DC Generator MCQ Multiple Choice Questions Answers - Page 2 for Practice
31. The e.m.f. generated in a D.C. generator is directly proportional to
Correct Answer is: speed of armature
32. The insulating material used between the commutator segments is normally
Correct Answer is: mica
33. The voltage drop for which of the following types of brush can be expected to be least ?
Correct Answer is: Metal graphite brushes
34. In D.C. generators, lap winding is used for
Correct Answer is: low voltage, high current
35. If a D.C. generator fails to build up the probable cause could not be
Correct Answer is: field resistance less than the critical resistance
36. In a D.C. generator in case the resistance of the field winding is increased, then outputvoltage will
Correct Answer is: decrease
37. In a D.C. generator the critical resistance can be increased by
Correct Answer is: increasing its speed
38. In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in thecoil is neutralised by all of the following except
Correct Answer is: dummy coils
39. In a separately excited generator supplying rated load the armature reaction ,
Correct Answer is: is always present
40. A separately excited generator as compared to a self-excited generator
Correct Answer is: has all above features
41. In D.C. generators the polarity of the interpoles
Correct Answer is: is the same as that of the main pole ahead
42. Welding generator will have
Correct Answer is: lap winding
43. The number of armature parallel paths in a two-pole D.C. generator having duplex lapwinding is
Correct Answer is: 4
44. A D.C. welding generator has
Correct Answer is: lap winding
45. The resistance of armature winding depends on
Correct Answer is: all of the above
46. A D.C. generator works on the principle of
Correct Answer is: Faradays law of electromagnetic induction
47. In D.C. generators, the brushes on commutator remain in contact with conductorswhich
Correct Answer is: lie under interpolar region
48. Flemings right-hand rule regarding direction of induced e.m.f., correlates
Correct Answer is: magnetic flux, direction of motion and the direction of e.m.f. induced
49. Compensating windings are used in D.C. generators
Correct Answer is: to neutralise the cross-magnetising effect of the armature reaction
50. The field coils of D.C. generator are usually made of
Correct Answer is: copper
51. The material for commutator brushes is generally
Correct Answer is: carbon
52. The terminal voltage of a series generator is 150 V when the load current is 5 A. If theload current is increased to 10 A, the terminal voltage will be
Correct Answer is: greater than 150 V
53. According to Flemings right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of
Correct Answer is: lines of force
54. In the case of lap winding resultant pitch is
Correct Answer is: difference of front and back pitches
55. In a level compounded D.C. generator, full load terminal voltage is
Correct Answer is: equal to no-load terminal voltage
56. Interpole flux should be sufficient to
Correct Answer is: neutralise both the armature reaction flux as well as commutating e.m.f. induced in thecoil
57. Flashing the field of D.C. generator means
Correct Answer is: creating residual magnetism by a D.C. source
58. In case of D.C. machine winding, number of commutator segments is equal to
Correct Answer is: number of armature coils
59. Number of tappings for each equilizer ring is equal to
Correct Answer is: number of pole pairs
60. A series generator can self-excite
Correct Answer is: only if the load current is not zero
