Electrical Flashcards

1
Q

What is the secondary power source for the Main Standby bus?

A

Main standby inverter

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2
Q

During autoland below 1500’, automatic isolation of which buses occurs?

A

AC and DC buses 1, 2, 3

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3
Q

What is the secondary power source for the FO transfer bus?

A

AC Bus 1

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4
Q

What does the main deck cargo handling bus power?

A

Nose and side cargo doors

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5
Q

When is the main deck cargo handling bus powered?

A

APU Gen 2 or Ext PWR 2 is AVAIL

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6
Q

What does the ground service bus powers?

A
  • Flight deck flood,
  • Nav and service lights,
    and
  • Battery chargers
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7
Q

If AC bus 1 is unpowered on the ground how can the Ground Service Bus be powered?

A

GND SERVICE switch at Door 1L

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8
Q

How is the Ground Service Bus normally powered?

A

AC bus 1

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9
Q

What does the Ground Handling Bus power?

A
  • Lower lobe cargo handling equipment and lights;
    and
  • AUX hydraulic pump 4 (and 1 if installed).
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10
Q

When is the Ground Handling Bus powered?

A

When APU GEN 1 or EXT PWR 1 is avail or ON

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11
Q

How is the Main Standby Bus normally powered?

A

AC Bus 3

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12
Q

What is the secondary power source for the Captain Transfer Bus?

A

AC Bus 1

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13
Q

How is the FO transfer bus normally powered

A

AC Bus 2

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14
Q

What does the Main Standby Bus power?

A

Left:
1) EIU,
2) CDU,
3) ILS,
4) VOR,
5) ADC,
6) Transponder,
7) EFIS panel.

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15
Q

The Split System Breaker opens and divides the synchronous bus allowing what to happen?

A

Separate APU or EXT sources to power each side

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16
Q

Which bus powers fire detection for the APU and engines?

A

APU Battery Bus

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17
Q

What buses isolate when a BTB is manually selected to ISLN?

A

The associated AC and DC buses

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18
Q

The synchronous bus allows how many IDGs to be connected at the same time?

A

4

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19
Q

What is the purpose of the sync bus?

A

To prevent an AC bus from becoming unpowered, if its respective generator fails.

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20
Q

How does each AC bus connect to the synchronous bus?

A

BTB

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21
Q

Which sources of power may be connected to the synchronous bus at the same time

A

All four IDGs

22
Q

When will the generator DRIVE light illuminate? and when would an IDG automatically disconnect?

A

IDG oil temp high

23
Q

What are the main sources of AC power?

A
  • 4 IDGs,
  • 2 APU genrt,
  • 2 Ext Pwr srcs.
24
Q

How is the Captain Transfer bus normally powered?

A

AC bus 3

25
Q

The FO Transfer bus is normally powered by which AC bus?

A

AC bus 2

26
Q

What conditions would cause the generator DRIVE light to illuminate in the Generator Drive Disconnect (DRIVE DISC) switch (accompanied by the EICAS message ELEC DRIVE) provide the engine is operating?

A
  • GCB open due to uncontrollable generator frequency fault;
    and
  • IDG oil temperature high.
27
Q

Which bus provides power for all fire extinguishing

A

Main hot battery bus

28
Q

The main and APU battery busses are normally powered by which DC bus?

A

DC bus 3

29
Q

If an AC bus is unpowered or TRU fails, what powers the respective DC bus?

A

DC tie bus

30
Q

The APU standby bus powers which equipment items?

A

Left FMC, ND, PFD

31
Q

With the battery switch ON, Standby power selector OFF and no other electrical sources are connected or available, which buses are powered?

A

Main and APU battery and hot battery buses

32
Q

With the Battery switch ON, standby power selector in AUTO and the Captain Transfer Bus not powered, what is the power source for the APU standby bus?

A

APU Standby inverter

33
Q

What is the normal power source for the APU standby bus?

A

Captain Transfer bus

34
Q

The main standby bus is normally powered by which AC bus?

A

AC bus 3

35
Q

Assume the aircraft dispatches with AC gen 2 inoperative. During automatic ILS approach once below 1500’ AGL and LAND 3 is displayed on the AFDS which AC bus would power the sync bus?

A

AC bus 4

36
Q

The main deck cargo handling bus is powered on the ground only when what conditions are met?

A

When APU GEN 2 or EXT PWR 2 is AVAIL

37
Q

How is the APU Standby bus normally powered?

A

Captain transfer bus

38
Q

If both AC bus 1 and 3 are unpowered what is the power source for the Captain Transfer bus?

A

The bus will be unpowered

39
Q

If AC bus 3 is unpowered, which AC bus would then power the Captain transfer bus?

A

AC bus 1

40
Q

The Captain tranfer bus is normally powered by which AC bus?

A

AC bus 3

41
Q

On the ground, with only External PWR 1 AVAIL light illuminated (AC Bus 1 unpowered), how can the ground service bus be powered?

A

Through the ground service switch (cabin panel door 1L)

42
Q

The ground service bus is powered on the ground and in flight whenever which AC bus is powered?

A

AC bus 1

43
Q

With external power connected to each side of the electrical system (SSB open), when engine 4 and 3 are started, what is the configuration of the SSB?

A

OPEN

44
Q

What condition would disconnect the IDG automatically if not manually disconnected by the flight crew?

A

Excessive oil temperature

45
Q

How is each DC bus normally powered?

A

Its respective AC bus through its TRU

46
Q

The APU and Main batteries will provide Standby power for how long?

A

Minimum of 30 minutes

47
Q

Which bus powers fire protection for the APU and all engines?

A

Main hot battery bus

48
Q

What is the secondary power source for the APU standby bus?

A

APU standby inverter

49
Q

During automatic ILS approach, once below 1500’ AGL and LAND 3 is displayed on the AFDS which AC bus powers the sync bus

A

AC bus 4

50
Q

What are the main sources of DC electrical power?

A

Four TRU’s, main battery and APU battery