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Synchronous Motors - section-1
Synchronous Motors - Section-2
  1. A synchronous motor working on leading power factor and not driving any mechanical, is known
    2. A.
    synchronous induction motor
    B.
    spinning motor
    C.
    synchronous condenser
    D.
    none of the above

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  2. Which motor can conveniently operate on lagging as well as leading power factor ?
    3. A.
    squirrel cage induction motor
    B.
    wound rotor induction motor
    C.
    synchronous motor
    D.
    any of the above

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  3. The back emf in the stator of a synchronous motor depends on
    4. A.
    speed of rotor
    B.
    rotor excitation
    C.
    number of poles
    D.
    flux density

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  4. Which of the following motors is non-self starling ?
    5. A.
    squirrel cage induction motor
    B.
    wound rotor induction motor
    C.
    synchronous motor
    D.
    DC series motor

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  5. In case of a synchronous motor we have
    I. Load
    II. Speed
    III. DC excitation

    The magnitude of stator back emf depends on
    6. A.
    I only
    B.
    I and II only
    C.
    III only
    D.
    I, II and III

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  6. A synchronous motor is switched on to supply with its field windings shorted on themselves. It will
    7. A.
    not start
    B.
    start but continue to run as an induction motor
    C.
    start as an induction motor and then run as a synchronous motor

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  7. The purpose of embedding the damper winding in the pole face is to
    8. A.
    eliminate hunting and provide adequate starting torque
    B.
    reduce windage losses
    C.
    eliminate losses on account of air friction
    D.
    reduce bearing friction

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  8. A 3 phase, 400 V, 50 Hz salient pole synchronous motor is fed from an infinite bus and is running at no load. Now if the field current of the motor is reduced to zero
    9. A.
    the motor will stop
    B.
    the motor will run
    C.
    the motor will run at synchronous speed
    D.
    the motor will run at less than synchronous speed

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  9. A synchronous motor is connected to supply voltage V drawing current /. Resultant of v and back emf Eb is represented by E in the figure. From this diagram it can be concluded that


    10. A.
    power factor it lagging
    B.
    the resultant of V and Eb is consumed by synchronous impedance
    C.
    current I leads the applied voltage by I
    D.
    motor is running on full load

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  10. In a synchronous motor if the back emf generated in the armature at no load is approximately equal to the applied voltage, then
    11. A.
    the torque generated is maximum
    B.
    the excitation is said to be zero percent
    C.
    the excitation is said to be 100%
    D.
    the motor is said to be fully loaded

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