1. Which of the following component is usually fabricated out of silicon steel ?
2. The frame of an induction motor is usually made of
3. The shaft of an induction motor is made of
4. The shaft of an induction motor is made of
5. In an induction motor, no-load the slip is generally
6. In medium sized induction motors, the slip is generally around
7. . In squirrel cage induction motors, the rotor slots are usually given slight skew in order to
8. . In case the air gap in an induction motor is increased
9. Slip rings are usually made of
10. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be
11. . In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be
12. The efficiency of an induction motor can be expected to be nearly
13. . A double squirrel-cage induction motor has
14. The starting torque of a squirrel-cage induction motor is
15. The number of slip rings on a squirrel cage induction motor is usually
16. . Star-delta starting of motors is not possible in case of
17.The term ‘cogging’ is associated with
18. In case of the induction motors the torque is
19. An induction motor with 1000 r.p.m. speed will have
20. . The good power factor of an induction motor can be achieved if the average flux density in the air gap is
21. An induction motor is identical to
22. The injected e.m.f. in the rotor of induction motor must have
23. Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor ?
24. . The crawling in the induction motor is caused by
25. The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type
26. The torque developed in the cage induction motor with autostarter is
27. When the equivalent circuit diagram of double squirrel-cage induction motor is constructed the two cages can be considered
28. It is advisable to avoid line-starting of induction motor and use starter because
29. Stepless speed control of induction motor is possible by which of the following methods ?
30. Rotor rheostat control method of speed control is used for
31. In the circle diagram for induction motor, the diameter of the circle represents
32. For which motor the speed can be controlled from rotor side ?
33. An induction motor is
34. If any two phases for an induction motor are interchanged
35. The maximum torque in an induction motor depends on
36. . In three-phase squirrel-cage induction motors
37. In a three-phase induction motor, the number of poles in the rotor winding is always
38. DOL starting of induction motors is usually restricted to
39. The speed of a squirrel-cage induction motor can be controlled by all of the following except
40. The ‘crawling” in an induction motor is caused by
41. The power factor of an induction motor under no-load conditions will be closer to
42. The ‘cogging’ of an induction motor can be avoided by
43. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as
44. Slip of an induction motor is negative when
45. Size of a high speed motor as compared to low speed motor for the same H.P. will be
46. A 3-phase induction motor stator delta connected, is carrying full load and one of its fuses blows out. Then the motor
47. A 3-phase induction motor delta connected is carrying too heavy load and one of its fuses blows out. Then the motor
48. Low voltage at motor terminals is due to
49. In an induction motor the relationship between stator slots and rotor slots is that
50. As load on an induction motor goes on increasing
51. Slip ring motor is recommended where
52. If a 3-phase supply is given to the stator and rotor is short circuited rotor will move
53. It is advisable to avoid line starting of induction motor and use starter because
54. The speed characteristics of an induction motor closely resemble the speed load characteristics of which of the following machines
55. Which type of bearing is provided in small induction motors to support the rotor shaft ? None of the above
56. A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will
57. 5 H.P., 50-Hz, 3-phase, 440 V, induction motors are available for the following r.p.m. Which motor will be the costliest ?
58. A 3-phase slip ring motor has
59. The starting torque of a 3-phase squirrel cage induction motor is
60. Short-circuit test on an induction motor cannot be used to determine
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