Electrical System Flashcards
Which Bus powers the right recirculation fan?
The right recirculation fan is powered by the right utility bus.
What does the Hydraulic Driven Generator produce?
The HDG produces AC Power and via its own TR unit DC power as well.
Which busses can be powered by the HDG?
The HDG can power the following busses:
via its own TR unit DC power to the Hot Battery Bus, Battery Bus, Standby DC Bus.
and AC power to the Standby AC Bus, Left and Right Transfer Bus as well as the Capt. Flight Instr. Transfer Bus.
What do the AC Bus Tie Breakers do?
The Bus Tie Breakers isolate or parallel the right and left Main AC Busses.
In Auto the BTB maintain power to main busses.
BTB position is not indicated in normal operation.
What can be the reason for a Generator DRIVE Light to illuminate?
The Generator DRIVE Light illuminates when
a) oil temperature is high
b) oil pressure is low
c) engine is not running
Which bus powers the left recirculation fan?
The left recirculation fan is powered by the left main AC Bus.
Load Shedding due to loss of an engine generator.
What components will shed?
When there is only one engine generator left to power the system, the Utility and Galley Busses, some cabin lights and the Center Fuel Pump on the failed generators side will shed.
Before Engine start, APU or GPU online.
Hydraulic pumps all on.
Which components will load shed?
Center Electric Hydraulic Pump No. 2 will shed.
The Galley Busses will shed, no indication in the cockpit. Utility Busses will remain on.
What are the components of the Ground Handling Bus?
The Ground Handling Bus can only be powered on Ground by APU or GPU.
It provides power to cargo handling and refueling features as well as cabin lighting.
On Ground the Ground Service Bus can also be powered by the Ground Handling Bus.
What is the power source of the Ground Service Bus?
What is the main feature of the Ground Service Bus?
The Ground Service Bus is normally powered by the right main AC Bus. On Ground it can be powered by the Ground Handling Bus (switch at forward attendant panel).
The Ground Service Bus powers the main and APU Battery Chargers.
What is the backup power source of the Cpt/FO Flight Instrument Transfer Bus?
The Cpt/FO Flight Instrument Transfer Bus is normally powered by its respective Main AC Bus, backup is provided by Transfer Bus of the opposite side when the power from AC Bus is lost and Respective Bus Tie Switch is in Auto.
What is the backup source for the L and R DC Busses?
If BOTH Bus Tie switches are in Auto, the DC BTB will close if power from one TR unit is lost to supply both DC Busses from one TR unit.
