Availability analysis of series redundancy models with imperfect switchover and interrupted repairs

This paper considers N + 1 series redundancy, where N components are active and 1 component is standby in normal state. The active components execute the service, while the standby component is ready to take over the active role if the active components fail. When an active component fails, the standby, if available, automatically takes over system operations. However, the automatic switchover of the standby component to active mode might not be possible due to hardware or software issues. When a component failure or an imperfect switchover occurs, it immediately begins to be repaired. However, the repair process is possible to be interrupted. The most existing literature of redundancy models has focused on Markovian systems with uninterrupted repairs. This paper considers a non-Markovian redundancy model with interrupted repairs, where the repair time, the non-automatic switchover time, and the interrupted time are generally distributed. Using supplementary variable method and integro-differential equations, we obtain the steady-state availability for the redundancy model.