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Electrical Machine Design

Study 103 Electrical Engineering MCQs with correct answers and explanations.

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11Electrical EngineeringMedium

The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are________?

A0.8 to 1.0 Wb/m2

B0.5 to 0.8 Wb/m2

C1.1 to 1.35 Wb/m2

D1.4 to 1.8 Wb/m2

Correct answer

C. 1.1 to 1.35 Wb/m2

Explanation

The correct answer is 1.1 to 1.35 Wb/m2.

12Electrical EngineeringMedium

________are always double layer type?

AEither of the above

BClosed windings

CNone of the above

DOpen windings

Correct answer

B. Closed windings

Explanation

The correct answer is Closed windings.

13Electrical EngineeringMedium

In ________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft?

Amedium

Bsmall

Clarge

Dany of the above.

Correct answer

C. large

Explanation

The correct answer is large.

14Electrical EngineeringMedium

D.C. machines designed with a large value of air gap length have________?

Apoor ventilation

Bnone of the above

Cbetter ventilation

Dworst, ventilation

Correct answer

C. better ventilation

Explanation

The correct answer is better ventilation.

15Electrical EngineeringMedium

________are used for construction of core of electromagnets?

AEither A. or B.

BNone of the above

CHard magnetic materials

DSoft magnetic materials

Correct answer

D. Soft magnetic materials

Explanation

The correct answer is Soft magnetic materials.

16Electrical EngineeringMedium

In induction motors, the length of air gap in kept as small as mechanically possible is order to have________?

Ahigh over load capacity

Bhigh power factor

Cany of the above

Dlow power factor

Correct answer

B. high power factor

Explanation

The correct answer is high power factor.

17Electrical EngineeringMedium

Direct water cooling of rotor winding presents________?

Agreater mechanical difficulties

Bnone of the above

Cno mechanical difficulties

Dlesser mechanical difficulties

Correct answer

A. greater mechanical difficulties

Explanation

The correct answer is greater mechanical difficulties.

18Electrical EngineeringMedium

Disc windings are primarily used in________-?

Amedium capacity transformers

Bany of the above

Chigh capacity transformers

Dshort capacity transformers

Correct answer

C. high capacity transformers

Explanation

The correct answer is high capacity transformers.

19Electrical EngineeringMedium

With conventional hydrogen cooling it is possible to increase the rating of a single unit to________?

Anone of the above

B100 MW

C200 MW

D50 MW

Correct answer

C. 200 MW

Explanation

The correct answer is 200 MW.

20Electrical EngineeringMedium

When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of________?

Aeither of the above

Bshort pitch

Cnone of the above

Dfull pitch

Correct answer

D. full pitch

Explanation

The correct answer is full pitch.

11Electrical EngineeringMedium

The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are________?

A0.8 to 1.0 Wb/m2

B0.5 to 0.8 Wb/m2

C1.1 to 1.35 Wb/m2

D1.4 to 1.8 Wb/m2

Correct answer

C. 1.1 to 1.35 Wb/m2

Explanation

The correct answer is 1.1 to 1.35 Wb/m2.

12Electrical EngineeringMedium

________are always double layer type?

AEither of the above

BClosed windings

CNone of the above

DOpen windings

Correct answer

B. Closed windings

Explanation

The correct answer is Closed windings.

13Electrical EngineeringMedium

In ________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft?

Amedium

Bsmall

Clarge

Dany of the above.

Correct answer

C. large

Explanation

The correct answer is large.

14Electrical EngineeringMedium

D.C. machines designed with a large value of air gap length have________?

Apoor ventilation

Bnone of the above

Cbetter ventilation

Dworst, ventilation

Correct answer

C. better ventilation

Explanation

The correct answer is better ventilation.

15Electrical EngineeringMedium

________are used for construction of core of electromagnets?

AEither A. or B.

BNone of the above

CHard magnetic materials

DSoft magnetic materials

Correct answer

D. Soft magnetic materials

Explanation

The correct answer is Soft magnetic materials.

16Electrical EngineeringMedium

In induction motors, the length of air gap in kept as small as mechanically possible is order to have________?

Ahigh over load capacity

Bhigh power factor

Cany of the above

Dlow power factor

Correct answer

B. high power factor

Explanation

The correct answer is high power factor.

17Electrical EngineeringMedium

Direct water cooling of rotor winding presents________?

Agreater mechanical difficulties

Bnone of the above

Cno mechanical difficulties

Dlesser mechanical difficulties

Correct answer

A. greater mechanical difficulties

Explanation

The correct answer is greater mechanical difficulties.

18Electrical EngineeringMedium

Disc windings are primarily used in________-?

Amedium capacity transformers

Bany of the above

Chigh capacity transformers

Dshort capacity transformers

Correct answer

C. high capacity transformers

Explanation

The correct answer is high capacity transformers.

19Electrical EngineeringMedium

With conventional hydrogen cooling it is possible to increase the rating of a single unit to________?

Anone of the above

B100 MW

C200 MW

D50 MW

Correct answer

C. 200 MW

Explanation

The correct answer is 200 MW.

20Electrical EngineeringMedium

When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of________?

Aeither of the above

Bshort pitch

Cnone of the above

Dfull pitch

Correct answer

D. full pitch

Explanation

The correct answer is full pitch.