Electrical Flashcards
The ground service bus is normally powered by the ____.
Right Main AC Bus
Whenever the right main bus is powered, the ground service bus is powered.
TRUE
To allow for automatic landings with the lowest possible minimums, the electrical system configures so that each of the 3 autopilots is powered by a separate power source.
TRUE
If the ADIRU switch is left on after alignment and all electric power is switched off, the ADIRU continues to operate and the Nose Gear Horn sounds.
True
The primary electrical power sources for the flight control Power Supply Assemblies (PSAs) are the ____.
permanent magnet generators (PMGs)
The ground handling bus can be powered by ____.
primary external or APU power
Voltage of the main battery is read on the ____.
ELECTRICAL synoptic
After the loss of AC power, when the RAT electrically load sheds or prior to RAT deployment, the ____ powers the standby power system.
main battery
Primary external power and the APU are the two possible sources of power for the Ground Handling Bus.
TRUE
What indicates that external power is connected to the airplane and is of usable quality?
The AVAIL light is illuminated.
When the APU is running and primary external power is on line, the APU powers ____.
the left main bus
Backup power to the Transfer Buses is provided by one variable speed/variable frequency generator mounted on each engine. Which of the following is true regarding the Backup AC Electrical System?
A frequency converter converts the backup generator frequency to a constant 400 hz.
If the RAT fails to deploy automatically, can the crew deploy it manually?
Yes, by the RAM AIR TURBINE switch located on the hydraulic panel.
Illumination of the Ram Air Turbine PRESS light on the hydraulic panel indicates that the ____.
center system primary flight control hydraulic pressure is greater than 1500 psi
For primary electrical power system failures, the standby electrical system provides ____.
both AC and DC power
When the RAT deploys, if both hydraulic and electrical demands can be met, it will power the ____.
C1 and C2 TRUs
The RAT operates ____.
at all airspeeds and altitudes
What electrical components are powered by the RAT generator, if deployed?
The C1 and C2 TRUs.
Cargo Handling and Fueling/Defueling operations are powered by which electrical bus?
Ground Handling Bus.
What is the result of pushing a generator DRIVE DISC switch?
Disconnects the Integrated Drive Generator (IDG) input from the engine and can only be reset by maintenance on the ground
What does an illuminated DRIVE light on the Integrated Drive Generator DISC switch AND an OFF light in the Generator Control switch represent?
Generator drive temperature is high and the IDG drive has disconnected.
What is the function of the bus tie system when AUTO is selected on the BUS TIE switches?
During power source transfers on the ground the system is designed to prevent power interruption.
Bus Tie relays isolate or link the right and left main buses.
All of the above.
Identify the condition(s) that will cause the Backup Generators to automatically power one or both AC Transfer Buses (Select all correct answer(s)).
When only one main AC generator (includes the APU) is available.
Power to one or both of the Main AC buses is lost.
Approach (APP) mode is selected for autoland.
During the automatic system test after engine start.
The Electrical Load Management System (ELMS) provides load management and protection to ensure power is available to critical and essential equipment.
True
An illuminated DRIVE light on the Integrated Drive Generator DISC switch represents (Generator Control Switch NOT illuminated)?
IDG oil pressure is low.
The Ground Handling Bus can be powered on the ground only by either, the APU Generator or the Primary External Power Source.
True
What is the purpose of the Permanent Magnet Generators (PMGs) housed within each Backup Generator?
To supply power to the PSAs/Flight Control busses.
What occurs automatically if both AC Transfer Buses lose power in-flight?
The Ram Air Turbine deploys and the APU starts automatically.
What does an illuminated AVAIL light in the Primary External Power switch indicate?
Primary external power is plugged in and power quality is acceptable.
If electrical loads exceed the power available, ELMS automatically sheds AC loads by priority. The ____ is/are shed first.
Galleys
The primary function of the converter in the backup electrical system is to ____.
Convert frequency to a constant 400 Hz.
The Ground handling bus can be powered on the ground only from the APU generator or from the ____.
Primary External Power Source
DC power is normally supplied to the left and right Main DC busses and Captain’s and First Officer’s flight instrument busses from the ____.
four transformer rectifier units (TRUs)
Through a bus tie, the First Officer’s Instrument Bus can be a backup power source for the ___.
Captain’s Flight Instrument Bus
The Left and Right DC Busses support each other through a bus tie.
TRUE
