Instrumentation and Control Systems

Aims

This book has the aims of covering the new specification of the Edexcel Level 4 BTEC units of Instrumentation and Control Principles and Control Systems and Automation for the Higher National Certificates and Diplomas in Engineering and also providing a basic introduction to instrumentation and control systems for undergraduates. The book aims to give an appreciation of the principles of industrial instrumentation and an insight into the principles involved in control engineering. 

Structure of the book

The book has been designed to give a clear exposition and guide readers through the principles involved in the design and use of instrumentation and control systems, reviewing background principles where necessary. Each chapter includes worked examples, multiple-choice questions and problems; answers are supplied to all questions and problems. There are numerous case studies in the text and application notes indicating applications of the principles.

Coverage of Edexcel units

Basically, the Edexcel unit Instrumentation and Control Principles is covered by chapters 1 to 6 with the unit Control Systems and Automation being covered by chapters 8 to 13 with chapter 5 including the overlap between the two units. Chapter 7 on PLCs is included to broaden the coverage of the book from these units.

Performance outcomes

The following indicate the outcomes for which each chapter has been planned. At the end of the chapters the reader should be able to:

Chapter 1: Measurement systems Read and interpret performance terminology used in the specifications of instrumentation.

Chapter 2: Instrumentation system elements Describe and evaluate sensors, signal processing and display elements commonly used with instrumentation used in the measurement of position, rotational speed, pressure, flow, liquid level and temperature.

Chapter 3: Instrumentation case studies Explain how system elements are combined in instrumentation for some commonly encountered measurements.

Chapter4:

Control systems Explain what is meant by open and closed-loop control systems, the differences in performance between such systems and explain the principles involved in some simple examples of such systems.

Chapter 5: Process controllers Describe the function and terminology of a process controller and the use of proportional, derivative and integral control laws. Explain PID control and how such a controller can be tuned. Chapter

6: Correction elements Describe common forms of correction/regulating elements used in control systems. Describe the forms of commonly used pneumatic/hydraulic and electric correction elements.

Chapter 7: PLC systems Describe the functions of logic gates and the use of truth tables. Describe the basic elements involved with PLC systems and devise programs for them to carry out simple control tasks.

Chapter 8: System models Explain how models for physical systems can be constructed in terms of simple building blocks.

Chapter 9: Transfer function Define the term transfer function and explain how it used to relate outputs to inputs for systems. Use block diagram simplification techniques to aid in the evaluation of the overall transfer function of a number of system elements.

Chapter 10: System response Use Laplace transforms to determine the response of systems to common forms of inputs. Use system parameters to describe the performance of systems when subject to a step input. Analyze systems and obtain values for system parameters. Explain the properties determining the stability of systems.

Chapter 11: Frequency response Explain how the frequency response function can be obtained for a system from its transfer function. Construct Bode plots from a knowledge of the transfer function. Use Bode plots for first and second-order systems to describe their frequency response. Use practically obtained Bode plots to deduce the form of the transfer function of a system. Compare compensation techniques.

Chapter 12: Nyquist diagrams Draw and interpret Nyquist diagrams. Chapter 13: Controllers Explain the reasons for the choices of P, PI or PID controllers. Explain the effect of dead time on the behavior of a control system. Explain the uses of cascade control and feedforward control.