Brainscape's Knowledge GenomeTM

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


See full index

AV Fundies > MAG > Flashcards

MAG Flashcards

1
Q

Operating characteristics of the following DC generator?
(voltage - speed / Output - load applied)

Permanent magnet
Separately excited shunt
Shunt wound
Series wound
Compound

A

Permanent magnet - Voltage is directly proportional to speed / Output drops SLIGHTLY with a load applied

Separately excited shunt - Voltage is directly proportional to speed / Output drops SLIGHTLY with a load applied

Shunt wound - Voltage is NOT LINEAR to speed / Output drops MORE THAN permanent magnet with a load applied

Series wound - Voltage RISES RAPIDLY with load applied

Compound - FLAT voltage output

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

Aircraft applications for the following DC generator?

Permanent magnet
Separately excited shunt
Shunt wound
Series wound
Compound

A

Permanent magnet - Tacho generators

Separately excited shunt - None / Only in labs

Shunt wound - Light aircrafts

Series wound - None

Compound - Medium to heavy aircrafts

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

Operating characteristics of the following DC motors?
(Speed - load / Torque - load)

Permanent magnet
Shunt wound
Series wound
Split field series
Compound

A

Permanent magnet - Speed drops SLIGHTLY on load / Torque is directly proportional to the applied load

Shunt wound - Speed drops SLIGHTLY on load / Torque is APPROXIMATELY proportional to the applied load
(Approximately a cunt)

Series wound - Speed decreases and torque increases with load applied

Split field series - Speed decreases and torque increases with load applied
(Can reverse direction with switch)

Compound - Speed drops MORE THAN shunt and torque increases MORE THAN shunt

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

Aircraft applications for the following DC motor?

Permanent magnet
Shunt wound
Series wound
Split field series
Compound

A

Permanent magnet - None / Small machines only

Shunt wound - Electric fans, fuel boost pumps, motor generator units

Series wound - Starter motor, landing gear, fuel / hydraulic shut-off valves

Split field series - Actuators (flaps, trim tabs, landing gear)

Compound - Presses, shears, hydraulic pumps, reciprocating machines

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

4 main components of a single loop AC generator?

A
  • Single conductive loop (rotor)
  • Pair of slip rings
  • Pair of brushes
  • 2 x permanent magnets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

4 main components of a single loop DC generator?

A
  • Single conductive loop (rotor)
  • Commutator
  • Pair of brushes
  • 2 x permanent magnets
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do the letters in the following equation stand for?

E = β L V Sinθ

A

E - Generator output voltage
β - Strength of magnetic field
L - Active length of conductor
V - Velocity / speed of cutting
Sinθ - Angle of cutting

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

What happens to the generator output when the rotor is spun in the opposite direction?

A

180 degrees out of phase

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

Describe the positioning of each finger as well as the applications for each of the following:

Flemming’s left hand rule (generators)

A

Flemming’s left hand rule -
Thumb - Direction conductor is traveling
Fingers - Current flow direction

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

What do the following components do?

Slip rings
Commutator
Brushes

A

Slip rings - Allows current to flow to the external circuit

Commutator - Allows current to flow to the external circuit / converts from AC to DC

Brushes - Used to transfer current from the slip rings or commutator to the external circuit

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

How can the DC ripple coming out of a DC generator be reduced?

A

Add more windings to smooth out the ripple

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

Difference between the stator and rotor?

A

Stator - STATIONARY part of the motor or generator

Rotor - ROTATING part of the motor or generator

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

Difference between a field and armature?

A

Field - Electromagnetic / current is applied to a ‘field coil’ to produce an electromagnetic field / can be part of a stator (motor) or rotor (generator)

Armature - Not a physical term like rotor or stator / Power producing component - where current comes out of

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

Components of a DC generator?

A
  • End bell
  • Brush assembly (Brush spring, brush, brush holder)
  • Armature
  • Frame
  • Field coil (Field pole, field pole bolt)
  • Commutator
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Define self excited?

A

Does not rely on an external power source for field excitation

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

Define residual magnetism?

A

In self excited DC generators, the pole pieces are required to retain a small amount of magnetism so they can produce enough EMF to excite the armature upon start up

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

What can be done if we lose magnetism?

A

Flash the field

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

What would be the output of a generator in the following situations?

Open circuit field winding
Open circuit armature
Loss of residual magnetism

A

Open circuit field winding - Lower than the rated output

Open circuit armature - If there is only one winding, the output would be zero / If there was more than one winding, the output would be lower than the rated output but not zero

Loss of residual magnetism - Field would fail to build up / start

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

What causes armature reaction?

