Brainscape's Knowledge GenomeTM

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


See full index

ATPL > AGK - Electricity > Flashcards

AGK - Electricity Flashcards

1
Q

What is current?

A

Charge over time

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

How do electric field lines flow?

A

Out from positive

In toward negative

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

What is coulomb’s law?

A

The strength of the electric force/field can be increased by

increasing the amount of charge
decreasing the distance between charges

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

What is Kirchoff’s 1st law?

A

Total current flowing into a point must be the current flowing out of that point.

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

What is Kirchoff’s 2nd law?

A

The sum of the voltage drops of a circuit must equal the emf.

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

Which factors affect resistance?

A

Length - Proportional
Cross-sectional area - Inversely proportional
Material
Temperature - Proportional

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

Resistors in series?

A

Add resistances together

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

Resistors in paralell?

A

1/Rt = 1/R1 + 1/R2 + 1/R3 …

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

What is a pole?

A

The connector

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

What is throw?

A

Moving from 1 position to another

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

Another name for push switches?

A

Light switches because they have lights in indicating condition.

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

What is momentary and alternative action on a switch?

A

Momentary - only while holding

Alternate - Toggle

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

What does a thermo switch do?

A

Make or break circuit when it reaches certain temps

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

What is a unipole system?

A

Old aircraft using ground as airframe.

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

What is a dipole system?

A

Composite aircraft have a return wire to ground.

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

What is a non-trip free circuit breaker?

A

Old type of breaker where the button can be pushed in again to complete the circuit even if the fault still exists.

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

What is a trip free circuit breaker?

A

Trip free circuit breaker prevents current from returning if the button is held in and the fault is still present through the use of secondary contacts.

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

What are thermal circuit breakers used for?

A

Protected circuits in event of prolonged over current.

Through use of two bitmetallic strips with two different coefficients of expansions

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

What is a magnetic circuit breaker and what is it used for?

A

A magnetic circuit breaker uses current instead of heat to generate a magnetic field to pull the breaker at a very specific point.

They are used in sensitive circuits where there is no delay and strict current limits.

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

How many spare fuses must an aircraft carry?

A

10% of number of fuses which use that specific rating
3 of each specific rating of fuse

The higher of these 2 values.

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

What are current limiters? (4 facts)

A

Allow short term overloads
High current fuses
Cannot be changed in flight
Normally found in series with busbars

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

How is static electricity generated?

A

Rubbing and friction exchanging electrons

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

What is a static discharge wick?

A

Static electricity likes sharp discharge points, a wick is a sharp discharge point which can be used to dissipate static electricity back into the atmosphere from the airframe.

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

Where do we find out how many static discharge wicks we can lose?

A

The Minimum equipment list (MEL)

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

What is bonding?

A

Bond each part of the airframe together to allow a low resistance path between all parts of the airframe and the static wicks.

Allows a uniform potential across the airframe.

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

What is grounding?

A

Airframe can still have charge after landing.

Ground to prevent arcing from fuel nozzle and prevent fire.

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

Why are cables covered in protection screening?

A

Wires carrying current have magnetic field.

This can interfere with other circuits.

Shield prevents this.

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

What is in a cell?

A

Anode (-)
Cathode (+)
Electrolyte separating them

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

How is a primary cell different to a secondary cell?

A

You can’t recharge a primary cell

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

Why is a secondary cell different to a primary cell?

A

You can recharge it

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

What are the two types of secondary cell?

A

Lead
Alkaline (NiCad)

The ELECTROLYTE determines the type!

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

What is the electrolyte in a lead acid battery?

A

Dilute sulphuric acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is in a lead acid battery

A

Anode - Lead peroxide
Cathode - Spongy lead
Electrolyte - Dilute sulphuric acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the terminal voltage of a lead acid cell?

A

2.2 V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the nominal voltage of a lead acid cell?

A

2 V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is terminal voltage?

A

Voltage of battery/cell off load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is nominal voltage?

A

Voltage of battery/cell on load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the terminal voltage of a lead acid battery?

A

13.2 V (off load)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the nominal voltage of a lead acid battery?

A

12 V (On load)

40
Q

How many cells in a lead acid battery?

A

6 Cells (2.2 V Term, 2 V nom)

41
Q

What does the voltage of a battery/cell depend on?

A

Material and not size

42
Q

Characteristics of lead acid discharge?

A

Voltage drops off gradually with discharge

Think of dimming torch

43
Q

What is Sulphation?

A

Lead acid battery suffers from sulphites blocking pours in the cathode (spongy lead) preventing charging of the battery.

Occurs when left discharged for a long period.

44
Q

How do we prevent sulphation of lead acid batteries?

A

Store them fully charged

45
Q

What is specific gravity?

A

Similar to density

46
Q

What is the specific gravity of a charged lead acid battery?

A

1.27 SG

47
Q

What is the specific gravity of a discharged lead acid battery?

A

1.17 SG

48
Q

How many cells in NiCad battery?

A

10

49
Q

NiCad terminal cell voltage?

A

1.3V

50
Q

NiCad nomimal cell voltage?

A

1.2V

51
Q

NiCad battery terminal voltage?

