Electrical Systems Flashcards

1
Q

3 things that determine the amount of current in a circuit resulting from magnetic induction:

A

1) Strength of the magnetic field.
2) Number of conductors passing through the field.
3) Speed with which the field is crossed.

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2
Q

Type of electricity produced by magnetism:

A

AC

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3
Q

The armature coils of a DC generator produce _______ electricity.

A

AC

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4
Q

A device that allows electrons to flow in one direction while preventing their flow in the opposite direction:

A

Rectifier

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5
Q

A mechanical rectifier mounted on the armature shaft of a DC generator:

A

Commutator

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6
Q

AC is rectified in a DC generator by ____ and ____.

A

Commutator and brushes.

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7
Q

In an AC generator, the brushes ride on __________ to carry current in and out of the rotor coil.

A

Slip rings.

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8
Q

An electrical current flowing through a coil of wire will produce a/an _______.

A

Electromagnet.

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9
Q

The field frame of a typical aircraft DC generator has 4 ______ wound in _______.

A

Field poles.

Field coils.

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10
Q

The _______ controls the amount of current flowing into the field coils.

A

Voltage regulator.

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11
Q

T/F

The voltage regulator determines the voltage produced by the generator.

A

True.

Via the strength of the magnetic field produced by the electromagnets.

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12
Q

DC generators are said to be _______ because of the field frame’s residual magnetism that is used when starting.

A

Self-excited

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13
Q

Residual voltage is a result of _______ and should amount to _______.

A

Residual magnetism.

2 volts or less.

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14
Q

The process to restore residual magnetism to the field frame:

A

Flashing the field.

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15
Q

How to flash the field:

A

A pulse of current from the battery is sent through the field coils in the direction in which current normally flows.

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16
Q

Types of generators:

A

1) Series-field generator
2) Shunt-field generator
3) Compound generator

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17
Q

The _________ arrangement is used for low output aircraft generators.

A

Shunt-field

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18
Q

The _______ arrangement is used for high output aircraft generators.

A

Compound

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19
Q

The coils of a practical generator are wound around a core of __________.

A

Laminated soft iron.

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20
Q

The point in the rotation at which there is no voltage or current from the ends of the coil is the ______ or _______.

A

Neutral position.

Neutral plane.

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21
Q

Required basic controls or protection devices for DC generators:

A

1) Current limiter
2) Voltage regulator
3) Reverse-current cutout and switch.

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22
Q

A type of circuit protection device (current limiter) that allows a momentary flow of excess current, but opens the circuit if the excessive flow is continued:

A

Slow blow fuse.

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23
Q

Automatic current limiters monitor output current and reduce ______ to prevent excessive generator output voltage.

A

Field current

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24
Q

What is the result of voltage being supplied to the output terminal of a DC generator?

A

The generator will act as a motor.

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25
Q

The reverse-current cutout/switch does what?

A

Disconnects generator from electrical system to prevent battery discharge and generator damage when gen voltage is lower than batt voltage.

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26
Q

T/F

The reverse-current cutout and switch can be manually operated by the pilot.

A

True.

It can be both automatically and manually operated.

27
Q

Types of voltage regulators:

A

1) Carbon pile

2) Vibrating type (three unit electromagnetic)

28
Q

Which voltage regulator is used for higher output applications?

A

Carbon pile type.

29
Q

How does a carbon pile voltage regulator reduce generator voltage?

A

A voltage increase in the regulator’s coil causes a magnetic pull on the spring that holds pressure on the carbon pile, loosening the stack and increasing its resistance.

30
Q

Piston engines use ______ power.

A

DC

31
Q

Benefit of brushless motors:

A

No brush arcing at high altitudes caused by the low dielectric strength of low density air.

32
Q

Ideal generator belt tension:

A

1/2 inch of deflection

33
Q

A multimeter reading of “O.L” means ______ and “I” means _______.

A

Open lead.

Infinite.

34
Q

The specific gravity of battery electrolyte is ______.

A

1.27

35
Q

Higher frequency (Hertz) means less ______ is needed.

A

Current.

Lower current means smaller components

36
Q

AC generators on large aircraft are also called _______.

A

Alternators.

37
Q

As frequency drops, some components may overheat due to __________.

A

An increase in current.

38
Q

AC generators are driven by the turbine engines through ________.

A

Constant speed drive units. (CSD)

39
Q

The _______ holds AC generator speed and frequency constant as engine speed varies.

A

CSD

Constant speed drive

40
Q

Define hertz.

A

A unit of frequency equal to one cycle per second.

41
Q

A component that contains both the generator and the CSD in one unit:

A

Integrated drive generator.

IDG

42
Q

Red wire insulation is for _______ gauge wire.

A

22-18

43
Q

Blue wire insulation is for _____ gauge wire.

A

16 and 14.

44
Q

Yellow wire insulation is for _____ gauge wire.

A

12 and 10.

45
Q

____ is the max number of wire terminals that may be stacked in a terminal strip.

A

4

46
Q

How does the vibrator type voltage regulator work?

A

When voltage rises above the regulated value, the relay pulls the contacts open and inserts a resistor in the generator field. It vibrates open and closed to control the amount of voltage produced.

47
Q

What three things must be synchronized before a three phase AC generator can be connected to a bus that is being served by another generator?

A

1) Frequency
2) Voltage
3) Phase rotation

48
Q

T\F

DC motors have a low starting torque.

A

False.

High torque.

49
Q

T/F

The starter motor circuit does not normally contain a fuse or circuit breaker.

A

True.

50
Q

Two things that receive current for starter generator operation in start mode.

A

Field and armature windings.

51
Q

What is done to ensure that each generator shares the load in a multi generator system?

A

The generators are paralleled.

52
Q

How is the voltage of a DC generator controlled?

A

By varying the field current strength.

53
Q

Most common type of alternator used in aircraft systems:

A

3 phase

54
Q

Voltage regulators and current limiters regulate DC generator voltage and limit current by controlling the ______.

A

Generator field current.

55
Q

The field coil in a DC alternator is in the _______ element.
(rotating or stationary)

A

Rotating.

56
Q

DC alternator benefits over generators:

A

1) More field poles (produce current at lower speeds).
2) High current is produced in the stationary component.
3) Lighter charging system than a generator

57
Q

A starter generator has an additional set of ________.

A

Series motor windings.

58
Q

The IDG (integrated drive generator) has the ______ and ______ in a single unit.

A

Generator and CSD

59
Q

3 basic types of circuit breakers used in aircraft electrical systems:

A

1) Push to reset
2) Push-pull
3) Toggle type

60
Q

Purpose of the constant speed drive (CSD).

A

Hold AC generator speed and frequency constant as the speed of the aircraft varies.

61
Q

Reason DC power is used in small aircraft.

A

They require the ability to store electrical energy (battery) for starting the engine.

62
Q

Conditions that can affect the state of charge of a battery:

A

1) Damp/dirty surface of battery.
2) Terminal corrosion.
3) Poor ground-to-structure connection.
4) Improper electrolyte level.
5) Low generator output voltage.
6) Acidic residue on top of battery.

63
Q

Generator inspection consists of:

A

1) Checking the mounting.
2) Electrical connections.
3) Check commutator for indications of arcing.
4) Blowing out brush dust.
5) Indications of overheating (solder from the commutator)
6) Check output voltage.