Time dependent reliability assessment of electrical auxiliary systems

This paper describes techniques that evaluate time dependent reliability of electrical auxiliary systems. It facilitates the assessments of subsequent safe operations of a power station following an abnormal operating condition. These include the identification of primary initiating events that lead to system failure and subsequently the evaluation of the likelihood of reestablishing supply and then of maintaining supply within predetermined mission times. In addition, this paper extends the operating time beyond the maintaining supply period and establishes the effect of system failures and restoration in this extended time. The analysis of a typical electrical auxiliary system is included to illustrate the various techniques and their advantages. The time factor is stressed throughout these analyses to demonstrate the stochastic nature of the system. These analyses reflect the importance of the time dependent reliability assessment in making realistic engineering judgements between various alternative proposals