Abstract
Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only system parameters, such as configuration, hazard rate, coverage, repair rate, etc. along with periodic proof-tests (or inspection). Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants, chemical plants, etc. In this paper, a basic model of IEC 61508 is used. The basic model is extended to incorporate process demand and behavior of electronic-and/or computer-based system following diagnosis or proof-test. A new safety index, probability of failure on actual demand (PFAD) based on extended model and demand rate is proposed. Periodic proof-test makes the model semi-Markovian, so a piece-wise continuous time Markov chain (CTMC) based method is used to derive mean state probabilities of elementary or aggregated state. Method to determine probability of failure on demand (PFD) (IEC 61508) and PFAD based on these state probabilities are described. In example, safety indices of PFD and PFAD are compared.
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IEC 61508, Functional Safety of Electric/Electronic/Programmable Electronic Safety-related Systems, Parts 0-7, IEC Geneva, Switzerland, October 1998–May 2000.
T. Zhang, W. Long, Y. Sato. Availability of Systems with Self-diagnostic Components-applying Markov Model to IEC 61508-6. Reliability Engineering and System Safety, vol. 80, no. 2, pp. 133–141, 2003.
J. V. Bukowski. Modeling and Analyzing the Effects of Periodic Inspection on the Performance of Safety-critical Systems. IEEE Transactions on Reliability, vol. 50, no. 3, pp. 321–329, 2001.
P. Hokstad, K. Corneliussen. Loss of Safety Assessment and the IEC 61508 Standard. Reliability Engineering and System Safety, vol. 83, no. 1, pp. 111–120, 2004.
J. V. Bukowski, W. M. Goble. Defining Mean Time-to-failure in a Particular Failure-state for Multi-failure-state Systems. IEEE Transactions on Reliability, vol. 50, no. 2, pp. 221–228, 2001.
M. Kumar, A. K. Verma, A. Srividya. Modeling Demand Rate and Imperfect Proof-test and Analysis of their Effect on System Safety. Reliability Engineering and System Safety, submitted for publication.
J. V. Bukowski. Incorporating Process Demand into Models for Assessment of Safety System Performance. In Proceedings of the Annual Reliability and Maintainability Symposium, Newport Beach, CA, pp. 571–581, 2006.
C. Scherrer, A. Steininger. Dealing with Dormant Faults in an Embedded Fault-tolerant Computer System. IEEE Transactions on Reliability, vol. 52, no. 4, pp. 512–522, 2003.
T. A. DeLong, T. Smith, B. W. Johnson. Dependability Metrics to Assess Safety-critical Systems. IEEE Transactions on Reliability, vol. 54, no.3, pp. 498–505, 2005.
C. Y. Choi, B. W. Johnson, J. A. Profeta III. Safety Issues in the Comparative Analysis of Dependable Architectures. IEEE Transactions on Reliability, vol. 46, no. 3, pp. 316–322, 1997.
Y. Yangyang, B.W. Johnson. A Comparison of Two Safety-critical Architectures Using the Safety Related Metrics. In Proceedings of the Annual Reliability and Maintainability Symposium, Los Angeles, USA, pp. 621–627, 2004.
J. L. Rouvroye, A. C. Brombacher. New Quantitative Safety Standards: Different Techniques, Different Results? Reliability Engineering and System Safety, vol. 66, no. 2, pp. 121–125, 1999.
J. V. Bukowski. Using Markov Model to Compute Probability of Failed Dangerous When Repair Times are not Exponentially Distributed. In Proceedings of the Annual Reliability and Maintainability Symposium, Newport Beach, CA, pp. 273–277, 2006.
S. K. Khobare, S. V. Shrikhande, U. Chandra, G. Govindarajan. Reliability Analysis of Micro Computer Modules and Computer Based Control Systems Important to Safety of Nuclear Power Plants. Reliability Engineering and System Safety, vol. 59, no. 2, pp. 253–258, 1998.
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Manoj Kumar graduated with a degree in electronics and communication engineering from Faculty of Engineering & Technology, Jamia Millia Islamia, New Delhi, in 1998. Since 1998, he has been working as a scientific officer at Control Instrumentation Division of Bhabha Atomic Research Centre (BARC), Mumbai. Currently, he is a Ph.D. candidate at the Indian Institute of Technology (IIT) Bombay, India.
His research interests include design and development of embedded / computer based control systems, performance, reliability, and safety analysis.
A. K. Verma received the B.Tech (Hons) and Ph.D. (Engg.) degrees from Department of Electrical Engineering, IIT Kharagpur. He has been with IIT Bombay as a faculty since 1988. He is currently a professor in reliability engineering, Department of Electrical Engineering at IIT Bombay. He has over 130 research papers to his credit and has supervised eighteen Ph.D. thesis and seventy Master_s thesis at IIT Bombay. He has been a guest editor of special issues on Quality Management of Electronics, Communications & IT of IETE Technical Review, International Journal of Performability Engineering, International Journal of Reliability, Quality and Safety Engineering, and is on the editorial board of various journals. He has been a conference chairman of various international conferences, ICQRC 2001, ICMD 2002, ICQRIT 2003, ICQRIT 2006 and a patron of ICRESH 2005. He has authored a book on Fuzzy Reliability Engineering: Concepts and Applications. He is a senior member of IEEE and life fellow of IETE.
His research interests on reliability engineering include interdisciplinary applications in software engineering, computing, maintenance, and power system.
A. Srividya received her B.E. degree in 1982, M.Tech. degree in reliability engineering in 1985, and Ph.D. degree in 1994 from IIT Bombay. She has been with IIT Bombay as a faculty since 1988 and is currently a professor in reliability engineering, Department of Electrical Engineering at IIT Bombay.
She has over 28 publications in various international and national journals. She has published over 60 papers in conferences. She has supervised/co-supervised fourteen Ph.D. theses and thirty four master_s thesis at IIT Bombay. She is a life member of ISTE and ISPS. She has been conference chairperson of International Conference on Reliability, Safety and Hazard 2005 (Advances in Risk Informed Technology). She was instrumental in editing and reviewing the proceedings of various international conferences like International Conference on Quality Reliability and Control 2001, International Conference on Multimedia and Design 2002 and International Conference on Quality Reliability and Information Technology 2003. She is a recipient of Leadership in Reliability Engineering Education & Research award by Society of Reliability Engineering, Quality & Operations Management.
Her research interests include probabilistic safety assessment, reliability centered maintenance, and reliability in system design.
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Kumar, M., Verma, A.K. & Srividya, A. Analyzing effect of demand rate on safety of systems with periodic proof-tests. Int J Automat Comput 4, 335–341 (2007). https://doi.org/10.1007/s11633-007-0335-6
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DOI: https://doi.org/10.1007/s11633-007-0335-6