DC Generator MCQ Quiz - Multiple Choice Questions & Answers Page 4

31. The e.m.f. generated in a D.C. generator is directly proportional to

1. flux/pole
2. speed of armature
3. number of poles
4. all of the above

32. The insulating material used between the commutator segments is normally

1. graphite
2. paper
3. mica
4. insulating varnish

33. The voltage drop for which of the following types of brush can be expected to be least ?

1. Graphite brushes
2. Carbon brushes
3. Metal graphite brushes
4. None of the above

34. In D.C. generators, lap winding is used for

1. high voltage, high current
2. low voltage, high current
3. high voltage, low current
4. low voltage, low current

35. If a D.C. generator fails to build up the probable cause could not be

1. imperfect brush contact
2. field resistance less than the critical resistance
3. no residual magnetism in the generator
4. faulty shunt connections tending to reduce the residual magnetism

36. In a D.C. generator in case the resistance of the field winding is increased, then outputvoltage will

1. increase
2. decrease
3. remain unaffected
4. fluctuate heavily

37. In a D.C. generator the critical resistance can be increased by

1. increasing its field resistance
2. decreasing its field resistance
3. increasing its speed
4. decreasing 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

1. interpoles
2. dummy coils
3. compensating winding
4. shifting of axis of brushes

39. In a separately excited generator supplying rated load the armature reaction ,

1. is always present
2. is always absent
3. may be sometimes present
4. none of the above

40. A separately excited generator as compared to a self-excited generator

1. is amenable to better voltage con-trol
2. is more stable
3. has exciting current independent of load current
4. has all above features