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Reliability in instrumentation and control
282
Book reviews
Reliability in Instrumentation and Control. By J. C. Cluley. Butterworth-Heinemann Ltd, Oxford, 1993. ISBN 0-7506-0737-8.
Automatic control systems are increasingly used in situations where failures can result in serious risk to human life, therefore demanding very high reliability. Public awareness of these risks is also increasing, particularly in regard to the generation of electricity using nuclear power and the processing of dangerous chemicals. The stated purpose of this book is to provide an understanding of all of the main factors which affect reliability in instrumentation and control systems. It is intended for practicing engineers involved with such systems, as well as for students in system and component reliability courses. There are 12 chapters in the book, which are intended to address the reliability of a system throughout its specification, design, construction and maintenance. Short descriptions of each of the chapters follow (the numbers in parentheses refer to the number of pages in each chapter):
1. Introduction to control systems (lOpp). This chapter provides a basic introduction to closed-loop, feedback control systems. It discusses methods of data storage and transmission, signal processing and power amplification, and technologies for measuring, displaying and recording data. Both analogue and microprocessor-based systems are considered 2. Reliability principles and terminology (12pp). This chapter defines reliability, availability and MTBF, and provides example calculations of the reliability of some simple compound systems using block diagrams. The Poisson and exponential probability distributions are also introduced. Several factors which must be taken into account when specifying operating conditions are listed, and a discussion of factors affecting the optimum level of reliability for a system (such as cost, regulations, etc.) is presented. 3. Reliability assessment (17pp). This chapter deals primarily with the failure rates and failure modes of individual components and introduces the concept of the bathtub curve. Because the book concerns itself primarily with electronic components, fairly detailed discussions are presented concerning the estimation of component temperatures, the effect of temperature on component failure rates, and the effect of operating voltage on component failure rates. Accelerated life testing, component and assembly screening, environmental testing and the concept of confidence intervals are also discussed. The estimation of system failure rates is then presented using the block diagram methods of the previous chapter. However, the analysis of common cause failures is ignored.
4. System design (13pp). This consists primarily of a discussion of the reliability and performance aspects of analogue versus digital signal processing. The chapter deals with performance margins, tolerances, temperature effects, and sneak circuits. Automated design and testing are also briefly discussed. 5. Building high-reliability systems (12pp). This chapter discusses the establishment of reliability targets and documents standards for electronic components. The use of redundancy is discussed and a fairly detailed discussion of majority voting circuits is also presented. Common mode faults are also mentioned in this regard, but are treated solely as a design consideration; no guidance is offered on common cause failure analysis. 6. The human operator in control and instrumentation (12pp). This provides a discussion of the tradeoffs in reliability and performance with human operators versus automatic control. Particular attention is paid to user friendly design, visual displays, and safety procedures. 7. Safety monitoring (Spp). Catastrophic versus degradation failures, safety monitoring systems, and 'fail-safe' versus 'fail-dangerous' errors are discussed. Topics involved in the design of fail-safe systems, such as relay tripping circuits and circuit fault analysis, are also discussed. 8. Software reliability (16pp). Due to the increasing use of computers in instrumentation and control systems, a fair amount of attention is paid to the issue of software reliability. Several topics involved with the design of highly reliable software, such as structured programming, specification languages and fault tolerance, are discussed at some length. However, the analysis methods discussed are limited to the estimation of fault density and reliability growth models associated with testing. Software fault trees and formal proofs are not discussed. 9. Data transmission (7pp). This chapter discusses the reliability of analogue transducers, analogue signal transmission, data validation, and the detection and correction of errors in digitally codes signals. Redundant data links are also briefly discussed. 10. Electronic and avionic systems (llpp); 11. Nuclear reactor control systems (13pp), 12. Process and plant control (13pp). The last three chapters present applications of the concepts introduced in the book to instrumentation and control systems in a variety of industries. Examples include radio transmitters, satellite links, aircraft control systems, railway signaling and control, robotic systems, nuclear reactor control, reactor protection logic, chemical plants and oil platforms. The book provides a fairly broad, comprehensive overview of the topics involved in the reliability of instrumentation and control systems in a variety of
Book reviews industries. However, it does not present these subjects in sufficient detail to permit one who was previously unfamiliar with these techniques to be able to apply them directly, nor is it likely to be useful as a classroom textbook. Nevertheless, as introductory material for risk analysts who are unfamiliar with the reliability characteristics of electronic components or for conventional engineers who are unfamiliar with risk assessment techniques, this book is both an informative and enjoyable read, well organized and
well written investigation.
