11.8 Flashcards
Uses of electrical power
Electrical heating
Lighting
Mechanical power
Electronic devices
Lighting equipment is used where
Cockpit
Cabin area
Outside
Why light cockpit
Illuminate panels , maps , instruments
Why light outside aircraft
Visability to other aircraft
Illuminate ground during take off/ landing
2 electrical power subsystems
Generation subsystem
Distribution subsystem
How is ac power generated
By engines during flight
How is ac generated in an emergency
By hydraulic motor or propeller
How many generators per engine for ac supply
1 per engine
787 has 2
How do you convert ac to dc
TRU
How is ac voltage distributed
115v at 400hz
How many phases is ac voltage generated
3
% of energy supply ac consumers need
95
What are the ac voltage consumers
Heating
Lighting
Mechanical equipment
How many sources does dc voltage come from
2
What are the sources of dc voltage
Tru - convert 115v ac to 28v dc
Nickel cadmium Battery - gives 24v dc
% of energy dc consumers use
5%
What are dc consumers
Electrical equipment
Control and monitoring
What are the dc generators
Alternators and starter generator
What do batteries do in dc
Provide power for emergency distribution, apu starting and engine start
Power distribution parts
Main , essential , emergency
What is essential power distribution for
Allow safe flying
What is emergency power distribution for
Safe landing
What does a bus do
Connects power source to electrical consumer
How many ac buses
3 main buses , one for each phase
What does load shedding do
Improves reliability of power relays
How is manual load shedding done
Via push button
What’s auto load shedding used for
Prevent overload or detect overload of generators
Where is emergency power available
Aircraft battery , power for 30 minutes