CRJ 700 Electrical System

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wcpilot5
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11188
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CRJ 700 Electrical System
Updated:
2010-10-04 13:03:02
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CRJ Study Questions
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CRJ 700 Electrical System
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  1. What is the primary source of AC electrical power?
    Two engine driven integrated drive generators (IDG).
  2. What is the nominal electrical rating of the engine driven integrated drive generators (IDG)?
    115 volt ac, 400 Hz three-phase electrical power with a nominal rating of 40 kva to an altitude of 41,000 feet.
  3. What is the function of the integrated drive mechanism?
    The integrated drive is a hydromechanical device that is driven by the variable-speed engine accessory gearbox which uses an integral oil system to drive the generator at a constant speed.
  4. What is the function of the oil within the integrated drive unit?
    Oil is used within the lDG unit as a lubricant, for generator cooling and as a hydraulic fluid for the csd speed adaptation. The oil system is monitored for faults and indicated to the pilots by EICAS messages as well as electrical power control panel (EPCP) switchlights.
  5. What does the amber "FAULT" illumination indicate in the IDG switch light located on the Electrical Power Control Panel (EPCP)?
    The IDG oil has overheated, or the oil pressure has dropped below predetermined limits.
  6. What does an illuminated IDG "DISC" switchlight indicate to the pilots?
    An electrical solenoid has been energized inside the IDG housing that caused the integrated drive gear (input shaft) to retract from the engine accessory gearbox. The IDG stops rotating after disconnect.
  7. When can IDG be reset after being disconnected via the IDG switchlight located on the Electrical Power Control Panel (EPCP)?
    The drive can only be reconnected on the ground after the engine is shut down.
  8. What will occur if the IDG electrical disconnect feature fails?
    Mechanical disconnect of the IDG will occur when the internal temperature exceeds a predetermined limit or by shearing of the IDG drive shaft when an over torque condition is detected. It prevents damage to the accessory gearbox due to IDG failure.
  9. Where can the output parameters of the IDG be monitored in the cockpit?
    The output of the IDG's can be monitored via the EICAS AC synoptic page. Output indications are provided in a parameter block at the bottom of the display.
  10. What is the primary function of the Auxiliary Power Unit (APU) generator?
    To provide an electrical power to the aircraft buses during ground operations with the engines off. It can also be used to power the buses in flight should an engine generator fail.
  11. What is the nominal electrical rating of the APU generator?
    115 volt ac, 400 Hz three-phase electrical power with a nominal rating of 40 kva to an altitude of 41,000 feet.
  12. How is the APU AC generator constant rpm maintained?
    The APU operates at a constant speed so there is no requirement for a constant speed drive (CSD) interface between the APU generator and the AC generator.
  13. When is the APU generator capable of supplying electrical power?
    After a minimum rotor speed of 99% for 2 seconds or longer.
  14. What is the function of the external power system?
    The external power system is used to connect AC electrical power from a ground source.
  15. What is the location of the AC external power receptacle?
    The forward right side of the aircraft below the external services panel and above the right nose gear door.
  16. What is the location of the external services panel?
    The forward right side of the aircraft nose above the AC external power receptacle.
  17. How is the status of the AC external power monitored from the cockpit?
    The status of the AC external power source is displayed on the EICAS AC electrical synoptic page and the AC AVAIL/IN USE switch light located on the Electrical Power Control Panel (EPCP).
  18. How is the status of the AC external power monitored from outside the aircraft?
    The status of the AC external power source can be verified via the AC AVAIL/IN USE switch light located on the external services panel.
  19. What has priority, internal or external power?
    Internal power.
  20. What is the electrical requirements of the AC external power?
    Three-phase electrical power 115/200 volt 400 Hz
  21. What does the green illuminated "AC AVAIL" button located on the Electrical Power Control Panel (EPCP) indicate in the cockpit & on the external services panel?
    The external power is connected to the external receptacle and the power is acceptable (115/200v 400 Hz) to the aircraft.
  22. What does the white "IN USE" illumination of the AC external power button located on the Electrical Power Control Panel (EPCP) signify?
    The "IN USE" portion of the switch light will illuminate after the pushbutton is depressed and the AC external power source is supplying the aircraft electrical system.
  23. What is the function of the white "IN USE" portion of the AC external power switchlight located on the external services panel?
    When external AC is selected on from this switchlight, only the AC Service Bus is powered while AC buses 1 & 2 remain unpowered. When connected using this switch light, the "IN USE" light illuminates. The EICAS AC synoptic page shows the legend "SERVICE CONFIGURATION" at the upper left of the display.
  24. How is the AC Service Configuration established?
    Connecting AC external power in the external receptacle illuminates the "AVAIL" lamp in the external AC switch light on the external services panel. If no other AC electrical power is supplying the AC buses, pressing the "EXT AC" switchlight allows AC external power to energize only the AC Service Bus and illuminates the white "IN USE" portion of the switch light.
  25. What is the function of the DC SERVICE switch located on the Electrical Control Panel?
    When selected ON, the DC Service Bus is connected directly to the APU Battery Direct Bus to supply passenger cabin lighting and power the external navigation lights.
  26. How is the DC Service Configuration established?
    Selecting the DC service switch located on the EPCP to the ON position connects the DC Service Bus directly to the battery powered APU Battery Direct Bus.
