Electrical (B747 400)

Controls and Indicators 6.10.1 Electrical Panel 6.10.1 Standby Power, Battery, and Utility Bus Controls 6.10.2 APU Generator and External Power Controls 6.10.4 AC Bus and Generator Controls 6.10.6 Overhead Maintenance Panel 6.10.8 Generator Field Manual Reset and Split System Breaker Switches 6.10.8 Electrical Synoptic Display 6.10.9 Battery Condition 6.10.11 System Description 6.20.1 Introduction 6.20.1 AC Electrical System 6.20.1 Electrical Load Management and Load Shedding 6.20.1 AC Electrical System Power Sources 6.20.1 AC Electrical Power Distribution 6.20.3 AC Standby Power System 6.20.8 AC Standby Power System Schematics 6.20.11 AC Standby Power System Schematic 6.20.12 AC Standby Power System (AC Bus 3 Unpowered) 6.20.14 AC Standby Power System (AC Busses 1 and 3 Unpowered) 6.20.16 AC Standby Power System (Standby Power selector - BAT) 6.20.18 DC Electrical System 6.20.20 Main DC Electrical System 6.20.20 Main DC Power Distribution 6.20.20 Battery Busses 6.20.20 Electrical Power System Schematic 6.20.22 Electrical - 747 Flight Crew Operations Manual Electrical Chapter 6 T a ble of Contents Section 0April 1, 2006 Copyright © The Boeing Company. See title page for details. D6-30151-400 6.TOC.0.1 Table of Contents 747 Flight Crew Operations Manual EICAS Messages 6.30.1 Electrical EICAS Messages 6.30.1 Copyright © The Boeing Company. See title page for details. 6.TOC.0.2 D6-30151-400 April 1, 2006 AUTO ISLN AUTO ISLN Controls and Indicators Section 10 Electrical Panel ON OFF ON OFF ON OFF A V A I L A V A I L AUTO ISL N ON OFF DRI VE AUTO I SLN ON OFF DRIVE AUTO ISLN ON OFF DRIVE AUTO ISLN ON OFF DR IVE A V A I L A V A I L APU ON OFF START L UTILITY R STANDBY POWER AUTO OFF BAT 1 BATTERY EXT PWR 1 APU GEN 1 APU GEN 2 EXT PWR 2 2 ON ON ON ON BUS TIE BUS BUS BUS BUS 3 GEN CONT 1 2 3 4 DRIVE DISC OVERHEAD PANEL DRI VE 1Standby Power and Utility Bus Controls 2External Power, APU Generator, and Battery Controls 3AC Bus and Generator Controls Copyright © The Boeing Company. See title page for details. D6-30151-400 6.10. 4 May 1, 2002 Copyright © The Boeing Company. See title page for details. D6-30151-400 October 1, 2004 6.10. 3 STANDBY POWER L UTILITY R APU AUTO ON OFF BAT ON ON OFF START OFF OFF BATTERY EXT PWR 1 APU GEN 1 APU GEN 2 EXT PWR 2 ON A A A A V V OFF V V A ON A ON A ON A ON I I I I L L L LStandby Power, Battery, and Utility Bus Controls ON OFF ON OFF OFF A V A I L APU ON OFF START A V A I L A V A I L A V A I L L UTILITY R STANDBY POWER AUTO 4 OFF BAT 1 BATTERY 5 EXT PWR 1 APU GEN 1 APU GEN 2 EXT PWR 2 ON ON ON ON 3 OVERHEAD PANEL 1 STANDBY POWER Selector Push to turn. OFF – · standby power not available 006, 008 · standby bus disconnected from all power sources 203 · main and APU standby busses disconnected from all power sources 006, 008 AUTO – allows standby bus to be powered from available sources. 203 AUTO – allows main and APU standby busses to be powered from available sources. BAT – · powers main battery bus from main battery through the main hot battery bus with battery switch ON · powers APU battery bus from APU battery through the APU hot battery bus with battery switch ON · disables main and APU battery chargers 006, 008 · powers standby bus from the main battery through the main hot battery bus and the standby inverter with Battery switch ON Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual 203 · powers main and APU standby busses from their related batteries through their hot battery busses and standby inverters with Battery switch ON Note: BAT position for ground maintenance use only. 2 BATTERY Switch ON - 006, 008 · main battery available as backup power source for main battery bus and standby bus · APU battery available as backup power source for APU battery bus 203 · main battery available as backup power source for main battery bus and main standby bus · APU battery available as backup power source for APU battery bus and APU standby bus OFF - disconnects main and APU batteries from related battery busses. 3 BATTERY Switch OFF Light Illuminated (amber) - Battery switch off 4 UTILITY Power Switches ON - each switch powers two utility Electrical Load Control Units (ELCUs), and on passenger and combi airplanes two galley ELCUs. OFF - · removes power from related ELCUs · resets fault logic circuitry 5 UTILITY Power OFF Lights Illuminated (amber) - · power removed from related ELCUs by fault protection logic, or · related Utility Power switch OFF, or · on passenger/combi airplanes, one or more Galley Emergency Power Off switch OFF · not illuminated during load shedding STANDBY POWER L UTILITY R APU AUTO ON OFF BAT ON ON OFF START OFF OFF BATTERY EXT PWR 1 APU GEN 1 APU GEN 2 EXT PWR 2 ON A A A A V V OFF V V A ON A ON A ON A ON I I I I L L L LAPU Generator and External Power Controls L UTILITY R STANDBY POWER AUTO APU ON OFF BAT ON ON OFF START 1 OFF OFF BATTERY 4 EXT PWR 1 APU GEN 1 APU GEN 2 EXT PWR 2 A V A ON I L A V A ON I L OFF A V A ON I L A V A ON I L 5 3 6 OVERHEAD PANEL 1 APU Generator (APU GEN) Control Switches Push – · AVAIL light illuminated: connects related APU generator to AC electrical system Note: On freighter airplanes, when the main deck cargo handling bus is powered by APU generator 2, pushing APU generator 2 Control switch causes main deck cargo handling