Reliability aspects of a series load–sharing system

Abstract

In reliability engineering, load–sharing is typically associated with a system in parallel configuration. Examples include bridge support structures, electric power supply systems, multiprocessor computing systems, etc. We consider a reliability maximization problem for a high–voltage commutation device, wherein the total voltage across the device is shared by the components in series configuration. Here, the increase of the number of load–sharing components increases component–level reliability (as the voltage load per component reduces) but may decrease system–level reliability (due to the increased number of components in series). We review optimal solutions for the proportional hazard and accelerated life models with the underlying exponential & Weibull distributions and elaborate on the log–linear, power, and Eyring laws used in the life–load models. voltage switching devices is to put single switching components in a series configuration. Shown in Figure 1 is a high voltage thyristor switch (Gurevich & Krivtsov 1991), wherein the total switching voltage is shared by the serially connected thyristors. In this case, the increase of the number of thyristors increases thyristor–level reliability (as the voltage load per thyristor reduces) but may decrease system–level reliability (due to the increased number of components in series). Clearly, the system reliability function in this case should have a maximum associated with an optimal number of thyristors in series. We derived (Krivtsov et al. 2017) optimal solutions to the two popular life–load models: the