CAT: PROCESSES DYNAMIC AND CONTROL
Answer all questions to be submitted before Wednesday 11 at 12.00 may 2022
Question 1
On the graph paper provided, sketch the Bode plot for the transfer function and state the stability.
𝐻(𝑠) =
(𝑠+20)(𝑠+1)
𝑠2 (𝑠+500)
10mrks
Question 2
The dynamic behaviour of temperature in an electrically heated tank can be expressed by the
following differential equation
𝑑2𝑇
𝑑𝑇
+
1.2
+ 0.16𝑇 = 0.1𝑄
𝑑𝑡 2
𝑑𝑡
where Q and T are the input and output respectively. Assume that initial conditions at 𝑡 = 0 and
T=0, Determine the damping coefficient, undamped natural frequency and process gain of the
system. Also determine the rise time tr, peak time tp, maximum overshoot Mp, and settling time
2% and 5% criterion ts when the system is subjected to a unit-step input. 10marks
Question 5
The following data table 1 was obtained by a Process Engineer who subjected equipment to a step
function of 20 units. The Engineer wanted to determine the transfer function of the equipment and
the best control parameters.
Time
0
2
4
6
8 10 12 14
16 18 20 22
variable
0 0.1 0.5
3
6
9 12 14 14.5 15 15 15
Table 1: Time verse change in process variable.
Using Ziegler-Nichols method, determine transfer function of the system and the best PI control
Parameters. 10 marks