M.Tech. [ 24 103 ] Degree Examination ndustrial Process nstrumentation First Semester COMPUTER CONTROL OF PROCESSES (Effective from the Admitted Batch of2003-2004) Time: 3 Hours Maximum marks: 100 Answer any FVE questions. All questions carry equal marks. 1. a) Explain the concept of state variable feedback with a block diagram and an example. b) The state equations of a linear time-invariant system are represented dx(t) = A x (t) + B utt), by d{ _-=-=- ~j Find the state transition matrix and characteristic equation when A= [: ~5] andb= [:] 2. Explain with a block diagram a computer based data acquisition system with alarm facility required for a process industry wherein 120 analog signals (each 4-20 ma) have to be logged. Give the details of the signal conditioning circuits and interfacing circuits also. 3. a) t is required to start motor A 5 minutes after START, button is pressed, motor B 10 minutes after motor A is started, and motor C 8 minutes after motor B is started. After one hour of combined operation, all the motors should be switched off simultaneously. Give the details of the PLC for this problem including ladder diagram. 1 [p.t.o]
24103 b) Explain why it is necessary to design a digital controller with all of its poles being positive. 4. a) Discuss the significance of (i) sampling time, and (ii) order of hold circuit on the design of digital controllers. b) Explain Kalman's digital control algorithm by means of an example. 5. a) Describe a method of tuning digital P++D controller. b) Explain with a block diagram a self tuning control system in which on-line system identification is used. 6. a) Discuss the merits and demerits of distributed control system over centralised control system. b) Explain the various functions carried out at the following levels of hierarchy in a Des: field level, area control level, plant control level and plant management level. 7. a) What is an industrial computer? List a few industrial computers available in the market. Describe the processing capabilities and other features of industrial computers. b) Explain how personal computers are used for quality control in a process industry. 8. Write short notes on the following: a) Cascade control b) Features of commercial DeS c) Analog and digital subsystems for process control computers [041S/201]
~ [ 24-107 1 M.Tech. Degree Examination ndustrial Process nstrumentation f. First Semester PROCESS DYNAMCS AND CONTROL (Effective from the admitted batch of2007-2008) Time: 3 Hours Maximum marks: 70, Answer any FVE question's. All questions carry equal marks.. ;y) Draw the block diagram of a generalized feedback control system and explain the function of each block. b) A steady heat flow occurs in 1/8 inch thick carbon steel plate with area of 2.0 sq.ft. The temperature drop is from 300 F to 160 F. Calculate the resistance, if thermal conductivity is 29 Btu/ft deg+hr". Derive the expression used to compute the resistance. -2.-a) Describe in detail, the process characteristics of.atypical.vthermal process" and its associated variables. b) Determine the effective time constant for a 2-tank inter-dependent system when the outlet from bottom of the first tank is connected to the bottom of the second and latter discharges to atmosphere, when the tank diameters are 6 ft and the levels are 10ft and 6 ft for a flow of3000 ftyhr., Q) a). Show that a liquid level system can be effectively controlled by using a proportional controller with zero effect for servo problem..l1) Draw schematic and describe how op-amps can be used to implement the proportional, integral and derivative modes of analog contro!. {J a). Describe how do you arrive for optimum controller settings in a rtae system. [p.t.o.}
D [ 24-107 1 ~ n the Ziegler-Nichols method, the critical gain was found to be 4.2, and the critical period 'was 2.21 min. Find the standard settings for (i) propoltiona! mode control, (ii) P control and (iii) Pro control. <i) a) Explain the constructional details and operation of any two control valves. b) An equal percentage valve has a maximum flow of 50 cm 3 /sec and a minimum of2 cmt/sec. lfthe full travel is 3 em, find the flow at a 1 em opening. <, 6. a) Explain briefly the principjes of different types of pneumatic actuators. b) Explain how the saturation ofthe actuator affects the performance of a PD controller. Suggest one scheme for overcoming the problem. Explain its operation. 7. a) Describe the typical dynamic response 6f a controlled variable in an uncompensated feed-forward system. How is lead-lag compensation introduced into the system? b) Are the outer loops in the ~1RAC and STR configurations, offeed forward or feedback nature? 4) Describe the basic controls necessary in distillation process as case study... [09Yi19] -~ 2 r
u,'")' 0 \' y ) u.- -' Q t;o "..r 24-109 ] M.Tech. Degree Examination ndustrial Process nstrumentation First Semester NDUSTRAL NSTRUMENTATON (Effective from the admitted batch 0[2007-2008) Time: 3 Hours Maximum marks: 70 Answer any FVE questions. All questions carry equal marks. 0f,l What is force-balance principle? Differentiate the principle and performance of the following feedback methods in pressure measurement. (8) i) Force-balance and ii) Electrostatic feedback.l1) Explain the functioning of variable gap and variable dielectric type capacitive transducers. Explain suitable circuits for A.C. and D.C. operation. (6) 2. a) Mention the three pressure standards along with their pressure ranges. Describe a method of calibrating a pressure gauge of 0-1 0 kg/ern- range.. (6) 31 Explain with a neat sketch, the working principle of a piezo electric pressure meter. What are the environmental effects that may introduce errors in measurements and how do you OVercomethem? (8),... --- -s, (:0 M' Describe the constructio~ and working principle of a magnetic flow meter. What are its limitations?. (7).9f Why is it recommended to have smaller taper angle for rotameters? Give the relative merits and demerits of variable lead and variable area flow meters. (7). [pto.] _..
