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ECE :: Automatic Control Systems

  1. A system is highly oscillatory if

  2. A.

     Gain margin is high

    B.

     Gain margin is close to 1

    C.

     Gain margin is close to 1 or phase margin is zero

    D.

     Gain margin is high and phase margin is 180°


  3. In a two phasor servomotor, the direction of rotation of the rotating field depends on

  4. A.

     Magnitudes of voltages applied to the two stator windings

    B.

     Phase relation of voltages applied to the two stator windings

    C.

     Both magnitude and phase relationship of voltages applied to the two stator windings

    D.

     None of the above


  5. Which of the following is open loop system?

  6. A.

     Wind screen wiper

    B.

     Aqualing

    C.

     Respiratory system of animal

    D.

     System for controlling antirocket missiles


  7. The poles with greater displacement from the real axis correspond to

  8. A.

     Higher frequencies of oscillations

    B.

     Stable response

    C.

     Lower frequencies of oscillations

    D.

     Unbounded output


  9. The sensor generally used in incremental optical encoder is

  10. A.

     LED

    B.

     LCD

    C.

     Photodiode

    D.

     Either (a) or (b)


  11. In force current analogue, mechanical mobility is analogous to

  12. A.

     Impedance Z

    B.

     Admittance Y

    C.

     Reactance X

    D.

     Conductance G


  13. Nichols chart consists of

  14. A.

     Constant magnitude loci

    B.

     Constant phase angle loci

    C.

     Magnitude and phase angle loci in log-magnitude versus phase diagram

    D.

     None of the above


  15. Magnetic amplifier is used for

  16. A.

     Voltage amplification

    B.

     Power amplification

    C.

     Current amplification

    D.

     Frequency amplification


  17. Which control action can never be used alone?

  18. A.

     Proportional

    B.

     Derivative

    C.

     Integral

    D.

     Both (b) and (c)


  19. Nyquist stability criterion uses open loop frequency response characteristics.

  20. A.

     True

    B.

     False