Reliability and Cost-Benefit Analysis of 2-Out-of-3 Redundant Systems with General Distribution of Repair and Waiting Time

Abstract

Two probabilistic models for 2-out-of-3 redundant system o f identical units are developed. The system is
considered in up-state if 2-out-of-3 units are operative. Repair facility is provided immediately whenever
needed in model 1 while server takes some time to arrive at the system in m odel 2. The distribution o f repair and
w aiting tim e are taken as general w ith different probability density fu n ctions (pdf) whereas failure time
distribution o f the unit is negative exponential. Regenerative point technique is adopted to derive the
expressions fo r some reliability and economic measures. Graphs are plotted to discuss reliability and costbenefit analysis o f the models for a particular case. The applications o f the present models can be seen in
computer, electrical and m echanical systems. The paper suggests that 2-out-of-3 redundant systems can be
m ade more reliable and profitable by providing components oflow failure rates vand im mediate repairfacility.