Electrical (SYS4) Flashcards
What does the External Power AVAIL light indicate when illuminated?
External power is plugged in and power quality is acceptable
When selected manually, what electrical power source will trip off any existing power source?
External Power
What does an illuminated APU Generator OFF light indicate?
With the APU running, the APU generator breaker was commanded to close but remained open because of a fault or the APU Generator Control switch is selected OFF
What does a Generator OFF light indicate when illuminated?
The Generator Control Breaker is open
What does an illuminated Generator DRIVE light indicate?
High oil temp or low oil pressure
When can a disconnected IDG be reconnected?
Only on the ground by maintenance
What happens during an AUTOLAND if one of the Generators fails below 200’ RA?
Autoland will continue. Loss of associated Autopilot will occur and the ASA will NOT change from LAND 3
What is the purpose of the Bus Tie System in AUTO?
Provides power to both main AC buses, Prevents paralleling of electrical sources, Isolates faults, Allows the DC Bus Tie Breaker to close with the loss of DC power, Allows the CA and FO’s flight instruments to remain powered with the loss of the respective AC bus
What is the power source priority for powering left and right main buses?
Respective IDG, APU, opposite IDG
What happens to the Electrical System when the engines are started with external or APU electrical power in use?
The IDG automatically powers the respective main bus and the previous power source is disconnected from that bus
What does an illuminated AC Bus ISLN light indicate when the Bus Tie switch is in the AUTO position?
A fault has occurred automatically opening the AC bus tie breaker
With a Left AC bus fault, will the CA’s Flight Instruments fail?
No. They will automatically be powered from the right main AC bus
With the Bus Tie Switches in AUTO, what happens to a DC bus if its respective T/R fails?
Powered by the opposite DC bus through the DC Bus Tie Breaker
What items are normally powered by the Ground Handling Bus?
Fueling and Cargo handling
How is the Ground Handling Bus powered?
External power connected to the aircraft or from the APU Generator
What is the main source of power for the Aircraft Battery Charger?
Ground Service Bus
What items are normally powered by the Ground Service Bus?
Aircraft battery charger, APU battery charger, and misc cabin/system loads
What is the normal source of power for the Ground Service Bus?
Right main AC bus
What normally powers the left and right utility buses?
Their respective main AC bus
What conditions would cause Utility bus load shedding?
Both Thrust Levers advanced to takeoff range on the ground with single power source, Overload, Starting Engines with the APU providing electrical power, and Single Generator source in flight
What happens to the utility busses when a single engine generator is powering the electrical system and an additional power source becomes available?
Electrical power is automatically restored to the Utility Buses
What is the purpose of Automatic Load Shedding?
To ensure power is available to essential equipment
What is the function of the OFF position of the STBY power selector?
Unpowers the standby busses
What is the function of the BAT position of the STBY power selector?
Powers STBY Buses from the main battery
