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EEE :: Synchronous Motors

  1. A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as

  2. A.

     static condenser

    B.

     condenser

    C.

     synchronous condenser

    D.

     none of the above

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  3. For V-curves for a synchronous motor the graph is drawn between

  4. A.

     field current and armature current

    B.

     terminal voltage and load factor

    C.

     power factor and field current

    D.

     armature current and power factor

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  5. The armature current of the synchronous motor has higher values for

  6. A.

     high excitation only

    B.

     low excitation only

    C.

     both (A) and (B)

    D.

     none of the above

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  7. In which of the following motors the stator and rotor fields rotate simultaneously ?

  8. A.

     D.C. motor

    B.

     Reluctance motor

    C.

     Universal motor

    D.

     Synchronous motor

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  9. A rotory converter can also be run as a

  10. A.

     d.c. shunt motor

    B.

     d.c. series motor

    C.

     d.c. compound motor

    D.

     induction motor

    E.

     synchronous motor

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  11. The oscillations in a synchronous motor can be damped out by

  12. A.

     maintaining constant excitation

    B.

     running the motor on leading power factors

    C.

     providing damper bars in the rotor pole faces

    D.

     oscillations cannot be damped

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  13. A synchronous motor can be used as a synchronous capacitor when it is

  14. A.

     under-loaded

    B.

     over-loaded

    C.

     under-excited

    D.

     over-excited

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  15. Slip-rings in a synchronous motor carry

  16. A.

     direct current

    B.

     alternating current

    C.

     no current

    D.

     all of the above

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  17. An over-excited synchronous motor takes

  18. A.

     leading current

    B.

     lagging current

    C.

     both (A) and (B)

    D.

     none of the above

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  19. While starting a synchronous motor by induction motor action, field winding is usually

  20. A.

     connected to D.C. supply

    B.

     short-circuited by low resistance

    C.

     kept open-circuited

    D.

     none of the above

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