Question Paper: Control System Engineering : Question Paper Jun 2014 - Electronics & Telecomm (Semester 4) | Gujarat Technological University (GTU)
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## Control System Engineering - Jun 2014

### Electronics and Comm. Engg. (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
1 (a) Explain open loop and closed loop control system with suitable example & gives its advantages and disadvantages.(7 marks) 1 (b) Find the transfer function of Fig.1 using Mason's gain formula.
IMAGE
(7 marks)
2 (a) Explain the advantages of state space approach over classical methods and obtain state variable equation.X=AX+BU and CX+DU Also draw the block diagram.(7 marks) 2 (b) Explain Rules for block diagram reduction technique.(7 marks) 2 (c) Write the differential equations for the mechanical system shown in Fig.2. Also obtain an analogous electrical circuit based on force-current analogy.
IMAGE
(7 marks)
3 (a) By means of Routh criterion, determine the stability of the system described by characteristic equations.
(1) S4+2S3+8S2+4S+3=0
(2) 3S4+10S3+5S2+5S+2=0.
(7 marks)
3 (b) Explain following terms with necessary diagrams.
(1) Delay Time (2) Rise Time (3) Peak Time
(4) Steady state error (5) Settling Time.
(7 marks)
3 (c) Explain standard Test signals & derive equation of steady state error.(7 marks) 3 (d) A certain Feedback control system is described by the following transfer Function
G(s) = K / S2 (S+20) (S+30) , H(s) =1
Determine steady state error coefficients & also determine the value of K to limit the steady state error to 10 units due to input r(t) = 1+ 10t+20t2 .
(7 marks)
4 (a) Discuss Nyquist's stability criterion.(7 marks) 4 (b) What are the Bode plots? With necessary diagrams explain the following terms.
(1) Gain cross over frequency
(2) Phase cross over frequency
(3) Gain Margin
(4) Phase Margin.
(7 marks)
4 (c) Sketch the Root Locus of unity feedback control system with G(s) = K/S(S+1)(S+3) and determine the value of K for Marginal stability.(14 marks) 5 (a) Write a short note on thermal system , its modeling and analysis for two different inputs.(7 marks) 5 (b) Explain Rules for construction of Root Locus.(7 marks) 5 (c) What is Transfer function ? Discuss its properties, advantages & disadvantages of it(7 marks) 5 (d) Find Polar Plots of G(s) = 1/ (1+P 1 S) (1+P2 S)(7 marks)