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EEE :: Single Phase Induction Motors

  1. Which of the following statements regarding a reluctance motor is incorrect ?

  2. A.

     It cannot be reversed, ordinarily

    B.

     It requires no D.C. field excitation for its operation

    C.

     It is nothing else but a single-phase, salient pole synchronous-induction motor

    D.

     Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluc-tance path between stator and rotor

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  3. Which of the following statements regarding repulsion-start induction motor is incorrect ?

  4. A.

     It requires more maintenance of commutator and other mechanical devices

    B.

     It makes quite a bit of noise on starting

    C.

     In fractional horse power motors, it has replaced the capacitor motors

    D.

     It is not easily reversed

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  5. In a universal motor, the most common cause of brush sparking is

  6. A.

     open armature winding

    B.

     shorted armature winding

    C.

     shorted field winding?

    D.

     high commutator mica

    E.

     all of the above

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  7. In repulsion motor direction of rotation of motor

  8. A.

     is opposite to that of brush shift

    B.

     is the same as that of brush shift

    C.

     is independent of brush shift

    D.

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  9. Centrifugal switch disconnects the auxiliary winding of the motor at about ____ percent of synchronous speed

  10. A.

     30 to 40

    B.

     70 to 80

    C.

     80 to 90

    D.

     100

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  11. Burning out of winding is due to

  12. A.

     short circuited capacitor

    B.

     capacitor value hiving changed

    C.

     open circuiting of capacitor

    D.

     none of the above

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  13. Which of the following statements regarding single-phase induction motoris correct ?

  14. A.

     It requires only one winding

    B.

     It can rotate in one direction only

    C.

     It is self-starting

    D.

     It is not self-starting

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  15. Which of the following statements regarding hysteresis motor is in incorrect ?

  16. A.

     It is extremely sensitive to fluctuations in supply voltage

    B.

     Its high starting torque is due to its high rotor hysteresis loss

    C.

     It is extremely quiet in operation

    D.

     It accelerates from rest to full-speed almost instantaneously

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  17. Which of the following single-phase motors has relatively poor starting torque ?

  18. A.

     Universal motor

    B.

     Repulsion motor

    C.

     Capacitor motor

    D.

     All single phase motors have zero starting torque

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  19. If a single phase induction motor runs slower than normal, the most likely defect is

  20. A.

     worn bearings

    B.

     short-circuit in the winding

    C.

     open-circuit in the winding

    D.

     none of the above

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