bus to lose power. · ON light illuminated: disconnects related APU generator from AC electrical system 2 APU Generator Power Available (AVAIL) Lights Illuminated (white) - · APU generator power quality acceptable · on freighter airplanes, main deck cargo handling bus powered when APU generator 2 AVAIL light illuminated · extinguishes when ON light illuminates 3 APU Generator Power ON Lights Illuminated (white) - · related APU generator connected to AC electrical system · extinguishes when AVAIL light illuminates 4 External Power (EXT PWR) Control Switches Push - · AVAIL light illuminated: connects related external power to AC electrical system Note: On freighter airplanes, when the main deck cargo handling bus is powered by external power 2, pushing External Power 2 Control switch causes main deck cargo handling bus to lose power. · ON light illuminated: disconnects related external power from AC electrical system 5 External Power ON Lights Illuminated (white) - · related external power connected to AC electrical system · extinguishes when AVAIL light illuminates 6 External Power Available (AVAIL) Lights Illuminated (white) - · related external power source plugged in, power quality acceptable · extinguishes when ON light illuminates · on freighter airplanes, main deck cargo handling bus powered when external power 2 AVAIL light illuminated Note: On freighter airplanes, when both external power 2 and APU generator 2 AVAIL lights are illuminated, external power 2 powers the main deck cargo handling bus. Pushing the External Power 2 Control switch transfers main deck cargo handling loads to APU generator 2. Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual May 1, 2002 Copyright © The Boeing Company. See title page for details. D6-30151-400 6.10.5 AUTO ISLN AUTO ISLN AUTO AUT O BUS AUTO AUTO ISLN ISL N TIE I SLN ISLN BUS BUS BUS BUS ON ON ON ON GEN OFF OFF CONT OFF OFF 1 2 3 4 DRIVE DISC DR IVE DRI VE DRIVE DRIVE AUTO ISLN AUTO ISLNAC Bus and Generator Controls AUTO ISL N ON OFF DRI VE AUTO I SLN ON OFF DRIVE AUTO ISLN ON OFF DRIVE AUTO ISLN ON OFF DR IVE 1 2 BUS TIE 5 BUS BUS BUS BUS GEN CONT 1 2 3 4 6 3 DRIVE DISC 4 OVERHEAD PANEL DRI VE DRI VE 1BUS TIE Switches AUTO – · arms automatic AC bus tie circuitry · closes related DC isolation relay (DCIR) OFF - · BTB and related DCIR · resets fault logic circuitry 2Bus Isolation (ISLN) Lights Illuminated (amber) - · BTB open · AC bus isolated from synchronous bus 3Generator Drive Disconnect (DRIVE DISC) Switches Push - · disconnects IDG from engine when above idle speed · opens related Generator Control Breaker (GCB) Note: Ground maintenance action required to reconnect IDG. Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual Copyright © The Boeing Company. See title page for details. 6.10.6 D6-30151-400 October 1, 2004 4 Generator DRIVE Lights 008, 203 (SB changes 006 ; improved generator control units for added IDG protection installed) Illuminated (amber) - · IDG oil pressure low, or · IDG oil temperature high, or · GCB open due to uncorrectable generator frequency fault (SB changes 006 ; before SB, improved generator control units for added IDG protection not installed) Illuminated (amber) - · IDG oil pressure low, or · IDG oil temperature high 5 Generator Control (GEN CONT) Switches ON - arms GCB to close when generator power quality acceptable OFF - · opens generator field and GCB · resets fault control logic circuitry · isolates generator from its related AC bus 6 Generator OFF Lights Illuminated (amber) - GCB open Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual October 1, 2004 Copyright © The Boeing Company. See title page for details. D6-30151-400 6.10.7 Overhead Maintenance Panel Generator Field Manual Reset and Split System Breaker Switches FI ELD OFF FI ELD OFF FI ELD OFF FI ELD OFF FI ELD OFF FI ELD OFF OPEN GEN FIEL D MAN RESE T 1 2 3 4 1 2 1 APU 2 SP LIT SYSTEM BREAKER 3 4 OVERHEAD MAINTENANCE PANEL 1 Generator Field Manual Reset (GEN FIELD MAN RESET) Switches Push - (spring-loaded toggle, guarded) opens or closes generator field if related Generator Control or APU Generator Control switch off 2 Generator FIELD OFF Lights Illuminated (white) - generator field open. 3 SPLIT SYSTEM BREAKER Switch Push - (spring-loaded toggle, guarded) opens or closes split system breaker Note: Operative on ground only. 4 Split System Breaker OPEN Light Illuminated (white) - split system breaker open Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual Copyright © The Boeing Company. See title page for details. 6.10.8 D6-30151-400 May 1, 2002 Electrical Synoptic Display The electrical synoptic displays by pushing the ELEC Synoptic switch on the display select panel. Display select panel operation is described in Chapter 10, Flight Instruments, Displays. The synoptic displays the configuration of the AC power system in a simplified schematic format. DC power flow is not represented. The depiction is generated by the status of various system breakers and conductors and does not represent actual power flow. Therefore, the display may not be an accurate representation of system operation. Symbols display in low intensity white when source data is invalid or unavailable. During autoland, with bus tie breakers 1, 2, and 3 open, the message “ELECTRICAL SYNOPTIC INHIBITED FOR AUTOLAND” appears on the synoptic display. DR IV E TEMP / PR ESS 1 EX T 1 APU 1 APU 2 EX T 2 SSB 2 3 4 IS LN BUS TI E IS LN U TILIT Y G ALL EY UTI LI TY UT ILIT Y GAL LE Y BUS 1 BUS 2 UT ILIT Y GA LLEY GA LL EY BUS 3 BUS 4 5 GEN CO NT OF F OF F 6 DR IV E 1 2 3 4 7 POWER FLOW (green) NO POWER FLOW LOWER EICAS DISPLAY Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual Copyright © The Boeing Company. See title page for details. D6-30151-400 May 1, 2002 6.10. 