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Synchronous Motors

Study 122 Electrical Engineering MCQs with correct answers and explanations.

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31Electrical EngineeringMedium

The net armature voltage of a synchronous motor is equal to the________?

Avector difference of Eh and V

Barithmetic sum of Eb and V

Carithmetic difference of Eb and V

Dvector sum of Eb and V

Correct answer

A. vector difference of Eh and V

Explanation

The correct answer is vector difference of Eh and V.

32Electrical EngineeringMedium

In a synchronous motor, the maximum power developed depends on all of the following except:

Amaximum value of coupling angle

Brotor excitation

Cdirection of rotation

Dsupply voltage

Correct answer

C. direction of rotation

Explanation

The correct answer is direction of rotation.

33Electrical EngineeringMedium

Which of the following losses, in a synchronous motor, does not vary with load?

AWindage loss

BAny of the above

CCopper losses

DNone of the above

Correct answer

A. Windage loss

Explanation

The correct answer is Windage loss.

34Electrical EngineeringMedium

A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as________?

Acondenser

Bstatic condenser

Csynchronous condenser

Dnone of the above

Correct answer

C. synchronous condenser

Explanation

The correct answer is synchronous condenser.

35Electrical EngineeringMedium

The armature current of the synchronous motor

Ahas large values for high excitation only

Bhas large values for low excitation i niy

Chas large values for low and high excitation

Dany of the above

Correct answer

C. has large values for low and high excitation

Explanation

The correct answer is has large values for low and high excitation.

36Electrical EngineeringMedium

An over excited synchronous motor is used for________?

Afluctuating loads

Bpower factor corrections

Clow torque loads

Dvariable speed loads

Correct answer

B. power factor corrections

Explanation

The correct answer is power factor corrections.

37Electrical EngineeringMedium

Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?

ALow short circuit ratio

BLow field current

CHigh core losses

DHigh field current

Correct answer

B. Low field current

Explanation

The correct answer is Low field current.

38Electrical EngineeringMedium

The working of a synchronous motor is similar to________?

Agear train arrangement

Bnone of the above

Ctransmission of mechanical power by shaft

Dturbine

Edistribution transformer

Correct answer

C. transmission of mechanical power by shaft

Explanation

The correct answer is transmission of mechanical power by shaft.

39Electrical EngineeringMedium

A pony motor is basically a________?

Adouble winding A.C./D.C. motor

BD.C. shunt motor

Csmall induction motor

DD.C. series motor

Correct answer

C. small induction motor

Explanation

The correct answer is small induction motor.

40Electrical EngineeringMedium

Synchronous motor always runs at________?

Aless than synchronous speed

Bnone of the above

Cthe synchronous speed

Dmore than synchronous speed

Correct answer

C. the synchronous speed

Explanation

The correct answer is the synchronous speed.

31Electrical EngineeringMedium

The net armature voltage of a synchronous motor is equal to the________?

Avector difference of Eh and V

Barithmetic sum of Eb and V

Carithmetic difference of Eb and V

Dvector sum of Eb and V

Correct answer

A. vector difference of Eh and V

Explanation

The correct answer is vector difference of Eh and V.

32Electrical EngineeringMedium

In a synchronous motor, the maximum power developed depends on all of the following except:

Amaximum value of coupling angle

Brotor excitation

Cdirection of rotation

Dsupply voltage

Correct answer

C. direction of rotation

Explanation

The correct answer is direction of rotation.

33Electrical EngineeringMedium

Which of the following losses, in a synchronous motor, does not vary with load?

AWindage loss

BAny of the above

CCopper losses

DNone of the above

Correct answer

A. Windage loss

Explanation

The correct answer is Windage loss.

34Electrical EngineeringMedium

A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as________?

Acondenser

Bstatic condenser

Csynchronous condenser

Dnone of the above

Correct answer

C. synchronous condenser

Explanation

The correct answer is synchronous condenser.

35Electrical EngineeringMedium

The armature current of the synchronous motor

Ahas large values for high excitation only

Bhas large values for low excitation i niy

Chas large values for low and high excitation

Dany of the above

Correct answer

C. has large values for low and high excitation

Explanation

The correct answer is has large values for low and high excitation.

36Electrical EngineeringMedium

An over excited synchronous motor is used for________?

Afluctuating loads

Bpower factor corrections

Clow torque loads

Dvariable speed loads

Correct answer

B. power factor corrections

Explanation

The correct answer is power factor corrections.

37Electrical EngineeringMedium

Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?

ALow short circuit ratio

BLow field current

CHigh core losses

DHigh field current

Correct answer

B. Low field current

Explanation

The correct answer is Low field current.

38Electrical EngineeringMedium

The working of a synchronous motor is similar to________?

Agear train arrangement

Bnone of the above

Ctransmission of mechanical power by shaft

Dturbine

Edistribution transformer

Correct answer

C. transmission of mechanical power by shaft

Explanation

The correct answer is transmission of mechanical power by shaft.

39Electrical EngineeringMedium

A pony motor is basically a________?

Adouble winding A.C./D.C. motor

BD.C. shunt motor

Csmall induction motor

DD.C. series motor

Correct answer

C. small induction motor

Explanation

The correct answer is small induction motor.

40Electrical EngineeringMedium

Synchronous motor always runs at________?

Aless than synchronous speed

Bnone of the above

Cthe synchronous speed

Dmore than synchronous speed

Correct answer

C. the synchronous speed

Explanation

The correct answer is the synchronous speed.