A

Displacement of the neutral plane

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

What happens if we get armature reaction?

A

Reactive sparking

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

3 ways to correct armature reaction?

A
  • Brush positioning
  • Compensation windings
  • Interpoles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe back EMF in DC motors?

A
  • Creates the total speed limitations of the motor
  • As the motor is starting to build up speed, the back EMF is small
  • As the motor gets faster and faster, the back EMF increases proportionally
  • Once the motor stops, the back EMF is zero
  • Affects the efficiency of the motor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Fill in the missing words:

In a compound generator or motor the series winding has _______ turns of _______ wire

A

Few turns of heavy gauge wire

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

Fill in the missing words:

In a compound generator or motor the shunt winding has _______ turns of _______ wire

A

Many turns of fine wire

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

Advantages of a starter generator system?

A

Starter motor and generator in one

  • Ideal for small gas turbine aircrafts where weight is a major consideration

(Diagram with the start button)

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

Applications for a linear actuator?

A

Linear actuator - Goes in a straight line

  • Flight controls (trim system)
  • Primary flight controls
  • Secondary flight controls
  • Auto pilot
  • Undercarriage
  • Cargo doors
  • APU ducting
  • Cargo ramp on (fixed wing and rotary wing transport aircrafts)
  • Cooling air ducts
  • Cargo locking
  • Seat positioning
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Applications for a rotary actuator?

A
  • Flight controls (trim system)
  • Fuel control
  • Hydraulic controls
  • Bleed air control
  • Heating and cooling control
  • Radar
  • Satcom
  • Water flow control
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Components of a DC linear actuator?

A
  • Lead screw
  • DC motor
  • Ball mechanism!!!!!!!!!!!!!!
  • Gear train
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What prevents an actuator from exceeding its limits?

A

Limit switches

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

What provides positional feedback for a rotary actuator?

A
  • Potentiometer
  • Hall effect (magnets)
  • Digital encoder type devices
31
Q

Components of a rotary actuator?

A
  • Worm screw
  • worm gear
  • potentiometer!!!!!!

Potentially a wormy worm

32
Q

3 main sections in a brushless generator?

A
  • PMG (Permanent magnement)
  • Exciter
  • Main generator
33
Q

Output voltage and frequency of an AC brushless generator?

A

Output voltage - 115v
Frequency - 400Hz

34
Q

6 functions of a GCU?

A

GCU - Generator control unit

  • Voltage regulation
  • Frequency protection
  • Voltage protection
  • Phase sequence
  • Differential current protection
  • Warning system
35
Q

Maximum and minimum voltage that a GCU will allow?

A

100V - 130V

36
Q

Maximum and minimum Frequency that a GCU will allow?

A

365Hz - 430Hz

37
Q

How does a GCU regulate output voltage

A
  • A sample of the 3 phase AC voltage levels from main genrator is sent to the GCU, if the output voltage is higher or lower that 115V GCU will add or reduce voltage to the excitor to make the main output 115V again
  • Remember a brushless AC geerator is made of 3 parts, permanent magnet generator, exciter and main generator
38
Q

Advantages of the following:

IDG
Variable speed constant frequency generator
Variable frequency generator

A

IDG (Integrated drive generator) - Ideal for fault finding / AC brushless generator combine with a CSD

Variable speed constant frequency generator - Voltage and frequency control imbedded into the generator

Variable frequency generator - No longer requires a CSD

39
Q

Maximum and minimum limits for frequency in a variable frequency generator?

A

360Hz - 800Hz

40
Q

Describe the construction of a single phase induction motor:

Rotor
Stator

A

Rotor - No traditional copper wire / Steel laminations with aluminium or copper bars embedded

Stator - Laminated iron core with copper windings

41
Q

Describe the construction of a 3 phase induction motor:

Rotor
Stator

A

Also known as a ‘Polyphase motor’

Rotor - Laminated iron core / Heavy copper bars laid into slots

Stator - Sheet metal punching with slots on the inner surface

Punched steel - both cannot be steel

42
Q

What is a main issues with a single phase induction motor?

A
  • Constantly changing polarity
  • No starting torque is produced
  • Rotor will begin the oscillate back and forth between the poles
43
Q

3 starting systems for a single phase AC induction motor?

A
  • Split phase
  • Capacitor start
  • Shaded poles
44
Q

Applications for the following single phase AC induction motor starting systems?

Split phase
Capacitor start
Shaded poles

A

Split phase - Most common

Capacitor start - Small blower motors in equipment cooling and ECS

Shaded poles -Light duty fridge circulation and air cons / environmental conditioning

45
Q

Applications for a 3 phase squirrel cage induction motor?

