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Electrical Machines Theory Period 4 SAIT-Alberta > Alternators and Generators > Flashcards

Flashcards in Alternators and Generators Deck (17)
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1

Which two machines convert mechanical energy into electrical energy?

Alternators and Generators.

2

I am a rotating electrical machine, which converts mechanical energy into electrical energy or electrical energy into mechanical energy; What am I?

A dynamo.

3

I am a rotating electrical machine, which converts mechanical energy into electrical energy; I typically produce a direct current; What am I?

A generator.

4

I am a rotating electrical machine, which converts mechanical energy into electrical energy; I typically produce an alternating current; What am I?

An alternator. (synchronous generator)

{Generally moving at a synchronous speed to maintain a standard frequency}

5

I am a rotating machine, which converts explosive and gravitational forces into mechanical energy; What am I?

A prime mover.

6

I am a rotating electrical machine, which converts electrical energy into mechanical energy; I have a stationary part and a rotating part; What am I? What are they called?

A motor.

Stator, Rotor.

7

I am the point in space where the least flux is cut; What am I?

The neutral plane.

8

I rotate rapidly getting worn by brushes all day, I like to do the wave; What am I?

A slip ring.

9

I rotate rapidly getting worn by brushes all day, my conjoined twin brother and I always go in the same direction; What are we?

A commutator.

10

I am made of carbon and I operate very differently wether my flow is direct or alternating; What am I?

Brushes

11

How is electromotive force produced in an electrical machine?

Through electromagnetic induction.

{The polarity of emf generated may be found using Flemmings left hand rule}

12

What is the magnitude of generated emf proportional to?

Flux density,

Effective length of conductor within field,

Velocity of the conductor.

13

What is the way to control output voltage of an AC machine?

By varying field flux intensity.

{Changing speed would change the frequncy of the supply}

14

How is a smoother direct current waveform achieved with a commutator?

By splitting the commutator further and adding more coils in series.

15

How is output voltage of a DC machine controlled?

By varying field flux intensity generally,

Speed may be varied occasionally, however most machines run at a relatively constant speed.

16

What is the simplest way to vary field flux intensity?

To add a rheostat in series with the field winding.

17

When is there a danger of overheating the field winding?

Nearing the point of magnetic saturation of the core material (the knee).