The system average interruption duration index (SAIDI) is commonly used as a reliability index by electric power utilities. SAIDI is the average cumulative outage duration for each customer served, and is calculated as:
where is the number of customers and is the annual outage time for location , and is the total number of customers served. In other words,
SAIDI is measured in units of time, often minutes or hours; it is usually measured over the course of a year. According to IEEE Standard 1366–1998, the median value for North American utilities is approximately 1.50 hours. According to the U.S. Energy Information Administration annual electric power industry report, it is 2.0 hours, rising to the range of 3.5 to 8 hours, when "major events" are included."U.S. electricity customers averaged seven hours of power interruptions in 2021", (published November 14, 2022), Average duration of total annual electric power interruptions, United States (2013-2021) hours per customer.
Comparison of SAIDI by country The following is a table of SAIDI for different countries, calculated using the methodology in the World Bank's Doing Business 2016-2020 studies: CountryPopulation (million) in 2020The World Bank, Data Bank "World Development Indicators", total population 2020, https://databank.worldbank.org/reports.aspx?source=2&series=SP.POP.TOTL&country=SAIDI (hours) in 2019The World Bank, Data Bank "Doing Business", SAIDI index WB 2019, https://databank.worldbank.org/SAIDI-Index-WB/id/dd1d6036SAIDI (hours) in 2020The World Bank, Data Bank "Doing Business", SAIDI index WB 2020, https://databank.worldbank.org/SAIDI-Index-WB/id/dd1d6036Austria8.90.70.6Belgium11.50.70.4Croatia4.04.83.3Cyprus1.20.30.6Czechia10.70.50.5Denmark5.80.50.5Estonia1.30.30.3Finland5.50.60.2France67.60.20.4Germany83.20.20.3Greece10.71.91.6Hungary9.82.82.6Ireland5.00.30.8Italy59.40.51.3Latvia1.91.01.0Lithuania2.80.40.4Luxembourg0.60.40.4Malta0.50.60.8Netherlands17.40.80.8Norway5.40.71.5Poland37.91.31.1Portugal10.30.60.5Romania19.32.13.1Slovakia5.51.00.9Slovenia2.10.60.1Spain47.40.50.5Sweden10.40.60.6Switzerland8.60.20.2United Kingdom67.10.30.3United States331.51.21.3
References
External links EIA Reliability Metrics video by the U.S. Energy Information Administration on YouTube