Electrical Flashcards
What are the three main divisions of the electrical system?
AC Power, DC Power, Standby Power
The aircraft battery supplies _____ power
DC
What sources supply AC power to the aircraft?
Engine generators, APU generator, & External Power all produce AC power
T/F: There is no paralleling of AC sources of power
True
T/F: The source of power being connected to a transfer bus automatically disconnects an existing AC source
True
External ground power provides __________ to both AC Transfer Busses.
115 volt AC electrical power
The blue APU GEN OFF BUS light on the Forward Overhead Panel indicates what?
The APU is running but the APU generator is not powering a bus.
T/F: The APU provides complete aircraft power by powering both AC Transfer Busses simultaneously.
True
What is the IDG?
Integrated Drive Generator. This is the engine-driven generator that provides electrical power (AC)
T/F: Reactivation of an IDG may be accomplished in flight.
False. This can only be done on the ground my maintenance personnel
The DRIVE light on the overhead panel illuminates for what conditions?
IDG Failure, Engine Shutdown, IDG automatic disconnect (usually if oil temp exceeds limits), IDG disconnected via the disconnect switch
Each engine-driven generator produces the required _____ volt and _____ hertz power required by the aircraft
115 volt; 400 hertz
When does the blue GEN BUS OFF light illuminate?
Anytime respective IDG is not providing power to the related transfer bus
T/F: The Bus Tie Breakers (BTBs) are controlled by the BUS TRANS switch located on the overhead panel
True. When this switch is in AUTO and the source powering the Transfer Bus is disconnected or fails, the source powering the opposite Transfer Bus automatically picks up the unpowered bus.
The Ground Service Buses provide power to what?
Aircraft cabin and to the battery charger
The Galley Power Switch supplies electrical power to ______ and the ________ when AC transfer busses are powered.
galleys; broadband satellite system
Which buses are typically shed if an electrical overload occurs?
Galley Bus(s) and the Main Bus(s) (same side first, then opposite side if required)
What do the Transformer Rectifiers do?
Convert AC power to DC power
Transformer Rectifier #3 (TR 3) can be powered from what sources?
AC Transfer Bus 2 (normal) & AC Transfer Bus 1 (during a power loss)
TR 3 primarily supplies DC power to what ?
Battery Bus. It also serves as a backup power source to TR 1 & 2
The TR UNIT light on the forward overhead panel indicates what
In Flight: TR1 has failed, or TR2 & TR3 have failed (at the same time)
On Ground: Any TR fault has occurred
The Cross Bus Tie Relay connects what?
DC Bus 1, DC Bus 2, and DC Standby Bus (In flight, this relay is normally closed and the buses are connected)
What is the AC Standby Bus’s normal source of electrical power?
AC Transfer Bus 1 (The bus can also be powered by the main battery via through the static inverter)
During normal operations, the DC Standby Bus receives power from what sources?
TR1, TR2, and TR3. (The bus can also be powered directly by the battery)
