Reliability modeling of A warm standby redundancy configuration with active → standby → active units

This paper presents a new reliability model for a warm standby redundant configuration with units that are originally operated in active mode, and then, upon turn-on of originally standby units, are put into warm standby mode. These units can be used if a standby-turned-into-active unit fails later. Numerical results of an example configuration are presented and discussed, with comparison to established lower and upper bounds, and Monte Carlo simulation results obtained from BlockSim software. Results show that (1) the reliability value calculated from the developed theoretical models does fall in between the established lower and upper bounds, and (2) the Monte Carlo simulation model gives virtually identical reliability value when the simulation uses a high number of replications, confirming the developed theoretical model.