INSTRUMENTATION & PROCESS CONTROL Question Papers (Regular, 2006)

SET : 1

1. Name five flow laws relating to fluids, heat & electricity and state these laws.
2. Repeated
3. Repeated
4. Repeated
5. Repeated
6. Explain the baffle – nozzle system with the help of its characteristic curves.

Explain the pneumatic booster & what is its need.

Differentiate between direct & reverse action final control operation

7. The area of opening a valve versus left is given by A = a + bx2. Derive the flow versus left characteristic for this parabolic valve.

Liquid glycerine (density 78lb/ft3) is required at maximum flow of 18gpm. The line drop is 40psi and the valve. Pressure drop is 10psi. what size plug valve is required.

8. How do you select the desired value of ratio in the ratio control system.

Explain the ratio control system with respect to :

a) Distillation column

b) Exit vapour stream.

SET : 2

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 step response of this process.
2. Repeat
3. Discuss the effects of an integral controller on the closed loop response of first order process.

With neat sketches, explain the principle of derivative control action. Summarize its characteristics.

4. Repeat
5. A proportional – integral controller is used on a pure time delay process. Calculate the response to a step change in load if the controller gain is half the maximum value and the reset time is half the time delay. Calculate the integral of the absolute error.

Suggest & explain the control schemes for better control of process with dead time.

6. Repeat
7. Distinguish different types of butterfly valves.

Mention which are the rotating shaft valves.

8. Explain the principles of cascade control tuning.

State the fundamental difference between feed forward and conventional feedback control.

SET : 3

1. A pressure vessel connected as shown in below figure has a supply pressure u1 of 45 psig, a vessel pressure of 15 psig and an air to atmosphere. The average flow rate is 1 pounds per minute & the vessel volume is 0.3 cubic meter.

Calculate the time constant.

Derive and calculate the system function.

2. Differentiate between a servo problem and regulator operation

Give a typical example for servo operation and explain.

Explain regulator operation and explain.

3. With an example explain how offset error can be eliminated with an integral controller.

With an illustration explain the response of an integral controller to a constant error. Show the effect of integral time on the response.

4. Explain with a neat sketch, the working principle of a displacement type pneumatic proportional controller. Discuss the effect of adding the negative feed back.

With necessary diagrams describe a hydraulic integral controller. Explain how integral time can be adjusted.

5. Repeat
6. A feed hopper requires 30 lb of force to open. Find the pneumatic actuator area to provide this force from a 9 psi input signal.

A hydraulic system uses positions of diameter 2cm & 30cm. what pneumatic pressure is required an the small piston to produce the necessary force.

7. Repeat
8. What control strategy is needed for improved performance when input of a process affected by significant disturbance.

What is compensation in a closed operation. Explain with neat diagram.

SET : 4

1. Derive the process differential equations and the transfer function for the following two capacity level process as shown in figure.

This level system is an interacting system. Say true or false. Support your answer.

Define the system time constants of the above process.

2. Differentiate between a non interacting system and an interacting system.

Give an example each of non-interacting system & interacting system.

Derive transfer functions for the above 2 systems and discuss how they differ.

3. Repeat.
4. With a neat sketch explain the realization of electronic single speed floating controller. How realization rate can be adjusted in such a controller?

State the kind of control action realized in the following circuit figure 3. Also determine the input output relationship.

5. Repeat
6. Give the principle of the control valve and give its output equation.

A pressure difference of 1.5 Psi across a construction in a 4cm diameter pipe. The construction constant is 6.008 w³/s/(Kpa)^1/2.

Find 1) flow rate in m³/sec 2) flow velocity in m/sec

7. Repeat
8. Explain the principles of ratio control with the suitable examples.