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DC Machines > DC Machines > Flashcards

DC Machines Flashcards

1
Q

6 components of a dc machine

A 
Armature
Pole pieces
Inter poles
Commutator
Frame
Windings
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2
Q

Series field windings are wound with _____ turns of _____ wire

A

Few

Large

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3
Q

Shunt field windings are wound with _____ turns of _____ wire

A

Lots of

Small

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4
Q

What component of a dc generator that converts AC to DC called?

A

Commutator

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5
Q

_____ operate on the principle that current flowing through a conductor produces a magnetic field around the conductor.

A

The induction of currents

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6
Q

When a conductor cuts through magnetic lines of flux, a voltage is induced into the conductor. What is this principle called?

A

Magnetic Induction

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7
Q

Three types of armature windings

A

Lap wound
Wave wound
Frog leg wound

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8
Q

What type of armature winding provides moderate voltage and moderate current

A

Frog leg wound

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9
Q

What type of wound armatures have their windings connected in parallel?

A

Lap wound

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10
Q

What type of armature winding provides high voltage and low current?

A

Wave wound

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11
Q

Two ways the series and shunt windings of a compound generator can be connected?

A

Long shunt

Short shunt

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12
Q

The relationships of the strengths of the two fields in a compound generator determines the amount of ______ for the machine.

A

Compounding

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13
Q

A generator is _____ compounded when the output voltage is the same at full load as it is at no load.

A

Flat

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14
Q

When a generator is _______ compounded, it has characteristics similar to those of a shunt generator.

A

Under

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15
Q

What is compounding controlled by?

A

A variable resistor in parallel with the series field

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16
Q

A _________ compound generator has its fields connected in such a manner that they oppose each other in the production of magnetism.

A

Differential

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17
Q

A ________ compound generator has its fields connected in such a manner that they aid each other in the production of magnetism.

A

Cumulative

18
Q

What components ride against the commutator segments and connect the armature to the external circuit of the generator?

A

Brushes

19
Q

What is the distortion of the main magnetic field of a generator called?

A

Armature reaction

20
Q

What causes armature reaction

A

Magnetic field in the current of the armature

21
Q

How is the winding of an inter pole connected in relation to the armature?

A

In series

22
Q

What are brushes made of?

A

Carbon

23
Q

What does an armature consist of?

A

Iron core
Windings
Commutator
Shaft

24
Q

Shunt windings are of _____ resistance and connected in ____ with the armature

A

High

Parallel

25
Q

What is a measure of a materials ability to become magnetized?

A

Permeability

26
Q

What is resistance to magnetism called?

A

Reluctance

27
Q

When an electromagnet reaches a point where strength increases only slightly with an increase in current, it is known as a point of ____

A

Saturation

28
Q

What is the amount of magnetism left in a material after magnetizing force has stopped called?

A

Residual magnetism

29
Q

The main magnetic field is sometimes provided by electromagnets. This is done by windings that are wound around what components of a DC machine?

A

Pole pieces/ field poles

30
Q

Another word for inter poles

A

Commutating windings

31
Q

What is the position at which the armature windings are parallel to the lines of flux and there is no induced voltage called?

A

Neutral Plane

32
Q

What are three ways that armature reaction can be corrected?

A

Rotate brushes
Inter poles
Compensating windings

33
Q

How is a series generator connected?

A

A1, A2 to S2, S1

34
Q

How should a shunt generator be connected?

A

F1 to A1, F2 to A2

35
Q

What would you use to clean a commutator?

A

Emory paper

36
Q

Field windings are wound into magnetic pole pieces to form ______.

A

An Electromagnet

37
Q

Series generators ____ in speed and ______ their output voltage and current as load is added.

A

Decrease speed, increase voltage and current

38
Q

Shunt generators ______ in speed and ______ their output voltage and current as load is added.

A

Increase in speed, decrease the voltage and current

39
Q

When a generator supplies current to a load, what is produced?

A

Counter EMF

40
Q

What is the measure of useful energy produced by a generator?

A

Counter torque

DC Machines (1 decks)

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