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MCQs

Dc Motors

Total Questions : 240 | Page 2 of 24 pages
Question 11. Which of the following method of speed control of D.C. machine will offer minimum efficiency?
  1.    Voltage control method
  2.    Field control method
  3.    Armature control method
  4.    All above methods
 Discuss Question
Answer: Option C. -> Armature control method
Question 12. A D.C. series motor is that which
  1.    Has its field winding consisting of thick wire and less turns
  2.    Has a poor torque
  3.    Can be started easily without load
  4.    Has almost constant speed
 Discuss Question
Answer: Option A. -> Has its field winding consisting of thick wire and less turns
Question 13. Sparking at the commutator of a D.C. motor may result in
  1.    Damage to commutator segments
  2.    Damage to commutator insulation
  3.    Increased power consumption
  4.    All of the above
 Discuss Question
Answer: Option D. -> All of the above
Question 14. For which of the following applications a D.C. motor is preferred over an A.C. motor?
  1.    Low speed operation
  2.    High speed operation
  3.    Variable speed operation
  4.    Fixed speed operation
 Discuss Question
Answer: Option C. -> Variable speed operation
Question 15. Which D.C. motor has got maximum self relieving property?
  1.    Series motor
  2.    Shunt motor
  3.    Cumulatively compounded motor
  4.    Differentially compounded motor
 Discuss Question
Answer: Option A. -> Series motor
Question 16. In a manual shunt motor starter
  1.    Over load relay is connected in series and no volt relay in parallel with the load
  2.    Over load relay is connected in parallel and no volt relay in series with the load
  3.    Over load relay and no volt relay are both connected in series with the load
  4.    Over load relay and no volt relay are both connected in parallel with the load
 Discuss Question
Answer: Option A. -> Over load relay is connected in series and no volt relay in parallel with the load
Question 17. In Ward-Leonard control the lower limit of speed is imposed by
  1.    Residual magnetism of the generator
  2.    Core losses of motor
  3.    Mechanical losses of motor and generator together
  4.    All of the above
 Discuss Question
Answer: Option A. -> Residual magnetism of the generator
Question 18. Which motor should not be started on no-load?
  1.    Series motor
  2.    Shunt motor
  3.    Cumulatively compounded motor
  4.    Differentially compounded motor
 Discuss Question
Answer: Option A. -> Series motor
Question 19. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
  1.    Reducing the field current
  2.    Decreasing the armature current
  3.    Increasing the armature current
  4.    Increasing the excitation current
 Discuss Question
Answer: Option A. -> Reducing the field current
Question 20. D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this
  1.    Series motor
  2.    Shunt motor
  3.    Compound motor
  4.    Any of the above
 Discuss Question
Answer: Option C. -> Compound motor

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