9 1 SSB (Split System Breaker) Closed - SSB closed, both sides of synchronous bus connected Open - synchronous bus split. 2 BUS TIE · power flow bar present - BTB closed · ISLN (amber) - BTB open 3 UTILITY · green - utility bus powered · amber - utility bus not powered 4 BUS · green - AC bus powered · amber - AC bus not powered 5 GEN CONT · power flow bar present - GCB closed · OFF (amber) - GCB open 6 DRIVE · blank (green) - normal operation · DRIVE TEMP/PRESS (amber) - IDG has high oil temperature or low oil pressure 7 GALLEY (passenger/combi) · green - galley bus powered · amber - galley bus unpowered Copyright © The Boeing Company. See title page for details. 6.10.10 D6-30151-400 October 1, 2004 Battery Condition Battery condition displays on the status page by pushing STAT Display switch on the display select panel. Display select panel operation is described in Chapter 10, Flight Instruments, Displays. 1 2 MA IN BA TT V - DC 28 A- DC 15 DIS 3 APU BAT T V - DC 27 A- DC 10 CHG LOWER EICAS DISPLAY 1 Battery Voltage (V-DC) Main and APU battery voltage 2 Battery Current (A-DC) Main and APU battery amperage 3 Battery Charge Status DIS (Discharge) - battery discharging CHG (Charge) · battery charging · if battery current is zero, charge status is blank Electrical - Controls and Indicators 747 Flight Crew Operations Manual Electrical - Controls and Indicators 747 Flight Crew Operations Manual Copyright © The Boeing Company. See title page for details. D6-30151-400 May 1, 2002 6.10. 11 Intentionally Blank Copyright © The Boeing Company. See title page for details. 6.10.12 D6-30151-400 May 1, 2002 747 Flight Crew Operations Manual Electrical System Description Chapter 6 Section 20 Introduction The electrical system generates and distributes AC and DC power to other airplane systems and is comprised of main AC power, DC power, and standby power components. System operation is automatic. Electrical faults are automatically detected and isolated. AC Electrical System The AC electrical system is the main source of airplane electrical power. Electrical Load Management and Load Shedding Electrical system overload protection is provided by a load management system configured to ensure power is available to critical and essential equipment. If electrical loads exceed power available (airplane or external), the load management system sheds AC loads by priority until the loads are within the capacity of airplane or ground power generators. Loads are shed one at a time through ELCUs in a programmed sequence until the overload condition is relieved. In passenger and combi airplanes, galley busses are shed first, followed by utility busses. In the freighter airplane, utility bus loads are shed. When an additional AC power source is available, loads are restored in reverse order. During load shedding, the ELEC UTIL BUS L and R messages and utility off lights are inhibited. However, the following EICAS alert messages may display in the order shown depending upon fuel system configuration and the extent of load shedding: · FUEL PUMP 3 FWD · FUEL OVRD 2 FWD · FUEL OVRD 3 FWD · FUEL OVRD CTR L · FUEL PUMP 2 FWD AC Electrical System Power Sources The main AC electrical power sources are: · four IDGs · two auxiliary power sources (APU generators) · two external power sources Copyright © The Boeing Company. See title page for details. D6-30151-400 6.20. 10 April 1, 2006 Copyright © The Boeing Company. See title page for details. D6-30151-400 April 1, 2006 6.20. 9 During normal operation, IDG power output to the four AC busses is synchronized. Each bus is interconnected through a single synchronous bus, which distributes electrical power and allows individual AC busses to remain powered when their related generators are inoperative. The split system breaker (SSB) divides the synchronous bus allowing each side of the AC electrical system to be powered by separate auxiliary or external power sources. IDGs One IDG is mounted on each engine accessory gearbox. Each IDG incorporates an AC generator, drive unit with self-contained lubrication system, and automatic control and protection components. When an engine is started with auxiliary or external power connected to each side of the electrical system (SSB open), the IDG powers its side of the synchronous bus when voltage and frequency are acceptable. The previous power source is disconnected. When an engine on the opposite side of the airplane is started, the IDG powers its side of the synchronous bus. The previous power source is disconnected and the SSB closes. When a single auxiliary or external power source is powering the electrical system and an engine is started, the IDG powers the entire synchronous bus when voltage and frequency are acceptable. The SSB remains closed and the original power source is disconnected. During power source