Electrical System Flashcards
In descending order, the priority for electrical power is
Onside engine generator, external power, APU, remaining engine generator
According to the graphic, what she powering the airplane
Engine driven generators (from the synoptic page)
What is a characteristic of the APU electrical system?
Can power the entire plane on the ground
What is a characteristic of the electrical system
System operation is normally automatic
The bus tie contractors open or close automatically to maintain power supply to AC busses 1 and 2 when the bus tie switch is in the _____ position
Auto (lights out)
While the APU is running and external power plugged in, what is the indication that the APU generator is powering the AC tie bus?
EXT PWR AVAIL light illuminated
EXT PWR AVAIL light indicates external power is
Plugged in and electrical parameters are normal
Following pushback, what is the configuration of the electrical system when engine 1 is running and the APU is operating
GEN 1 powers AC bus 1 and the APU generator powers AC bus 2
Do not hold the IDG disconnect switch for more than _____ to prevent possible damage to the disconnect mechanism
3 seconds
In the event of a single IDG failure, the remaining IDG powers
The entire electrical system, except for the main galley bus
Do not disconnect the IDG when the
Engine is not running or not windmilling
If the IDG 1 switch is pushed in-flight
IDG 1 can only be reconnected on the ground by maintenance
What occurs when an IDG is disconnected
The corresponding generator can no longer supply power
GALY & CAB FAULT light indicates
A generator load exceeds 100% of rated output
A GEN FAULT light indicates
The line contactor is open without selecting the respective GEN switch OFF
In flight, with only one-engine generator operating, how is the electrical system configured
The main galley power supply is automatically shed
In the event of a single TR failure, how is the DC system affected?
DC busses 1 and 2 will interconnect through the DC BAT bus. ESS TR powers the DC ESS bus
With the loss of TR 1, what pilot action is required
No action required: system automatically powers DC bus 1 with TR 2
Which bus normally powers the AC ESS bus
AC bus 1
AC ESS FEED FAULT light
Illuminates amber when AC ESS bus is not electrically powered
In case of AC bus 1 failure, the AC ESS bus can be transferred to AC bus 2 by
Doing nothing, system switching is automatic
AC and DC ESS SHED busses
Are shed when aircraft is on battery power only
What is a characteristic of the battery power system
An automatic cutoff logic prevents the batteries from becoming completely discharged on the ground
When flying on battery power only, what is the approximate battery endurance
22 minutes
