Reliability Analysis of a Hot Standby Industrial System

AbstractIndustries/plants, such as Fibre Optic plant and casting plants, often use programmable logic controllers (PLC) as a two-unit/two-PLC hot standby systems. Optimizing profit and avoiding the major losses are the main objectives of using a two-unit hot standby PLC system. In the two-unit system, one unit is operative and the other is a hot standby. The hot standby unit also fails, but with lower failure rate than the operative unit. The paper outlines a reliability analysis of a two-unit hot standby PLC system, and the real data from an industrial system has been used for the purpose. Four types of failure are seen in the PLCs: input module failure, digital relay burnt/power supply failure, complete unit burnt failure and failure due to corrupted software. The concept of inspection is introduced to detect the type of failure. The model developed is embedded by the types of failure actually depicted in the data and the real failure, repair, replacement, reinstallation rates are used for analysis. Measures of system effectiveness in terms of reliability indices are obtained using semi-Markov processes and regenerative point techniques. Profit incurred to the system is evaluated and related graphs pertaining to the case example are also shown.Key Words: Programmable logic controller (PLC)failuresrepairssemi-Markov Processregenerative process Additional informationNotes on contributorsS.M. RizwanS.M. Rizwan obtained his Ph.D. degree in Reliability Modelling and analysis in 1996. He has about 18 years of teaching and research experience. He is currently head of the Department of Mathematics and Statistics, Caledonian (University) College of Engineering, Sultanate of Oman. His research interest is reliability modelling and analysis, in this area and related ones he has published about 57 research papers.V. KhuranaVipin Khurana obtained his Ph.D. degree in Reliability Modelling from UP Technical University, India. He has about 11 years of teaching Experience. He is currently associate dean, IBS Noida, India. He has Published about 13 research papers in reputed journals & National/International Conferences in India and abroad. His area of research is reliability engineering and mathematical modelling.G. TanejaGulshan Taneja M.Sc., Ph.D. (Statistics), M.D. University, India), P.G.D.C.A (IGNOU, New Delhi) is currently associate professor, Department of Statistics, University college, M.D. University, Rohtak. He has published over 59 research papers in Journals of repute. His area of research is reliability modelling and analysis.