Electrical System Flashcards

0
Q

What are the 2 distinct power distribution methods?

A

Primary or Remote.

Direct distribution from the respective AC/DC buses or distribution via the Remote Power Distribution System.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What is an RPDU? How many are there?

A

Remote Power Distribution Unit. 17

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What amperage loads do the RPDU’s distribute?

A

10 amps or less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many main 235Vac power system buses are there?

How are they designated?

A

4

L1, L2, R1, R2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do the generators power the main AC buses with both engines online?

A

Each VFSG is connected to a main AC bus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do the generators power the main AC buses with one engine running and the APU online?

A

VFSG’s power the on side main AC buses, ASG’s power the P150 Auxiliary power panel which provides power to the other side main AC buses through the tie bus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How are the main AC buses powered with external power online?

A

External power connected directly to 115Vac buses. Main AC buses connected by the bus tie and powered by power converters from the 115Vac buses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

On the ground with only forward external power selected, what powers the 115Vac buses?

A

115Vac buses powered by external power directly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the BPCU and what does it provide?

A

Bus Power Control Unit

  • Overall load management.
  • Electrical power transfers.
  • Flight deck control and indications.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What power sources can the aircraft use for engine starts?

A

VFSG’s, ASG’s or external power.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Aft external power can only be used to assist a start for which engine?

A

The right engine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many starters are needed to start the APU?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many starters are needed to start an engine?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Are both ASG’s required to maintain the electrical load in flight?

A

Yes, but there will be load shedding.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the primary and backup power sources for the airplane brakes?

A

Primary: 28Vdc system
Backup: Main battery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

On which side of the aircraft are the external power receptacles located?

A

Left side of the fuselage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How many external ground sources are required to energize the “Ground Handling Mode”?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In flight, when will the RAT automatically deploy?

A
  • Both engines have failed
  • All three hydraulic system pressures are low
  • Loss of all electrical power to the captains flight instruments
  • Loss of all four EMP’s and faults in the flight control system occur on approach
  • Loss of all four EMP’s and an engine fails on takeoff or landing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which cockpit displays are powered during RAT operations?

A
  • Captain inboard DU
  • Captain outboard DU
  • Lower DU
  • ISFD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What major systems are not available on “In-air RAT only mode, Standby Power)?

A

Flaps, Slats, Stabilizer trim, Packs, Thrust reversers, Auto speedbrakes, HUD, WIPS, (window heats, autothrottle, TAT, TAP, HF radios, SATCOM, TCAS, GPWS, XPDR, WX radar, external lighting, LNAV/VNAV, FMC predictions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is load shedding determined by the bus power control unit?

A

Loads are shed in order of priority to stay within the capacity of the available power sources.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What equipment is energized in the “In-air Battery only” mode (Standby Power)?

A

Captains flight instruments and other essential equipment for flight controls, navigation and communication.

  • CPT and Lower DU’s
  • ISFD, ECL, FMC (Limited)
  • MCP, Autoflight & Autopilot (Limited)
  • DSP L, MFK L, CCD L
  • CPT/FO ACP & Interphone
  • VHF L, TCP L, CCR L
  • IRU, AHRU, INR, PFC
  • ENG/APU fire detection
  • Misc lighting
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How can load shedding be monitored in the aircraft?

A

Electrical synoptic shows a list of systems affected by load shedding. Affected system synoptic (AIR, FUEL, HYD) also indicate equipment that is inhibited or shed.

23
Q

What does the main battery power directly?

A

Hot battery bus

24
Q

What are the primary and backup power sources for the flight control computers?

A

Primary: 3 engine driven Permanent Magnet Generators (2 left eng, 1 right eng)
Backup: Airplane 28Vdc system, airplane battery and dedicated batteries.

25
Q

What does the APU battery power on the ground?

A

APU start and Navigation lights (during battery only towing)

26
Q

How can the circuit breakers be accessed in the aircraft?

A

Through the Circuit Breaker Indication and Control (CBIC)

27
Q

What is the maximum number of load shed items that can be displayed on the electrical synoptic?

A

Maximum 8

28
Q

Does “Ground Handling Mode” have priority over “On-ground Battery only mode”?

