Motors Book - Chapter 2
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Questions and Answers
- 1.
A(n) ___ is a metal tag permanently attached to an electric motor frame that gives the required electrical ratings, operating rating, and mechanical-design codes of the motor.
- A.
Nameplate
- B.
Insulation class
- C.
Identification tag
- D.
Motor label
Correct Answer
A. NameplateExplanation
A nameplate is a metal tag permanently attached to an electric motor frame that provides important information about the motor, such as its electrical ratings, operating rating, and mechanical-design codes. This information is crucial for ensuring that the motor is used correctly and safely. The nameplate serves as a reference guide for technicians and engineers who need to know the specifications of the motor for maintenance, repairs, or replacements. It is an essential component of the motor that helps in identifying and understanding its capabilities and limitations.Rate this question:
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- 2.
Electrical ratings included on motor nameplates include a ___ rating and phase.
- A.
Current
- B.
Frequency
- C.
Voltage
- D.
All of the above
Correct Answer
D. All of the aboveExplanation
The electrical ratings included on motor nameplates include a current rating, frequency rating, and voltage rating. These ratings provide important information about the motor's operating characteristics. The current rating indicates the amount of electrical current the motor requires to function properly. The frequency rating specifies the frequency of the electrical power supply that the motor is designed to operate on. The voltage rating indicates the voltage level at which the motor should be operated. Therefore, all of the given options - current, frequency, and voltage - are included in the electrical ratings on motor nameplates.Rate this question:
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- 3.
The ___ rating is the amount of current a motor draws when delivering full rated power output.
- A.
Frequency
- B.
Voltage
- C.
Current
- D.
Flux
Correct Answer
C. CurrentExplanation
The current rating is the amount of current a motor draws when delivering full rated power output. This indicates the maximum amount of electric current that the motor can handle without overheating or causing damage. It is important to ensure that the motor's current rating matches the electrical system it is connected to in order to prevent any potential issues or failures.Rate this question:
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- 4.
___ current, or starting current, or inrush current, is the amount of current a motor draws on startup or when the rotor is locked.
- A.
Unlocked-rotor
- B.
Locked-rotor
- C.
Wound-rotor motor
- D.
Eddy
Correct Answer
B. Locked-rotorExplanation
Locked-rotor current refers to the amount of current that a motor draws when the rotor is locked or unable to rotate. This typically occurs during motor startup or when there is a mechanical fault causing the rotor to be stuck. The locked-rotor current is usually higher than the normal operating current and is important to consider for motor sizing and protection.Rate this question:
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- 5.
The ___ rating is a description of the expected or allowed application of a motor.
- A.
Service factor
- B.
Speed
- C.
Power
- D.
Usage
Correct Answer
D. UsageExplanation
The rating that describes the expected or allowed application of a motor is known as the usage rating. This rating provides information about the specific purposes or applications for which the motor is designed and can be safely used. It helps users determine whether a particular motor is suitable for their intended purposes and ensures that the motor is used within its specified capabilities.Rate this question:
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- 6.
The ___ is the difference between the winding temperature of a running motor and the ambient temperature.
- A.
Ambient temperature rating
- B.
Permissible temperature rating
- C.
Temperature rise
- D.
Permissible temperature rise
Correct Answer
B. Permissible temperature ratingExplanation
The permissible temperature rating refers to the maximum temperature difference allowed between the winding temperature of a running motor and the ambient temperature. It indicates the limit within which the motor can safely operate without overheating. This rating is crucial for ensuring the motor's longevity and preventing any damage or malfunction caused by excessive heat.Rate this question:
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- 7.
___ motors are used in applications such as compressors, waste-disposal systems, electric hoists, gate opening motors, and other applications in which the motor need only be turned on for short time periods to meet the application requirements.
- A.
Intermittent-rated
- B.
Continuous-duty
- C.
Locked-rotor torque
- D.
High-inertia
Correct Answer
A. Intermittent-ratedExplanation
Intermittent-rated motors are used in applications where the motor only needs to be turned on for short time periods to meet the application requirements. These motors are designed to handle the intermittent nature of the workload and are not meant for continuous operation. They are commonly used in applications such as compressors, waste-disposal systems, electric hoists, gate opening motors, and other similar applications.Rate this question:
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- 8.
The NEMA ___ letter is a code letter representing a National Electrical Manufacturers Association (NEMA) motor classification for the torque and current curves of a motor.
- A.
Identification
- B.
Insulation class
- C.
Design
- D.
None of the above
Correct Answer
C. DesignExplanation
The NEMA design letter is a code letter that represents the National Electrical Manufacturers Association (NEMA) motor classification for the torque and current curves of a motor. This letter indicates the motor's ability to withstand certain operating conditions and provides information about its performance characteristics. It is used to classify motors based on their design features and is an important factor in selecting the right motor for a specific application.Rate this question:
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- 9.
A design ___ motor is an integral-horsepower 3-phase induction motor design mode for full-voltage starting and high locked-rotor torque, with locked-rotor current not exceeding a specified value.
- A.
B
- B.
C
- C.
E
- D.
F
Correct Answer
C. EExplanation
The correct answer is E. The design E motor is specifically designed for full-voltage starting and high locked-rotor torque, while also ensuring that the locked-rotor current does not exceed a specified value.Rate this question:
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- 10.
A ___ is a machine component used to reduce friction and maintain clearance between stationary and moving parts.
- A.
Motor shaft
- B.
Motor bearing
- C.
Plug fuse
- D.
Bimetallic-strip overload relay
Correct Answer
B. Motor bearingExplanation
A motor bearing is a machine component that is used to reduce friction and maintain clearance between stationary and moving parts in a motor. It helps to support and guide the rotating shaft of the motor, allowing it to spin smoothly and efficiently. Without a motor bearing, there would be excessive friction and wear between the moving parts, leading to decreased performance and potential damage to the motor.Rate this question:
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- 11.
The ___ is a code letter signifying the maximum operating temperature of the insulation used in a motor.
- A.
Insulation class
- B.
Design letter
- C.
Frame size
- D.
Motor rating
Correct Answer
A. Insulation classExplanation
The insulation class is a code letter that indicates the maximum operating temperature of the insulation in a motor. This is important because the insulation must be able to withstand the heat generated during operation to prevent damage to the motor. Different insulation classes are assigned different temperature limits, allowing motor manufacturers and users to select the appropriate insulation class based on the specific requirements of the application.Rate this question:
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- 12.
A design ___ motor is an integral-horsepower single-phase motor design made for full-voltage starting and locked-rotor torque higher than for design M, N, and O motor
- A.
H
- B.
J
- C.
K
- D.
L
Correct Answer
D. LExplanation
Design L motor is an integral-horsepower single-phase motor design made for full-voltage starting and locked-rotor torque higher than for design M, N, and O motor.Rate this question:
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- 13.
The ___, or duty cycle, is the amount of time a motor can be operated without being turned OFF to allow for cooling.
- A.
Running time
- B.
Operating time rating
- C.
Operating cycle
- D.
Rotor rating
Correct Answer
B. Operating time ratingExplanation
The operating time rating refers to the amount of time a motor can be continuously operated without being turned off in order to allow for cooling. This rating is important as motors generate heat during operation, and continuous running without adequate cooling can lead to overheating and potential damage to the motor. Therefore, the operating time rating provides a guideline for the maximum duration that the motor can be operated before it needs to be turned off to prevent overheating.Rate this question:
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- 14.
___ type is the type of protection given to a motor to shield the motor from the outside environment as well as to protect individuals from the electrical and rotating parts of the motor.
- A.
Enclosure
- B.
Design
- C.
Shield
- D.
None of the above
Correct Answer
A. EnclosureExplanation
An enclosure is the type of protection given to a motor to shield it from the outside environment as well as to protect individuals from the electrical and rotating parts of the motor. The enclosure acts as a barrier, preventing dust, moisture, and other contaminants from entering the motor and potentially causing damage or malfunction. It also serves as a safety measure, preventing accidental contact with the electrical and rotating parts of the motor, reducing the risk of injury.Rate this question:
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- 15.
___ motor enclosures include general, dripproof, splashproof, guarded, semiguarded, and dripproof fully guarded types.
- A.
Enclosed
- B.
Reactive
- C.
Open
- D.
Stator
Correct Answer
C. OpenExplanation
The given statement mentions different types of motor enclosures, such as general, dripproof, splashproof, guarded, semiguarded, and dripproof fully guarded. However, "open" is not mentioned as one of the types. Therefore, the correct answer is "open" because it is not included in the list of motor enclosure types provided.Rate this question:
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Oct 18, 2024Quiz Edited by
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Dec 18, 2012Quiz Created by
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