Four Power sourcesPowering 2 TransferBusses.
  • AC Power System.Four Power sourcesPowering 2 TransferBusses. Which normally power. Main busses Galley Busses Ground service Busses.
  • What is the meaning of this indication?
  • What is the meaning of this indication?The related transfer bus is NOT POWERED.
  • Given the indications on the right, Is AC Transfer bus 2 powered?
  • Given the indications on the right, Is AC Transfer bus 2 powered? GCB2 is open! BTB1 and BTB2 are closed! AC Transfer bus 2 is powered by GEN 1.
  • Given the indications on the right, Is AC Transfer bus 2 powered? The TRANSFER BUS OFF light is not illuminated. Therefore it is powered.
  • Integrated Dive Generators (IDG) Primary electrical power is provided by two engine driven integrated drive generators (IDG) Each IDG supplies Three-phase, 115 volts, at 400 Hz alternating current (AC) – Maximum load is 90 Kva per generator.
  • Integrated Dive Generators (IDG) The IDG takes the variable input speed and changes it into a constant speed of 24,000 RPM for its internal AC generator.
  • Integrated Dive Generators (IDG) The IDG takes the variable input speed and changes it into a constant speed of 24,000 RPM for its internal AC generator.The IDG requires a constant RPMto supply 400 Hz.
  • Generator DriveThe IDGs contain the generator and drive in a common housing, and are lubricatedand cooled by a self–contained oil system. An integral electro–mechanicaldisconnect device provides for complete mechanical isolation of the IDG.The IDG will automatically disconnect due to high oiltemperature if the temperature exceeds 182⁰ CIDG oil is cooled using an Air/Oil heat exchanger and fan airAnd a Fuel cooled oil cooler using the fuel being delivered tothe engine to cool the IDG oil and heat the fuel.
  • Automatic generator on–line featureThe system incorporates an automatic generator on–line feature in case theairplane takes off with the APU powering both transfer busses. If the APU is eithershut down or fails, the engine generators are automatically connected to theirrelated transfer busses. This action occurs only once in flight and only under thecircumstances described above.
  • What brings on the IDG DRIVE light?
  • GCU <165psiThe GCU gets an input from a low oil pressureswitch in the IDG to monitor oil pressure. If lessthan 165 psi with the engine running.The DEUs supply an engine run signal.The GCU controls the DRIVE light.
  • 2. DC POWER SUPPLY
  • The DC power generation system makes andcontrols 28 volts DC for use by aircraft systems.
  • The DC power generation system makes andcontrols 28 volts DC for use by aircraft systems.The DC power system is a two-wire system thatoperates at 28 volts (nominal).The DC system has these power sources:1.2.3.
  • The DC power generation system makes andcontrols 28 volts DC for use by aircraft systems.The DC power system is a two-wire system thatoperates at 28 volts (nominal).The DC system has these power sources:1. * Three transformer rectifiers units (TRUs)2. * Battery charger3. * Battery.
  • Each TRU can supply up to 75 Amps.The Transformer steps 115Volts down to 28 Volts.The Rectifier converts ACto DCThe TRU converts 115 VACto 28 volts DC.
  • Each TR can supply up to 75 Amps.The DC cross bus tie relay isnormally closed.TR1 and TR2 share the DC loads.TR 3 can act as a backup to TR2
  • Each TR can supply up to 75 Amps. The DC cross bus tie relay is normally closed. TR1 and TR2 share the DC loads. TR 3 can act as a backup to TR2The cross bus tie relay automatically opens, isolating DC bus 1 from DC bus 2, under the following conditions:• At glide slope capture during a flight director or autopilot ILS approach.This isolates the DC busses during approach to prevent a single failure from affecting both navigationreceivers and flight control computers• Bus transfer switch positioned to OFF.
  • Each TR can supply up to 75 Amps.TRU 1 gets power from the ACtransfer bus 1.TRU 1 output connects directlyto DC bus 1.
  • Each TR can supply up to 75 Amps.TRU 2 gets power from the ACtransfer bus 2.TRU 2 outputconnects directly to DC bus 2.
  • Each TR can supply up to 75 Amps.TRU 3 usually gets power from AC transfer bus 2.AC transfer bus 1 supplies back up powerthrough R622 if normal power is lost.The primary use of TRU 3 is as a power sourcefor the battery bus.
