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asys 320 > Mod 3-4-5 > Flashcards

Mod 3-4-5 Flashcards

1
Q

What are some characteristics of a series wound motor?

A
  • Field windings are wound in series
  • Increase in current strengthens the field of both the field and armature
  • Gives high start torque
  • However, speed changes with varying load
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2
Q

What are some characteristics of a shunt wound motor?

A
  • Field windings are wound in parallel
  • Field current and output speed is fairly constant regardless of changes in the load
  • However, does not have a high starting torque
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3
Q

What are characteristics of a compound wound motor?

A
  • Best of both worlds of series and shunt

- High starting torque speed, fairly constant output in varying load conditions.

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4
Q

Difference between intermittent and continuous duty?

A 
Intermittent = Can only be operated for brief periods of time before needing to cool down
Continuous = Can operate at rated power for long periods
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5
Q

How can motor direction be reversed?

A

Either with a SPDT switch and a split winding OR a DPDT switch to reverse the current within either the field windings or the armature

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6
Q

How can motor speed be changed?

A

Increasing / decreasing the amount of current to the field windings

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7
Q

What is torque?

A

Tendency of a force to produce rotation - Developed by the reacting field of a conductor through another magnetic field

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8
Q

List the 4 main parts of a motor

A
  • Armature assembly
  • Field assembly
  • Brush assembly
  • End frames
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9
Q

What is counter EMF?

A

Counter EMF = The reverse current that fights back against the current flowing through the armature

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10
Q

How do we calculate the Net EMF?

A

Applied EMF - Counter EMF = Net EMF

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11
Q

What is motor braking?

A

When the motor needs to be stopped at precise points - Used for landing gear, flaps, autopilots, etc.

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12
Q

What does a motor clutch do?

A

Disengages the motor from the load (gearbox) if necessary - Uses spring pressure

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13
Q

Difference between generator and motor?

A
  • Generator turns the rotor in a field to produce current

- Motor applies current to a rotor in a field to make it turn

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14
Q

Difference between generator armature and alternator armature?

A 
Generator = armature moves in stationary field
Alternator = Moving field around a stationary armature
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15
Q

3 main parts of an alternator?

A

Stationary armature, rotating field, rectifier bridge circuit

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16
Q

Main advantage of having an alternator over a generator?

A

Eliminates the need for a commutator and brushes. They are potential contact issue points. Alternators can supply current to the aircraft directly

17
Q

How many phases on a typical aircraft alternator?

A

3

18
Q

How does an alternator produce DC output?

A

By rectifying the AC input with 6 diodes

19
Q

Why does an alternator not need a reverse current relay?

A

The diodes resist any current flow to the armature

20
Q

What 2 means of control are required for an alternator?

A

Voltage regulator or a current limiter

21
Q

Whats the purpose of the zener diode in a solid state voltage regulator

A

It acts as a voltage reference or as a relief valve that opens at a given pressure. When conducting, the control transistor shuts off the power transistor

22
Q

Advantage of using transistorized voltage regulator?

A

No moving parts, no contacts, less wear and tear

23
Q

3 differences between aircraft and automotive alternators?

A

Through bolts are made of stronger steel
Includes signal interference protection
Rotor has shorter shaft and smaller thread

24
Q

Whats an ACU and what does it do?

A

Alternator Control Unit - Regulates alternator output voltage and turns off the charging system if over voltage exists

25
Q

4 steps in overhaul of generator?

A

Disassembly
Cleaning
Inspection and repair
Reassembly

26
Q

How is an armature tested for opens?

A

PLace it on the growler and turn it on. Using probes and a test lamp, test each pair of segments, the lamp should light with each set of commutator bars

27
Q

How to test armature for shorts?

A

Place it on growler, turn it on. if any shorts occur, the blade will vibrate vigorously

asys 320 (3 decks)

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