Renewal Theoretic Aspects of Two-Unit Redundant Systems

This expository paper discusses four two-unit redundant systems: 1) parallel redundancy; 2) standby redundancy; 3) standby redundancy with priority; 4) standby redundancy with noninstantaneous switchover. In models 1), 2), and 3) the switchover time is instantaneous. The integral equation of renewal theory is applied by using the concept of a cycle. Applying the integral equation of renewal theory and the cycle, we obtain systematically for each model the Laplace-Stieltjes transform of the distribution of the time to first failure and its mean.