Availability of 3-out-of-4:G Warm Standby System

Standby techniques are used to improve system availability. Usually, a k-out-of-n:G standby system is assumed that when an operating component fails, a standby component becomes active and the system is working if at least k components are fault-free. In general, there are three types in component standby, i.e., cold, hot and warm standby. Cold standby implies that inactive components have a zero failure rate. Hot standby implies that an inactive component has the same failure rate as when it is in operation. Warm standby implies that an inactive component has a failure rate between cold and hot, it is also called dormant failure in some papers. k-out-of-n:G warm standby systems have been used in several research fields including medical diagnosis, redundant-system testing, power plant system and so on. There have been many articles concerning study on availability of k-out-of-n:G systems according to system configuration and connection of components, and the way of redundancy [1]–[9]. Schneeweiss [5] reviewed a general (non Markov) 1-out-of-2:G system with statistically-identical component, repair and cold standby, and studied the mean time to first failure of repairable systems with one cold standby. Akhtar [6] investigated reliability of k-out-of-n:G systems with imperfect fault-coverage where recursive expressions for mean time between failures and mean time to failure were obtained for repairable systems. Gnedenko, et al. [7] analyzed the 1-out-of-n warm standby case. She and Pecht [8] made a brief review on standby redundancy techniques and concluded that the modeling of standby redundancy, especially warm standby has not been emphasized. In their research, a general closed-