D.C. Generators MCQ Questions & Answers

61

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) $$\frac{{\text{E}}}{2}$$ B) 2E C) Slightly less than E D) E

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Answer & Solution

Answer: Option B

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62

In the case of lap winding resultant pitch is

A) Multiplication of front and back pitches B) Division of front pitch by back pitch C) Sum of front and back pitches D) Difference of front and back pitches

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Answer & Solution

Answer: Option D

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63

Armature reaction in a generator results in

A) Demagnetization of leading pole tip and magnetization of trailing pole tip B) Demagnetization of trailing pole tip and magnetization of leading pole tip C) Demagnetizing the center of all poles D) Magnetizing the center of all poles

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Answer & Solution

Answer: Option A

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64

Which of the following statement about D.C. generators is false?

A) Compensating winding in a D.C. machine helps in commutation B) In a D. C. generator interpoles winding is connected in series with the armature winding C) Back pitch and front pitch are both odd and approximately equal to the pole pitch D) Equalizing bus bars are used with parallel running of D.C. shunt generators

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Answer & Solution

Answer: Option D

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65

Following D.C. generator will be in a position to build up without any residual magnetism in the poles

A) Series generator B) Shunt generator C) Compound generator D) Self-excited generator

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Answer & Solution

Answer: Option D

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66

The following constitute short-circuit in the armature winding.

A) Insulation failure between two commutator bars B) Insulation failure between two turns of a coil C) Two of more turns of the same coil getting grounded D) All of the above

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Answer & Solution

Answer: Option D

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67

In a D.C. generator the actual flux distribution depends upon

A) size of air gap B) shape of the pole shoe C) clearance between tips of the adjacent pole shoes D) all of the above

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Answer & Solution

Answer: Option D

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68

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

A) Severe sparking B) Rough commutator surface C) Imperfect contact D) Any of the above

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Answer & Solution

Answer: Option D

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69

In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when

A) r.p.m. is more than 300 B) r.p.m. is less than 300 C) Number of poles is 4 D) Number of poles is 2

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Answer & Solution

Answer: Option D

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70

In a commutator

A) Copper is harder than mica B) Mica and copper are equally hard C) Mica is harder than copper D) None of the above

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Answer & Solution

Answer: Option C

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D.C. Generators MCQ Questions & Answers | Electrical Engineering