D.c. Generators

[amp_mcq option1=”Lenz’s law” option2=”Ohm’s law” option3=”generator works on the principle of A. Lenz’s law B. Ohm’s law C. Faraday’s law of electromagnetic induction” option4=”None of the above” correct=”option3″]

Detailed SolutionA D.C. generator works on the principle of

[amp_mcq option1=”Electromagnets” option2=”Permanent magnets” option3=”generator is produced by A. Electromagnets B. Permanent magnets C. Both (A) and (B)” option4=”None of the above” correct=”option3″]

Detailed SolutionMagnetic field in a D.C. generator is produced by

[amp_mcq option1=”Separately excited generator” option2=”Shunt generator” option3=”Series generator” option4=”Compound generator” correct=”option1″]

Detailed SolutionAn exciter for a turbo generator is a

[amp_mcq option1=”Brushes” option2=”Field” option3=”generator the critical resistance refers to the resistance of A. Brushes B. Field C. Armature” option4=”Load” correct=”option1″]

Detailed SolutionIn a D.C. generator the critical resistance refers to the resistance of

[amp_mcq option1=”Severe sparking” option2=”Rough commutator surface” option3=”generators, the cause of rapid brush wear may be A. Severe sparking B. Rough commutator surface C. Imperfect contact” option4=”Any of the above” correct=”option4″]

Detailed SolutionIn D.C. generators, the cause of rapid brush wear may be

[amp_mcq option1=”Only if the load current is zero” option2=”Only if the load current is not zero” option3=”Irrespective of the value of load current” option4=”None of the above” correct=”option3″]

Detailed SolutionA series generator can self-excite

[amp_mcq option1=”2″ option2=”4″ option3=”generator having duplex lap winding is A. 2 B. 4 C. 6″ option4=”8″ correct=”option1″]

Detailed SolutionThe number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is

[amp_mcq option1=”Zero” option2=”About 2 V” option3=”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” option4=”220 V” correct=”option1″]

Detailed SolutionA 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be

[amp_mcq option1=”Series field” option2=”Compensating field” option3=”machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure. A. Series field B. Compensating field C. Inter pole field” option4=”Shunt field” correct=”option4″]

Detailed SolutionFollowing energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.

[amp_mcq option1=”Is amenable to better voltage control” option2=”Is more stable” option3=”Has exciting current independent of load current” option4=”Has all above features” correct=”option4″]

Detailed SolutionA separately excited generator as compared to a self-excited generator