Electrical Flashcards
What is initiated by selecting the Battery switch to ON?
The L CCR start-up sequence
In the Generator Control (GEN CTRL) switch, what does the amber OFF light indicate?
The generator breaker is open
In the external power switches: -
a. What does the AVAIL light indicate?
b. WhatdoestheONlightindicate?
a. External power is plugged in and power quality is acceptable b. External power is selected ON
With an engine running, what is indicated when the generator DRIVE light illuminates?
A generator drive malfunction has occurred
In addition to traditional electrically powered systems, what other systems are electrically powered?
Engine start, pressurization, wing ice protection, stabilizer trim and wheel brake systems
a. How many engine driven generators are there to power the main AC
buses?
b. What other aircraft power source for the main AC buses is available in
flight?
a. Four variable frequency engine starter/generators b. Two variable frequency APU starter/generators
a. What AC power sources are available on the ground before engine start?
b. Can any of these AC power sources normally be connected to run
together?
a. Three external AC power receptacles as well as the two APU generators b. No
a. What electrical sources can be used for engine start?
b. What electrical sources can be used for APU start?
a. External AC power, APU generated power, or the opposite engine’s generated power
b. Forward external power, APU battery, or engine generated power
a. On the ground, how many APU generators are available to power the
main AC buses?
b. If the APU is not available, how many external power sources are
required for optimal engine start performance?
a. Both
b. Three, both forward and one aft receptacle
a. How many primary batteries does the aircraft have?
b. Can the Main battery be used to start the APU?
a. Two, the Main and APU batteries b. Yes, it assists the APU battery
What are the primary sources of power for the flight control electronics?
Three engine driven Permanent Magnet Generators (PMGs)
If PMG power is lost, what secondary sources of flight control power are available?
The 28Vdc bus distribution system, and the main battery
a. How are higher amperage loads distributed throughout the airplane’s electrical system?
b. How are lower amperage loads distributed throughout the airplane’s electrical system?
a. They are distributed directly by the bus systems which are located in the forward & aft E/E bays (Primary)
b. Via Remote Power Distribution Units (RPDUs) located throughout the airplane (Remote)
What is the purpose of the power conversion devices?
They change power from one voltage or current type (AC/DC) to another
How many main AC buses are there?
Four 235v AC buses, designated L1, L2, R1 & R2
What do the main AC buses provide power to directly?
A limited number of high voltage AC systems
How do the main AC buses provide power to other (lower voltage) bus
systems?
Through power conversion devices
On the ground, with only forward external power selected ON, how are the main AC buses powered?
Via the 115v AC bus distribution system through the power conversion devices
With both engines running, if an engine generator is not available, how is its respective main AC bus powered?
The main AC buses through the power conversion devices
In flight, what is the primary power source for the 115v AC and 28v DC buses?
The main AC buses through the power conversion devices
a. Which units condition variable frequency power to energize the large motor loads?
b. Which system energizes these motor controllers?
c. List the large motor loads these motor controllers convert power for?
a. Motor controllers
b. The Large Motor Power System (LMPS) located in the aft E/E bay c. - Hydraulic Pumps
- Cabin Air Compressors
- Ram Fans
- Engine & APU Start
- Center Tank Fuel Pumps
- Nitrogen Generation System - Captain’s heated seat
a. What system provides flight deck control/indication, power transfer functions, electrical load management and protection?
b. How many of these units does the aircraft have?
a. The Bus Power Control Unit (BPCU) b. Two
When is Ground Handling mode active?
When the first forward external power receptacle is connected (not
selected ON) and there are no other power sources
How is the Ground Service mode activated?
Selecting the GROUND SERVICE switch to ON while in Ground
Handling mode
Which additional loads are energized in the Ground Service mode?
Limited cabin systems & lighting
Can the packs run when the aircraft is in External Power On mode?
Only if forward and aft external power is ON
