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ELECTRICMOTORSEXAM > Chapter10-DCMotors&Generators > Flashcards

Chapter10-DCMotors&Generators Flashcards

1
Q

DC motors perform better than AC motors in most traction equipment applications

A

T

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2
Q

The purpose of the compensating windings is to help interpoles maintain neutral position on the commutator.

A

T

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3
Q

Since each DC source has one positive and one negative terminal, there must be at least two brushes and two brush holders

A

T

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4
Q

Three styles of brushes are radial-edge, trailing, and leader brushes.

A

F

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5
Q

A DC motor can be reversed by changing the polarity of both the armature winding and the field winding.

A

F

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6
Q

A DC motor can be made into a DC generator if an external prime mover is coupled to the motor shaft.

A

T

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7
Q

DC series motors can develop only about 125% of full load torque upon starting

A

F

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8
Q

DC series motors are used where constant or adjustable speed is required and starting conditions are moderate.

A

F

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9
Q

A DC shunt motor has lower starting torque than a DC series motor

A

T

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10
Q

A DC shunt motor can be run above its full-voltage base speed by reducing the current in the shunt fields.

A

T

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11
Q

The commutators are magnets or stationary windings used to produce the magnetic field in an alternator or motor.

A

F

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12
Q

Because they cannot overheat, all DC permanent-magnet motors are designed to run continuously

A

F

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13
Q

DC generators consist of field windings, an armature, a commutator, and brushes

A

T

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14
Q

A DC generator always has a rotating field and a stationary armature

A

F

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15
Q

A benefit of DC generators is their ability to increase the voltage under changing load conditions.

A

T

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16
Q

A(n) _____________ is a machine that uses DC connected to the field windings and armature to produce shaft rotation.
a. alternator b. generator
c. direct-current motor d. shunt motor

A

c. Direct-current motor

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17
Q

A ____________ is the stationary part in a DC motor or generator.
a. DC permanent magnet b. field frame c. neutral plane
d. brush

A

b. Field frame

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18
Q

________________ are auxiliary poles placed between the main field poles of the motor.
a. windings b. interpoles c. spacers d. field poles

A

b. Interpoles

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19
Q

_____________ brushes are at an angle to the commutator and have less restricted up-and-down movement.
a. Radial b. Trailing-edge c. Leading-edge d. All of the above

A

c. Leading-edge

20
Q

A(n) ______________ is a voltage induced in the windings that is opposite in polarity to that of the power supply.
a. counter voltage b. indirect voltage c. armature reaction
d. back voltage

A

a. Counter-voltage

21
Q

_____________ is the process where the armature current is periodically reversed in order to keep the motor torque in the same direction during the entire armature rotation.
a. communication b. Alternating DC c. DC inversion d. Commutation

A

d. Commutation

22
Q

The basic types of DC motors are DC series motors and __________________ motors
a. DC Shunt b. DC compound c. permanent-magnet
d. All of the above

A

d. All of the above

23
Q

A(n)_______________ motor is a DC motor that has the field wiring connected in parallel with the armature.
a. series b. shunt c. design DC d. induction

A

b. Shunt

24
Q

A. _____________________ motor is a motor where the current flows in the opposite direction in the series and shunt coils and the resulting net flux is the difference between the two fluxes.
a. DC differential-compounded b. DC cumulative-compounded
c. DC permanent-magnet d. DC brushless

A

a. DC differential-compounded

25
Q

A ________________ motor is a motor that uses magnets, not a coil of wire, for the field windings.
a. rare-earth magnet b. cobalt c. DC permanent-magnet
d. nickel-chromium

A

c. DC permanent-magnet

26
Q

_______________ is the ability of a source to vary the output voltage in order to maintain system voltage as the load varies.
a. Voltage regulation b. Voltage maintenance c. Constant voltage
d. Constant current

A

a. Voltage regulation

27
Q

A ____________ - wound generator is a type of DC generator.
a. Series b. Shunt c. Compound d. All of the above

A

d. All of the above

28
Q

A(n) ________________ is the rotating part of a DC motor, consisting of the laminated core with slots for the coils, the main shaft, and the commutator brushes
a. stator b. rotor c. armature d. permanent magnet

A

c. Armature

29
Q

The ________________ is a line through the armature cross section that is perpendicular to the maximum amount of magnetic flux.
a. armature field b. neutral plane c. armature plane
d. magnetic field

A

b. Neutral plane

30
Q

In a _________________, the series field windings and shunt field windings are combined in a manner to take advantage of the characteristics of each.
a. direct-current generator b. single-voltage motor
c. self-excited shunt field d. compound-wound generator

A

d. Compound-wound generator

31
Q

_______________ are magnets or stationary windings used to produce the magnetic field in an alternator or motor.

A

Field windings

32
Q

_____________ is the distortion of the magnetic fields that happens when a current-carrying wire is placed with a fixed magnetic field.

A

Armature reaction

33
Q

A(n) ________________ motor is a DC motor that has the field winding connected in series with the armature.

A

Series

34
Q

____________________ is the position of the brushes where commutation can occur with minimal induced voltage in the armature coils.

A

Brush neutral

35
Q

A(n)________________ shunt field is shunt field connected to a different power supply than the armature.

A

Separately excited

36
Q

A(n) _________________ motor is a DC motor with the field connected in both series and shunt with the armature.

A

Compound

37
Q

A(n) _________________ generator is a generator that has its field windings connected in series with the armature and the external circuit (load).

A

Series-wound

38
Q

A(n)_________________ generator is a generator that has its field windings connected as a shunt in parallel with the armature and external circuit.

A

Shunt-wound

39
Q

_______________ motors provide excellent speed control for acceleration and deceleration, with effective and simple torque control.

A

DC

40
Q

_________________ are used to reduce sparking at the brushes of larger DC motors.

A

Interpoles

41
Q

Armature current in a(n)_________________ is forced to flow in the opposite direction to that of the countervoltage.

A

Motor

42
Q

A(n)______________ field winding is a small series field winding placed over the top of a shunt field winding that improves stability of the fields while running with the reduced current in the field circuit.

A

Stabilizing

43
Q

An external prime mover applies ________________ torque to the armature and series field circuit, which induces voltage and current in the generator.

A

Mechanical

44
Q

A(n)______________ generator includes series and shunt field windings.

A

Compound-wound

45
Q

A(n) _________________ is a ring made of insulated segments that keep the armature windings in the correct polarity

A

Commutator

ELECTRICMOTORSEXAM (3 decks)

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