Electrical Flashcards
What are the sources of dc power?
4 engine generators 1 APU generator 2 nickel cadmium batteries 1 lead acid backup battery External power cart
What 2 electrical systems does the emb 145 have?
28v dc system
115v 400hz ac system
Which generators are driven by the left and right engines?
Left engine are 1 and 3
Right engine are 2 and 4
How many hours can an aircraft be operated with a generator bearing fail message?
20 hours.
How are the engine generators cooled in the air and on the ground?
NACA air inlets in the air
Fan on the ground.
What are the engine generator output limits?
400 amps
600 amps for 5 minutes
800 amps for 5 seconds
What controls the contactors in the electrical system?
Electrical distribution logic
When are all the dc buses powered on the ground?
3 generators are operating
1 generator and shed bus override
GPU
When do the engine and APU generators come online?
Engines at 56.4% N2
APU 95% +7 seconds
What are the APU generator output limits?
400 amps below 30,000’
300 amps above 30,000’
600 amps for 2 minutes
800 amps for 5 seconds
What happens when you release the APU generator button?
The APU line contactor is commanded open and disconnects APU power.
How is the APU powered when starting?
By the central bus through the APU starting contactor.
What can power the APU for start?
External power
Battery 2
Battery 2 plus main generators
Why isn’t there electrical interruption while starting the APU?
Battery 1 is isolated from the load busses.
Describe the 2 main batteries and how long will they hold power for?
24 volt, 44 amp hour nickel cadmium batteries
40 minutes.
How are the batteries cooled?
NACA inlets
What busses are connected to battery 1 and 2?
Hot bus 1 and 2
What do the hot busses power?
Elt, engine fire extinguishers, fuel pressure refueling, fuel shutoff valves, hydraulic shutoff valves, courtesy lights, main door, generator control units.
Can the batteries be charged with the GPU? And why?
No, when the GPU is plugged in the battery contactors open and disconnect the batteries.
What is the backup battery? And function?
1 24dcv 5 amp hour battery
Powers backup hotbus
Electrical distribution logic
Generator control unit
What are the volts and amps for the GPU?
28.5 volts
1600 amps
Has priority over all batteries and generators.
What busses does the GPU power?
The central bus. Connects dc bus 1 and 2 Shed bus 1 and 2 Essential bus 1 and 2
How is the electrical system protected from GPU malfunctions?
An over voltage circuit disconnects the GPU over 32 volts or under 23.5 volts
How are the shed buses powered on the ground?
By placing the shed bus switch in the override position.
What buses do you have in electrical emergency mode?
Batteries supply, Hot bus 1 and 2 Backup essential bus Backup hot bus Central bus Essential bus 1 and 3
How do you manually enter emergency mode?
By pressing the essential power button.
What does the ground service bus power?
Cockpit dome lights Courtesy/stair lights Galley lights Cabin lights Lavatory lights Baggage service lights
How is ac power produced?
By a 250 volt 400 hertz single phase static inverter.
250vdc to 115vac
What is on the ac system?
EGPWS
Windshear
FOQA
Battery 1 controls what busses?
Hot bus 1
Backup essential bus
Backup hot bus
What is powered by the backup essential bus?
AHRS 1
DAU 1 and 2
EICAS
What is powered by the backup battery?
Electrical Distribution Logic
Generator Control Unit
Do the batteries charge with the GPU powering the airplane?
No, you have to take the batteries out to charge them. Minimum of 30 minutes.
What electrical condition exists with 4 or 5 generators online?
Two systems all buses energized
What electrical condition exists with 3 generators online?
One network all busses energized
What electrical condition exists with 1 or 2 generators?
One system all buses energized in the air, lose shed buses on the ground
What electrical condition exists with a loss of all generators?
Batteries supply essential buses in flight only.
