6.4. ERMUSR 01-13-2004 - Laserfiche WebLink

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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.