Comparison the maintenance between two-unit parallel standby systems and 2-out-of-3 standby systems

Both two-unit parallel systems and 2-out-of-3 systems are common used standby systems. Several research has studied the maintenance policy for two-unit parallel systems. In this study, a cost-effective maintenance schedule, including testing strategy and surveillance test interval, for a 2-out-of-3 standby system is presented. For systems with identical units, uniformly staggered testing is shown to be the best testing strategy. The maintenance performance of the systems is compared with that of two-unit parallel systems (also considered as 1-out-of-2 system). Moreover, the results are also can be extended to general n-1-out-of-n systems.