Interview Questions for DC Motor - Electronic Engineering


Electronic Engineering MCQs Interview questions and answers (objective type, multiple choice). The device converts electrical energy into mechanical energy.


    Question 1: The series parallel system of speed control of DC series motors widely used in traction work gives a speed range of about?

  • 1:10
  • 1:8
  • 1:4
  • 1:6
  • Answers: 1:4

    Question 2: If the speed of a DC shunt motor is increased the back EMF of the motor will?

  • increase
  • decrease
  • remain same
  • become zero
  • Answers: increase

    Question 3: Sparking is discouraged in a DC motor because?

  • it increases the input power consumption
  • none of the above
  • both (a) and (b)
  • commutator gets damaged
  • Answers: commutator gets damaged

    Question 4: Which DC motor bas got maximum self loading property?

  • Series motor
  • Differentially compounded motor
  • Shunt motor
  • Cumulatively compounded motor
  • Answers: Differentially compounded motor

    Question 5: The speed of a series motor at no load is?

  • 4000 RPM
  • 2000 RPM
  • infinity
  • 1000 RPM
  • Answers: infinity

    Question 6: In DC machines the residual magnetism is of the order of?

  • 20 to 25 per cent
  • 50 to 75 per cent
  • 10 to 15 per cent
  • 2 to 3 per cent
  • Answers: 2 to 3 per cent

    Question 7: Which of the following statements is correct, in case of a DC series motor?

  • It cannot be used where high starting torque is required
  • It should be directly connected to the load
  • It is a constant speed motor
  • It may run away if its field becomes open
  • Answers: It should be directly connected to the load

    Question 8: If a DC shunt motor is working at no load and if shunt field circuit suddenly opens?

  • nothing will happen to the motor
  • this will make armature to take heavy current, possibly burning it
  • this will result in excessive speed, possibly" destroying armature due to excessive centrifugal stresses
  • motor will run at very "slow speed
  • Answers: this will result in excessive speed, possibly" destroying armature due to excessive centrifugal stresses

    Question 9: Which DC motor will have least percentage increase of input current, for the same percentage increase in the torque?

  • Series motor
  • Shunt motor
  • Cumulative compound motor
  • Separately excited motor
  • Answers: Series motor

    Question 10: A shearing machine has cyclic load consisting of intermittent light and henry loads. Which of the following DC motor will be suitable for this purpose?

  • Series motor
  • Shunt motor
  • Differential compound motor
  • Cumulative compound motor
  • Answers: Cumulative compound motor

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Correct: 0 Wrong: 0



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