283 with
ample
references
for
further
C. J. Garrett Mechanical Aerospace and Nuclear Engineering Department University of California Los Angeles, CA 90024-1597 USA
Book reviews
Reliability in Instrumentation and Control. By J. C. Cluley. Butterworth-Heinemann Ltd, Oxford, 1993. ISBN 0-7506-0737-8.
Automatic control systems are increasingly used in situations where failures can result in serious risk to human life, therefore demanding very high reliability. Public awareness of these risks is also increasing, particularly in regard to the generation of electricity using nuclear power and the processing of dangerous chemicals. The stated purpose of this book is to provide an understanding of all of the main factors which affect reliability in instrumentation and control systems. It is intended for practicing engineers involved with such systems, as well as for students in system and component reliability courses. There are 12 chapters in the book, which are intended to address the reliability of a system throughout its specification, design, construction and maintenance. Short descriptions of each of the chapters follow (the numbers in parentheses refer to the number of pages in each chapter):
1. Introduction to control systems (lOpp). This chapter provides a basic introduction to closed-loop, feedback control systems. It discusses methods of data storage and transmission, signal processing and power amplification, and technologies for measuring, displaying and recording data. Both analogue and microprocessor-based systems are considered 2. Reliability principles and terminology (12pp). This chapter defines reliability, availability and MTBF, and provides example calculations of the reliability of some simple compound systems using block diagrams. The Poisson and exponential probability distributions are also introduced. Several factors which must be taken into account when specifying operating conditions are listed, and a discussion of factors affecting the optimum level of reliability for a system (such as cost, regulations, etc.) is presented. 3. Reliability assessment (17pp). This chapter deals primarily with the failure rates and failure modes of individual components and introduces the concept of the bathtub curve. Because the book concerns itself primarily with electronic components, fairly detailed discussions are presented concerning the estimation of component temperatures, the effect of temperature on component failure rates, and the effect of operating voltage on component failure rates. Accelerated life testing, component and assembly screening, environmental testing and the concept of confidence intervals are also discussed. The estimation of system failure rates is then presented using the block diagram methods of the previous chapter. However, the analysis of common cause failures is ignored.
4. System design (13pp). This consists primarily of a discussion of the reliability and performance aspects of analogue versus digital signal processing. The chapter deals with performance margins, tolerances, temperature effects, and sneak circuits. Automated design and testing are also briefly discussed. 5. Building high-reliability systems (12pp). This chapter discusses the establishment of reliability targets and documents standards for electronic components. The use of redundancy is discussed and a fairly detailed discussion of majority voting circuits is also presented. Common mode faults are also mentioned in this regard, but are treated solely as a design consideration; no guidance is offered on common cause failure analysis. 6. The human operator in control and instrumentation (12pp). This provides a discussion of the tradeoffs in reliability and performance with human operators versus automatic control. Particular attention is paid to user friendly design, visual displays, and safety procedures. 7. Safety monitoring (Spp). Catastrophic versus degradation failures, safety monitoring systems, and 'fail-safe' versus 'fail-dangerous' errors are discussed. Topics involved in the design of fail-safe systems, such as relay tripping circuits and circuit fault analysis, are also discussed. 8. Software reliability (16pp). Due to the increasing use of computers in instrumentation and control systems, a fair amount of attention is paid to the issue of software reliability. Several topics involved with the design of highly reliable software, such as structured programming, specification languages and fault tolerance, are discussed at some length. However, the analysis methods discussed are limited to the estimation of fault density and reliability growth models associated with testing. Software fault trees and formal proofs are not discussed. 9. Data transmission (7pp). This chapter discusses the reliability of analogue transducers, analogue signal transmission, data validation, and the detection and correction of errors in digitally codes signals. Redundant data links are also briefly discussed. 10. Electronic and avionic systems (llpp); 11. Nuclear reactor control systems (13pp), 12. Process and plant control (13pp). The last three chapters present applications of the concepts introduced in the book to instrumentation and control systems in a variety of industries. Examples include radio transmitters, satellite links, aircraft control systems, railway signaling and control, robotic systems, nuclear reactor control, reactor protection logic, chemical plants and oil platforms. The book provides a fairly broad, comprehensive overview of the topics involved in the reliability of instrumentation and control systems in a variety of
Book reviews industries. However, it does not present these subjects in sufficient detail to permit one who was previously unfamiliar with these techniques to be able to apply them directly, nor is it likely to be useful as a classroom textbook. Nevertheless, as introductory material for risk analysts who are unfamiliar with the reliability characteristics of electronic components or for conventional engineers who are unfamiliar with risk assessment techniques, this book is both an informative and enjoyable read, well organized and
well written investigation.
283 with
ample
references
for
further
C. J. Garrett Mechanical Aerospace and Nuclear Engineering Department University of California Los Angeles, CA 90024-1597 USA