Following are some of the multiple choice questions on the Electrical Machine Design with answers that will help the students in developing their knowledge.
Electrical Machine Design MCQ
1. In D.C. machines the number of slots per pole usually lies
2. In D.C. machines the usual limit of slot pitch is
3. Which of the following methods may be adopted to reduce the effects of armaturereaction ?
4. The operation of a D.C. machine with large air gap lengths is comparatively
5. In D.C. machines, the ____ in field mmf results in increase in size and cost of machines.
6. In D.C. machines, ir order to prevent excessive distortion of field form by the armaturereaction, the field mmf must be made
7. D.C. machines designed with a large value of air gap length have
8. In D.C. machines the width of the duct is usually
9. In a D.C. machine, the value of peripheral speed should not, normally, exceed
10. In a D.C. machine the current per brush arm should not be more than
11. In a D.C. machine the number of brush arms is _____ the number of poles.
12. The weight of copper of both armature and field windings decreases with _____ innumber of poles.
13. Which of the following problem arises in D.C. motors which are fed from thyristorbridge circuits ?
14. ________ is the common method of applying brushes to the commntator.
15. Which of the following brushes can be used for high values of current density ?
16. ______ brushes are fragile and cause excessive wear of commutator,
17. Is usually used for brush rockers
18. The laminations of the armature of a D.C. machine are usually _____ thick.
19. A practical formula for determining the thickness of insulation between low voltageand high voltage windings is
20. Dummy coil should not be used in
21. Power transformers have rating
22. Power transformers should be designed to have maximum efficiency
23. In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core
24. Yokes with rectangular cross-section are used for
25. The cold rolled grain oriented steel has ______ permeability in the direction of thegrain orientation.
26. Cylindrical windings using circular conductors, employed in transformers, are
27. Helical windings are used in
28. Multi-layer helical windings are commonly used in the transformers as high voltagewindings
29. Disc windings are primarily used in
30. The heat dissipating capability of transformers of ratings higher than 30 kVA inincreased by providing which of the following ?
31. Transformers with a capacity of upto _____ have a cooling radiator system with naturalcooling
32. The forced oil and air circulation method is usual one for transformers of capacities
33. The flash point of transformer oil should be higher than
35. The stator of a D.C. machine comprises of
36. D.C. servomotors are used in
37. Which of the following in an application of D.C. motors?
38. The surge phenomenon is particularly important in case of
39. The cylindrical windings using circular conductors are used for current rating of
40. The insulation between windings and grounded core and the insulation between thewindings of the same phase is called
41. Which of the following is the basic consideration in the design of insulation ?
42. The high voltage winding is usually which of the following type ?
43. A current density of _____ is ilsed for large power transformers with forced circulationof oil or with water cooling coils
44. For large power transformers, self oil cooled type or air blast type which of thefollowing values of current density may be used ?
45. For 275 kV transformers, using cold rolled grain oriented steel, which of the followingvalues of flux density may be used?
46. The usual values of maximum flux densities for distribution transformers using hotrolled silicon steel are
47. The voltage control in electric supply networks in required on account of which of the following reasons ?
48. Are always double layer type.
49. The distance between the starts of two consecutive coils measured in terms of coilsides is called
50. The winding where dummy coils are used is sometimes called
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