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6.4. ERMUSR 01-13-2004 Elk Rivetr Municipal Utilities 322 King Avenue phone: 763.441.2020 Elk River, MN 55330 Fax 763 441.8099 December 30, 2003 To: Elk River Municipal Utilities Commission John Dietz Jerry Taale James Tralle From: Bryan Adams Subject: Electric Outage Report The Minnesota Energy, Security and Reliability Act enacted in 2001, contains a distribution reliability section. One section of this legislation requires, on an annual basis, an outage report be submitted to their governing bodies, which in our case is the Elk River Municipal Utilities Commission. Your staff for a number of years, has been documenting electrical outages to keep track of causes, number of customers out of power and for how long in an effort to track trends and resolve continued outage problems. This tracking now has the benefit of complying with the distribution reliability section of this legislation. Our electric outage reporting has been formalized so we can better track and analyze the number and causes of our outages. The attached two page spread sheet reflects the outage history for 2003. In summary, the distribution of outages are as follows. Minnesota Municipal Utilities Association(MMUA) is currently drafting a Municipal Utility Distribution Reliability Standard that complies with the requirements of the Minnesota Energy, Security, and Reliability Act. This commission will need to adopt that standard when it becomes available. 2002 2003 Types of # of % Customer ft of Customer Faults Faults Minutes % Faults % Minutes % U.G. Faults 6 12 24,730 6.9 6 11.3 1,045 2.7 Dig-Ins 4 8 52,980 14.9 2 3.8 3,000 7.6 Termination Failure 5 10 450 0.1 1 1.9 600 1.7 Transformer Failure 3 6 1,620 0.5 3 5.7 565 1.4 Fuse Failure 5 ' 10 13,935 3.9 10 18.9 3,445 8.8 Connector - - - - 2 3.8 1,830 4.7 Branches 1 2 60 0.0 1 1.9 450 1.1 Animal 9 18 2,460 0.7 11 20.7 14,530 37.0 Transformer Failure 3 6 605 0.2 1 1.9 300 .8 Lighting Arrestor 0 0 0 0.0 2 3.8 1,950 5.0 Weather 9 18 17,340 4.9 10 18.9 10,695 27.2 Vehicle Hit Pole 3 6 29,220 8.2 3 5.7 415 1.0 Wholesale Supplier 2 4 213,000 59.8 1 1.9 400 1.0 48 100 356,400 100 53 100 39,285 100 The above table reflects no alarming trends or patterns. A number of reliability indexes are evolving in the electric industry to make it easier to compare performance of electrical utilities. These reliability indexes are: 1. ASAI (average service availability index) ASAI is a measure of the average availability of the sub-transmission and distribution systems to serve customers. It is the ratio of the total customer minutes that service was available to the total customer minutes demanded in a time period. It is normally expressed as a percentage. ERMU's 2003 ASAI is 99.99%. This is a very good percentage for any utility. 2. CAIDI (customer average interruption duration index) This is defined as the average length of an interruption, weighted by the number of customers affected, for customers interrupted during a specific time period. It is calculated by summing the customer minutes off during each interruption in the time period and dividing this sum by the number of customers experiencing one or more sustained interruptions during the time period. The resulting unit is minutes. The index enables utilities to report the average duration of a customer outage for those customers affected. ERMU's 2003 CAIDI is 70.03. We do not as yet have a feel for this number if it is good, average, or bad. 3. SAIDI (system average interruption duration index) This is defined as the average interruption duration for customers served during a specified time period. It is determined by summing the customer-minutes off for each interruption during a specified time period and dividing the sum by the average number of customers served during that period. The unit is minutes. This index enables the utility to report how many minutes customers would have been out of service if all customers were out at one time. ERMU's SAIDI is 5.46. We do not as yet have a feel for this number if it is good, average, or bad. 4. SAIFI (system average interruption frequency index) This is defined as the average number of times that a customer is interrupted during a specified time period. It is determined by dividing the total number of customers interrupted in a time period by the average number of customers served. The resulting unit is "interruptions per customer". Separate SAIFI indexes are sometimes calculated for long and for short interruptions. ERMU's 2003 SAIFI is .78 with GRE's transmission outage and .051 w/o GRE transmission outage. .051 equals to a customer will experience an electric outage every 19.6 years. This appears to be a very good number. Another statistic staff gets concerned about is the overage length of any outage. ERMU's 2003 average length of outage is 101.37 minutes. Electric utilities with a high percent of underground facilities will exhibit higher length of outage times than electric utilities with high percent of overhead facilities. We are currently trying to find these statistics from other electric utilities. Staff has reviewed these statistics in detail to find ways to improve. My experience tells my these statistics are very complementary to ERMU. 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