R05322304-instrumentation-and-process-control

Set No. 1

Code No: R05322304

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. A process of unknown transfer function is subjected to a unit impulse input. The output of the process is measured accurately and is found to be represented by the function. Y (t) = t e−t Determine the unit step response of this process. [16] 2. (a) Distinguish between interacting and non-interacting systems with examples. (b) Write the differential equations for the interacting and non-interacting Systems. [8+8] 3. (a) An open loop transient response test shows a temperature system to have an apparent dead time L of 0.8 min, a reaction rate N of 0.5 degrees per minute and a process ultimate temperature change K of 10 degrees for a change in manipulated variable M of 10% of valve setting. Calculate the proportional sensitivity for proportional control. (b) For a process with R = 0.5, what is the decrease in period of oscillation if derivative control is used with proportional control. [8+8] 4. (a) Explain briefly the principle of operation of a displacement type pneumatic PD controller. How the derivative time can be adjusted in this controller. (b) Explain the principle of electronic proportional integral controller.

[8+8]

5. (a) What control strategy is needed for improved performance when input and output of a process affected by significant disturbance? (b) What is compensation in a closed operation? Explain with neat diagram. [8+8] 6. Illustrate with relavant graphs the following methods of optimum settings from the plant response (a) Reaction-curve method (b) Damped oscillation method

[8+8]

7. What are different types of actuators used in final control element? Explain about electrical actuator with a neat diagram? [16] 8. Explain the primary and secondary loop gain adjustment in a cascade control system? [16] 1 of 2

Set No. 1

Code No: R05322304 ⋆⋆⋆⋆⋆

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Set No. 2

Code No: R05322304

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Write the relations of time constant with process parameters with reference to mercury thermometer, liquid level and pressure processes. Do not derive. (b) An open loop cylindrical tank 1.2m in diameter is filled with water to a depth of 0.9 meter. The water flows out through a 2 inch control valve at an average rate of 0.136m3 per min. If the input is increased from 0.136 to 0.182 m3 /min, what is the new depth in the tank and about how long will it take to accomplish 95% of the change in level. [6+10] 2. (a) Explain transportation lag and derive its tansfer function. (b) Explain the under damped, over damped and critically damped responses for a step input with necessary plots. [7+9] 3. (a) An open loop transient response test shows a temperature system to have an apparent dead time L of 0.8 min, a reaction rate N of 0.5 degrees per minute and a process ultimate temperature change K of 10 degrees for a change in manipulated variable M of 10% of valve setting. Calculate the proportional sensitivity for proportional control. (b) For a process with R = 0.5, what is the decrease in period of oscillation if derivative control is used with proportional control. [8+8] 4. (a) Explain briefly the principle of operation of a displacement type pneumatic PD controller. How the derivative time can be adjusted in this controller. (b) Explain the principle of electronic proportional integral controller.

[8+8]

5. Sketch the reaction curve for a process with one time constant and one time delay. Use the Ziegler-Nichols method to obtain the optimum settings of a three mode controller for the ratios L/T = 0.1, 0.3, 1 and 3. [16] 6. Explain the detailed procedure for Ziegler-Nichols method PID Settings

[16]

7. What is meant by pressure to close action? & pressure to open action? Explain about double seated valve with a neat diagram? [16] 8. What is multivariable control? What are its merits & demerits? ⋆⋆⋆⋆⋆

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[16]

Set No. 3

Code No: R05322304

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Show that the mercury thermometer, which is suddenly immersed in hot water at some temperature, will follow first order dynamics. (b) A thermometer which is at 500 C initially is immersed in a bath maintained at 800 C at t=0. Determine the temperature reading at 1.0 min and 1.2 min. [8+8] 2. (a) Write the differential equations of the following liquid level process and derive the transfer function of the system as shown in figure 2a.

Figure 2a (b) What is the order of the system? (c) How is the order determined?

[12+2+2]

3. A PID controller is at steady state with an output pressure of a 9 psig. The set point and pen point are initially together. At time t=0, the set point is moved away from pen point at a rate of 0.5 in/min. The motion of the set point is in the direction of lower readings. The settings are Kc =2 psig/inch of pen travel, τ1 =1.25 minute and τd = 0.4min. Plot the output pressure vs time. [16] 4. Describe the mechanism of hydraulic proportional controller and hydraulic proportional integral controller with neat sketches and equations. [8+8] 5. Write a short notes on 1 of 2

Set No. 3

Code No: R05322304 (a) Continuous cycling method (b) Reaction curve method

[8+8]

6. Discuss process reaction method for control loop tuning?

[16]

7. What are different types of final control element? Explain a pneumatic actuator with diagram? [16] 8. Write short note on (a) Multivariable control system (b) Ratio control (c) Split range control system.

[5+6+5] ⋆⋆⋆⋆⋆

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Set No. 4

Code No: R05322304

III B.Tech Supplimentary Examinations, Aug/Sep 2008 INSTRUMENTATION AND PROCESS CONTROL (Bio-Technology) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Define time constant of a system. Write the expression for the time constant in terms of the process parameters of a liquid level system. (b) A tank operating at 3 meter head and 0.022m3 /min outflow through valve has a cross section area of 0.9 m2 . Calculate the time constant. (c) If this system requires 5minutes to indicate 98% of the response, what will be the time constant? [4+6+6] 2. Detemine the transfer function H(s)/Q(s) for the non-interacting liquid level system in the figure 2 . The resistances R1 and R2 are linear.The flow rate from tank3 is maintained constant at b by means of a pump. [16]

Figure 2 3. A PID controller is at steady state with an output pressure of a 9 psig. The set point and pen point are initially together. At time t=0, the set point is moved away from pen point at a rate of 0.5 in/min. The motion of the set point is in the direction of lower readings. The settings are Kc =2 psig/inch of pen travel, τ1 =1.25 minute and τd = 0.4min. Plot the output pressure vs time. [16] 1 of 2

Set No. 4

Code No: R05322304

4. (a) Explain the principle of operation of a force type pneumatic proportional controller. (b) A proportional pneumatic controller has equal area bellows. If 3-15psi signals are used on input and output, find the ratio of pivot distances that provides 25% proportional band. [8+8] 5. Write a short notes on (a) Integral square error (b) Integral absolute error (c) Integral time weighted absolute error.

[4+5+7]

6. Discuss typical control system used to study the effect of control modes on various load responses and sketch load response of a typical control system using various modes of control? [16] 7. What are different types of actuators used in final control element? Explain about electrical actuator with a neat diagram? [16] 8. Write short note on (a) Multivariable control system (b) Ratio control (c) Split range control system.

[5+6+5] ⋆⋆⋆⋆⋆

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