Motors Book - Chapter 10
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Questions and Answers
- 1.
A(n) ___ is a machine that uses DC connected to the field windings and armature to produce shaft rotation.
- A.
Alternator
- B.
Capacitor
- C.
Direct-current motor
- D.
Shunt motor
Correct Answer
C. Direct-current motorExplanation
A direct-current motor is a machine that uses DC connected to the field windings and armature to produce shaft rotation. Unlike an alternator, which generates alternating current, a DC motor operates using direct current. A capacitor is a device used to store electrical energy and is not directly involved in producing shaft rotation. A shunt motor is a type of DC motor that uses a parallel connection between the field windings and armature, but it is not the only type of DC motor.Rate this question:
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- 2.
A ___ is the stationary part in a DC motor or generator.
- A.
DC permanent magnet
- B.
Field frame
- C.
Neutral plane
- D.
Brush
Correct Answer
B. Field frameExplanation
The field frame is the correct answer because it refers to the stationary part in a DC motor or generator. The field frame is responsible for creating a magnetic field that interacts with the moving part (the rotor) to generate electricity in a generator or mechanical motion in a motor. It is typically made of a magnet or a set of magnets that produce a constant magnetic field.Rate this question:
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- 3.
___ are auxiliary poles placed between the main field poles of the motor.
- A.
Windings
- B.
Interpoles
- C.
Armatures
- D.
Field poles
Correct Answer
B. InterpolesExplanation
Interpoles are auxiliary poles placed between the main field poles of the motor. These interpoles are used to improve the performance and efficiency of the motor by reducing the effects of armature reaction and commutation. They help in reducing the sparking and arcing that occurs during the commutation process, thereby ensuring smooth operation of the motor. Interpoles also help in maintaining a constant magnetic field, which leads to better control and stability of the motor.Rate this question:
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- 4.
___ 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
Correct Answer
C. Leading-edgeExplanation
The brushes that are at an angle to the commutator and have less restricted up-and-down movement are called leading-edge brushes. These brushes are positioned in a way that allows them to make better contact with the commutator and have more flexibility in their movement. This helps in reducing friction and wear on both the brushes and the commutator, resulting in better performance and longevity of the electrical machine.Rate this question:
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- 5.
A(n) ___ is a voltage induced in the windings that is opposite in polarity to that of the power supply.
- A.
Countervoltage
- B.
Indirect voltage
- C.
Armature reaction
- D.
True power
Correct Answer
A. CountervoltageExplanation
Countervoltage refers to a voltage that is induced in the windings of a device, such as a motor or transformer, which is opposite in polarity to that of the power supply. This countervoltage is generated due to the electromagnetic induction principle and is often used to counteract the effects of the power supply voltage. It helps regulate the current flow and protect the device from damage caused by excessive voltage.Rate this question:
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- 6.
___ 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.
Inrush
- B.
Hysteresis
- C.
Reversing
- D.
Commutation
Correct Answer
D. CommutationExplanation
Commutation 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. This is necessary because the armature windings are connected to the commutator, which is a rotating switch, and in order to maintain a constant torque, the current direction needs to be reversed at specific points in the rotation. This ensures that the motor continues to rotate in the desired direction without any interruptions.Rate this question:
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- 7.
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
Correct Answer
D. All of the aboveExplanation
The basic types of DC motors are DC series motors, DC shunt motors, DC compound motors, and permanent-magnet motors. Each type has its own unique characteristics and applications. DC series motors are used in applications that require high starting torque, while DC shunt motors are used in applications that require constant speed. DC compound motors combine the characteristics of both series and shunt motors, making them suitable for applications that require both high starting torque and constant speed. Permanent-magnet motors use permanent magnets to produce the magnetic field, making them simple and efficient. Therefore, all of the above options are correct.Rate this question:
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- 8.
A(n) ___ motor is a DC motor that has the filed winding connected in parallel with the armature.
- A.
Series
- B.
Shunt
- C.
Design
- D.
Induction
Correct Answer
B. ShuntExplanation
A shunt motor is a DC motor that has the field winding connected in parallel with the armature. In this configuration, the field winding and the armature receive the same voltage, but the current flowing through them is different. The field winding is designed to have a high resistance, allowing only a small amount of current to flow through it. This results in a strong magnetic field being generated, which interacts with the armature to produce the desired rotational motion. Shunt motors are commonly used in applications where precise speed control is required.Rate this question:
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- 9.
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.
Reversing single-phase
- D.
Revering capacitor-motor
Correct Answer
A. DC differential-compoundedExplanation
A DC differential-compounded 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. This means that the motor has both series and shunt windings, and the direction of current flow in these windings is opposite to each other. The net flux produced is the difference between the fluxes produced by the two windings.Rate this question:
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- 10.
A ___ motor is a motor that uses magnets, not a coil of wire, for the field windings.
- A.
Split-phase
- B.
Reversing shaded-pole
- C.
DC permanent-magnet
- D.
Revolving-field
Correct Answer
C. DC permanent-magnetExplanation
A DC permanent-magnet motor is a motor that uses magnets instead of a coil of wire for the field windings. The magnets create a permanent magnetic field, which interacts with the current-carrying conductors to produce rotational motion. This type of motor is commonly used in applications where a compact and efficient motor is required, such as in small appliances, electric vehicles, and industrial machinery.Rate this question:
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- 11.
___ 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.
Usage rating
- C.
Rotor frequency
- D.
Current rating
Correct Answer
A. Voltage regulationExplanation
Voltage regulation is the ability of a source to vary the output voltage in order to maintain system voltage as the load varies. This means that even if the load changes, the source will adjust the output voltage to ensure that the system voltage remains constant. This is an important feature in electrical systems to ensure that devices receive the appropriate voltage for their operation, regardless of changes in the load.Rate this question:
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- 12.
A ___-wound generator is a type of DC generator
- A.
Series
- B.
Shunt
- C.
Compound
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
The correct answer is "all of the above". This means that a series-wound generator, a shunt-wound generator, and a compound-wound generator are all types of DC generators. A series-wound generator has the field winding connected in series with the armature winding, a shunt-wound generator has the field winding connected in parallel with the armature winding, and a compound-wound generator has both series and shunt field windings. Therefore, all three types of generators fall under the category of DC generators.Rate this question:
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- 13.
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 and brushes.
- A.
Stator
- B.
Armature
- C.
Pigtail
- D.
Permanent magnet
Correct Answer
B. ArmatureExplanation
The armature is the rotating part of a DC motor that includes the laminated core with slots for the coils, the main shaft, and the commutator and brushes. It is responsible for converting electrical energy into mechanical energy by interacting with the magnetic field created by the stator. The armature's rotation allows for the generation of a continuous torque, making it a crucial component in the functioning of a DC motor.Rate this question:
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- 14.
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
Correct Answer
B. Neutral planeExplanation
The neutral plane is a line through the armature cross section that is perpendicular to the maximum amount of magnetic flux. This means that the neutral plane is the location where there is no net magnetic force acting on the armature. It is the point of equilibrium where the magnetic forces from the armature field and the magnetic field are balanced, resulting in no movement or torque being generated.Rate this question:
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- 15.
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
Correct Answer
D. Compound-wound generatorExplanation
A compound-wound generator combines the series field windings and shunt field windings in a way that allows it to take advantage of the characteristics of each. The series field windings provide high starting torque, while the shunt field windings provide good voltage regulation. This combination allows the generator to have both high starting torque and good voltage regulation, making it suitable for a wide range of applications.Rate this question:
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Oct 29, 2024Quiz Edited by
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Dec 19, 2012Quiz Created by
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