Steady-State Profit in a 2-unit Standby System

Three models are presented for a 2-unit standby system, Models 1 and 2 deal with a 2-unit warm-standby system with and without preventive maintenance (pm) to standby unit. Model 3 is a 2-unit cold-standby system with pm to operative unit. An income structure has been superimposed on the semi-Markov processes generated by the systems to obtain s-expected profit. For models 2 and 3, s-expected profit is suggested as the measure of maintenance effectiveness. Numerical examples are included to illustrate the results.