electrical machine design MCQs – Page 2

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

electrical machine design Mcqs

21. D.C. windings are____________?
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A. none of the above

B. never 2-layer type

C. always 2-layer type

D. sometimes 2-layer type

22. By which of the following methods the temperature rise of windings and other parts may be determined ?
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A. Embedded temperature detector method

B. Resistance method

C. Thermometer method

D. Any of the above

23. Commercial available medium size machines have a speed range of __________ ?
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A. 600 to 1000 r.p.m

B. 2000 to 2500 r.p.m

C. 1000 to 1500 r.p.m

D. 200 to 400 r.p.m

24. The surge phenomenon is particularly important in case of_______________?
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A. high voltage transformers

B. medium voltage transformers

C. any of the above

D. low voltage transformers

25. The voltage control in electric supply networks in required on account of which of the following reasons ?
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A. All of the above

B. Control of active and reactive power

C. Adjustment of voltage at consumers premises within statutory limits

D. Adjustment of short period daily and seasonal voltage variations in accordance with variations of load

26. The laminations of the armature of a D.C. machine are usually ___________ thick?
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A. 0.2 to 0.3 mm

B. 0.3 to 0.4 mm

C. 0.1 to 0.2 mm

D. 0.4 to 0.5 mm

27. Tractive magnets are operated from____________?
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A. either a.c. or d.c. supply

B. d.c. supply

C. none of the above</strong>

D. a.c. supply

28. Machines cooled by direct cooling method may be called_____________?
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A. any of the above

B. supercharged

C. inner cooled

D. conductor cooled

29. In a D.C. machine the current per brush arm should not be more than_____________?
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A. 300 A

B. 200 A

C. 400 A

D. 100 A

30. The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?
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A. nil

B. maximum

C. minimum

D. none of the above

31. Electrical machines having a power output up to about 750 W may be called__________machines?
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A. any of the above

B. large size

C. medium size

D. small size

32. The value of exciting or magnetizing current depends upon which of the following factors ?
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A. The number of turns in the exciting winding

B. All of the above

C. The way in which the winding is distributed

D. Total m.m.f. required

33. Yokes with rectangular cross-section are used for_______________?
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A. any of the above

B. large capacity transformers

C. medium capacity transformers

D. small capacity transformers

34. In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made____________?
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A. less in comparison with the armature mmf

B. large in comparison with the armature mmf

C. none of the above

D. equal to that of armature mmf

35. Which of the following methods is most accurate ?
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A. Method of average losses

B. Equivalent power method

C. Equivalent torque method

D. Equivalent current method

36. Electrical machines having power outputs ranging from a few kW up to approximately 250 kW may be classified as_____________?
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A. any of the above

B. medium size machines

C. large size machines

D. small size machines

37. __________ has a low relative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable?
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A. Soft steel

B. Aluminium

C. Cast iron

D. Cast steel

38. Disc windings are primarily used in_____________-?
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A. medium capacity transformers

B. short capacity transformers

C. high capacity transformers

D. any of the above

39. Transformers with a capacity of up to __________ have a cooling radiator system with natural cooling?
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A. 5 MVA

B. 2 MVA

C. 7.5 MVA

D. 10 MVA

40. In D.C. machines the usual limit of slot pitch is________________?
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A. between 5 to 10 mm

B. between 15 to 20 mm

C. between 10 to 15 mm

D. between 25 to 35 mm

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