Laserfiche WebLink
III. Outage Causes <br /> Equipment failure, extreme weather events, wildlife and vegetation are some of the most common causes <br /> of electric system outages. However, certain factors, such as regional weather and animal/vegetation <br /> patterns, can make a different set of causes more prevalent to a specific group of utilities. The following <br /> sections of this report include graphs depicting common causes of outages for your individual utility, all <br /> utilities in your region, and all utilities using the eReliability Tracker. The charts containing aggregate <br /> information are customer-weighted to account for differences in utility size for a better analytical <br /> comparison. For example, a particularly large utility will have a large number of outages compared to a <br /> small utility; in order to not have the collective information be more representative of the large utility, the <br /> number of occurrences is divided by customer size to account for the differences. In the figures below, the <br /> data represent the number of occurrences for each group of 1000 customers. For instance, a customer- <br /> weighted occurrence rate of"1" means 1 outage of that outage cause per 1000 customers on average in <br /> 2013. <br /> Note that the sustained outage cause analysis is more comprehensive than the momentary outage cause <br /> analysis due to a bigger and more robust sample size for sustained outages. Regardless, tracking both <br /> sustained and momentary outages helps utilities understand and reduce outages. To successfully use the <br /> outage information tracked by your utility, it is imperative to classify and record outages in detail. The <br /> more information provided per outage, the more conclusive and practical your analyses will be. <br /> Sustained Outage Causes <br /> In general, sustained outages are the most commonly tracked outage type. In many analyses of <br /> sustained outages, utilities tend to exclude scheduled outages, partial power, customer-related problems, <br /> and qualifying major events from their reliability indices calculations. While this is a valid method for <br /> reporting, these outages should be included for internal review to make utility-level decisions. In this <br /> section, we evaluate common causes of sustained outages for your utility, corresponding region, and for <br /> all utilities that use the eReliability Tracker. It is important to note that in this report, sustained outages are <br /> classified as outages that last longer than five minutes, as defined by IEEE 1366. <br /> 10 <br /> 61 <br />