Electrical System

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  1. 3 Major Systems
    • DC Electrical
    • AC Electrical
    • STBY Power System
  2. DC Electrical
    • Tied in parallel
    • Share and balance electrical loads
    • 3 Sources
    • -- A/C battery
    • -- GPU
    • -- Left/Right hand Load bus
  3. DC Power Source Components:

    Starter Generators
    • 28Vdc, 400amp engine driven generators
    • Mounted on front of engine driven accessory gear box
    • Provide starting torque to engines until 35-40% N2 then switch to generators
  4. DC Power Source Components:

    Generator Control Units (GCU)
    • Monitor generators and switch them from starters to generators
    • Provide Fault Protection
    • Reverse Current Protection
    • Load Sharing
    • Over voltage protection
  5. DC Power Source Components:

    • Located in aft fuselage
    • 24Vdc lead acid
    • Approximately 30 minute life span
  6. DC Power Source Components:

    Battery Feeder Protection Unit
    • Detects ground faults that may occur in battery and external power feeder and ground lines
    • If fault occurs-
    • -- Illuminates red BATT FDR FAIL
    • -- Deenergizes the battery relay and battery tie-in relays which illuminate BATT CUT OFF and EMER BUS FDR FAIL
  7. DC Power Source Components:

    External Power Receptacle
    • 28 –28.5Vdc
    • 1,000 – 1,500amps
  8. DC power distribution system
    • -- Primary power distribution from Main Buses to Load Buses
    • -- The Battery charge bus acts as a connection bus for all DC power
    • -- L/R BUS FDR FAIL annunciator means third feeder line between Main and Load bus is active. Will shut off if third line c/b trips
    • -- Feeder lines between Main and Load buses are have two c/b on each of them one 100amp RCCB and 1 ½ amp c/b
  9. Secondary Power distribution
    • (9 buses)
    • L/R load bus
    • L/R nonessential bus
    • L/R overhead bus
    • L/R radio master bus
    • Standby bus
  10. AC Power Supply
    • 2 inverters
    • -- Supply 115Vac and 26Vac single phase electrical power at an apparent power rating on 250voltamperes each
    • -- Located in the nose of the aircraft
  11. AC Power Distribution Controls
    • -- Inverter selector switch is located in the main circuit breaker panel
    • -- AUTO means the number one inverter supplies power to primary buses and number 2 provides power to secondary buses
    • -- NO. 1 position forces the number one inverter to supply power to primary buses and number 2 to secondary buses
    • -- This bypasses the number one inverter fault sensing circuits, but not the number 2 fault sensing circuits
    • -- NO. 2 position forces the number 2 inverter to power the primary buses and the number 1 to power the secondary buses
    • -- In this case all fault sensing circuits are bypassed
  12. AC BUS SHED indicator illuminates when:
    • Number 1 inverters is not supplying 115Vac
    • Number 2 inverter is on
    • Number 2 inverter power relay is deenergized
  13. DC Standby battery
    • 24Vdc lead acid
    • Located in nose electronics compartment
    • STBY PWR ARM means the standby battery is connected to the standby bus
    • STBY PWR ON means the standby battery is the only source powering the standby bus
    • If STBY PWR is not armed it will not automatically be powered with lost of all electrical power
  14. DC Standby AHRS battery
    • 24Vdc lead acid
    • Located in avionics rack
    • Provides power to either or both AHRS computers if the Left and/or Right Load buss power fails
    • Power is provided for up to 10 or approximately 11 minutes depending on where you look in the dash one
  15. Emergency Power
    • Normally receives power from generators through battery
    • If EMER BUS FDR FAIL illuminates power is supplies through LH load bus
    • With battery in EMER power is from the battery only
  16. Standby Power Bus
    • (CRUISSE)
    • Co-pilot lights
    • RTU #1
    • UHF radio
    • ITT (left)
    • Standby attitude indicator
    • Standby altimeter
    • EFC for engine start
  17. Emergency Power Bus
    • (SLEEVES)
    • Standby bus
    • Landing Gear lights
    • Engine Ignition & control
    • Emergency pitch trim
    • VHF Nav 1
    • Engine Fire Detect/Fuselage Smoke Detector
    • Selected LH instrument
  18. AC Instruments
    • 26 VAC Primary Shed
    • --Flap Position --R/L Oil Pressure
    • 115 VAC Primary --GPWS
    • 26 VAC Primary-- Pitch Trim Position Indicator
    • 26 VAC Secondary-- GRE
  19. Generator Control Units
    • Provide Fault Protection
    • Reverse Current Protection
    • Load Sharing
    • Over voltage protection
Card Set:
Electrical System
2011-08-20 22:47:18

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