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Reg. No. : ..................................... Name : ..........................................
Third Semester B.Tech. Degree Examination, November 2009 (2003 Scheme) Branch : Computer Science 03.306 : CONTROL AND INSTRUMENTATION (R) Time : 3 Hours
Max. Marks : 100
Instruction: Answer all questions. PART â€“ A 1. Define transfer function. 2. What is a signal flow graph ? How is it different from block diagram ? Explain with an example. 3. The characteristic equation of a feedback control system is S5 + S4 + 4S3 + 4S2 + 2S + 1 = 0. Check the stability of the system. 4. Discuss briefly the effect of damping ratio on the transient response of a secondorder system. 5. What do you understand by steady state error of a system ? 6. Define the typical test signals used to determine the time response of a system. 7. Explain the Nyquist stability criterion. 8. Enumerate the various sources of error encountered in a measurement system. 9. How an instrument can be calibrated ? 10. Sketch a pressure sensor and explain its working.
(10Ă—4=40 Marks) P.T.O.
PART – B Module – I 11. a) Distinguish between an open-loop and a closed-loop control system with a suitable example of each case. Critically discuss the advantages and disadvantages of open-loop and closed-loop systems. b) Obtain the mathematical model for the following mechanical system and determine the transfer function.
OR 12. a) Using suitable illustration, explain how feedback loops are eliminated in block diagram. b) Reduce the given block diagram and obtain the transfer function.
Module – II 13. a) What are generalized error coefficients ? Give the relationship between generalized error coefficients and static error coefficients.
b) Find the range of K for closed loop stability and the value of K for marginal stability for the following control system.
OR 14. a) For a general second-order system, derive expressions for peak resonance and bandwidth. b) A negative feedback control system is characterized by G (S) =
K , H(S) = 1. S(S + A )
Find the values of ‘K’ and ‘A’ so that peak resonance, Mr = 1.04 and resonant frequency, Wr = 11.55 rad/sec. For the values of ‘K’ and ‘A’ determined, calculate the settling time and the bandwidth of the system. Module – III 15. a) What is the difference between accuracy and precision ? b) Explain in short how a thermistor differs from a thermocouple as a temperature sensor. c) Describe with a diagram how the flow rate of liquids can be measured by electromagnetic flow meter. OR 16. a) What is a transducer ? What is the difference between active and passive transducers ? Name some of the active transducers which are used in the measurement system. b) Explain with the help of diagrams, the principle of operation of : i) Photoelectric transducers ii) Digital transducers iii) LVDT iv) Platinum resistance thermometer. (3×20=60 Marks) —————————