Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Airframe Electrical > Airframe Electrical midterm > Flashcards

Airframe Electrical midterm Flashcards

0
Q

Give the three purposes of the primary battery in an aircraft application.

A

Ground ops (engine startup)
To absorb spikes from the generator/alternator
Emergency backup voltage

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

Name the two minimum controls necessary for any alternator.

A

Voltage regulator and current limiter.

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

What are the two batteries most widely used in aircraft application? Are they primary or secondary cells?

A

NiCads, lead acid, secondary cells.

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

State lenz’s law.

A

An induced emf always gives rise to a current whose magnetic field opposes the original change in magnetic flux.

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

What battery terminal must be disconnected first and reconnected last?

A

The negative terminal.

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

Name and explain the basis of the principles of operation of both generators and alternators.

A

Electromagnetic induction: electrical energy is produced by cutting lines of flux.

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

Name the four major components of a generator.

A

Field, armature, brush assembly, structural parts.

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

What principle is the operation of a generator based on?

A

Electromagnetic induction.

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

What does initial excitation in a generator come from?

A

It is provided by lines of flux produced by what is called “residual magnetism”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the three types of windings of a generator?

A

Shunt, series, compound.

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

What is excitation current?

A

The current passed through the electromagnet, used to produce, strengthen and control the flux field.

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

What is the purpose of the field in a DC generator?

A

To provide lines of magnetic flux for the conductor to cut through.

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

Describe the construction of a field in a DC generator.

A

Soft iron highly permeable cores called pole shoes are wrapped with copper wire (field windings), the pole shoes hold the windings in place.

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

What is the purpose of the armature in a generator?

A

It acts as a conductor, which cuts the lines of flux, into which the voltage is induced to produce current.

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

Describe the construction of the armature in a generator.

A

It consists of windings of wire called armature coil, multiple windings are used to increase the efficiency of the generator.

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

What is the armature in a DC generator known as?

A

A commutator, it is used to rectify the induced AC into pulsating DC.

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

What is the armature in an AC generator called?

A

In AC, slip rings are used to transfer the system current from the armature windings to be used by the system.

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

What is the purpose of the brush assembly in a generator?

A

To transfer the system current from the commutator to the housing wiring?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the construction of the brush assembly in a generator.

A

Constructed of carbon and held against the commutator with springs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the construction of the structural parts of a generator.

A

Consists of an end frame, field frame, and a brush frame, bearings.

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

What are the three types of DC generators?

A

Series, shunt, compound.

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

What is an advantage/disadvantage associated with using a series wound generator?

A

It has higher output capabilities, it is very hard to control that output.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an advantage associated with a shunt wound generator?

A

It is easier to control output.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is an advantage/disadvantage associated with using a compound wound generator?

A

Higher current and voltage output capability and is easy to control, more complex and heavier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are three controls for low output generators?

A

Voltage regulator, current limiter, RCCR.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are three controls for a high output generator?

A

Voltage regulator, current limiter, RCCR.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does RCCR stand for?

A

Reverse current cutout relay.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How is output controlled for an AC generator?

A

Voltage regulator, current limiter, RCCR.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is an APU?

A

Auxiliary power unit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the purpose of a CSD?

A

To take the rotational power from the engine and no matter the engine speed, turn the generator at a constant speed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is an IDG?

A

A CSD and generator combined into one unit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What does IDG stand for?

A

Integrated drive generator.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the fundamental difference between an alternator and a generator?

A

The relationship between the conductor and the flux field.

33
Q

What are the four major components of a DC Alternator?

A

Stator, rotor, rectifier, structural parts.

34
Q

What is the purpose of the stator in an alternator?

A

It serves the same purpose as the armature in a generator.

35
Q

Describe the construction of a stator.

A

Three stator windings, 120 degrees apart.

36
Q

What are the two types of stator windings?

A

Delta, wye wound.

37
Q

What is the purpose of the rotor in an alternator?

A

To provide lines of magnetic flux for the conductor to cut through.

38
Q

Describe the construction of the rotor.

A

The rotor usually consists of 8-12 poles with windings around.