1. ~ o afexplain r 24-1091 the installation detajl~ and working of a Doppler type ultrasonic flow meter. Mention its advantages over transit-time type flow meter.. (8)!2Y 1 Explain the principje of operation and applications of a vortex shedding type flow meter. (6) 5. a) Discuss a scheme of monitoring the flow in an oil pipe-line transporting different petroleum products along the same line at =-different times. Choose an appropriate transducer and signal conditioning circuitry and indicate the design procedure in detail and explain its operation. (8) b) Discuss the working principle of a Turbine type flow meter with a neat sketch. State its drawbacks. (6) @).a1 Explain the basic principle of ultrasonic radiation and microwave sensors for the measurement of liquid leyels. Describe anyone method with a neat schematic diagram. '" ',';, (8) b) Describe a capacitance method or-measurement of powder level in a'pharmaceutical industry. (6) 7, a) What is a local cell? Explain how do you measure static and dynamic forces using load cell. (8) b) Design a -strain gauge load cell of cantilever type capable of measuring a force of 5 N with an accuracy of 5% given that the gauge factor is 2, battery voltage 6 V, the cantilever is made of mild steel and the read out resolution is 10-2 V. (6) 8. Write short notes on the following: Ji1C pressure sensors, (3) b) NMR mass flow meter. (4) c) Hydraulic loadcell. (3) fidiaphragms and bellows for the measurement of levels, (4) 2 [09 1S/19]
/ r 24-106 1 M.Tech. Degree Examination ndustrial Process nstrumentation!first Semester TRANSDUCERS AND MEASUREMENTS (Effective from the admitted batchof2007-2008) Time: 3 Hours Maximum marks: 70 Answer any FNE questions. Allquestions carry equal marks. 1. a) Give the step response of a second order instrument and explain. (4) b? Elaborate on the static and dynamic characteristics of instruments. (4) c) A second order instrument is subjected to a sinusoidal input. Undamped natural frequency is 3 Hz and the damping ratio is 0.5. Caleulate the amplitude ratio and phase angle for an input frequency of2 Hz. (6) 2. a1 What are the effects of temperature changes on a strain gauge? How do you compensate for the effects? (6) b) Two active strain gauges are connected in series in one of the arms of a Wheatstone bridge network. The bridge is adjusted initially for balance. Assuming both the strain gauges are to be identical, derive the sensitivity of the bridge. Discuss the salient features of this arrangement. (8) 3. ~ Explain the basic principle of temperature measurement using thermocouple. What materials are used for construction of thermocouples? Discuss their properties. (8) b) A thermistor has a resistance of 3980 ohms at the ice point (O C) and 794 ohms at 50 C. Calculate the constants 'a' and 'b'. Calculate the range of resistance to be measured in case the temperature varies from 40 C to 100 C, (6) [pto.] : ; ~;;
{ 24-106 1 4'. M What are piezo electric transducers? Explain the modes of operation of a piezo electric force transducer with a neat sketch. (8). b) A quartz piezo electric crystal having a thickness of 2 mm and ~ voltage sensitivity 0[0.055 V-mfN is subjected to a pressure of 1.5 MN/m 2 Calculate the voltage output. ffthe permittivity of quartz is 40.6 x J 0-12 Flm, calculate its charge sensitivity. (6) 5. a) Explain the pulse-cooling technique adopted in an industry to measure the temperature of a hot gas with necessary diagrams and equations. (8) b) Derive the necessary expression for the dynamic response of a manometer for laminar flow case and discuss the result obtained. (6) 6. a) Explain Hall effect and show how this effect may be used for measurement of (i) magnetic fields, (ii) high currents and (iii) electrical power.. (8) b) What is.meant by magnetostriction? What are the merits of magnetostriction transducers? Outline the constructional features and principle of working of a magnetostrictive transducer for the measurement of force. (6) 7'. a) What is the basic difference in the characteristics of ionization chambers on one hand and radioactivd pulse counters on the other? Explain the principle of operation of an' ionization chamber. (6) b) Distinguish clearly between photo emissive, photo conductive and photo-voltaic phenomena and indicate one application of each and explain their operation. (8) 8. Write short notes on the following: a) Frequency modulated and frequency generated transducers. (5)..})) Digital transducers.. (4) o Bourdon tube and its applications. (5) 2 [09 Y/9]