Reliability analysis of a redundant series system with common cause failures and delayed vacation

We study a redundant series system with a single repairman in which each primary unit has a standby one. The system is subject to common cause failure (CCF), and it may also break down either when a failed primary unit is unsuccessfully switched to the standby, or when all units are down in a subsystem. If no failed units exist in the system, the repairman takes a delayed vacation. For such a system, by establishing the system's balance equations and solving a second-order linear nonhomogeneous difference equation with variable coefficients, we first obtain the steady-state distribution of the system and derive some reliability and queueing measures. Moreover, by adopting Markov renewal technique, we carry out an extensive reliability analysis and obtain the Laplace-transform of the time to first failure starting from an arbitrary working state. Some numerical examples arising from a solar energy generating system are presented to illustrate the applicability and effectiveness of the proposed model and results. Finally, a cost-benefit discussion is presented from the perspective of economic profit analysis and some managerial insight.