Practice Exam on DC Generators- Set 07 - ObjectiveBooks

# Practice Test: Question Set - 07

1. The rapid wear of brushes takes place due to
(A) Abrasion from dust
(B) Excessive spring pressure
(C) Rough commutator bars
(D) All of the above factors

2. A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be
(A) Zero
(D) 220 V

3. The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be
(A) 150 V
(B) Less than 150 V
(C) Greater than 150 V
(D) None of the above

4. The field coils of D.C. generator are usually made of
(A) Mica
(B) Copper
(C) Cast iron
(D) Carbon

5. In lap winding, the number of brushes is always
(A) Double the number of poles
(B) Same as the number of poles
(C) Half the number of poles
(D) Two

6. In D.C. generators, current to the external circuit from armature is given through
(A) Commutator
(B) Solid connection
(C) Slip rings
(D) None of above

7. Welding generator will have
(A) Lap winding
(B) Wave winding
(C) Delta winding
(D) Duplex wave winding

8. D.C. series generator is used
(B) To supply industrial load at constant voltage
(C) Voltage at the toad end of the feeder
(D) For none of the above purpose

9. The purpose of providing dummy coils in a generator is
(A) To reduce eddy current losses
(B) To enhance flux density
(C) To amplify voltage
(D) To provide mechanical balance for the rotor

10. In a D.C. generator in case the resistance of the field winding is increased, then output voltage will
(A) Increase
(B) Decrease
(C) Remain unaffected
(D) Fluctuate heavily

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