Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

AV Fundies > MAG > Flashcards

MAG Flashcards

(74 cards)

Start Studying
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
Advantages of a starter generator system?
Starter motor and generator in one - Ideal for small gas turbine aircrafts where weight is a major consideration (Diagram with the start button)
26
Applications for a linear actuator?
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
27
Applications for a rotary actuator?
- Flight controls (trim system) - Fuel control - Hydraulic controls - Bleed air control - Heating and cooling control - Radar - Satcom - Water flow control
28
Components of a DC linear actuator?
- Lead screw - DC motor - Ball mechanism!!!!!!!!!!!!!! - Gear train
29
What prevents an actuator from exceeding its limits?
Limit switches
30
What provides positional feedback for a rotary actuator?
- Potentiometer - Hall effect (magnets) - Digital encoder type devices
31
Components of a rotary actuator?
- Worm screw - worm gear - potentiometer!!!!!! Potentially a wormy worm
32
3 main sections in a brushless generator?
- PMG (Permanent magnement) - Exciter - Main generator
33
Output voltage and frequency of an AC brushless generator?
Output voltage - 115v Frequency - 400Hz
34
6 functions of a GCU?
GCU - Generator control unit - Voltage regulation - Frequency protection - Voltage protection - Phase sequence - Differential current protection - Warning system
35
Maximum and minimum voltage that a GCU will allow?
100V - 130V
36
Maximum and minimum Frequency that a GCU will allow?
365Hz - 430Hz
37
How does a GCU regulate output voltage
- 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
Advantages of the following: IDG Variable speed constant frequency generator Variable frequency generator
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
Maximum and minimum limits for frequency in a variable frequency generator?
360Hz - 800Hz
40
Describe the construction of a single phase induction motor: Rotor Stator
Rotor - No traditional copper wire / Steel laminations with aluminium or copper bars embedded Stator - Laminated iron core with copper windings
41
Describe the construction of a 3 phase induction motor: Rotor Stator
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
What is a main issues with a single phase induction motor?
- Constantly changing polarity - No starting torque is produced - Rotor will begin the oscillate back and forth between the poles
43
3 starting systems for a single phase AC induction motor?
- Split phase - Capacitor start - Shaded poles
44
Applications for the following single phase AC induction motor starting systems? Split phase Capacitor start Shaded poles
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
Applications for a 3 phase squirrel cage induction motor? (Squirrel cage induction motor)
- Hydraulic pumps - Galley and lavatory pumps - Flap power drive units - Horizontal stabiliser trim actuators
46
How do you reverse the direction of a 3 phase induction motor?
Reverse any 2 supply connections to the stator winding
47
Construction of a single phase synchronous motor?
- Induction motor - Rotor with a strong magnetic field
48
Applications for a single phase synchronous motor?
- Clocks - Timers - Recording systems - Tachometer system
49
What is the construction of a polyphase synchronous motor rotor?
Rotor - Wire wound Salient pole for low speed Cylindrical pole for high sped
50
Applications for a 3 phase synchronous motor?
- Constant speed power application (15w-75Kw) - Electrically driven hydraulic pumps
51
What is the difference between synchronous speed and actual speed called?
Slip
52
Describe the following electrical connection methods: Plugs and receptacles Terminal lugs
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
Steps of de-powering an aircraft?
- Shut down engine and/or auxiliary power unit - Shut down ground power and remove ground-power receptacle - Raise appropriate power restriction in CARS
54
Steps of de-powering a specific system?
- Trip relevant circuit - Tag relevant braker - Raise applicable entry into AMD
55
8 electrical system safety considerations?
- High voltage - Working at heights - Heavy objects - Rotating parts - Liquid / chemical spills - Concurrent maintenance - Battery safety - Jewellery / hair
56
Publication for aircraft maintenance on a operational level?
Relevant - 2 / relevant aircraft pubs and manuals
57
3 main components of the Main generator in an AC brushless generator
- Output stator winding - Rotating Field winding - Rotating Rectifier
58
Stater generator characteristics?
- Start the engine of aircraft - Used to recharge battery and to supply DC bus
59
When is Flemming's left hand rule used?
Generators
60
Describe the attachment methods: Flange mounted devices
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
Describe the following attachment methods: Direct mounted hardware
Types of fastenings can include: bolts, nuts, lock washers, self locking nuts, plate number and screws
62
Describe the following attachment methods: Quick attach detach ring
Adapter that is bolted into the drive unit and a rotating ring / requires special maintenance Circle clamps
63
Describe the following attachment methods: Rack mounted
Quick release trays are common among avionic devices
64
Describe the following attachment methods: Vibration isolation
Shock mounts fitted under the tray, device or rack / ideal for sensitive aircraft electrical hardware
65
Describe the following attachment methods: Aircraft battery mounting
Fixed on the aircraft frame / Type of tray in dictated by the type of battery, size and location
66
What is the make up of the rotary in a generator (AC or DC)
- Windings - Commutator (DC) / Split ring (AC) - Armature - Shaft
67
Make up of the stator in a generator (AC or DC)
ANYTHING THAT IS STATIONARY!!!! - Frame / end bell - Field assembly (Pole, coil, bolt) - Brush assembly (Brush, holder, spring)
68
The button has been pressed - Starter generator or motor?
Starter motor
69
The button has been released - Starter generator or motor?
Starter generator
70
Describe differential current protection?
- Used to detect imbalances in each phase of the generator - Current in should equal current out / DCP transformer is used to detect this
71
What is special about the variable frequency generator?
- No longer requires the CSD - Weight saving advantage
72
What connects the brushes to the external circuit?
Pig tails
73
Fill in the blanks: Squirrel cage induction motor exhibits ______ speed characteristics and _______ starting torque.
Constant Low
74
How is frequency determined?
- Speed of spinning - Number of poles

AV Fundies (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions