Online Practice Test on DC Generators - Set 10 - ObjectiveBooks

# 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
(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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