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
- (B) About 2 V
- (C) About 50 V
- (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
- (A) To supply traction load
- (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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