A

13V

52
Q

NiCad battery nominal voltage?

A

12V

53
Q

Discharge characteristics of NiCad?

A

Alkaline batteries - Bright torch

Voltage drops slightly with charge, remains constant then drops off suddenly.

54
Q

What happens to NiCad specific gravity with charge?

A

Doesn’t change.

55
Q

How is a battery connected with a generator to charge it?

A

In paralell.

56
Q

Why does generator produce higher voltage then battery?

A

So when generator is running, forces current into the battery charging it.

57
Q

What is a NiCad thermal runaway?

A

In NiCads resistance decreases with temperature

Temp increases -> Resistance decreases -> Current increases -> Temp increases more

58
Q

How do we stop NiCad thermal runaway?

A

Monitor the temperature of the battery and adjust current accordingly.

59
Q

What do we clear up lead acid electrolyte spillage with?

A

Acid electrolyte

Alkaline - Bicarbonate of soda

60
Q

What do we clear up NiCad spillages with?

A

Alkaline electrolyte

Acid - Boric Acid

61
Q

What is the electrolyte in a NiCad?

A

Potassium hydroxide

62
Q

What do we measure battery capacity in?

A

Amp-hours

63
Q

How are battery capacities tested?

A

At 1 hour rate.

I.e current discharging battery in an hour
So 25 Ah battery would be 25 Amps for an hour.

64
Q

How does battery capacity change in series?

A

It doesn’t

Voltage changes but capacity same

65
Q

How does battery capacity in paralell change?

A

Add together the capacities of the batteries

66
Q

What happens to capacity of a battery in lower temperatures?

A

It goes down

67
Q

What is the minimum capacity of a battery?

A

80%

68
Q

How long must main batteries last (CS25)

A

30 Minutes

69
Q

How long must emergency light batteries last? (CS 25)

A

10 Minutes

70
Q

What demagnetises a permenant magnet (2 things)?

A

Heat

Vibration

71
Q

How do we find field direction in a coil electromagnet?

A

Right hand rule
Fingers are field direction
Thumb is current direction

72
Q

What 3 things strengthen electromagnets?

A

Current
Number of coils
Soft iron core

73
Q

What is a relay?

A

Low voltage control circuit operates electromaget switch to high voltage operating circuit.

Fixed core single contact EM switch allowing remote control of heavy loads

74
Q

What is a solenoid?

A

Have a moving core with twin contacts

Heavy duty loads

75
Q

Why is a relay different to a solenoid?

A

Relay light duty device
Solenoid heavy duty device

Relay has a fixed core

76
Q

What is a contactor and how is it different to a solenoid?

A

The contactor latches on/off and stays in position unlike a solenoid.

Will not move until powered up again

77
Q

What is Lenz’s law?

A

The current generated in a conductor produces it’s own magnetic field which opposes the field creating the current.

78
Q

When do we use the right hand rule (FBI)?

A

Generators

79
Q

When do we use the left hand rule (FBI)?

A

Motors

80
Q

How does a DC generator create DC from the AC output in the armature?

A

It uses a split ring commutator

81
Q

What is an armature?

A

Where we induce an emf (drive current)

82
Q

Why is it bad to rotate the armature?

A

The armature is where we generate electricity and to extract this we will need to use brushes with rings to extract it, high currents will pass through these brushes causing wear.

83
Q

What is the difference between a DC generator and alternator?

A

The alternator has a rotating field and a fixed armature.

84
Q

How do we convert AC in the armature to DC in a DC alternator?

A

Bridge rectifier

85
Q

What happens to the series wound field in a DC generator?

A

As load and current increases, current increases and so does field

86
Q

What happens to the shunt wound paralell coil in a DC generator with load?

A

Emf stays constant even with load

But output goes down with load as current varies

87
Q

What is a compound wound field?

A

Use both effects of series and shunt coils to smooth out voltage and excitation field drops in DC generator.

88
Q

What is the purpose of a voltage regulator on a DC generator?

A

We place it in series with the shunt coil, it is a variable resistor which senses the voltage of the output and controls current through the shunt coil/field.

89
Q

What do you monitor on your DC electric system?

A

Monitor Voltage and Current

90
Q

Two types of voltage regulator?

A

Carbon pile, vibrating contact

91
Q

What does a current regulator in a DC generator do?

A

Opens contact to field coil to prevent overload

92
Q

How does DC generator overvoltage work and why is it needeD?

A

Electromagnet sense overvoltage cutting contacts to field coil and disconnects the entire generator. Now just rotating armature.

It is required because overvolting can cause electrical components on the aircraft to be damaged.

93
Q

What is the reverse current cut out relay used for on a DC generator?

A

Protects you in the event the generator voltage drops lower than the battery, this stops the battery driving the generator.

94
Q

In a system with 2 DC generators, what does the Differential cut out prevent?

A

If there is a larger than 2 voltage difference between the two generators, it removes one of them to prevent it doing all the work and going past it’s rating.

95
Q

In a system with 2 DC generators, what does the equalising circuit/load sharing circuit do?

A

It fine tunes generator voltage regulators to balance field coil and generator voltages to get the same voltage out of both generators.

ATPL (5 decks)

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