transfers on the ground, such as switching from IDG to auxiliary or external power, output from IDG and another power source is momentarily synchronized before one source is disconnected. This provides smooth, uninterrupted electrical power switching. Each IDG can be electrically disconnected from its related bus by pushing the Generator Control switch OFF. On the ground, an IDG can also be disconnected from its related bus by selecting an available auxiliary or external power source. IDG Disconnect Each IDG can be mechanically disconnected from its engine accessory gearbox by pushing the Generator Drive Disconnect switch. When an IDG is disconnected, generator power output is lost and cannot be restored by flight crew action. The EICAS message ELEC DRIVE displays for low IDG oil pressure or high IDG oil temperature. 008, 203 (SB changes 006 ; improved generator control units for added IDG protection installed) The ELEC DRIVE message also displays if a GCB is open due to an uncorrectable generator frequency fault. Electrical - System Description 747 Flight Crew Operations Manual Electrical - System Description 747 Flight Crew Operations Manual Excessively high drive oil temperature disconnects the IDG automatically if not manually disconnected by flight crew action. The resulting loss of generator power output opens the GCB and displays the EICAS message ELEC GEN OFF. Pushing the Generator Drive Disconnect switch after automatic disconnect replaces the ELEC DRIVE message with the DRIVE DISC message. Auxiliary and External Power Auxiliary power is available only on the ground from generators mounted on the APU. External power is available from ground sources through two power receptacles located on the lower right forward fuselage. Either source can power main AC busses through connection to the synchronous bus. Auxiliary and external power sources cannot be connected to the same side of the synchronous bus simultaneously. The SSB is commanded open or closed to ensure all AC main busses are powered on the ground. On an unpowered airplane with auxiliary and external power available, when a single power source is selected, the SSB closes and power is provided to the entire synchronous bus by the selected source. When the other same-type power source is selected on the opposite side, the SSB opens and each source powers its side of the synchronous bus. If one power source is disconnected or fails, the SSB closes maintaining power to the entire synchronous bus from the remaining source. When IDGs are powering the electrical system with auxiliary or external power available, selecting a single power source disconnects IDGs on the same side and opens the SSB. The selected source powers its side of the synchronous bus, while the opposite side remains powered by IDGs. Selecting a second auxiliary or external power source on the opposite side disconnects the remaining IDGs and completes the power transfer from IDG to auxiliary/external power; the SSB remains open. Note: On the freighter airplane, when cargo handling is required, selecting only the number one auxiliary or external power source ON ensures the main deck cargo handling bus remains powered. AC Electrical Power Distribution AC power is distributed by the following busses: · four main busses · two transfer busses · ground service and ground handling busses · four galley busses (passenger and combi) · four utility busses 006, 008 · one standby bus 203 · two standby busses AC Main Busses Each IDG normally powers its related AC bus through a GCB. Each AC bus is connected to the synchronous bus by a BTB. With the Bus Tie switch in AUTO, the related BTB controls the AC bus connection to the synchronous bus. If power on an AC bus is unacceptable, the related BTB opens and the bus disconnects from the synchronous bus. However, the AC bus remains powered by its IDG. If the IDG is not able to maintain acceptable power quality, the GCB opens and the BTB closes to provide power from the synchronous bus. The EICAS message ELEC BUS ISLN displays if the BTB is open. Pushing the Bus Tie switch OFF, then AUTO, resets logic circuitry and allows the BTB to close if the fault is corrected. The AC bus is reconnected to the synchronous bus. The main AC busses power individual equipment items such as: · TRUs · navigation radios and flight control computers · flight deck lighting · pitot and window heat The main AC busses also power other AC busses: · AC bus 1 powers the ground service bus and provides back-up power for both transfer busses · AC bus 2 powers the First Officer’s transfer bus · Each AC bus powers a utility and galley bus (passenger and combi) 006, 008 · AC bus 3 powers the Captain’s transfer bus and the standby bus 203 · AC bus 3 powers the Captain’s transfer bus and the main standby bus Ground Service Bus The ground service bus is powered on the ground and in flight whenever AC bus 1 is powered. The ground service bus powers individual equipment items such as: · main and APU battery chargers · fuel pumps for APU start · upper deck doors · flight deck flood, navigation, and service lights · miscellaneous service outlets and equipment 006, 008 · horizontal stabilizer fuel pump for defueling On the ground when AC bus 1 is not powered, the ground service bus can be connected to the same