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eReliability Annual Report. It contains published averages that can be used by utilities to better <br /> understand the performance of their electric system relative to other utilities nationally, and to <br /> those within their region or size class. <br /> Average Service Availability Index(ASAI) <br /> ASAI is a measure of the average availability of the sub-transmission and distribution systems <br /> to serve customers. It is the ratio of the total customer minutes that service was available to <br /> the total customer minutes available in a time period.This is normally expressed as a <br /> percentage. <br /> ERMU's 2018 ASAI is 99.9980%Availability ERMU's 2017 ASAI is 99.9938%Availability <br /> Customer Average Interruption Duration Index(CAIDI) <br /> CAIDI is defined as the average duration (in minutes) of an interruption experienced by <br /> customers during a specific time frame. It is calculated by summing the customer minutes off <br /> during each sustained' interruption in the time period and dividing this by the number of <br /> customers experiencing one or more sustained' interruptions during the time period.The <br /> resulting unit is minutes. The index enables utilities to report the average duration of a <br /> customer outage for those customers affected. <br /> ERMU's 2018 CAIDI is 58.147 minutes ERMU's 2017 CAIDI is 103.718 minutes <br /> System Average Interruption Duration Index(SAID!) <br /> SAIDI is defined as the average interruption duration (in minutes)for customers served <br /> during a specified time period. It is determined by summing the customer minutes off for each <br /> sustained' interruption during a specified time period and dividing that sum by the average <br /> number of customers served during that period.The resulting unit is minutes. This index <br /> enables the utility to report how many minutes' customers would have been out of service if all <br /> customers were out at one time. <br /> ERMU's 2018 SAIDI is 10.009 minutes ERMU's 2017 SAID! was 32.3938 minutes <br /> System Average Interruption Frequency Index(SAIFI) <br /> SAIFI is defined as the average number of times that a customer is interrupted during a <br /> specified time period. It is determined by dividing the total number of sustained' interrupted <br /> customers in a time period by the average number of customers served. The resulting unit is <br /> "interruptions per customer." <br /> ERMU's 2018 SAIFI is 0.172 ERMU's 2017 SAIFI was 0.3123 <br /> ' Only outages lasting longer than five minutes are included in the calculations, as defined by IEEE 1366. <br /> Page 2 of 3 <br /> 79 <br />