Practice Test: Question Set - 10
1. The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be
- (A) 640 V
- (B) 620 V
- (C) 600 V
- (D) 580 V
2. If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be
- (A) Zero
- (B) Small
- (C) The same as rated voltage
- (D) High
3. In D.C. generators the pole shoes are fastened to the pole core by
- (A) Rivets
- (B) Counter sunk screws
- (C) Brazing
- (D) Welding
4. D.C. generators are connected to the bus-bars or disconnected from them only under the floating condition
- (A) To avoid sudden loading of the prime mover
- (B) To avoid mechanical jerk to the shaft
- (C) To avoid burning of switch contacts
- (D) All above
5. The e.m.f. generated by a shunt wound D.C. generator is E. Now while pole flux remains constant, if the speed of the generator is doubled, the e.m.f. generated will be
- (A) E/2
- (B) 2E
- (C) Slightly less than E
- (D) E
6. Armature coil is short circuited by brushes when it lies
- (A) Along neutral axis
- (B) Along field axis
- (C) In any of the above positions
- (D) In none of the above positions
7. Which generator would you prefer for feeding long D.C. transmission lines?
- (A) Series generator
- (B) Shunt generator
- (C) Over compound generator
- (D) Flat compound generator
8. Number of tapings for each equalizer ring is equal to
- (A) Number of pole pairs
- (B) Number of poles
- (C) Number of parallel paths
- (D) Number of commutator segments
9. The number of brushes in a commutator depends on
- (A) Speed of armature
- (B) Type of winding
- (C) Voltage
- (D) Amount of current to be collected
10. While applying Fleming's right-hand rule to and the direction of induced e.m.f., the thumb points towards
- (A) Direction of induced e.m.f.
- (B) Direction of flux
- (C) Direction of motion of the conductor if forefinger
points in the direction of generated e.m.f.
- (D) Direction of motion of conductor, if
forefinger points along the lines of flux
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