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A number of reliability indexes are used in the electric industry to make it easier to compare <br /> performance of electric utilities. Listed below are the reliability indexes along with ERMU's <br /> 2014 and 2015 statistics. Also included are APPA's published averages that can be used by <br /> utilities to better understand the performance of their electric system relative to other utilities <br /> nationally and to 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 to <br /> serve customers. It is the ratio of the total customer minutes that service was available to the total <br /> customer minutes available in a time period. This is normally expressed as a percentage. <br /> ERMU's 2015 ASAI is 99.9943%Availability ERMU's 2014 ASAI is 99.9945%Availability <br /> Customer Average Interruption Duration Index(CAIDI) <br /> CAIDI is defined as the average duration (in minutes)of an interruption experienced by customers <br /> during a specific time frame. It is calculated by summing the customer minutes off during each <br /> interruption in the time period and dividing this by the number of customers experiencing one or more <br /> sustained interruptions during the time period. The resulting unit is minutes. The index enables utilities to <br /> report the average duration of a customer outage for those customers affected. <br /> ERMU's 2015 CAIDI is 71.157 minutes ERMU's 2014 CAIDI is 199.883 minutes <br /> System Average Interruption Duration Index(SAID!) <br /> SAID! is defined as the average interruption duration for customers served during a specified time <br /> period. It is determined by summing the customer minutes off for each interruption during a specified <br /> time period and dividing that sum by the average number of customers served during that period. The <br /> unit is minutes. This index enables the utility to report how many minutes' customers would have been <br /> out of service if all customers were out at one time. <br /> ERMU's 2015 SAIDI is 23.723 minutes ERMU's 2014 SAIDI was 25.54 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 specified <br /> time period. It is determined by dividing the total number of customers interrupted in a time period by the <br /> average number of customers served. The resulting unit is"interruptions per customer." <br /> ERMU's 2015 SAIFI is 0.3 ERMU's 2014 SAIFI was 0.1428 <br /> Another statistic staff gets concerned about is the average length of any outage. Elk River <br /> Municipal Utilities' 2015 average length of outage was 134.23 minutes. In 2014 the average <br /> length of outage was 131.07 minutes. Electric utilities with a high percentage of underground <br /> facilities will exhibit higher length of outage time than electric utilities with more overhead <br /> facilities. <br /> P0WE0ED 11 <br /> Eq <br /> Page 2 of 4 NATURE <br /> Reliable Public, <br /> Power Provider P OWERED T O S ERV E <br /> 102 <br />