5.2a ERMUSR 04-11-2023 - Laserfiche WebLink

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11. IEEE Statistics When it comes to reliability, the industry standard metrics are defined in the Institute for Electrical and Electronics Engineers' Guide for Electric Power Distribution Reliability Indices, or IEEE 1366 guidelines. For each utility, the eReliability Tracker performs IEEE 1366 calculations for System Average Interruption Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI), Customer Average Interruption Duration Index (CAIDI), Momentary Average Interruption Frequency Index (MAIFI) and Average Service Availability Index (ASAI). It is important to note how major events (MEs) are calculated and used in this report. An example of a ME includes severe weather, such as a tornado or hurricane, that leads to unusually long outages in comparison to your distribution system's typical outage. This report uses the APPA ME threshold, which is based directly on the SAIDI for specific outage events, rather than a daily SAIDI. The APPA ME threshold allows a utility to remove outages that exceed the IEEE 2.5 beta threshold for outage events, which considers up to 10 years of the utility's outage history. In the eReliability Tracker, if a utility does not have at least 36 outage events prior to the year being analyzed, then no threshold is calculated. If this is the case for your utility, then you will have a NULL value in the following field and the calculations without MEs in the SAIDI, SAIFI, CAIDI, and ASAI sections of this report will be the same as the calculations with MEs for your utility. More outage history will provide a better threshold for your utility. Your utility's APPA major event threshold is 98 minutes. For each of the reliability indices, this report displays your utility's metrics alongside the mean values for all utilities using the eReliability Tracker and within the same calss and region as your utility. The first table within each of the following subsections allows you to better understand the performance of your electric system relative to other utilities nationwide and to those within your same region or size class. The second table breaks down the national data into quartile ranges, a minimum value, and a maximum value. All indices, except MAIFI, are calculated for outages with and without MEs. Furthermore, the tables show indices for scheduled and unscheduled outages. Note that scheduled and unscheduled calculations include MEs. Also note that wherever MEs are excluded, the exclusion is based on the APPA ME threshold for your system. 5 187