39
Q

What is used to bring the excitation in an alternator rotor?

A

Brushes.

40
Q

What is the purpose of a rectifier in an alternator?

A

It is used to convert AC to DC.

41
Q

Describe the construction of an alternator rectifier.

A

Solid state (electronic) rectifier consists of 6 diodes, two for each winding.

42
Q

What is the purpose of the structural parts in an alternator.

A

To support the stator and rotor.

43
Q

Describe the construction of the structural parts of an alternator

A

Main frame, end frame, cooling fins.

44
Q

Where does the alternator receive its excitation from?

A

The bus

45
Q

What are two different devices used to control alternator output?

A

Voltage regulator and current limiter.

46
Q

Alternator control units are usually in the form of what?

A

Solid state components.

47
Q

What test is used for NiCad batteries?

A

High rate discharge test.

48
Q

What tests are used on lead acid batteries?

A

High rate discharge test , load test , hydrometer test.

49
Q

What does the high rate discharge test indicate?

A

The capacity.

50
Q

What do the load test and hydrometer tests indicate?

A

State of charge.

51
Q

How is flux produced in an alternator?

A

By the rotor.

52
Q

How is flux produced in a generator?

A

By the field.

53
Q

How is the system current produced in an alternator?

A

By the stator.

54
Q

How is system current produced in a generator?

A

The armature.

55
Q

Why are the brushes much smaller in an alternator?

A

They only need to carry excitation current.

56
Q

Why are the brushes large in a generator?

A

They are necessary to carry system current.

57
Q

What kind of rectifier is used in an alternator?

A

Solid state

58
Q

What kind of rectifier is used in a generator?

A

Mechanical

59
Q

What is one advantage of an alternator over a generator?

A

Physical size, since the rotating body of alternator is smaller, it can be turned at a greater rate. So it is capable of a greater output.

60
Q

What are the three classifications of DC motors?

A

Series wound, shunt wound, compound wound.

61
Q

What is an advantage/disadvantage associated with series wound DC motors?

A

Very high torque capabilities, very poor speed control.

62
Q

What is an advantage/disadvantage associated with shunt wound DC motors?

A

Very good speed control, lower torque capabilities.

63
Q

What is an advantage/disadvantage associated with Compound wound DC motors?

A

Relatively high torque capabilities with good speed control, heavier and more complex.

64
Q

How is DC motor control obtained?

A

By controlling the flux field.

65
Q

How is speed control obtained in a DC motor?

A

By controlling the strength of the flux field.

66
Q

How is direction control obtained in a DC motor?

A

By reversing the polarity of the flux field.

67
Q

What are two methods of reversing the direction of a DC motor?

A

Using a SPDT switch or by using a DPDT switch.

68
Q

How is the direction of rotation of a DC motor changed?

A

By changing the polarity.

69
Q

What are the different types of AC motors?

A

Universal, induction, synchronous.

70
Q

What is an advantage/disadvantage associated with using a Universal AC motor?

A

High torque very versatile, loss of efficiency when used with AC higher maintenance.

71
Q

What is an advantage associated with a synchronous AC motor?

A

Better speed control, higher torque capability than an induction motor.

72
Q

What is a typical use for a universal AC motor?

A

Household applications, vacuums, drills etc.

73
Q

What is a typical use for an induction AC motor?

A

Tachometer

74
Q

What is a typical use for a synchronous AC motor?

A

Tape recorder.

75
Q

What are the major parts of a DC motor?

A

Armature assembly,

Field assembly, brush assembly and end frame.

76
Q

What is the principle the operation of a DC motor is based upon?

A

Electromagnetic repulsion.

77
Q

What is the definition of electromagnetic repulsion.

A

The repulsion of an electromagnet by the pole of another electromagnet.

78
Q

Shaft, laminated soft iron core, mica separators, armature windings, armature winding slots, commutator.

A

What are the parts of the large armature on the quiz?

79
Q

What are the parts of the small armature on the quiz?

A

Field frame, pole shoes, field coils.

Airframe Electrical (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions