This set of Design of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Design of Machines, Limitations in Design”.
1. What does design mean?
a) creative physical relationship of theoretical concepts
b) producing the hardware
c) idea made into a drawing
d) idea laid out as a thesis
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Explanation: Design is one of the important steps in the manufacturing of a product. It involves the process of producing the creative physical relationship of theoretical concepts.
2. What are the factors which are employed in the engineering design?
a) application of science
b) application of science and technology
c) application of science and innovation
d) application of science, technology and innovation
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Explanation: Design is the process of producing the creative physical relationship of theoretical concepts. The application of science, technology and innovation is what called as engineering design.
3. How many considerations are present in the design?
a) 6
b) 4
c) 5
d) 3
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Explanation: There are 3 considerations present in the design of the machine. They are cost, durability, compliance with performance criteria as laid down in specifications.
4. What is the condition of the good design?
a) machine having operating life of 5-10 years
b) machine having operating life of 10-15 years
c) machine having operating life of 15-20 years
d) machine having operating life of 20-30 years
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Explanation: The machine having operating life span of 20-30 years is one of the signs of good design. This type of machines have initial cost to be low.
5. What are the factors which are important in design when it comes to the machines used in power systems?
a) reliability
b) durability
c) cost
d) reliability and durability
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Explanation: The machines used in the power system are given weightage to the reliability and durability. Thus the cost of the machines are not taken into account.
6. How many parts are used in the design of the machines?
a) 2
b) 3
c) 4
d) 5
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Explanation: There are 5 parts involved in the design of the machine. They are magnetic circuit, electric circuit, dielectric circuit, thermal circuit, mechanical parts.
7. How many limitations are present in the design of the machine?
a) 7
b) 8
c) 9
d) 10
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Explanation: There are basically 9 limitations in the design of the machines. They are saturation, temperature rise, insulation, efficiency, mechanical parts, commutation, power factor, consumer specification, standard specification.
8. How does the saturation levels limit the design?
a) saturation levels decrease the flux density
b) saturation levels increase the flux density
c) saturation levels provides no flux density
d) saturation levels provide very high flux density
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Explanation: The maximum allowable flux density to be used is determined by the saturation levels of ferromagnetic materials. The saturation levels provides high flux density which results in high cost.
9. What happens if the insulating material is operated beyond the maximum allowable temperature?
a) the insulation gets damaged
b) the insulation is boosted
c) the insulating materials peels off
d) the lifetime is drastically reduced
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Explanation: The temperature rise is one of the limitations present in the design of machines. The insulating material when operated beyond the maximum temperature leads to the lifetime being drastically reduced.
10. How many types of stresses are present in the machine?
a) 2
b) 3
c) 4
d) 5
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Explanation: There are basically 3 stresses available in the machine. They are electrical stress, mechanical stress and thermal stress.
11. What is the relationship between efficiency and the operating costs?
a) efficiency is directly proportional to the square of the operating cost
b) efficiency is directly proportional to the operating costs
c) efficiency is indirectly proportional to the operating costs
d) efficiency is indirectly proportional to the square of the operating costs
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Explanation: Efficiency is one of the limitations in the design of the machines. The efficiency should be as high as possible to reduce the initial cost.
12. The mechanical parts design is very much important in which type of machines?
a) low speed machines
b) high speed machines
c) medium speed machines
d) low voltage machines
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Explanation: The design of mechanical parts is very important in the high speed machines. It is so important because to reduce the mechanical stresses which occurs more in high speed machines.
13. What is the relationship between power factor, current and conductor sizes?
a) poor power factor leads to small amount of current and hence high conductor sizes should be used
b) high power factor leads to small amount of current and hence small conductor sizes should be used
c) poor power factor leads to high amount of current and hence high conductor sizes should be used
d) high factor leads to small amount of current and hence high conductor sizes should be used
View Answer
Explanation: The power factor is one of the limitations in the design of the machine. The poor power factor leads to high amount of current and in turn large conductor sizes have to be used.
Sanfoundry Global Education & Learning Series – Design of Electrical Machines.
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