Profit analysis of a two-unit cold standby system model operating under different weather conditions

Abstract

Generally, each machine or products are used by the human being up to its maximum capacity. If a system is performing beyond its capacity/defined conditions by the manufacturer called, the system is working under abnormal weather conditions. While, a system is performing within its capacities/stated conditions set by manufacturer called as the system working in abnormal weather conditions, for example; a car is functioning exceeding its accommodating capacity can be termed as working under abnormal weather conditions; a hydraulic machine exceeding its weight uplifting capacity of 500 tons by lifting 600 tons is termed as working under abnormal weather conditions. To overcome in such a situation, only effective maintenance strategies and suitable structure design of redundant system are the crucial factors which keep the standby system operational without failures for longer period of time. In fact, proper functioning of service mechanism and the reliability of system are strongly associated with each other. In the present paper, a water supply system simulate that is functioning of two-unit cold standby system with facilities of preventive maintenance, inspection and repair operating under different weather conditions with priority to preventive maintenance over inspection. The units are identical in nature. The single server only works under normal weather conditions capable of performing three operations inspection, repair and preventive maintenance responds to system instantly. The replacement of units is suggested if repair is impossible to perform during inspection. The operative unit undergoes for preventive maintenance after a specific time of operation. Repair of the unit is done by the server at its complete failure. All random variables are statistically independent. It is assumed that the failure rate and rate by which system undergoes for preventive maintenance are constant whereas the inspection rate, repair rate and maintenance rate follows negative exponential distribution. The expressions/graphs for several reliability measures are derived/depicted in steady state using regenerative point technique and semi-Markov process to determine the nature of the system.