Chemical Engineering Answers

Consider the following transfer function Gp=S/(2S+1)^4 the time constant is in seconds. The crossover frequency of the process in rad's is

a. 20 b. 0.1

c. 0.5

d. 0.05

Which of the following is more sensitive to errors in the process loop

a. Feed backward controllers b. Feed forward controllers

c.Ratio controllers. d. Cascade controllers

Which of the following controller is preferred in secondary controller of cascade control system

a. P

b. Pl c. PID

d. Any of the above can be used

Bode stability criterion is applied only when

a. Gain and phase curve decreases continuously with frequency. b. Gain curve increases and phase curve decreases with frequency

c. Gain curve and phase curve both increases with frequency

d. Gain curve decreases and phase curve increases with frequency.

If one of the poles of open loop transfer function lies on the origin, then the response is

a. Oscillations with decreasing amplitude b. Oscillations with increasing amplitude

c. Oscillations with constant amplitude

d. None of these

Using the data of above equation, the steady state gain is

a. Infinite

b. Zero

c. Any finite value d. None of these

The response of the process reaction curve for a step change of magnitude of 2.5 in the input is given as ym(t)= e^-{3t}(1-3t), then the slope at the point of inflection is

a. 0.00402 b. 0.149

c. 1.05 d. None of these

6 Which of the following gives robust tuning parameters. a. Integral of square error

b. Integral of absolute value of error

c. Integral of time weighted absolute error

d. None of these

The characteristic equation for a system is S^3 +9S² +26S +12(2+ Kc)=0, using

Routh test, the value of Kc that will keep system on the verge of instability

a, 20.9

b. 18.4

c.17.5

d. 15.3.

The closed loop pole of a stable second order system could be

A. Both real and positive

B. Complex conjugate with positive real parts

C. Both real and negative

D. One real positive and the other real negative