A

Yes, initialized regardless of battery switch position

29
Q

Does “Ground Handling Mode” need an external power supply connected and selected “ON”?

A

No, only connected

30
Q

Can Thermal Circuit Breakers (TCB) be reset from the flight deck?

A

No, only ECB

31
Q

What is the difference between load shed and load inhibit?

A

Load inhibit are loads inhibited at predefined operational phases. This is because the affected system is not necessary.

32
Q

What does the EICAS message “MAIN BATTERY DISCH” indicate?

A
  • Main battery discharging
  • Main battery failure
  • Hot Bus not energized
33
Q

What is the VFSG and ASG power output?

A

VFSG - 250 kVA

ASG - 225 kVA

34
Q

The P100 and P200 panels receive power from the VFSG’s, the P150 from the ASG’s. Where are the panels located?

A

Aft E/E bay

35
Q

P300 and P400 are the 115Vac and 28Vdc power distribution panels. Where are they located?

A

Forward E/E bay

36
Q

What are the different voltages used throughout the system?

A

235Vac, 115Vac, 270Vdc, 28Vdc, 130Vdc

37
Q

What is a EBPSU? How many are there and where are they located?

A

Electrical Brake Power Supply Unit

4 in total, located in the forward E/E bay on the P500 & P600 panels

38
Q

How many Common Motor Start Controllers are there?

A

8 in total.

39
Q

Which system uses the large rated DC motors powered by 270Vdc and controlled by the CMSC’s?

A
  • Hydraulic EMP’s
  • NGS
  • Center tank fuel pumps
  • Power for engine start
  • CAC’s
  • Ram Air Fans
40
Q

Why is part of the Large Motor Power System energized by the APU?

A

APU energizes only the motor controller required to perform an APU battery start.

41
Q

Which part of the electrical system is cooled by the PECS?

A
  • The high voltage motor controllers on P700 and P800 panels.
  • ATRUs on P700 and P800 panels.
42
Q

Why is part of the Large Motor Power System energized by the aft external power?

A

Aft external power energizes only the motor controller required to perform a right engine start using only external power.

43
Q

How many external power connections are required to perform and engine start using only external power?

A

2

44
Q

When is the PECS energized?

A
  • With one/both engines running, or
  • APU running, or
  • FWD external power connected and selected on
45
Q

What are the electrical power sources?

A
  • 1 main battery
  • 1 APU battery
  • 2 forward external power receptacles
  • 1 aft external power receptacle
  • 4 Variable Frequency Starter/Generators
  • 2 Variable Frequency APU Starter/Generators
  • 1 RAT
  • 3 Flight control Permanent Magnet Generators
  • 2 EEC Permanent Magnet Alternators
45
Q

How are the CMSCs powered?

A

Energized by 270Vdc through power conversion from 235Vac buses.

46
Q

Where are the CMSCs located?

A

P700 and P800 panels in the aft E/E bay.

47
Q

Where are the ATUs, TRUs and ATRUs located?

A

ATUs and TRUs on the P500/P600 power conversion panels in the fwd E/E.
ATRUs on the P700/P800 panels in the aft E/E.

48
Q

How are the VFSGs cooled?

A

By a Fuel/Oil Heat Exhanger and

Air/Oil Heat Exchanger

49
Q

Which condition will require a manual drive disconnect of the VFSG?

A

Low VFSG oil pressure.

50
Q

What is the purpose of the ATUs?

A

Autotransformer Units

  • Converts 235vac power from the main buses to 115vac power.
  • Converts 115vac power from external power to 235vac for the main buses.
51
Q

What is the purpose of the 4 TRUs?

A

Converts 235vac from the main buses to 28vdc.
Supplies 28vdc to:
-28vdc buses
-CPT & FO instrument buses
-EBPSUs
-Battery chargers through the instrument buses

52
Q

What is the purpose of the EBPSU’s?

A

Regulates power for exclusive use of the electrical braking system.

53
Q

What is the power input for the 4 EBPSUs?

A

Two separate 28Vdc inputs to each unit.

  • 28Vdc bus system (primary)
  • Main battery (backup)