ELECTRICAL (ASM) Flashcards

1
Q

What sources provide electrical power supply

A

DC Power
AC Power

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2
Q

What is the DC power system comprised of

A

Four independent generators (28V DC / 400 A)
One APU starter generator (28V DC / 400 A)
Two Nickel-Cadmium (24V DC / 44AH / 1 hour rate)
One lead-acid backup battery (24V DC / 5AH / 10 hour rate)
External Power source

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3
Q

How is DC power converted into AC power

A

Single phase static inverter

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4
Q

Purpose of the EDL and GCU

A

Perform system management, detects system failures and are automatically isolated de-energizing some buses

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5
Q

Engine 1 drives what generators

A

1 and 3

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6
Q

The left network operates what buses

A

DC Bus 1
Essential DC Bus 1
Shed DC Bus 1
Hot Bus 1

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7
Q

How is Battery 1 charged

A

Charged by generators connected to DC Bus 1

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8
Q

Engine 2 drives what generators

A

2 and 4

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9
Q

How are both networks interconnected

A

Through Bus Tie Contactors (BTC)

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10
Q

What happens if an over voltage is detected

A

Associated GCU de-energizes the generator and disconnects it from the bus

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11
Q

What happens if a generator exceeds 400A

A

Manual load shedding is required
If no action is taken, the system will be isolated and some buses may be de-energized

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12
Q

What does the GPU have priority over

A

Batteries and generators

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13
Q

What do the batteries supply

A

Essential loads in case of in-flight failure of all generators or both engines fail with no APU

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14
Q

How long can both batteries supply essential power for

A

40 minutes (3 APU start attempts)

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15
Q

What battery supplies power for APU

A

BATT 2

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16
Q

Does the GPU charge the batteries?

17
Q

Purpose of the backup battery

A

Provides stabilized power for operation of the GCU protective function

18
Q

Where are the generators installed

A

Two installed on each engine accessory gerbox

19
Q

What controls the generators

20
Q

When do the generators come online

21
Q

What controls the APU Starter Generator

A

Dedicated GCU

22
Q

What does the APU generator supply power to

23
Q

What generator can the APU generator replace

A

Any inoperative left network generator
After start, automatically any inop engine driven generator

24
Q

When is the APU available to provide power to the electrical system

A

95% RPM +7 seconds

25
Sources to start APU
GPU BATT 2 BATT 2 assisted by main generator
26
Can BATT 1 be used to start APU
No, it is isolated to prevent voltage fluctuation
27
EDL 1 and EDL 2
DC Bus 1, Shed DC Bus 1, Essential DC Bus 1, Hot Bus 1 DC Bus 2, Shed DC Bus 2, Essential DC Bus 2, Hot Bus 2
28
Purpose of the central DC Bus
Connects APU or GPU to load buses through BTC
29
When are the DC Buses energized (on the ground)
If one of the following occurs; 3 generators GPU 1 generator, shed bus OVRD
30
DC Distribution
5/4 Generators: 2 Isolated Networks 3: Both networks interconnected through BTC 1/2: Both networks interconnected through BTC, shed bus de-energized 0: Batteries provide essential power
31
AC System provides power to
TCAS GPWS Windshear