source powering the ground handling bus by pushing the Ground Service switch on the flight attendant’s panel at door 2L (passenger and combi), or on the cabin panel at door 1L (freighter). Ground Handling Bus The ground handling bus is powered on the ground when APU generator 1 or external power 1 is available. If both are available, external power is automatically used. The ground handling bus powers individual equipment items such as: · lower cargo handling equipment and compartment lights · fueling system 203 · auxiliary hydraulic pumps 1 and 4 006, 008 · auxiliary hydraulic pump 4 Transfer Busses Two transfer busses provide AC power to critical flight-related equipment. The transfer busses have a common back-up power source. Transfer to the back-up power source is automatic. Captain’s Transfer Bus 006, 008 The Captain’s transfer bus is normally powered by AC bus 3. If AC bus 3 is unpowered, AC bus 1 powers the Captain’s transfer bus. 203 The Captain’s transfer bus is normally powered by AC bus 3. If AC bus 3 is unpowered, AC bus 1 powers the Captain’s transfer bus. The Captain’s transfer bus powers the APU standby bus. The Captain’s transfer bus powers individual equipment items such as: · center EFIS/EICAS Interface Unit (EIU) · left HF 203 · center ADC 006, 008 · Left FMC, left ND, left PFD First Officer’s Transfer Bus The First Officer’s transfer bus is normally powered by AC bus 2. If AC bus 2 is unpowered, AC bus 1 powers the First Officer’s transfer bus. The First Officer’s transfer bus powers individual equipment items such as: · autothrottle servo · lower EICAS display · right ADC, right EFIS control, right EIU, right FMC · right CDU, right HF, right ND, right PFD Utility and Galley Busses In passenger and combi airplanes, each main AC bus powers one utility bus and one galley bus. Each utility/galley bus is controlled by an ELCU, which protects the electrical system from utility and galley bus faults and provides load management through automatic load shedding. With the Left Utility Power switch ON, utility busses 1 and 2 and galley busses 1 and 2 are powered according to ELCU logic. With the Right Utility Power switch ON, utility busses 3 and 4 and galley busses 3 and 4 are powered according to ELCU logic. In the freighter airplane, each main AC bus powers one utility bus. Each utility bus is controlled by an ELCU that protects the electrical system from utility bus faults and provides load management through automatic load shedding. With the Left Utility Power switch ON, utility busses 1 and 2 are powered according to ELCU logic. With the Right Utility Power switch ON, utility busses 3 and 4 are powered according to ELCU logic. Utility busses power individual equipment items such as: · forward main fuel pumps 2 and 3 · forward override/jettison pumps 2 and 3 · center override/jettison pump · recirculating fans (passenger/combi airplanes) Galley busses power the galleys located throughout the cabin of passenger and combi airplanes. The EICAS message ELEC UTIL BUS displays and the utility OFF light illuminates if one or more utility or galley (passenger and combi) bus become unpowered due to a fault. Cycling the Utility Power switch OFF, then ON restores power to the affected bus if the fault is corrected. In passenger and combi airplanes, a guarded ON Galley Emergency Power Off switch is located at each galley. If a Galley Emergency Power Off switch is selected OFF, the related ECAS message ELEC UTIL BUS displays and utility OFF light illuminates. Cycling the flight deck Utility Power switch OFF, then ON will not reset the indications. The flight deck Utility Power switch should remain ON after cycling, which permits the remaining utility and galley busses to be powered and controlled by their related ELCU. Main Deck Cargo Handling Bus (freighter) The main deck cargo handling bus is powered on the ground when external power 2 or APU generator 2 is available. An interlock prevents either source from powering main electrical busses and the main deck cargo handling bus simultaneously. Pushing the available Power source switch ON deengergizes the main deck cargo handling bus. When both external power 2 and APU generator 2 are available, external power is used. Pushing External Power 2 switch ON transfers main deck cargo handling loads to APU generator 2. Note: When cargo handling is required, selecting only the number one auxiliary or external power source ON ensures the main deck cargo handling bus remains powered. The main deck cargo handling bus powers equipment items such as: · main deck cargo handling equipment and lighting · nose and side cargo doors Main Deck Cargo Handling Bus (Combi) The main deck cargo handling bus is powered on the ground when external power 2 or APU generator 2 is available. When both external power 2 and APU generator 2 are available, external power is used. Pushing External Power 2 switch ON transfers main deck cargo handling loads to APU generator 2. The main deck cargo handling bus powers equipment items such as: · main deck cargo handling equipment and lighting · side cargo door Electrical bus Isolation during Autoland During automatic ILS approach below 1,500 feet radio altitude, AC and DC busses 1, 2, and 3 are automatically isolated. This provides an independent power source for each of the three autopilots. AC bus 4 continues to power the synchronous bus, and will power any other AC bus if its generator fails. During autoland, the AC bus isolation lights 1, 2, and 3 do not illuminate, the EICAS message ELEC BUS ISLN does not display, and the message “ELECTRICAL SYNOPTIC INHIBITED FOR AUTOLAND” appears on the electrical synoptic. Autoland is disengaged and the electrical system returned to normal configuration under the following conditions: · TO/GA mode active · autopilot disengaged · loss of autoland redundancy AC Standby Power System The AC standby power system provides electrical power to critical flight deck equipment. 