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ELKRNER <br />EN- RGYCITY <br />Electric System <br />Elk River comprehensive Plan <br />The Elk River Municipal Utilities operates an electric system in the City of Elk River that provides service <br />to approximately 44 square miles as shown in Figure 8 -4: Electrical Distribution Territory Map. The ERMU <br />purchases power from Connexus Energy and constructs and operates the distribution system, including lines <br />and substations, needed to provide power in its service area. There are approximately 315 miles of electric <br />lines throughout the City, of which approximately 70% are underground. As part of the long term growth <br />plan for the City of Elk River the utility has added an additional 65,000 kW of substation capacity to the <br />distribution system since 2004. <br />Elk River Municipal Utilities (ERMU) received national recognition in 2011 when awarded a high honor for <br />having reliable and safe electric service. There are more than 2,000 public power utilities and ERMU is one of <br />only 176 receiving the Reliable Public Power Provider (RP3 ®) award. The award is based off of four categories: <br />reliability, safety, workforce development and system improvement. <br />ERMU's reliability index numbers reflect the condition of its robust electrical system as well as its <br />commitment to long term growth and superb customer service. The ERMU reliability numbers are <br />comparing extremely well to other electric utilities in Minnesota. Elk River Municipal Utilities' 2012 <br />reliability numbers were as follow: <br />1. ASAI (average service availability index) is <br />a measure of the average availability of the <br />sub - transmission and distribution systems to <br />serve customers. It is the ratio of the total <br />customer minutes that service was available <br />to the total customer minutes available in <br />a time period. This is normally expressed <br />as a percentage. ERMU's 2012 ASAI is <br />99.999% Availability. <br />2. CAIDI (customer average interruption <br />duration index) is defined as the average <br />length of an interruption weighted by <br />the number of customers affected. It <br />is calculated by summing the customer <br />minutes off during each interruption in the <br />time period and dividing this by the number <br />of customers experiencing one or more <br />sustained interruptions during the time <br />period. The resulting unit is minutes. The <br />index enables utilities to report the average <br />duration of a customer outage for those <br />customers affected. ERMU's 2012 CAIDI is <br />66 minutes. <br />92 / Chapter 8: Utilities <br />3. SAIDI (system average interruption duration <br />index) is defined as the average interruption <br />duration for customers served during a specified <br />time period. It is determined by summing the <br />customer minutes off for each interruption <br />during a specified time period and dividing <br />that sum by the average number of customers <br />served during that period. The unit is minutes. <br />This index enables the utility to report how <br />many minutes' customers would have been out <br />of service if all customers were out at one time. <br />ERMU's 2012 SAIDI is 7.7 minutes. <br />4. SAIFI (system average interruption frequency <br />index) is defined as the average number of <br />times that a customer is interrupted during <br />a specified time period. It is determined <br />by dividing the total number of customers <br />interrupted in a time period by the average <br />number of customers served. The resulting unit <br />is "interruptions per customer." ERMU's 2012 <br />SAIFI is 0.117. <br />