  27. What is the function of the AC Service Configuration?
    AC power is supplied to the AC Service Bus to power service outlets in the passenger cabin so the aircraft can be cleaned without having to power all the other AC busses.
  28. What are the four electrical buses of the AC electrical system?
    • AC Bus 1
    • AC Bus 2
    • AC Essential Bus
    • AC Service Bus
  29. What is the function of the AC ESS XFER switchlight located on the Electrical Power Control Panel (EPCP)?
    • It illuminates to provide indication that the AC Essential Bus has automatically transferred from AC Bus 1 to AC Bus 2.
    • If pressed it the manually transfers the AC Essential Bus power source from AC Bus 1 to AC Bus 2.
  30. What will power the AC Essential Bus when normal AC power is lost in flight?
    The AC Essential Bus will be powered by the Air Driven Generator (ADG) and is latched (locked) to the ADG bus.
  31. What is the function of the Auto Transfer System?
    The Auto Transfer System operates to enable alternate sources of AC to power AC Bus 1 & AC Bus 2.
  32. What does the illuminated "FAIL" portion of the Auto XFER Inhibit switch light indicate?
    The Auto Transfer System is disabled due to the detection of either an AC Bus 1 or AC Bus 2 fault by the GCU over current or differential protection circuits. The faulted bus is isolated from the other power sources.
  33. What does the illumination of the white OFF side of the AUTO XFER switchlight on the Electric Control Panel indicate?
    The Automatic Transfer System has been manually inhibited.
  34. What are the Electric Control Panel indications after the failure of AC Bus #1?
    • FAIL side of the AUTO XFER switchlight illuminated
    • AC ESS XFER switch light illuminated
  35. How is emergency AC power supplied to the aircraft?
    By a deployable Air Driven Generator (ADG), when the normal AC electrical power (AC Bus 1 & AC Bus 2) sources become inoperative.
  36. What is the location of the Air Driven Generator (ADG)?
    The ADG is stowed in the right side of the aircraft nose, protected by a mechanically linked door.
  37. What buses are energized during Air Driven Generator (ADG) operation?
    • ADG Bus
    • AC Essential Bus
    • ESS TRU 1
    • DC Essential Bus
    • DC Battery Bus
    • DC Emergency Bus
    • Main Battery Direct Bus
    • APU Battery Direct Bus
  38. What is the function of the Air Driven Generator (ADG) Manual Deployment Handle?
    Should the auto deploy system fail, the ADG may be manually released by pulling the ADG manual deploy lever.
  39. What is the function of the Power Transfer Override switch located on the ADG auto deploy control panel?
    The AC Essential Bus can be transferred to a normal AC power source by selecting the power transfer override switch located on the ADG control panel It unlatches (unlocks) the AC Essential Bus from the ADG bus.
  40. What is the function of a transformer rectifier unit (TRU)?
    A TRU is an AC to DC converter
  41. What electrical power output is provided by the transformer rectifier units (TRU)?
    Each TRU provide 28 VDC rated at 120 amps.
  42. How many transformer rectifier units (TRU) are installed in the CRJ-700?
    Four
  43. What is the location of the transformer rectifier units (TRU)?
    The forward equipment bay.
  44. Which are the nine electrical buses powered by the DC system?
    • DC Bus 1
    • DC Bus 2
    • DC Essential Bus
    • DC Service Bus
    • DC Utility Bus
    • DC Battery Bus
    • DC Emergency Bus
    • Main Battery Direct Bus
    • APU Battery Bus
  45. What is the nominal output of the main battery?
    24 volts, 17 ampere-hours
  46. What is the location of the main battery?
    The forward equipment bay.
  47. What electrical source powers the main battery charger?
    AC Bus 1
  48. What is the nominal output of the APU battery?
    24 volts, 43 ampere-hours
  49. What is the location of the APU battery?
    The aft equipment bay.
  50. What electrical source powers the APU battery charger?
    AC Service Bus
  51. What is the function of the battery power distribution system?
    The batteries provide the energy needed to start the APU and get the APU generator on line. The batteries also supply emergency DC power (30 minutes) in flight should all AC power be lost and the ADG is not operational
  52. Which buses are the batteries capable of powering?
    • Main Battery Direct Bus
    • APU Battery Direct Bus
    • DC Battery Bus
    • DC Emergency Bus DC
    • Essential Bus (in flight only)
  53. What is the function of the DC Emergency Bus?
    The DC Emergency Bus provides power to the engine & APU fire extinguishers, fuel & hydraulic shutoff valves.
  54. When is the DC Emergency Bus displayed on the DC synoptic page?
    The DC Emergency Bus is only displayed on the EICAS DC electrical synoptic page when the bus is not powered as a result of a fault.
  55. What flight instruments are powered when the battery master is selected to the ON position while on the ground and this is the only source of electrical power?
    • EICAS Display 1 (ED 1)
    • Integrated Standby Instrument (ISI)
    • EICAS Display 2 (ED 2)
    • Back-up Tuning Unit (BTU)
  56. What flight instruments are powered when the battery master is selected to the ON position while in flight and this is the only source of electrical power?
    • Left Primary Flight Display (PFD)
    • EICAS Display 1 (ED 1)
    • Integrated Standby Instrument (ISI)
    • EICAS Display 2 (ED 2)
    • Back-up Tuning Unit (BTU)

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