Distribution feeder reliability studies

As the power industry moves into a new competitive era, the reliability of radial distribution feeders becomes a primary issue in comparing the "new" versus the "old" way of serving customers. In order to make the comparison, a distribution engineer needs to have the analysis tools to perform the necessary reliability studies. For the purposes of this paper, the reliability studies will be limited to the calculation of the annual "outage rate" and associated "restoration time" for a typical customer on a radial distribution feeder. This paper develops the background and theory for computing these reliability indices. The method can be applied to demonstrate how different devices and/or feeder configurations affect the average customer on a specific feeder.