Reliability and Safety Modelling in Reliable Systems Supported with Cold Standby Spares by a Markov Model

Abstract

Fault tolerance is one of the important issues in industries, such as transportation, military, chemical and nuclear sectors. Reliability and safety are two vital attributes of fault tolerant systems, and redundancy is a common way to improve these parameters. This article studies the impact of including cold standby spares in system architecture. To do this, it uses the Markov model of the system due to its capabilities in incorporating and modeling of priorities, functional dependencies, timing relations, reconfiguration issues and events sequences, existed in the system dynamic. The previous studies in the domain of reliable and fault tolerant systems have not presented general formulas to evaluate the reliability and safety of systems supported with cold spares. This article presents closed formulas for these attributes by which the impact of the number of spares, failure rate of modules, coverage factor, and switch quality can be studied on the system performance.