multiple choice questions on synchronous machines # 12

                                             Hi friends, this post is about objectives of synchronous machine. Mcq's on synchronous machines which are asked recently in various competitive exams like Gate , Upsc exams and so on. check out and comment if you have any doubts regarding this bits..

objectives on synchronous machine 12


1)  Synchronous motors generally have
A) salient pole rotor
B) smooth cylindrical rotor
C) either salient pole or smooth cylindrical rotor
D) none of the above

Ans:A

2) Number of slip rings in a 3-phase synchronous motor will be
A) 0
B) 1
C) 2
D) 3 or 4

Ans:C

3) A 3-phase synchronous motor has
A) high starting torque
B) no starting torque
C) low starting current
D) low starting torque

Ans:B

4) A 3-phase synchronous motor needs dc supply for excitation
A) continously
B) at the starting instant only
C) of stator
D) none of these

Ans:A

5) In a 3-phase synchronous motor the magnitude of field flux
A) remains constant at all loads
B) varies with load
C) varies with speed
D) varies with power factor

Ans:A

6) The relative speed between the magnetic fields of stator and rotor under steady state operation is zero for
A) a dc machine
B) an induction machine
C) a synchronous machine
D) all of the above machine

Ans:D

7) What is the angle between the induced voltage and supply voltage of a synchronous motor under running condition
A) Zero
B) Greater than zero but ≤ 90°
C) Between 90° and 180°
D) > 180

Ans:C

8) The value of load angle for a synchronous motor depends mainly upon its
A) excitation
B) load
C) speed
D) supply voltage

Ans:B

9) The armature current of a synchronous motor on no load
A) leads the applied voltage  by 90°
B) lags behind the applied voltage  by 90°
C) is in phase with applied voltage
D) zero

Ans:A

10) The coupling magnetic field reaction with ............... system is essential for extracting energy from an electrical system
A) mechanical
B) electrical
C) both electrical and mechanical

Ans:B

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AUTHOR
January 16, 2020 at 6:58 AM delete

Thanks sir very effective questions

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