(Squirrel cage induction motor)

A
  • Hydraulic pumps
  • Galley and lavatory pumps
  • Flap power drive units
  • Horizontal stabiliser trim actuators
46
Q

How do you reverse the direction of a 3 phase induction motor?

A

Reverse any 2 supply connections to the stator winding

47
Q

Construction of a single phase synchronous motor?

A
  • Induction motor
  • Rotor with a strong magnetic field
48
Q

Applications for a single phase synchronous motor?

A
  • Clocks
  • Timers
  • Recording systems
  • Tachometer system
49
Q

What is the construction of a polyphase synchronous motor rotor?

A

Rotor - Wire wound

Salient pole for low speed
Cylindrical pole for high sped

50
Q

Applications for a 3 phase synchronous motor?

A
  • Constant speed power application (15w-75Kw)
  • Electrically driven hydraulic pumps
51
Q

What is the difference between synchronous speed and actual speed called?

A

Slip

52
Q

Describe the following electrical connection methods:

Plugs and receptacles
Terminal lugs

A

Plugs and receptacles - Variety of sizes, pin configurations and wire gauges, convenient way to connect and disconnect

Terminal lugs - Used where a plug or socket is not suitable or appropriate

53
Q

Steps of de-powering an aircraft?

A
  • Shut down engine and/or auxiliary power unit
  • Shut down ground power and remove ground-power receptacle
  • Raise appropriate power restriction in CARS
54
Q

Steps of de-powering a specific system?

A
  • Trip relevant circuit
  • Tag relevant braker
  • Raise applicable entry into AMD
55
Q

8 electrical system safety considerations?

A
  • High voltage
  • Working at heights
  • Heavy objects
  • Rotating parts
  • Liquid / chemical spills
  • Concurrent maintenance
  • Battery safety
  • Jewellery / hair
56
Q

Publication for aircraft maintenance on a operational level?

A

Relevant - 2 / relevant aircraft pubs and manuals

57
Q

3 main components of the Main generator in an AC brushless generator

A
  • Output stator winding
  • Rotating Field winding
  • Rotating Rectifier
58
Q

Stater generator characteristics?

A
  • Start the engine of aircraft
  • Used to recharge battery and to supply DC bus
59
Q

When is Flemming’s left hand rule used?

A

Generators

60
Q

Describe the attachment methods:

Flange mounted devices

A

Popular on aircrafts, located on accessory case, auxiliary gearbox and reduction gearbox as well as starter motor, AC/DC generators

Like wheels on a car - partially threaded studs

61
Q

Describe the following attachment methods:

Direct mounted hardware

A

Types of fastenings can include: bolts, nuts, lock washers, self locking nuts, plate number and screws

62
Q

Describe the following attachment methods:

Quick attach detach ring

A

Adapter that is bolted into the drive unit and a rotating ring / requires special maintenance

Circle clamps

63
Q

Describe the following attachment methods:

Rack mounted

A

Quick release trays are common among avionic devices

64
Q

Describe the following attachment methods:

Vibration isolation

A

Shock mounts fitted under the tray, device or rack / ideal for sensitive aircraft electrical hardware

65
Q

Describe the following attachment methods:

Aircraft battery mounting

A

Fixed on the aircraft frame / Type of tray in dictated by the type of battery, size and location

66
Q

What is the make up of the rotary in a generator (AC or DC)

A
  • Windings
  • Commutator (DC) / Split ring (AC)
  • Armature
  • Shaft
67
Q

Make up of the stator in a generator (AC or DC)

A

ANYTHING THAT IS STATIONARY!!!!

  • Frame / end bell
  • Field assembly (Pole, coil, bolt)
  • Brush assembly (Brush, holder, spring)
68
Q

The button has been pressed - Starter generator or motor?

A

Starter motor

69
Q

The button has been released - Starter generator or motor?

A

Starter generator

70
Q

Describe differential current protection?

A
  • Used to detect imbalances in each phase of the generator
  • Current in should equal current out / DCP transformer is used to detect this
71
Q

What is special about the variable frequency generator?

A
  • No longer requires the CSD
  • Weight saving advantage
72
Q

What connects the brushes to the external circuit?

A

Pig tails

73
Q

Fill in the blanks:

Squirrel cage induction motor exhibits ______ speed characteristics and _______ starting torque.

A

Constant
Low

74
Q

How is frequency determined?

A
  • Speed of spinning
  • Number of poles

AV Fundies (11 decks)

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