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MCQs

Total Questions : 395 | Page 1 of 40 pages
Question 1. The maximum power developed in a synchronous motor occurs at a coupling angle of
  1.    30°
  2.    60°
  3.    90°
  4.    180°
 Discuss Question
Answer: Option C. -> 90°
Question 2. When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor
  1.    remains same as the original value
  2.    decreases to half the original value
  3.    tends to becomes zero
  4.    increases to two times the original value
 Discuss Question
Answer: Option D. -> increases to two times the original value
Question 3. In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
  1.    Universal motor
  2.    Synchronous motor
  3.    Induction motor
  4.    Reluctance motor
 Discuss Question
Answer: Option B. -> Synchronous motor
Question 4. The speed of a synchronous motor
  1.    increases as the load increases
  2.    decreases as the load decreases
  3.    always remains constant
  4.    none of the above
 Discuss Question
Answer: Option C. -> always remains constant
Question 5. In a synchronous motor, the breakdown torque is
  1.    directly proportional to applied voltage
  2.    directly proportional to the square of the applied voltage
  3.    inversely proportional to applied voltage
  4.    none of the above
 Discuss Question
Answer: Option A. -> directly proportional to applied voltage
Question 6. The angle between the rotating stator flux and rotor poles is called _____ angle.
  1.    torque
  2.    obtuse
  3.    synchronizing
  4.    power factor
 Discuss Question
Answer: Option A. -> torque
Question 7. A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed
  1.    the motor will stop
  2.    the motor continue to run in the same direction
  3.    the winding of the motor will burn
  4.    the motor will run in the reverse direction
 Discuss Question
Answer: Option B. -> the motor continue to run in the same direction
Question 8. Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?
  1.    High field current
  2.    Low short circuit ratio
  3.    High core losses
  4.    Low field current
 Discuss Question
Answer: Option D. -> Low field current
Question 9. When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
  1.    inductor motor torque
  2.    induction generator torque
  3.    synchronous motor torque
  4.    d.c. motor toque
 Discuss Question
Answer: Option B. -> induction generator torque
Question 10. The working of a synchronous motor is similar to
  1.    gear train arrangement
  2.    transmission of mechancial power by shaft
  3.    distribution transformer
  4.    turbine
 Discuss Question
Answer: Option B. -> transmission of mechancial power by shaft

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