006, 008 Major components of the system include: · standby bus · main battery · standby inverter · Standby Power selector 203 Major components of the system include: · main and APU standby busses · main and APU batteries · main and APU standby inverters · Standby Power selector Standby Bus 006, 008 The standby bus is normally powered by AC bus 3. With the Battery switch ON, Standby Power selector in AUTO, and AC bus 3 not powered, the standby bus is powered by the standby inverter. The standby inverter, normally unpowered, is activated and receives power from the main battery charger through the main hot battery bus. The main battery charger is normally powered by AC bus 1 through the ground service bus. With the Battery switch ON, Standby Power selector in AUTO, and both AC bus 1 and AC bus 3 not powered, the standby bus is powered by the standby inverter. The standby inverter, normally unpowered, is activated and receives power from the main battery through the main hot battery bus. With the main battery charger unpowered, the main battery can provide power to the standby bus for a minimum of 30 minutes. The standby bus powers individual equipment items such as: · left EIU, left CDU, left ILS, left VOR · various flight control components · standby ignition for all engines · primary EICAS display, RMI, standby instrument lights · left ADC, left EFIS control panel Main Standby Bus 203 The main standby bus is normally powered by AC bus 3. With the Battery switch ON, Standby Power selector in AUTO, and AC bus 3 not powered, the main standby bus is powered by the main standby inverter. The main standby inverter, normally unpowered, is activated and receives power from the main battery charger through the main hot battery bus. The main battery charger is normally powered by AC bus 1 through the ground service bus. With the Battery switch ON, Standby Power selector in AUTO, and both AC bus 1 and AC bus 3 not powered, the main standby bus is powered by the main standby inverter. The main standby inverter, normally unpowered, is activated and receives power from the main battery through the main hot battery bus. With the main battery charger unpowered, the main battery can provide power to the main standby bus for a minimum of 30 minutes. The main standby bus powers individual equipment items such as: · left EIU, left CDU, left ILS, left VOR · various flight control components · standby ignition for all engines · primary EICAS display, RMI, standby instrument lights · left ADC, left EFIS control panel APU Standby Bus 203 The APU standby bus is normally powered by the Captain’s transfer bus. With the Battery switch ON, Standby Power selector in AUTO, and the Captain’s transfer bus not powered (loss of AC busses 1 and 3), the APU standby bus is powered by the APU standby inverter. The APU standby inverter, normally unpowered, is activated and receives power from the APU battery through the APU hot battery bus. With the APU battery charger unpowered, the APU battery can provide power to the APU standby bus for a minimum of 30 minutes. The APU standby bus powers these equipment items: · left FMC · left ND · left PFD Standby Power Selector - BAT Position 203 With the Battery switch ON and Standby Power selector in BAT, main and APU battery chargers are disabled. Each AC standby bus is powered by its related battery and inverter. Each battery can provide power for a minimum of 30 minutes. 006, 008 With the Battery switch ON and Standby Power selector in BAT, the main and APU battery chargers are disabled. The standby bus is powered by the main battery through the main hot battery bus and standby inverter. The APU battery bus is powered by the APU battery through the APU hot battery bus. The main battery can provide power to the standby bus for a minimum of 30 minutes. Note: The Standby Power selector must be in AUTO for flight. The BAT position is for ground maintenance use only. AC Standby Power System Schematics The schematics on the following pages illustrate the configuration of the AC standby power system and functional relationships of its major components under specific conditions. Sources of electrical power and system components not required for this purpose have been intentionally omitted. Copyright © The Boeing Company. See title page for details. D6-30151-400 6.20. 20 October 1, 2004 Copyright © The Boeing Company. See title page for details. D6-30151-400 October 1, 2004 6.20. 