electrical

Alternator MCQ Questions and Answers Page - 1

1.

Alternator operates on the principles of

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2.

In a synchronous machine, if the field flux axis is ahead of the armature field axis in the direction of rotation, the machine operating is

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3.

The  armature of an alternator

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4.

In modern alternators, the rotating part is

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5.

The current from the stator of an alternator is taken oututo the external load circuit through

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6.

Which one of the following is the primary reason for placing field on rotor in an alternator

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7.

Which type of alternator is used in hydroelectric power stations

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8.

In a synchronous machine, the stator frame serves the purpose of

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9.

In a synchronous machine , the stator frame is made of

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10.

The stator core of a synchronous machine is built up of ___laminations

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11.

The stator core stampings also have opening which make____ ventilating ducts to provide efficient cooling

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12.

The open slots are more  commonly used in the stator of a synchronous machine as

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13.

The field system of an alternator is usually excited at

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14.

The slip rings employed in  a 3 phase  synchronous machines are insulated for

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15.

Squirrel cage bars placed in the rotor pole faces of an alternator help reducing hunting

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16.

Hydro generator s are generally employed to  run at ___rpm

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17.

In case of turbo alternator, rotor is made of

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18.

The salient pole rotors have

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19.

In salient pole field structure, the po9le shoes cover about ___of pole pitch

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20.

larger diameter salient pole rotors have shorter axial length because

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21.

In a salient pole synchronous machine, the air gap is

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Answer : B

Explanation :

22.

The number of poles on turbo alternator is usually

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Answer : A

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23.

To obtain sinusoidal flux distribution, chamfering of poles is done in

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Answer : A

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24.

The salient pole rotors are not suitable for high speed turbo generators due to

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Answer : C

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25.

In turbo alternators, smooth cylindrical rotors have very long axial length because it

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Answer : C

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26.

Cylindrical rotor alternators use ____ducts for efficient cooling

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Answer : C

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27.

In cylindrical rotor ____portion of rotor is wound

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Answer : B

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28.

The maximum possible speed at which an alternator can be driven to generate 50 Hz and 4,000 V is

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Answer : C

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29.

Two mechanically coupled alternators deliver power at 50Hz and 60 Hz respectively.  The highest speed of the alternator is

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Answer : C

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30.

The most appropriate operating speeds in rpm of generators used in Thermal, Nuclear and Hydropower plants would respectively be

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Answer : B

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31.

The speed of a 4-pole 60 Hz synchronous machine will be

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Answer : A

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32.

What is the largest size of alternators being manufactured in India?

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Answer : A

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33.

Which of the following organization is engaged in the manufacture of large size alternators for power plants in India?

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Answer : D

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34.

Hydrogen is used in large alternators mainly to

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Answer : B

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35.

An alternator coupled to which prime mover will usually have the highest rotating speed?

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Answer : D

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36.

In an alternator the voltage generated per phase is proportional to

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Answer : D

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37.

Salient pole type alternators are generally used on

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Answer : D

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38.

Turbo-alternators are generally used to run at

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Answer : B

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39.

The rotor preferred for alternators applied to hydraulic turbines are

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Answer : A

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40.

The frequency of voltage generated in the large alternators is

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Answer : A

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41.

Which of the following prime mover is least efficient?

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Answer : D

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42.

In which coil the harmonic component of the generated e.m.f will be more?

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Answer : A

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43.

In case of turbo-alternators the rotor is usually made of up

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Answer : B

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44.

The number of poles in turbo-alternators is usually

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Answer : A

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45.

In huge alternators, the moving part is

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Answer : B

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46.

In power generating stations (thermal stations), the usual number of poles employed in alternators are

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Answer : D

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47.

Harmonic component of generated e.m.f will be more in

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Answer : B

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48.

What kind of rotor is most suitable for turbo-alternator which are designed to run at high speed?

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Answer : B

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49.

Modern 3-phase alternator of a central power station will have generated voltage of

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Answer : B

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50.

The speed of a salient pole machine is nearly

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Answer : A

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51.

Where the terminal voltage of an alternator falls on throwing of the load, it indicates that the load is purely

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Answer : C

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52.

Alternators are usually designed to generate

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Answer : D

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53.

In case of uniformly distributed winding, the value of distribution factor is

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Answer : D

Explanation :

54.

Unbalanced three-phase stator currents cause

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Answer : D

Explanation :

55.

Which of the following is not integral part of synchronous generator system?

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Answer : D

Explanation :

56.

Which of the following is a prime mover?

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Answer : A

Explanation :

57.

In a large generator, dampers

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Answer : C

Explanation :

Alternator MCQ Questions and Answers Page - 1
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