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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 7 Examinations 200 10 / 11
Module Title: Energy Systems Control
Module Code: MECH
School: Engineering (Mechanical Engineering Department)
Programme Title: Bachelor of Science (Honours) in Sustainable Energy Technology
Programme Code: CR_ESENT_8_Y4 / EBESY_8_Y
External Examiner(s): Prof. E. Coyle, Mr. R. Linger Internal Examiner(s): Mr. Conor O’Farrell
Instructions: Answer any 4 from 6. All questions carry equal marks. 25 Marks per question
Duration: 2 Hours
Sitting: Winter 2010
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
Question 1:
(a) Draw a clear and labelled block diagram representing a complete single negative feedback loop. [7 Marks]
(b) Define the term process lag in relation to process control. Illustrate process lag on a fully labelled diagram for a process that experiences a step input change. On the same illustration show a process that experiences the same step input change but also suffers from dead time. [7 Marks]
(c) For a proportional controller
i. What gain corresponds to a PB% of 20% ii. What PB corresponds to a gain of 5? [4 Marks]
(d) In a heat exchange process, steam is transported through a pipe of length d = 132m with uniform cross-sectional area of A = 0.27 m^2. If the dead time in transporting the steam through the pipe is τD = 1.75 s, calculate the flow rate. [7 Marks]
Question 3:
(a) Explain clearly how one would calculate the effect load disturbances have on systems. [5 Marks]
(b) Calculate the relationship between the output C, the input R and the load disturbances N1 , N 2 and N 3 for the system in figure 2.
Figure 2 [10 Marks]
(c) Determine the following for the feedback system in figure 3 in which K 1 and K 2 are constants. i. Open loop Transfer Function ii. Closed loop Transfer Function iii. Error Ratio iv. Primary feedback Ratio v. Characteristic Equation
Figure 3 [10 Marks]
C
R G 1 G 2 G 3
+^ +
N 1 N 2 N 3
K 1 K 2
S(S +P)
R +
E C
K 1 K 2 S
Question 4:
(a) Figure 4 shows the response of a second order underdamped system to a step response. Determine the transfer function parameters for this second order system.
Figure 4 [10 Marks]
(b) A critically damped second order process has a steady state gain of 1 and a natural radiancy of 20 rad/s. It is controlled by a P-Only controller with gain kp using negative feedback. Derive the closed loop transfer function for the system. [10 Marks]
(c) Using the answer from question 4 (b), determine the value of kp if the closed-loop response to a step input is to have a maximum percentage overshoot of 10% [5 Marks]
Question 6:
a) Name the three basic network categories. In terms of distance what is the limitation with respect to LAN networks? Can a single LAN network be used in multiple buildings? What is the fundamental difference between a MAN, LAN and WAN? [6 Marks] b) What does an IP address consist of and what does IP stand for? What determines the network portion and the individual host portion in an IP address? [3 Marks] c) If there is more the one device on a network do they:
- Share the same network number or
- Share the same host number
[1 Marks] d) What portion of the IP address is inherited down through a network hierarchy? [2 Marks] e) Name the 3 classes of IP addresses. Which class can contain the most hosts? [4 Marks] f) What is the difference between a globally routable network IP address and a private network IP address? [4 Marks] g) Why can’t a host with a private IP address communicate with the Internet? How is this problem overcome? [5 Marks]
Laplace Transform of common functions
Time-domain function Laplace domain function f(t) F(s)
0 0 ( )^10 t ut t s
1
C s
C
f ( t d ) e s^ dF ( s ) t 2
1 s
dt
df sF^ (^ s ) f (^0 )
0
( )
t ^ f^^ ^ d ^1 s^ F s ( ) e at s a
1
te at ( )^2
1 s a t (^) e at 2
2 ( )^3
1 s a
t 1 e ( 1 )
1 s s sin t (^2) 2
s cos t s^2 ^2
s
e at sin t ( )^2 ^2
s a e at cos t ( )^2 ^2
s a
s a