19 AC Standby Power System Schematic 006, 008 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 STANDBY BUS STANDBY INVERTER TRU MAIN BAT BUS DC BUS 3 MAIN HOT BAT BUS DC TIE BUS MA IN BATTERYMAIN BAT CHARGER GRND SERVICE BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - AUTO 3. ALL BUSSES POWERED NORMALLY POWERED (AC) POWERED (DC) UNPOWERED 203 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 APU STBY BUS MA IN STBY BUS APU STANDBY INV ERTER MAIN STANDBY INV ERTER TRU 3 APU BA T BUS MAIN BAT BUS DC BUS 3 APU HO T BAT BUS MAIN HOT BA T BUS DC TIE BUS APU BAT CHARGER APU BATTERY MAIN BATTE RY M AIN BA T CHARGER GRND S ERVIC E BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - AUTO 3. ALL BUSSES POWERED NORMALLY POWERED (AC) POWERED (DC) UNPOWERED AC Standby Power System (AC Bus 3 Unpowered) 006, 008 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 STANDBY BUS STANDBY INVERTER TRU MAIN BAT BUS DC BUS 3 MAIN HOT BAT BUS DC TIE BUS MA IN BATTERYMAIN BAT CHARGER GRND SERVICE BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - AUTO 3. AC BUS 3 - UNPOWERED 4. STANDBY POWER AVAILABLE WITHOUT LIMITATION POWERED (AC) POWERED (DC) UNPOWERED 203 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 APU STBY BUS M AIN STBY BUS APU STANDBY INV ERTER MAIN STANDBY INV ERTER TRU 3 APU BA T BUS MAIN BAT BUS DC BUS 3 APU HOT BAT BUS MAIN HOT BA T BUS DC TIE BUS APU BAT CHARGER APU BATTERY MAIN BATTE RY M AIN BA T CHARGER GRND SERVIC E BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - AUTO 3. AC BUS 3 - UNPOWERED 4. STANDBY POWER AVAILABLE WITHOUT LIMITATION POWERED (AC) POWERED (DC) UNPOWERED AC Standby Power System (AC Busses 1 and 3 Unpowered) 006, 008 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 STANDBY BUS STANDBY INVERTER TRU MAIN BAT BUS DC BUS 3 MAIN HOT BAT BUS DC TIE BUS MAIN BATTERY MAIN BAT CHARGER GRND SERVICE BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - AUTO 3. AC BUSSES 1 AND 3 - UNPOWERED 4. STANDBY POWER AVAILABLE MINIMUM 30 MINUTES POWERED (AC) POWERED (DC) UNPOWERED 203 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 APU STBY BUS MAIN STBY BUS APU MAIN STANDBY INVERTER STANDBY INVERTER TRU 3 APU BAT BUS MAIN BAT BUS DC BUS 3 APU HOT BAT BUS MAIN HOT BAT BUS DC TIE BUS APU BA T CHARGER APU BATTE RYMAIN BATTERY MAIN BAT CHARGER GRND SERVICE BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - AUTO 3. AC BUSSES 1 AND 3 - UNPOWERED 4. STANDBY POWER AVAILABLE MINIMUM 30 MINUTES POWERED (AC) POWERED (DC) UNPOWERED AC Standby Power System (Standby Power selector - BAT) 006, 008 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 STANDBY BUS STANDBY INVERTER TRU MAIN BAT BUS DC BUS 3 MAIN HOT BAT BUS DC TIE BUS MAIN BATTERY MAIN BAT CHARGER GRND SERVICE BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - BAT 3. BATTERY CHARGER DISABLED 4. BATTERY POWER AVAILABLE MINIMUM 30 MINUTES POWERED (AC) POWERED (DC) UNPOWERED 203 AC BUS 1 CAPT TRANSFER BUS AC BUS 3 APU STBY BUS M AIN STBY BUS APU STANDBY INV ERTER MAIN STANDBY INV ERTER TRU 3 APU BAT BUS MAIN BAT BUS DC BUS 3 APU HOT BAT BUS MAIN HOT BA T BUS DC TIE BUS APU BA T CHARGER APU BATTE RY MAIN BATTE RY M AIN BAT CHARGER GRND SERVIC E BUS CONDITIONS 1. BATTERY SWITCH - ON 2. STANDBY POWER SELECTOR - BAT 3. BATTERY CHARGERS DISABLED 4. BATTERY POWER AVAILABLE MINIMUM 30 MINUTES POWERED (AC) POWERED (DC) UNPOWERED DC Electrical System The DC electrical system includes the main DC electrical system and the battery busses. Main DC Electrical System The main DC electrical system uses four transformer-rectifier units (TRUs) to produce DC power. Each TRU is powered by its related AC bus and provides DC power to a DC bus. The four DC busses are connected through DC isolation relays (DCIRs) to the DC tie bus, which allows each DC bus to remain powered if its related AC bus is unpowered or TRU fails. Pushing the Bus Tie switch to AUTO closes the related BTB and DCIR. Pushing the Bus Tie switch OFF opens the BTB and DCIR. This isolates the DC bus from the DC tie bus, leaving it powered by its AC bus and TRU. Automatic isolation of an AC bus due to an electrical fault opens the BTB, but does not open the DC isolation relay. Main DC Power Distribution TRU DC electrical power is distributed to four main DC busses. Main DC busses power individual equipment items such as: · cabin pressure, fuel jettison, and pack temperature controllers · wing anti-ice control · engine-driven and hydraulic demand pump control · fuel transfer and jettison valve control · individual nacelle anti-ice control Battery Busses The following battery busses distribute DC power in addition to the four main DC busses: · Main battery bus · APU battery bus · Main hot battery bus · APU hot battery bus The main and APU battery busses are normally powered by DC bus 3. If either AC bus 3 or DC bus 3 is unpowered, each battery bus is powered by its related hot battery bus. The main battery bus provides power to individual equipment such as: · APU controller (alternate), fuel valves (all engines), all crossfeed valves · dome, storm, and selected indicator lights · IDG disconnect (all engines), manual pressurization control, trailing edge flap control · Captain’s interphone, left radio tuning panel, left VHF The APU battery bus powers individual equipment items such as: · APU DC fuel pump, engine start air control · Cargo, First Officer’s, and service interphones, PA system · APU and engine fire/overheat detection loops A and B · APU fire warning horn Each hot