Electrical Systems

Question 1

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

Answer 1

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

Question 2

Type of electricity produced by magnetism:

Answer 2

AC

Question 3

The armature coils of a DC generator produce _______ electricity.

Answer 3

AC

Question 4

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

Answer 4

Rectifier

Question 5

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

Answer 5

Commutator

Question 6

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

Answer 6

Commutator and brushes.

Question 7

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

Answer 7

Slip rings.

Question 8

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

Answer 8

Electromagnet.

Question 9

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

Answer 9

Field poles.

Field coils.

Question 10

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

Answer 10

Voltage regulator.

Question 11

T/F

The voltage regulator determines the voltage produced by the generator.

Answer 11

True.

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

Question 12

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

Answer 12

Self-excited

Question 13

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

Answer 13

Residual magnetism.

2 volts or less.

Question 14

The process to restore residual magnetism to the field frame:

Answer 14

Flashing the field.

Question 15

How to flash the field:

Answer 15

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

Question 16

Types of generators:

Answer 16

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

Question 17

The _________ arrangement is used for low output aircraft generators.

Answer 17

Shunt-field

Question 18

The _______ arrangement is used for high output aircraft generators.

Answer 18

Compound

Question 19

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

Answer 19

Laminated soft iron.

Question 20

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

Answer 20

Neutral position.

Neutral plane.

Question 21

Required basic controls or protection devices for DC generators:

Answer 21

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

Question 22

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:

Answer 22

Slow blow fuse.

Question 23

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

Answer 23

Field current

Question 24

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

Answer 24

The generator will act as a motor.

Question 25

The reverse-current cutout/switch does what?

Answer 25

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

Question 26

T/F | The reverse-current cutout and switch can be manually operated by the pilot.

Answer 26

True. | It can be both automatically and manually operated.

Question 27

Types of voltage regulators:

Answer 27

1) Carbon pile | 2) Vibrating type (three unit electromagnetic)

Question 28

Which voltage regulator is used for higher output applications?

Answer 28

Carbon pile type.

Question 29

How does a carbon pile voltage regulator reduce generator voltage?

Answer 29

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.

Question 30

Piston engines use ______ power.

Answer 30

DC

Question 31

Benefit of brushless motors:

Answer 31

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

Question 32

Ideal generator belt tension:

Answer 32

1/2 inch of deflection

Question 33

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

Answer 33

Open lead. | Infinite.

Question 34

The specific gravity of battery electrolyte is ______.

Answer 34

1.27

Question 35

Higher frequency (Hertz) means less ______ is needed.

Answer 35

Current. | Lower current means smaller components

Question 36

AC generators on large aircraft are also called _______.

Answer 36

Alternators.

Question 37

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

Answer 37

An increase in current.

Question 38

AC generators are driven by the turbine engines through ________.

Answer 38

Constant speed drive units. (CSD)

Question 39

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

Answer 39

CSD | Constant speed drive

Question 40

Define hertz.

Answer 40

A unit of frequency equal to one cycle per second.

Question 41

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

Answer 41

Integrated drive generator. | IDG

Question 42

Red wire insulation is for _______ gauge wire.

Answer 42

22-18

Question 43

Blue wire insulation is for _____ gauge wire.

Answer 43

16 and 14.

Question 44

Yellow wire insulation is for _____ gauge wire.

Answer 44

12 and 10.

Question 45

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

Answer 45

4

Question 46

How does the vibrator type voltage regulator work?

Answer 46

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.

Question 47

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?

Answer 47

1) Frequency 2) Voltage 3) Phase rotation

Question 48

T\F | DC motors have a low starting torque.

Answer 48

False. | High torque.

Question 49

T/F | The starter motor circuit does not normally contain a fuse or circuit breaker.

Answer 49

True.

Question 50

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

Answer 50

Field and armature windings.

Question 51

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

Answer 51

The generators are paralleled.

Question 52

How is the voltage of a DC generator controlled?

Answer 52

By varying the field current strength.

Question 53

Most common type of alternator used in aircraft systems:

Answer 53

3 phase

Question 54

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

Answer 54

Generator field current.

Question 55

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

Answer 55

Rotating.

Question 56

DC alternator benefits over generators:

Answer 56

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

Question 57

A starter generator has an additional set of ________.

Answer 57

Series motor windings.

Question 58

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

Answer 58

Generator and CSD

Question 59

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

Answer 59

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

Question 60

Purpose of the constant speed drive (CSD).

Answer 60

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

Question 61

Reason DC power is used in small aircraft.

Answer 61

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

Question 62

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

Answer 62

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.

Question 63

Generator inspection consists of:

Answer 63

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.