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EEE :: D.C. Motors

  1. Which D.C. motor has got maximum self loading property?

  2. A.

     Series motor

    B.

     Shunt motor

    C.

     Cumulatively compounded motor

    D.

     Differentially compounded motor


  3. In D.C. machines the residual magnetism is of the order of

  4. A.

     2 to 3 percent

    B.

     10 to 15 percent

    C.

     20 to 25 percent

    D.

     50 to 75 percent


  5. In a D.C. generator, the iron losses mainly take place in

  6. A.

     Yoke

    B.

     Commutator

    C.

     Armature conductors

    D.

     Armature rotor


  7. For constant torque drive which speed control method is preferred?

  8. A.

     Field control

    B.

     Armature voltage control

    C.

     Shunt armature control

    D.

     Mechanical loading system


  9. By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?

  10. A.

     Frame

    B.

     Shaft

    C.

     Commutator

    D.

     Stator


  11. One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven

  12. A.

     Runs as a generator

    B.

     Does not run as a generator

    C.

     Also runs as a motor comes to stop after sometime

    D.

     None of these


  13. Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control

  14. A.

     Drum type controller is used

    B.

     Three point starter is used

    C.

     Four point starter is used

    D.

     All above can be used


  15. Ward-Leonard control is basically a

  16. A.

     Voltage control method

    B.

     Field diverter method

    C.

     Field control method

    D.

     Armature resistance control method


  17. Which of the following motors is most suitable for signalling devices and many kinds of timers ?

  18. A.

     D.C. shunt motor

    B.

     D.C. series motor

    C.

     Induction motor

    D.

     Reluctance motor


  19. The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is

  20. A.

     4.0

    B.

     2.0

    C.

     1.0

    D.

     0.5