- Sketch the transient response characteristics of
- a bare thermocouple
- a shielded thermocouple.
- Discuss the manometer dynamics with respect to the damping coefficient. On what physical parameters of the manometer does this coefficient depend?
- Draw the block diagram of a control system illustrating a cascade control loop. Explain its purpose.
- Discuss on the criteria for specifying the control and controller settings.
- Draw the instrumentation flow diagram for a shell and tube heat exchanger. State the importance of such diagrams.
- With a neat sketch, explain the working of a proportional plus derivative mode of control. Why the derivative controller cannot be used independently.
- Show by plot the transient output response of a derivative controller when it has been disturbed by
- Linear input
- Sinusoidal input
- Step input
- Write short notes on the dynamic behavior and dynamic characteristics of an instrument.
- Explain the terms 'amplitude ratio', 'proportional band', 'transducer', 'distance velocity lag' and 'offset'.
- Describe how proportional plus integral action can be generated in a pneumatic controller. State under what circumstances it is an advantage to use this combination. Under what conditions would you prefer to replace the integral by derivative action?
- State and explain Ziegler-Nichols rules for controller settings.
- Name and define all the basic elements of a control system and show in a block diagram their positions in the closed-loop which forms the system. Indicate where and how time lags can arise in the system and explain how they add to the difficulty of control.
- Give one example each of a system with zero order and first order dynamics. Derive the transfer function of a first order system.
- Discuss the merits and demerits in using hydraulic, pneumatic and electric control system in process control.
- Explain, what is meant by the terms 'capacity lag', 'transfer lag', 'transportation lag' and 'dead time'.
- Explain with the help of a control circuit, how temperature of water in a shell and tube heat exchanger, heated by hot oil (shell side) can be controlled.
- Explain how an on-off controller having no differential gap, is used to control liquid level in a tank and indicate the draw backs.
- Discuss the factors that are to be considered in choosing a feed back or feed forward controller in process control.
- Explain with the help of a neat sketch, the working of a pneumatic proportional plus integral (PI) controller to control temperature in a process.
- Write the expression for proportional (P), proportional plus integral (PI), proportional plus derivative (PD) and proportional plus integral plus derivative (PID) control actions and explain the terms used therein.
- Derive an expression for the step response in inlet flow rate to two non-inter acting tanks in series with equal time constant.
- Consider a chemical reactor in which a reaction takes place. Make a dynamic analysis of the system. Setup the block diagram.