Electrical Flashcards

0
Q

What are the sources of dc power?

A
4 engine generators
1 APU generator 
2 nickel cadmium batteries
1 lead acid backup battery
External power cart
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1
Q

What 2 electrical systems does the emb 145 have?

A

28v dc system

115v 400hz ac system

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2
Q

Which generators are driven by the left and right engines?

A

Left engine are 1 and 3

Right engine are 2 and 4

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3
Q

How many hours can an aircraft be operated with a generator bearing fail message?

A

20 hours.

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4
Q

How are the engine generators cooled in the air and on the ground?

A

NACA air inlets in the air

Fan on the ground.

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5
Q

What are the engine generator output limits?

A

400 amps
600 amps for 5 minutes
800 amps for 5 seconds

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6
Q

What controls the contactors in the electrical system?

A

Electrical distribution logic

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7
Q

When are all the dc buses powered on the ground?

A

3 generators are operating
1 generator and shed bus override
GPU

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8
Q

When do the engine and APU generators come online?

A

Engines at 56.4% N2

APU 95% +7 seconds

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9
Q

What are the APU generator output limits?

A

400 amps below 30,000’
300 amps above 30,000’
600 amps for 2 minutes
800 amps for 5 seconds

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10
Q

What happens when you release the APU generator button?

A

The APU line contactor is commanded open and disconnects APU power.

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11
Q

How is the APU powered when starting?

A

By the central bus through the APU starting contactor.

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12
Q

What can power the APU for start?

A

External power
Battery 2
Battery 2 plus main generators

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13
Q

Why isn’t there electrical interruption while starting the APU?

A

Battery 1 is isolated from the load busses.

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14
Q

Describe the 2 main batteries and how long will they hold power for?

A

24 volt, 44 amp hour nickel cadmium batteries

40 minutes.

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15
Q

How are the batteries cooled?

A

NACA inlets

16
Q

What busses are connected to battery 1 and 2?

A

Hot bus 1 and 2

17
Q

What do the hot busses power?

A

Elt, engine fire extinguishers, fuel pressure refueling, fuel shutoff valves, hydraulic shutoff valves, courtesy lights, main door, generator control units.

18
Q

Can the batteries be charged with the GPU? And why?

A

No, when the GPU is plugged in the battery contactors open and disconnect the batteries.

19
Q

What is the backup battery? And function?

A

1 24dcv 5 amp hour battery
Powers backup hotbus
Electrical distribution logic
Generator control unit

20
Q

What are the volts and amps for the GPU?

A

28.5 volts
1600 amps
Has priority over all batteries and generators.

21
Q

What busses does the GPU power?

A
The central bus.
Connects 
dc bus 1 and 2
Shed bus 1 and 2
Essential bus 1 and 2
22
Q

How is the electrical system protected from GPU malfunctions?

A

An over voltage circuit disconnects the GPU over 32 volts or under 23.5 volts

23
Q

How are the shed buses powered on the ground?

A

By placing the shed bus switch in the override position.

24
Q

What buses do you have in electrical emergency mode?

A
Batteries supply,
Hot bus 1 and 2 
Backup essential bus
Backup hot bus
Central bus
Essential bus 1 and 3
25
Q

How do you manually enter emergency mode?

A

By pressing the essential power button.

26
Q

What does the ground service bus power?

A
Cockpit dome lights
Courtesy/stair lights
Galley lights
Cabin lights
Lavatory lights
Baggage service lights
27
Q

How is ac power produced?

A

By a 250 volt 400 hertz single phase static inverter.

250vdc to 115vac

28
Q

What is on the ac system?

A

EGPWS
Windshear
FOQA

29
Q

Battery 1 controls what busses?

A

Hot bus 1
Backup essential bus
Backup hot bus

30
Q

What is powered by the backup essential bus?

A

AHRS 1
DAU 1 and 2
EICAS

31
Q

What is powered by the backup battery?

A

Electrical Distribution Logic

Generator Control Unit

32
Q

Do the batteries charge with the GPU powering the airplane?

A

No, you have to take the batteries out to charge them. Minimum of 30 minutes.

33
Q

What electrical condition exists with 4 or 5 generators online?

A

Two systems all buses energized

34
Q

What electrical condition exists with 3 generators online?

A

One network all busses energized

35
Q

What electrical condition exists with 1 or 2 generators?

A

One system all buses energized in the air, lose shed buses on the ground

36
Q

What electrical condition exists with a loss of all generators?

A

Batteries supply essential buses in flight only.