A reliability model of a warm standby configuration with two identical sets of units

•A new reliability model is developed for a warm standby redundancy with two sets of identical units.•The units subject to state change from active to standby then back to active mode.•A closed form analytical solution is developed with exponential distribution.•To validate the developed model, a Monte Carlo simulation for an exemplary configuration is performed.

This article presents a new reliability model and the development of its analytical solution 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 later if a standby- turned into active-unit fails. Numerical results of an example configuration are presented and discussed with comparison to other warm standby configurations, and to Monte Carlo simulation results obtained from BlockSim software. Results show that the Monte Carlo simulation model gives virtually identical reliability value when the simulation uses a high number of replications, confirming the developed model.