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Dc Machines > Midterm > Flashcards

Midterm Flashcards

(65 cards)

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1
Q

Label current flow diagram #1

A

Series field windings

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2
Q

Label current flow diagram#2

A

Shunt field windings

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3
Q

Label current flow diagram #3

A

Brushes

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4
Q

Label current flow diagram #4

A

Commutator

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5
Q

Label current flow diagram #5

A

Inter poles

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6
Q

Label current flow diagram #6

A

Commutating winding

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7
Q

Label current flow diagram #7

A

Compensating windings

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8
Q

Label current flow diagram #8

A

Main pole

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9
Q

Label current flow diagram #9

A

Shaft

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10
Q

Label current flow diagram #10

A

Armature

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11
Q

Left hand generator rule what do each finger represent

A

Thumb: direction of force
Middle: direction of current
Index: magnetic field (pointing south) think knuckle of index as North Pole

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12
Q

Shunt diagram which ones a long shunt which ones a short?

A

1: Short shunt is the one that encases just the motor
2: Long shunt goes from one end of the cct to the other

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13
Q

what’re the 4 main magnetic components of a dc machine

A

Main poles
Inter poles
Armature winding
Field winding

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14
Q

The relationship of the series and shunt fields in a compound generator determines the amount of_____________ for the machine

A

Stable output voltage

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15
Q

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

Options:
A: flat
B: Over
C: Under
D: Not

A

C: Under compounded

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16
Q

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

Options:
A: Over
B: Under
C: Flat
D: not

A

C: flat

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17
Q

Is the resistance of a shunt winding higher or lower than the resistance of the series field winding?

A

Shunt—-> smaller wire, higher resistance

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18
Q

What are the windings around the inter poles called

A

Commutating windings

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19
Q

What type of machine converts electrical input to mechanical output

A

Motor

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20
Q

What type of wound armatures have their wires connected in series?

Options:
A: Lap
B: Wave
C: Frog leg

A

B: Wave

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21
Q

What type of armature winding provides low and high current

Options:
A: Lap
B: Wave
C: Frog leg

A

A: lap

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22
Q

What component of a dc generator converts ac to dc

options:
A: armature
B: brushes
C: main poles
D: commutator

A

D: commutator

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23
Q

What 2 sources of magnetic flux interact to cause armature reaction

A

Current in field windings, current in armature windings

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24
Q

In a series motor are torque and speed inversely or directly proportional

A

Inversely

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25
Shunt field windings are wound with _______ turns of _______ wire relative to series field windings Options Block one: A: many B: less Block two: A: larger B: smaller
Many smaller
26
Series field windings are wound with ________ turns of ________ wire relative to shunt field windings Options: Block one : A: Less B: many Block two: A: larger B: smaller
less larger
27
Does the armature winding carry the same current as the shunt field winding
No
28
Once a dc motor is started and all the resistance is removed what limits the current through the armature?
Counter EMF
29
What is the mechanical force used to turn a generator called
Prime mover
30
What is an advantage of a separately excited dc machine
Better control of output voltage and speed
31
In reference to the left hand rule for electro magnets what do the fingers and thumb represent
Thumb; North Pole Fingers: direction of current flow
32
Is armature current proportional to armature reaction?
Yes
33
What type of compound generator has its shunt field windings connected in parallel with both the armature AND series field windings
Long shunt
34
With a constant load can armature reaction be corrected by shifting the brushes and therefore adjusting the neutral plane setting
Yes
35
What’re the four types of enclosures for dc machines
Open Weather Drip totally enclosed
36
Is the commutator an electrical or mechanical switch
Mechanical
37
What type of dc motor is used when constant or adjustable speed is extremely important Options: A: shunt motor B: generator C: series motor
A: shunt motor
38
What’re the 3 types of dc machine field windings
Series, shunt, compound
39
What’re the 3 types of dc machine field structures?
Permanent magnet, separately excited, self excited
40
What are the series field windings connected in series with Options: A: shunt B: brushes C: commutator D: armature
D: Armature
41
What is the purpose of the pole pieces in a dc machine Options: A: create a whole neutral plane B: create magnetic flux C: add resistance to limit current D: increase Lorentz force
B: create magnetic flux
42
3 factors that determine output of a generator pick 3 Magnetic field strength Armature surface area Rotational speed of the Commutator Speed armature is driven Brush spacing # of conductors in armature
Magnetic field strength # of conductors in armature Speed armature is driven by
43
Is the voltage induced into the armature windings of a dc generator ac or dc?
AC
44
What causes the shift of the neutral plane on a dc motor under load Options: A: magnetic field B: angle of which the field windings are wound C: armature vibrations
A: magnetic field
45
What’re the 3 different compound generators called
Over, flat, and under compounded
46
What is resistance to magnetism called Options A: Permiability B: reluctance C: saturation
B: Reluctance
47
Where are the magnetic flux lines most densely concentrated
Poles
48
Which way does current flow in electron flow theory? NEG to POS Or POS to NEG
NEG to POS
49
When an electromagnet reaches where strength increases slightly with an increase of current This is known as? Options A: permeability B: reluctance C: saturation
C: saturation
50
What are two types of magnets
Permanent, electro magnets
51
What component of a dc machine supports the shaft and allows it to rotate freely Options: A: commutator B: brushes C: bearings D: armature
C: bearings
52
What’re the brushes made of in a dc machine Options: A: iron B: lead C: magnesium and carbon D: carbon graphite
D: carbon graphite
53
Label realistic motor #1
End plate
54
Label realistic motor #2
Terminal block
55
Label realistic motor #3
Commutator
56
Label realistic motor #4
Armature winding
57
Label realistic motor #5
Iron core
58
Label realistic motor #6
Main poles
59
Label realistic motor #7
Field windings
60
Label realistic motor #8
Bearing
61
Label realistic motor #9
Shaft
62
Label realistic motor #10
Cooling fan
63
Label realistic motor #11
Enclosure
64
Label realistic motor #12
Base
65
Label realistic motor #13
Carbon graphite brushes

Dc Machines (1 decks)

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