Condition‐Based Maintenance and Switchover Policy for Cold‐Warm Mixed Standby Systems With Imperfect Switching and Maintenance

ABSTRACT Cold‐warm mixed standby systems are common redundancy structures in engineering practice, where periodic switching and maintenance play crucial roles in ensuring economic efficiency and reliable system operation. The switching and maintenance requirements depend on the combined states of the individual units in the system. However, imperfect switching and maintenance can directly affect system performance and the effectiveness of related policies. This study investigates optimal switching and condition‐based maintenance (CBM) decisions for cold‐warm standby systems under imperfect switchover conditions. First, a periodic switching and offline CBM policy was developed that addresses the challenges posed by imperfect switching and maintenance. Second, by analyzing various state transition characteristics, the probability distributions of system states and maintenance activities at each inspection were derived. Then, formulated an analytical optimization model that considers the constant inspection interval and non‐periodic inspection interval to minimize the average cost rate over a specified period, enabling the determination of optimal switching interval and maintenance thresholds using a genetic algorithm. Finally, the proposed method was validated on a stator cooling water pump system in a steam turbine generator. The results demonstrated that the proposed CBM policy reduced maintenance costs by 7.8%. The proposed policy offers a practical framework for reducing maintenance costs and improving reliability in cold‐warm mixed standby systems, particularly in industrial applications where imperfect switching and maintenance are unavoidable.