Typical specifications for design stipulates the gain margin and phase margin to be respectively__________________?

Related Mcqs:

1. Suppose that the gain, time constant and dead time of a process with the following transfer function: Gc(s) = 10 exp( – 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as________________?

   A. 8, 0.6, 0.08
   B. 12, 0.6, 0.12
   C. 8, 0.6, 0.12
   D. 12, 0.4, 0.08

2. A negative gain margin expressed in decibels means a/an ____________ system?

   A. Stable
   B. Unstable
   C. Critically damped
   D. None of these

3. Gain margin is equal to the_________________?

   A. Amplitude ratio
   B. Reciprocal of amplitude ratio
   C. Gain in P controller
   D. Gain in P-I controller

4. The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is________________?

   A. 5π/12
   B. π/6
   C. π/12
   D. π/3

5. Phase margin is equal to_______________?

   A. 180° – phase lag
   B. Phase lag – 180°
   C. Phase lag + 180°
   D. Phase lag + 90°

6. The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function ?

   A. e-ηS
   B. (T1S + 1)/(T2S + 1)
   C. (T1S/(T2S + 1)
   D. (T1S + 1)/(T2S

7. A typical example of a physical system with under damped characteristic is a____________________?

   A. U-tube manometer
   B. Spring loaded diaphragm valve
   C. CSTR with first order reaction
   D. Thermocouple kept immersed in a liquid filled thermowell

8. Find the ultimate gain and frequency for a proportional controller in the case of a process having the transfer function Gp(s) = 1/(4s + 1)(2s + 1)(s + 1) ?

   A. w = 1/√14, Kc = 45/7 √14
   B. w = √(7/6), Kc = 46/3
   C. w = 1, Kc = 13
   D. w = √(7/8), Kc = 45/4

9. The offset introduced by proportional controller with gain Kc in response of first order system can be reduced by ____________________?

   A. Reducing value of Kc
   B. Introducing integral control
   C. Introducing derivative control
   D. None of the above

10. A first order system with unity gain and time constant η is subjected to a sinusoidal input of frequency w = 1/η. The amplitude ratio for this system is______________?

    A. 1
    B. 0.5
    C. 1/√2
    D. 0.25