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ECE :: Automatic Control Systems

  1. The relative stability of a system is given by

  2. A.
    gain margin alone
    B.
    phase margin alone
    C.
    both phase and gain margins
    D.
    either (a) or (b)

  3. Assertion (A): Nyquist stability criterion uses the number of encirclements around (-1 + j0) point in GH plane to determine stability

    Reason (R): The (-1 + j0) point in the s plane lies in the Nyquist path.

  4. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    R is correct but A is wrong

  5. In a two phase servomotor the voltages applied to the two stator windings

  6. A.
    are equal in magnitude and are in phase
    B.
    are unequal in magnitude but are in phase
    C.
    are equal in magnitude but have a phase difference of 90°
    D.
    are unequal in magnitude and have a phase difference of 90°

  7. The phase angle characteristic in the given figure is for

  8. A.
    all pass function
    B.
    transport lag
    C.
    minimum phase function
    D.
    none of the above

  9. At low frequencies the factor e-jωT and behave simple.

  10. A.
    True
    B.
    False

  11. The overall transfer function for a unity feedback system is . Which of the following statements about this system are correct?

    1. Position error constant Kp is 4
    2. System is type 1
    3. Velocity error constant is finite
    Select the answer as per following code:

  12. A.
    1, 2, 3
    B.
    1, 2
    C.
    2, 3
    D.
    1, 3

  13. Bandwidth is proportional to speed of response.

  14. A.
    True
    B.
    False

  15. The complicated shapes in the polar plots are only due to time constants in the numerator of transfer functions.

  16. A.
    True
    B.
    False

  17. For a quadratic factor in denominator of transfer function the phase angle at corner frequency (in Bode phase angle plot)

  18. A.
    is -90°
    B.
    is +90°
    C.
    depends on the damping factor
    D.
    none of the above

  19. . It is required that response settles to within 2% of final value for a step input. The settling time is

  20. A.
    20 sec
    B.
    40 sec
    C.
    35 sec
    D.
    45 sec