Guru Gobind Singh Indraprastha Vishwavidyalaya 2007 B.E Mechanical Engineering MEASUREMENT & CONTROL - Question Paper
END TERM exam
FIFTH SEMESTER [B.TECH] – DEC - 2007
MEASUREMENT & CONTROL
(Please write your Exam Roll No.) ,.Exam RoU No.
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How strain gauges are used in diaphragms for .measuring differential pressure? If the radius of a 1.5mm thick metal diaphragm is 5cm and its Youngs Modulus is 1Q6kg/cmi,and its Poisspns ratio, is 0.3 and it. has 4 resistance strain gauges of gauge factor 2 and resistance strain gauges of gauge factor 2 and resistance 120 ohms each bonded to its surface as per the scheme shown below. Derive the values, of tangential and radial stresses at a distance of 1 cm from thejcentre.' (7.5)f'i '
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Q.1 (a) | ||||||
The open loop transfer function of a unity feedback system is G(S) = K/S (ST+1), where K and T are positive constants. How many times the gain should be increased to increase the overshoot from 40% to 60%? (7.5)
(b)
Q.2 (a)
(b)
Why is a cold junction compensation necessary in temperature measuring schemes using thermocouples? What is the recent trend in making such compensation? (7.5)
Given below is the figure shows PD controller used for controlling the system performance. Determine Td to make the system critically damped. Calculate settling time. * (7.5)
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Q.3 (a) What is Reynolds number? How does it come in for flow calculations?
How laminar and non-laminar flows are related to Reynolds number? (7.5) (b) Draw the, root locus of the system whose open loop transfer function is
G(S) Ii(S) ='-----:-. Comment on the stability. Write all the
S(S + 3)(S2 + 3S +11.25)
steps to get the plot. (7.5)
Q.4 (a) Distinguish between sensitivity and precision. Discuss installation errors and equipment errors. How can they be eliminated or minimsed? (7.5)
(b) Determine phase margin for a unity feedback standard second order system? (7.5)
Q.5 (a) Draw the Bode plot for a unity feedback system with
Is. (S + 0.3)
G(S) = ;:7r where K = 2000. Determine Gain margin,
(S + 4) (S2 + 30S + 20)
Phase margin, Gain cross over frequency, Phase cross over frequency, Stability. (7.5)
(b) What is tachogenerator? What is the difference between AC and CD tachogenerator with the help of diagram? (7.5)
Q.6 (a) Draw the Nycjuist plot and discuss the stability of the closed loop system.
G(S) H(S) =-----. (7.5)
S(S + l)(S + 5)
(b) What are compensators? Discuss all the compensators, by comparing
their features. (7.5)
Q.7 (a) Write and explain different classification of transducers. (7.5)
(b) Discuss the application of strain gauges for torsion measurement. (7.5)
Q.8 Write short notes on: - (15)
(a) Ultrasonic Flowmeter
(b) PI and PID Controllers
(c) Application of Thermistors
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