STOCHASTIC MODELING OF A SYSTEM WITH PRIORITY FOR OPERATION TO NEW UNIT AND PREVENTIVE MAINTENANCE AT PFS SUBJECT TO MOT

Abstract

A stochastic model for a cold standby system of two identical units is developed in which unit fails completely either directly from normal mode or via partial failure. The unit undergoes preventive maintenance (PM) after a maximum operation time (MOT) at its partial failure stage (PFS). There is a single server who visits the system immediately as and when needed to do preventive maintenance and repair. The priority for operation to new unit is given over the partially failed unit. The failure and maximum operation times of the unit are distributed exponentially while the distributions of PM and repair times are taken as arbitrary. The expressions for some reliability measures of the system are derived using semi-Markov process and regenerative point technique. The numerical results for the particular values of parameters and various costs are obtained to show the behavior of MTSF, availability and profit.