Single Phase Induction Motors(Electrical Engineering Questions ) Questions and Answers

Question 1. If a D.C. series motor is operated on A.C. supply, it will____________?
  1.    spark excessively
  2.    have poor efficiency
  3.    have poor power factor
  4.    all of the above
Explanation:-
Answer: Option D. -> all of the above
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 2. A universal motor is one which______________?
  1.    can be operated either on D.C. or A.C. supply at approximately the same speed and output
  2.    can be marketed internationally
  3.    runs at dangerously high speed on no-load
Explanation:-
Answer: Option A. -> can be operated either on D.C. or A.C. supply at approximately the same speed and output
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 3. The capacitors used in single-phase capacitor motors have no__________?
  1.    voltage rating
  2.    dielectric medium
  3.    polarity marking
  4.    definite value
Explanation:-
Answer: Option C. -> polarity marking
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 4. A repulsion motor is equipped with__________?
  1.    slip rings
  2.    commutator
  3.    both A. and (b)
  4.    none of the above
Explanation:-
Answer: Option B. -> commutator
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 5. Which of the following statements regarding a reluctance motor is incorrect ?
  1.    It cannot be reversed, ordinarily
  2.    It requires no D.C. field excitation for its operation
  3.    It is nothing else but a single-phase, salient pole synchronous-induction motor
  4.    Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor
Explanation:-
Answer: Option A. -> It cannot be reversed, ordinarily
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 6. A shaded pole motor does not possess___________?
  1.    centrifugal switch
  2.    capacitor
  3.    commutator
  4.    all of the above
Explanation:-
Answer: Option D. -> all of the above
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 7. In a A.C. series motor armature coils are usually connected to commutator____________?
  1.    through resistance
  2.    through reactances
  3.    through capacitors
  4.    solidly
Explanation:-
Answer: Option A. -> through resistance
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 8. Which of the following motors has two separate windings on the motor ?
  1.    Repulsion motor
  2.    Repulsion induction motor
  3.    Repulsion start induction run motor
  4.    None of the above
Explanation:-
Answer: Option B. -> Repulsion induction motor
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 9. In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will_____________?
  1.    become unstable
  2.    draw excessive armature current and may burn out
  3.    fall out of synchronism and come to stand still
  4.    run as induction motor
Explanation:-
Answer: Option D. -> run as induction motor
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
Question 10. To reverse the direction of rotation of acapacitor start motor while it is running we should___________?
  1.    disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding
  2.    disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding
  3.    reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply
  4.    reverse the direction of connections of the auxiliary winding and immediately connect it to supply
Explanation:-
Answer: Option A. -> disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding
NO EXPLANATION IS AVAILABLE FOR THIS QUESTION!
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