  • TR 1 via DC BUS 1 is the Normalpower supply for the DC STBY BUS
  • TR 1 via DC BUS 1 is the Normalpower supply for the DC STBY BUS The Hot Battery Bus can supply the DC STBY BUS if DC bus 1 is not powered.
  • Battery Charger is the Normal powersource for the Hot battery bus andSwitched hot battery bus.
  • Aux battery isNormallyisolated. Battery Charger is the Normal power source for the Hot battery bus and Switched hot battery bus. If the battery voltage is higher than the Charger output then the Battery will supply the Hot Battery bus.
  • The battery is a 48 ampere-hour, nominal 24v dc power source.It supplies power for APU starting and is a standby powersource if all other power supplies do not operate.
  • The battery is a 48 ampere-hour, nominal 24v dc power source.It supplies power for APU starting and is a standby powersource if all other power supplies do not operate.On older aircraft only the main battery was used to start the APU and the Auxiliary battery wasonly used for standby power.On newer aircraft both bateries are used for APU start.
  • Battery ChargerThe battery charger gives a DC voltage output to charge thebattery. After it charges the battery, the charger operates like aTRU. It sends a constant DC voltage to the battery and the hotand switched hot battery buses.
  • Battery ChargerThe battery charger gives a DC voltage output to charge thebattery. After it charges the battery, the charger operates like aTRU. It sends a constant DC voltage to the battery and the hotand switched hot battery buses. The battery charger has two basic modes of operation: * Battery charge mode * Transformer rectifier mode (constant voltage).
  • Battery ChargerThe battery charger gives a DC voltage output to charge thebattery. After it charges the battery, the charger operates like aTRU. It sends a constant DC voltage to the battery and the hotand switched hot battery buses. The battery charger has two basic modes of operation: * Battery charge mode * Transformer rectifier mode (constant voltage). The battery charger will go into the charge mode if any of these occur: 1. The battery charger input power is off for more than 1 second. 2. The battery voltage goes below 23 volts. Each charger can supply up to 65 amps in the charge mode.
  • The battery charger cannot go into the charge mode during anyof these conditions:* Fueling station door open* APU start* Standby power switch (P5-5) to the BAT position* Standby power switch (P5-5) to the AUTO position, batteryswitch ON, and DC BUS 1 and AC TRANSFER BUS 1 do nothave power* Battery overheat.
  • The battery charger cannot go into the charge mode during anyof these conditions:* Fueling station door open* APU start* Standby power switch (P5-5) to the BAT position* Standby power switch (P5-5) to the AUTO position, batteryswitch ON, and DC BUS 1 and AC TRANSFER BUS 1 do nothave power* Battery overheat.Battery Voltage Normally is 26 +/- 4 Volts.During Primary charge mode voltage may be as high as 30 +/- 3 volts
  • The amber BAT DISCHARGE light comes on when any one ofthese battery output conditions are true:* Current draw is more than 5 amps for 95 seconds* Current draw is more than 15 amps for 25 seconds* Current draw is more than 100 amps for 1.2 seconds.
  • 3. STANDBY DC POWER SYSTEM.
  • During Normal operation the STBY PWRswitch is in AUTO and the BATTERY switchis ON.
  • This will allow the battery to become thesole source of power if all other power islost!
  • With no other power available.What is powered with thisswitch selection?
  • With no other power available.What is powered with thisswitch selection?AC STBY Bus via the STBYInverter.DC STBY BUS Directly from theBattery.
  • With no other power available. What is powered with this switch selection? AC STBY Bus via the STBY Inverter.The Battery bus and Switched DC STBY BUS Directly from thehot battery bus are off Battery.because the battery switch isoff!
  • Given only the battery available.Which Busses have power?
  • Given only the battery available.Which Busses have power?ONLY THE HOT BATTERY BUS!
  • Given only the battery available. Which Busses have power? ONLY THE HOT BATTERY BUS!Battery switch off removes power from the Batterybus, switched hot battery bus, DC STBY bus, StaticInverter and STBY AC bus when the battery is theonly power source!
  • Non Normal operation and Indication.
  • What effect does this switch selection have on the electrical system?
  • What effect does this switch selection have on the electrical system? Isolates Transfer bus 1 from Transfer bus 2. Opens the DC cross bus Tie relay
  • In flight, what does this light indicate?
  • In flight, what does this light indicate?TR Unit 1ORTR UNITS 2 and 3 havefailed.
  • How can you identify which TRU hasfailed in flight?
  • How can you identify which TRU hasfailed in flight?
  • TR 1 and 2 will show Volts.A Zero AMPS indication is a failure.
