C-40 ELECTRICAL SYSTEM

  1. Image Upload 1
    What is indicated by #6?
    Illuminated (amber) – with BAT switch ON, excessive battery discharge detected
  2. Image Upload 2
    What is indicated by #7?
    On the ground:  TR1, TR2 or TR3 has failed

    In flight:  TR1 failed; or TR2 and TR3 failed
  3. Image Upload 3
    What is indicated by #8?
    Illuminated (amber) – a fault exists in DC power system or standby power system.

    Note: Operates only with airplane on ground
  4. Image Upload 4
    Will #8 illuminate in flight?
    NO
  5. Image Upload 5 
    What is indicated by #11?
    OFF: removes power from battery bus and switched hot battery bus when operating with normal power sources available

    -removes power from battery bus, switched hot battery bus, DC standby bus, static inverter, and AC standby bus when battery is only power source

    ON (guarded position): provides power to switched hot battery bus

    -energizes relays to provide automatic switching of standby electrical system to battery power with loss of normal power.
  6. Image Upload 6 
    What does #1 indicate?
    Illuminated (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
  7. Image Upload 7 
    What does #2 do?
    Disconnects IDG if electrical power is available and engine start lever is in IDLE. IDG cannot be reconnected in the air
  8. Image Upload 8 
    What does #3 indicate?
    Illuminated (amber) – one or more of the following busses are unpowered:

    - AC standby bus

    - DC standby bus

    - battery bus
  9. Image Upload 9 
    What does #4 do in AUTO?
    AUTO (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
  10. Image Upload 10 
    What does #4 do in OFF?
    OFF (center position) -

        -STANDBY PWR OFF light illuminates

    -AC standby bus, static inverter, and DC standby bus are not powered
  11. Image Upload 11 
    What does #4 do in BAT?
    BAT (unguarded position) –

    -AC standby bus is powered by battery through static inverter

    -DC standby bus and battery bus are powered directly by battery
  12. Can an IDG be automatically disconnected?
    Yes, due to high oil temperature
  13. What items make up the standby power system?
    Hot battery bus, switched hot battery bus, battery bus, standby AC, standby DC, static inverter
  14. Do the AC power sources normally operate in parallel or isolated?
    Isolated
  15. What is the normal IDG frequency?
    400CPS+/-10CPS
  16. What is the normal IDG voltage?
    115+/-5 V
  17. What is the normal battery voltage?
    24+/-4 V
  18. How many batteries are onboard and where are they located?
    2, located in the electronics compartment
  19. How long will the batteries provide standby power?
    A minimum of 60 minutes
  20. Image Upload 12 
    What does #1 indicate?
    Illuminated (blue) – ground power is connected and meets airplane power quality standards.
  21. What checks the incoming external power for quality?
    Bus power control unit
  22. When external power is connected, are both transfer busses powered?
    Yes
  23. Image Upload 13
    What does #4 indicate?
    Illuminated (amber) – no source has been manually selected to power the related transfer bus, or the manually selected source has been disconnected. 

    If a source has been selected to power the opposite transfer bus, both transfer busses are powered
  24. Image Upload 14 
    What does #5 indicate?
    Illuminated (blue) – IDG is not supplying power to the related transfer bus
  25. Image Upload 15 
    What does #7 do in AUTO and OFF?
    AUTO (guarded position) – BTBs operate automatically to maintain power to AC transfer busses from any operating generator or external power DC cross tie relay automatically provides normal or isolated 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 from DC bus 2
  26. Image Upload 16 
    What does #8 indicate?
    Illuminated (blue) – APU is running and not powering a bus.
  27. If the APU is supplying power to both transfer busses and one APU GEN switch is moved to OFF, what happens?
    The associated SOURCE OFF light illuminates and both TBs remain powered
  28. What happens if an IDG fails in flight?
    Auto bus transfer allows the other IDG to power the failed IDG’s transfer bus
  29. How many transformer rectifiers are there?
    TRs 1-3 plus a battery charger
  30. What normally powers the standby AC bus if AC power is not available?
    Transfer bus #1 through an inverter
  31. Is it possible to power one transfer bus from external power and one from the APU?
    No
  32. Is it possible to power one transfer bus from external power or APU and one transfer bus from an IDG?
    Yes
  33. What happens if you takeoff with the APU powering both transfer busses and the APU fails?
    Auto connect to the engine IDGs (one time only and in-flight only)
  34. Image Upload 17 
    What does #1 do/indicate?
    Provides manual control of ground service busses. Enables servicing of the airplane using external power without activating AC transfer busses.

    Illuminated (white) –

    ON – connects external power to ground service busses

    OFF – disconnects external power from ground service busses
  35. How does automatic load shedding work (engine generators)?
    The galleys on TB2 shed first.  If an overload is still sensed, the galleys on TB1 are shed.  If an overload still exists, main bus 1 and 2 are shed.
  36. If an automatic load shed occurs, does load restoration automatically occur when more source capacity (two generator operation) exists?
    Yes, automatic load restoration of the main busses and galley busses occurs.  Manual restoration of galley power can be attempted by moving the GALLEY power switch to OFF, then on.
  37. In flight, if the APU is on the only available power source will auto load shedding occur?
    Yes
  38. How does auto load shedding work when the APU is the only power source?
    On the ground:  the APU will attempt to carry a full electrical load.

    In-flight:  all galley busses are automatically shed.  If the electrical load still exceeds design limits, both main busses are also automatically shed.  Manual restoration of galley power can be attempted by moving the GALLEY power switch to OFF, then back on.
  39. When would an IDG automatically disconnect?
    High IDG oil temperature
  40. What normally powers DC BUS 1 and 2?
    TR 1-3
  41. What powers the Standby AC and Standby DC busses?
    Standby AC:  transfer bus 1

    Standby DC:  DC bus 1 (through TRs)
  42. What normally powers the Battery Bus, Hot Battery Bus and Switched Hot Battery Bus?
    Battery Bus:  TR 3

    Hot Battery Bus:  Battery Charger/TR

    Switched Hot Battery Bus:  Battery Charger/TR
  43. When are the DC busses automatically isolated?
    The DC 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 navigation receivers and flight control computers
  44. APU start attempts on Standby power are not recommended above what altitude?
    FL 250
  45. Which busses are powered after a loss of both generators?
    Hot battery bus, switched hot battery bus, battery bus, AC standby bus, DC standby bus, static inverter
Author
CForty
ID
347841
Card Set
C-40 ELECTRICAL SYSTEM
Description
C-40 ELECTRICAL SYSTEM
Updated