electrical machine design MCQs – Page 4

Practise focused electrical machine design questions with marked answers for exam preparation and subject revision.

electrical machine design Mcqs

61. Which of the following is the commonly used type of electromagnets ?
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A. All of the above

B. Horse shoe type

C. Flat-faced armature type

D. Flat-faced plunger type

62. The operation of a D.C. machine with large air gap lengths is comparatively_____________?
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A. quiet

B. either of the above

C. noisy

D. none of the above

63. The stator of a D.C. machine comprises of_____________?
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A. interpoles

B. frame

C. main poles

D. all of the above

64. is usually used for brush rockers____________?
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A. Aluminium

B. Cast-iron

C. Mild steel

D. Copper

65. By which of the following methods motor rating for variable load drives can be determined ?
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A. Equivalent power method

B. Equivalent torque method

C. Equivalent current method

D. Method of average losses

E. All of the above

66. In D.C. machines, the ________ in field mmf results in increase in size and cost of machines?
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A. either of the above

B. decrease

C. increase

D. none of the above

67. Which of the following is the basic consideration in the design of insulation ?
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A. Electrical considerations

B. Thermal considerations

C. All of the above

D. Mechanical considerations

68. Cylindrical windings using circular conductors, employed in transformers, are_____________?
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A. double layered

B. single layered

C. none of the above

D. multi-layered

69. Which of the following brushes can be used for high values of current density ?
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A. Electro-graphitic brushes

B. Natural graphite brushes

C. Hard carbon brushes

D. Metal graphite brushes

70. The resistivity of water should not be less than_____________?
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A. 2000 Q m

B. 10 Q m

C. 1000 Q m

D. 100 Q m

71. Which of the following is the major consideration to evolve a good design?
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A. Cost

B. Durability

C. Compliance with performance criteria as laid down in specifications

D. All of the above

72. In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?
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A. 5 percent

B. 30 percent

C. 15 percent

D. 10 percent

E. none of the above

73. Power transformers have rating_______________?
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A. none of the above

B. equal to 100 kVA

C. equal to 50 kVA

D. above 200 kVA

74. In induction motors, the length of air gap in kept as small as mechanically possible is order to have____________?
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A. any of the above

B. high power factor

C. low power factor

D. high over load capacity

75. ____________are used for construction of core of electromagnets?
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A. None of the above

B. Soft magnetic materials

C. Either A. or B.

D. Hard magnetic materials

76. The density of hydrogen is __________ times the density of air?
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A. 2.5

B. 0.07

C. 3.5

D. 1.5

77. Which of the following methods may be adopted to reduce the effects of armature reaction ?
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A. Increasing reluctance of pole tips

B. Increase in length of air gap at pole tips

C. All of the above

D. Interpoles

E. Compensating windings

78. Power transformers should be designed to have maximum efficiency________________?
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A. any of the above

B. at or near full load

C. at one-half load

D. at one-fourth load

79. The cylindrical windings using circular conductors are used for current rating of____________?
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A. upto 20 A

B. upto 80 A

C. upto 40 A

D. upto 60 A

80. The forced oil and air circulation method is usual one for transformers of capacities____________?
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A. upto 5 MVA

B. upto 10 MVA

C. 30 MVA upwards

D. upto 20 MVA

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