Reliability analysis and preventive maintenance for two‐unit standby redundant system with different failure time distributions

Abstract The two‐unit standby redundant repairable system considered herein has an operating unit and a standby unit which obey different failure time distributions. A reliability analysis performed when the operating unit is halted and undergoes preventive maintenance and the effect of preventive maintenance for the system are discussed. to avoid system failure caused by preventive maintenance, two practical preventive maintenance policies for an operating unit are considered: (1) Preventive maintenance of an operating unit is made by halting it after a certain operation interval only if the other unit is in standby; and (2) When a standby unit is being repaired (corrective maintenance), another operating unit forfeits preventive maintenance, undergoing preventive maintenance just upon repair completion of the failed unit. This paper also considers the case where two units fail simultaneously. Reliability analysis derives probable quantities by applying Markov renewal processes. the relation between system limiting availability and preventive maintenance and the effect of preventive maintenance for the system are shown by numerical examples.