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D.C. Generators

Study 120 Electrical Engineering MCQs with correct answers and explanations.

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51Electrical EngineeringMedium

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

ACompensating winding in a D.C. machine helps in commutation

BBack pitch and front pitch are both odd and approximately equal to the pole pitch

CEquilizing bus bars are used with parallel running of D.C. shunt gen¬erators

DIn a D. C. generator interpoles winding is connected in series with the armature winding

Correct answer

C. Equilizing bus bars are used with parallel running of D.C. shunt gen¬erators

Explanation

The correct answer is Equilizing bus bars are used with parallel running of D.C. shunt gen¬erators.

52Electrical EngineeringMedium

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________?

Anone of the above

Bgreater than 150 V

C150 V

Dless than 150 V

Correct answer

B. greater than 150 V

Explanation

The correct answer is greater than 150 V.

53Electrical EngineeringMedium

A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly________?

A240 V

B150 V

C175 V

D290 V

Correct answer

A. 240 V

Explanation

The correct answer is 240 V.

54Electrical EngineeringMedium

The critical resistance of the D.C. generator is the resistance of________?

Abrushes

Barmature

Cload

Dfield

Correct answer

D. field

Explanation

The correct answer is field.

55Electrical EngineeringMedium

Which of the following components of a D.C, generator plays vital role for providing direct current of a D.C. generator?

AEye bolt

BEquilizer rings

CCommutator

DDummy coils

Correct answer

C. Commutator

Explanation

The correct answer is Commutator.

56Electrical EngineeringMedium

The field coils of D.C. generator are usually made of________?

Acopper

Bcarbon

Ccast iron

Dmica

Correct answer

A. copper

Explanation

The correct answer is copper.

57Electrical EngineeringMedium

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

Aany of the above

Bimperfect contact

Crough commutator surface

Dsevere sparking

Correct answer

A. any of the above

Explanation

The correct answer is any of the above.

58Electrical EngineeringMedium

In case of D.C. machine winding, number of commutator segments is equal to________?

Anumber of armature conductors

Bnumber of armature turns

Cnumber of armature coil sides

Dnumber of armature coils

Correct answer

D. number of armature coils

Explanation

The correct answer is number of armature coils.

59Electrical EngineeringMedium

If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by________?

ABl2v2

BBlv

CBlv2

DBl2v

Correct answer

B. Blv

Explanation

The correct answer is Blv.

60Electrical EngineeringMedium

The armature core of a D.C. generator is usually made of________?

Acopper

Bcast-iron

Cnon-ferrous material

Dsilicon steel

Correct answer

D. silicon steel

Explanation

The correct answer is silicon steel.

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

ACompensating winding in a D.C. machine helps in commutation

BBack pitch and front pitch are both odd and approximately equal to the pole pitch

CEquilizing bus bars are used with parallel running of D.C. shunt gen¬erators

DIn a D. C. generator interpoles winding is connected in series with the armature winding

Correct answer

C. Equilizing bus bars are used with parallel running of D.C. shunt gen¬erators

Explanation

The correct answer is Equilizing bus bars are used with parallel running of D.C. shunt gen¬erators.