Engineering Answers

c) A process of unknown transfer function is subjected to unit impulse input. The process output is measured accurately and is found to be represented by Y(t)= te^t.Derive unit step response of the process.

b) The dynamic model of the tank has to be written for the given process. The objective of mixing is to cool the hot water stream entering into the tank at a flow rate of q: and feed temperature of T, with a cooled water stream entering into the tank with a flow rate of q₁ and feed temperature of To. A stream is drawn from the tank. bottom at flow rate of q, by the pump and the level in the tank is proposed to be controlled by drawing another water stream at flow rate of q. Neglect evaporation losses from the tank.

a) The tank having a cross sectional area of 100 cm² and the inlet flow rate (Qi, in cm³/s), the output flow rate (Qo in cm³ /s) is related to liquid height linearly as Q=3H^0.5, then derive the transfer function of the process around the steady state Qi,s=18 cm³/s and Hs₁=36 cm

A second order process with the transfer function KpGp(s) = 1/S²+2S+3 is controlled with a proportional integral controller. If all the other lags in the control loop are negligible and their steady state gains are equal to unity, find the relation between the parameters of the controller that should be satisfied for the control system to be stable.

State Bode stability criterion and define gain and phase margin.

feedback control loop with a proportional controller has an open loop transfer function GOL = Kc/S(5S+1)²where time is in minutes. Tune for PID controller using Zeigler Nicholas settings.

liquid flows through an equal percentage valve at a rate of 4m^3/h and valve is 25% open. When the valve opens to 50%, the flow rate increases to 8m^3/h. Assume that the pressure drop across the valve and the density of the liquid remains constant whe the valve opens at 70%, find the flow rate.

For the above problem, using the Ziegler- Nicholas settings, find the parameters for proportional integral controller

a. Kc= 0.5, τ1=10.47. b. Kc=0.38,τ1=10.47

c. Kc=0.5, τ1=10.9

d. Kc=0.364, τ1=10.47

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