battery bus is normally powered by the ground service bus through its related battery charger, which acts as a TRU for the hot battery bus while simultaneously maintaining its related battery fully charged. Each battery is directly connected to its related hot battery bus. With the Battery switch ON, the main and APU hot battery busses power their related battery busses if DC bus 3 is unpowered. The main hot battery bus powers individual equipment items such as: · APU fuel shutoff valve, spar valves (all engines) · APU and lower cargo fire extinguishers · engine fire extinguishers (all engines), fire switch unlock (all engines) The APU hot battery bus powers individual equipment items such as: · IRU left, center, right DC power · left and right outflow valves · APU inlet door, APU controller (primary) Copyright © The Boeing Company. See title page for details. D6-30151-400 6.20. 24 October 1, 2004 Copyright © The Boeing Company. See title page for details. D6-30151-400 October 1, 2004 6.20. 23 Electrical Power System Schematic The Electrical Power System Schematic illustrates configuration of the electrical power system and functional relationships of its major components. System components not required for this purpose have been intentionally omitted. DRIVE006, 008 APU BAT BUS STANDBY INVERTER DC BUS 1 DC BUS 2 DC BUS 3 DC BUS 4 BAT TERY EXT P WR 1 A PU GEN 1 A PU GEN 2 EXT PWR 2 ON ON A V A I L ON CONDITION: NO ELECTRICAL SYSTEM FAULTS. AUTO AUTO AUTO A UTO BU S TI E AC BUS 1 AC B US 2 AC B US 3 AC BUS 4 ON ON ON ON GEN CO NT OFF OFF OFF OFF 1 2 3 4 DR IV E DI SC DRIVE DRIVE DRIVE DRIVE F/O TRANSFER BUS AC BUS 2 POWERED CAPT TRANSFER BUS STBY BUS AC BUS 3 POWERED T T T T R R R R MAIN BAT BUS DC ISOLATION RELAY (typical) DC TIE BUS BATTERY SW APU HOT BAT BUS MAIN HOT BAT BUS APU BAT APU CHARGER BATTERY MAIN MAIN BAT BATTERY CHARGER GND SERVICE BUS GND SERVICE SW AC BUS 1 POWERED COMBI MAIN DECK CARGO HANDLING BUS (FLT ATTENDANT PANEL) APU GEN 2 EXT PWR 1 EXT PWR 2 APU GEN 1 GND HANDLING BUS DRIVE203 APU BAT BUS APU BAT CHARGER APU BATTERY MAIN STANDBY INVERTER DC BUS 1 DC BUS 2 DC BUS 3 DC BUS 4 B ATT ERY EXT PWR 1 AP U GEN 1 AP U GEN 2 EXT P WR 2 ON ON A V A I L ON CONDITION: NO ELECTRICAL SYSTEM FAULTS. AUTO AUT O A UTO AUTO BU S TI E AC BUS 1 AC BUS 2 AC BUS 3 AC B US 4 ON ON ON ON GEN CON T OF F OF F OF F OF F 1 2 3 4 DR IVE DIS C DRIVE DRIVE DRIV E DRIVE F/O TRANSFER BUS AC BUS 2 POWERED CAPT TRANSFER BUS APU STBY BUS AC BUS 3 POWERED MAIN STBY BUS APU STANDBY INVERTER T T T T R R R R MAIN BAT BUS DC ISOLATION RELAY (typical) DC TIE BUS BATTERY SW APU HOT BAT BUS MAIN HOT BAT BUS MAIN MAIN BAT BATTERY CHARGER GND SERVICE BUS GND SERVICE SW AC BUS 1 POWERED MAIN DECK CARGO HANDLING BUS (FLT ATTENDANT PANEL, DOOR 1L) APU GEN 2 EXT PWR 1 EXT PWR 2 APU GEN 1 GND HANDLING BUS Intentionally Blank 747 Flight Crew Operations Manual Electrical EICAS Messages Chapter 6 Section 30 Electrical EICAS Messages The following EICAS messages can be displayed. Message Level Aural Condition >BAT DISCH APU Advisory APU battery discharging. >BAT DISCH MAIN Advisory Main battery discharging. >BATTERY OFF Advisory Battery switch OFF. >DRIVE DISC 1, 2, 3, 4 Advisory Generator Drive Disconnect switch pushed, IDG disconnected. ELEC AC BUS 1, 2, 3, 4 Caution Beeper AC bus unpowered. Additional related messages displayed for unpowered equipment items. ELEC BUS ISLN 1, 2, 3, 4 Advisory Bus tie breaker open. Inhibited when ELEC AC BUS message displayed. (SB changes 006 ; before SB, improved generator control units for added IDG protection not installed) Message Level Aural Condition ELEC DRIVE 1, 2, 3, 4 Advisory IDG oil pressure low or oil temperature high. Inhibited when Generator Drive Disconnect switch pushed. 008, 203 (SB changes 006 ; improved generator control units for added IDG protection installed) Message Level Aural Condition ELEC DRIVE 1, 2, 3, 4 Advisory IDG oil pressure low, oil temperature high, or GCB open due to uncorrectable generator frequency fault. Inhibited when Generator Drive Disconnect switch pushed. Copyright © The Boeing Company. See title page for details. D6-30151-400 October 1, 2004 6.30.1 EICAS Messages 747 Flight Crew Operations Manual Electrical - Message Level Aural Condition ELEC GEN OFF 1, 2, 3, 4 Advisory Generator control breaker open. Inhibited when ELEC AC BUS message displayed. Message Level Aural Condition >ELEC SSB OPEN Advisory Split system breaker (SSB) open when commanded closed. 006, 008 Message Level Aural Condition ELEC UTIL BUS L, R Advisory One or more galley or utility busses unpowered, or Galley Emergency Power switch off. Busses may be unpowered due to electrical fault, or related Utility Power switch or Galley Emergency Power switch off. Inhibited during load shedding. 203 Message Level Aural Condition ELEC UTIL BUS L, R Advisory One or more utility busses unpowered. Busses may be unpowered due to electrical fault, or related Utility Power switch OFF. Inhibited during load shedding. 203 Message Level Aural Condition >STBY BUS APU Advisory APU standby bus not powered. >STBY BUS MAIN Advisory Main standby bus not powered. 006, 008 Message Level Aural Condition >STBY PWR OFF Advisory Standby bus not powered. Copyright © The Boeing Company. See title page for details. 6.30.2 D6-30151-400 April 1, 2005