D.c. Generators

1. The armature of D.C. generator is laminated to

reduce the bulk
provide the bulk
generator is laminated to A. reduce the bulk B. provide the bulk C. insulate the core
reduce eddy current loss

Detailed SolutionThe armature of D.C. generator is laminated to

2. D.C. generator generally preferred for charging automobile batteries is

Series generator
Shunt generator
generator generally preferred for charging automobile batteries is A. Series generator B. Shunt generator C. Long shunt compound generator
Any of the above

Detailed SolutionD.C. generator generally preferred for charging automobile batteries is

3. Armature reaction of an unsaturated D.C. machine is

Cross-magnetizing
Demagnetizing
machine is A. Cross-magnetizing B. Demagnetizing C. Magnetizing
None of above

Detailed SolutionArmature reaction of an unsaturated D.C. machine is

4. The critical resistance of the D.C. generator is the resistance of

Field
Brushes
generator is the resistance of A. Field B. Brushes C. Armature
Load

Detailed SolutionThe critical resistance of the D.C. generator is the resistance of

5. According to Fleming’s right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of

Motion of conductor
Lines of force
Either of the above
None of the above

Detailed SolutionAccording to Fleming’s right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of

6. In D.C. generators the polarity of the interpoles

Is the same as that of the main pole ahead
Is the same as that of the immediately preceding pole
generators the polarity of the interpoles A. Is the same as that of the main pole ahead B. Is the same as that of the immediately preceding pole C. Is opposite to that of the main pole ahead
Is neutral as these poles do not play part in generating e.m.f.

Detailed SolutionIn D.C. generators the polarity of the interpoles

7. In case of D.C. machines, mechanical losses are primary function of

Current
Voltage
machines, mechanical losses are primary function of A. Current B. Voltage C. Speed
None of above

Detailed SolutionIn case of D.C. machines, mechanical losses are primary function of

8. The following constitute short-circuit in the armature winding.

Insulation failure between two commutator bars
Insulation failure between two turns of a coil
Two of more turns of the same coil getting grounded
All of the above

Detailed SolutionThe following constitute short-circuit in the armature winding.

9. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage

Will be less than 250 V
Will always be 250 V
May be greater or less than 250 V
None of the above

Detailed SolutionThe open circuit voltage of a compound generator is 250 V. At full load the terminal voltage

10. In a D.C. generator in case the resistance of the field winding is increased, then output voltage will

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

Detailed SolutionIn a D.C. generator in case the resistance of the field winding is increased, then output voltage will

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