Availability of Parallel Triplicated Redundancy Models With Imperfect Switchovers and Interrupted Repairs

This paper presents the analysis of the three parallel triplicated redundancy models: model with one active and two standby components, model with one standby and two active components, and model with three active components. The time-to-failure and the time-to-repair of the components follow an exponential and a general distribution, respectively. The repairs of failed components are randomly interrupted. The time-to-interrupt is taken from an exponentially distributed random variable and the interrupt times are generally distributed. Using the supplementary variable method and integro-differential equations, we obtain the analytical expression of the availability for the redundancy models with imperfect switchovers and interrupted repairs. Numerical examples show the effect of failure rate of active components, repair interruption rate, and switchover failure probability on the steady-state availability. The triplicated redundancy model with one active component and two standby components has higher availability than the other triplicated models with more active components when the switchover failure probability is small.