  • TR 3 failure because of the diode will show ZERO VOLTS
  • What is Indicated by this light?
  • What is Indicated by this light?One or MORE of the following are unpowered!1. AC STBY BUS2. DC STBY BUS3. BATTERY BUS
  • With a double failure any ofthe 3 standby busses, can beleft unpowered. The StandbyPower off light is there toindicate this situation.
  • With a double failure any of the 3 standby busses, can be left unpowered. The Standby Power off light is there to indicate this situation.The AC Standby bus is normally poweredby AC transfer bus 1.If Transfer bus 1 is unpowered and theStandby inverter fails. There is no poweron the AC standby bus.
  • With a double failure any of the 3 standby busses, can be left unpowered. The Standby Power off light is there to indicate this situation.The Battery bus is normally powered byTRU 3. If TRU 3 fails and the breakerconnecting the battery bus to the batteryfails to close, then the battery bus iswithout power
  • With a double failure any of the 3 standby busses, can be left unpowered. The Standby Power off light is there to indicate this situation.The DC standby bus is normally poweredby DC bus 1.If DC bus 1 is not powered and thebreaker connecting the battery to the DCstandby bus fails to close then the DCstandby bus is unpowered.
  • What is indicated by this light?
  • What is indicated by this light?A Fault exists ineither the DC orSTBY Power system.
  • What is indicated by this light?A Fault exists ineither the DC orSTBY Power system. INHIBITED IN FLIGHT!
  • NO AC POWER AVAILABLE
  • NO AC POWER AVAILABLEWHAT ITEMS HAVE POWER?
  • NO AC POWER AVAILABLEWHAT ITEMS HAVE POWER?The standby power system ispowered by the batteries.
  • Aircraft on Standby power In addition to the panel instruments shown, the following equipment is available: • Left IRS • No.1GPS • Left FMC • Left CDU • No.1 DME • No.1 VHF Navigation • No.1 ADF • No.1 VHF Communications
  • If the TR UNIT light is illuminated in flight thisindicates:
  • If the TR UNIT light is illuminated in flight thisindicates:TR1 or TR 2 and 3 have failed.
  • If the TR UNIT light is illuminated in flight thisindicates:TR1 or TR 2 and 3 have failed. The transfer busses are connected by: One ..................... and two .....................
  • If the TR UNIT light is illuminated in flight thisindicates:TR1 or TR 2 and 3 have failed. The transfer busses are connected by: One ..................... and two ..................... ONE TIE BUS With 2 Bus Tie Breakers
  • The amber ELECT light on the electrical control panel indicates:In FLIGHT?On the Ground?
  • The amber ELECT light on the electrical control panel indicates:In FLIGHT? INHIBITEDOn the Ground? A Fault exists in the DC or Standby power system.
  • How are the IDG’s cooled?
  • How are the IDG’s cooled?Two heat exchangers, one is Air/oil the other Fuel /oil
  • The Cross bus tie relay opens at glide slope capture to:
  • The Cross bus tie relay opens at glide slope capture to:
  • The galley busses are powered from which busses?
  • The galley busses are powered from which busses? The AC Transfer busses distribute power to the Main busses. Galley busses Ground service busses IFE busses if installed.
  • What does the BAT DISCHARGE light on the FWD overhead panel indicate?
  • What does the BAT DISCHARGE light on the FWD overhead panel indicate? With the Battery switch ON Excessive Battery Discharge!
  • What is indicated by a SOURCE OFF light?
  • What is indicated by a SOURCE OFF light? No source has been manually selected. OR the last manually selected source is no longer powering the transfer bus
  • What is the voltage of an aircraft Nickel Cadmium battery?
  • What is the voltage of an aircraft Nickel Cadmium battery?
  • The purpose of a Transformer Rectifier (TR) is to:
  • The purpose of a Transformer Rectifier (TR) is to:
  • What is the maximum output of an IDG?
  • What is the maximum output of an IDG?90 KVA at 115 Volts 400 cycles (Hz)
  • Name the main divisions of the electrical system.
  • Name the main divisions of the electrical system.1. AC Power System.2. DC Power System3. Standby Power System.
  • Name the two main principles of the electrical system.
  • Name the two main principles of the electrical system.1. There is No paralleling of AC sources of power.2. The source of power being connected to a transfer bus automatically disconnects an existing source.
  • The END of ELECTRICAL POWER Now Take the test at www.theorycentre.com