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Cat B- Mod 11 Aircraft Systems > 11.6 Electrical Power > Flashcards

11.6 Electrical Power Flashcards

1
Q

What does the electrical power system consist of?

A

Generation and Distribution

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2
Q

What type of battery does the aircraft use?

A

Nickel cadmium storage

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3
Q

What is an Elcon connector?

A

Quick release battery connector

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4
Q

What type of wire locking is used for battery connectors?

A

Copper

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5
Q

What used to be an issue with Ni-Cad batteries?

A

Thermal runaway

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6
Q

How much does each cell of the battery produce in voltage?

A

1.2V

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7
Q

When is a cell completely discharged?

A

Drops below 1.0V

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8
Q

How often should batteries be checked in the workshop?

A

Every 2000 hours.

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9
Q
A
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10
Q

What are the two basic methods of charging?

A

Constant voltage or constant current.

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11
Q

What kind of battery is commonly charged using constant voltage?

A

Lead acid

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12
Q

What is it crucial to do when charging Ni-Cad batteries through constant current?

A

Monitor it due to the risk of overcharging

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13
Q

How long must a battery be able to provide all essential services?

A

30 minutes

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14
Q

What is the minimum capacity of a battery?

A

80%

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15
Q

What are the three different DC power sources?

A

DC battery
External DC power source
DC generators

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16
Q

What core do the brushes of the DC generator have?

A

Molybdenum Disulphide

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17
Q

What are DC generators rated in?

A

Volts and Amps

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18
Q

What is a flange mounting?

A

Generator is attached to an auxiliaries’ gearbox on the engine.

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19
Q

What is the manacle ring?

A

The massive ring clamp that holds the generator onto the gearbox.

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20
Q

What is the purpose of the TRU?

A

AC conversion to DC

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21
Q

What does PPDS stand for?

A

Parallel Power Distribution System

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22
Q

What is a PPDS?

A

Twin-engine or multiple-engine aircraft employ a parallel power distribution system. During normal flight conditions, both engine‑driven generators connect and power the DC loads.

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23
Q

What are the advantages of parallel DC operation?

A

TRU’s are loaded with the average current
No DC bus is lost

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24
Q

Why do aircraft use three phase brushless generators?

A

Output is constant, except in VSCF

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25
Q

What does the CSD do?

A

A device between the engines auxiliary gearbox and generator, converts the variable speed to constant.

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26
Q

What systems are driven by the gearbox?

A

Fuel/ Oil/ Hyd pumps
N2 Indication
AC generator

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27
Q

What does the mechanical flyweight governor keep the generator output at?

A

400Hz

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28
Q

What are the two basic types of CSD?

A

Variable Pitch Swashplate
Variable Gear Ratio

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29
Q

What is a swashplate pump?

A

Rotating cylinder containing pistons

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30
Q

What does the load control unit do?

A

Receives it’s electrical information from the GCU, when the output is too low it increases the load

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31
Q

What is the working pressure of the CSD oil?

A

250 psi

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32
Q

What does the IDG combine?

A

Generator and CSD

33
Q

In modern AC generators where does the excitation come from?

A

Rotating magnet to an internal PMG

34
Q

What version of generator is preferred, star or delta wound?

A

Star

35
Q

How is AC converted to DC?

A

Inverter

36
Q

What is a current transformer?

A

Three inductive pick up holes that have wires with AC going through.

37
Q

What is the differential protection circuit?

A

Detect short circuits

38
Q

What is EROP?

A

Extended range operation

39
Q

If the RAT is deployed what does the aircraft do?

A

EMER GEN ON

40
Q

What factors effect the magnitude of induced EMF?

A

Strength of the magnetic field
Number of turns in the coil
Rate of change in flux

41
Q

What is the most common voltage regulation system?

A

Solid state

42
Q

What is the purpose of a current limiter?

A

limit the current demanded from the generator

43
Q

What is an example of an electromechanical current limiter?

A

Triple Unit Regulator

44
Q

What happens when the shunt field current is reduced?

A

Flux and generator outputs fall

45
Q

What is RCCO?

A

Reverse current cut out, also known as differential protection

46
Q

How does over excitation get fixed?

A

The unit removes the generator from parallel

47
Q

What is the main distribution point of the DC system?

A

DC busbar

48
Q

What are the three power classifications of AC and DC systems?

A

Main Power
Essential Power
Emergency Power

49
Q

What do busbars provide?

A

A way of distributing electrical power and provide a physical connection for circuit breakers.

50
Q

What four types of bus bar are there?

A

Main buses
Sub busbars
Tie Buses
Transfer lines

51
Q

What is a main bus?

A

carry the main power be it Alternating Current (AC) or Direct Current (DC) power from a source to sub-buses

52
Q

What is the sub bus?

A

supply systems and sub-systems from the main buses and again are either AC or DC

53
Q

What is the tie bus?

A

tie different sources of the same power to the main buses

54
Q

What is a transfer bus/line?

A

allow the transfer of different sources of the same power from the main bus to the main bus

55
Q

What three settings does the bus bar coupling switch have?

A

Auto
Man
Dis

56
Q

What are VSG’s?

A

Variable speed generators

57
Q

What is a VFG?

A

Variable frequency generator

58
Q

What does a bus consist of?

A

consists only of a low resistance electrical connection between all the wires that lead to the different consumers

59
Q

How is power source switching performed?

A

Power relays

60
Q

What do all AC buses have?

A

Three others, A,B or C for the three phases

61
Q

What is a NPBT?

A

No power break transfer

62
Q

What is an inverter?

A

DC source to AC supply

63
Q

What is a transformer?

A

Step up or down voltages

64
Q

What is a rectifier?

A

AC to D, usually achieved by diodes

65
Q

What are the two classifications of rectifiers?

A

Half wave
Full Wave

66
Q

What two types of inverter are there?

A

Rotary
Static

67
Q

What does a rotary inverter consist of?

A

DC motor, which is powered from the DC bus bar mechanically coupled to a small AC generator.

68
Q

What does a static inverter consist of?

A

solid-state 400 Hz sinusoidal oscillator and a transformer

69
Q

What are the benefits of static inverters?

A

High efficiency
Low cost
Quiet etc etc

70
Q

What is the power factor of TRU’s?

A

Greater than 0.96

71
Q

What is required to full wave rectify single phase AC?

A

4 diodes

72
Q

How is AC ripple reduced?

A

Smoothing filter

73
Q

How are circuits protected?

A

Fuses
Breakers

74
Q

When does a short occur?

A

When there is a hard short between the high voltage side and the ground or different voltage potential

75
Q

What categories of C/B are there?

A

Push/Pull
Push
Switch
Thermal

76
Q

What does a green C/B mean as supposed to a black one?

A

It is part of the monitored system.

77
Q

What does the power selector switch stop GPU’s from doing?

A

Charging the battery directly

78
Q
A

Cat B- Mod 11 Aircraft Systems (28 decks)

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