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) ?

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. In a closed loop system, the process to be controlled is an integrating process with transfer function 1/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit__________________?

   A. Overdamped response
   B. Underdamped response
   C. Undamped response
   D. Unstable response

3. An ideal PID controller has the transfer function [1 + (1/0.55) + 0.25]. The frequency at which the magnitude ratio of the controller is 1, is________________?

   A. 0.5/0.2
   B. 0.2/0.5
   C. 0.2 × 0.5
   D. 1/√(0.2 × 0.5)

4. A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if________________?

   A. Kc is reduced
   B. Kc is increased
   C. Integral control action is introduced
   D. Derivative control action is introduced

5. The transfer function for an ideal proportional plus reset controller (reset time T) is_______________?

   A. Kc[1 + (1/TS)]
   B. Kc(1 + TS)
   C. Kc/(1 + TS)
   D. Kc/[1 + (s/T)]

6. 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

7. 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

8. The transfer function for a PID controller is (where, η i is the integral (reset) time and ηD is the derivative time.) ?

   A. Kc(1 + ηis + ηD ). s
   B. Kc[1 + (1/ηis) + ηD . s)
   C. Kc(1 + ηis + (1/ηD . s)
   D. None of these

9. The transfer function for a P-D controller is________________?

   A. Kc(1+ηD s)
   B. Kc(1 +1/ηD s)
   C. Kc ηD s
   D. Kc/ηD s

10. 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