A Comparative Analysis of Three Unit Redundant Systems with Three Types of Failures

ABSTRACT In this paper, three probabilistic models for a redundant system with three identical units have been developed to analyze and compare some reliability characteristics. Model II and model III are special cases of model I. In each model, the system is under three types of failures and attended by one repairman. Model I is under preventive maintenance before failure, while model II and III are analyzed without preventive maintenance, and in addition model III is viewed as linear consecutive 2-out-of-3. The objective is to see the effect of preventive maintenance and system design of 2-out-of-3. Mean time to system failure, availability, busy period and profit function for the three models are analyzed using Kolmogorov’s forward equations method. Furthermore, we compare these reliability characteristics for the three models and found that model I is more reliable and efficient than the remaining models.