SAIDI
The System Average Interruption Duration Index (SAIDI)<ref>Yeddanapudi, Sree. "Distribution System Reliability Evaluation". Iowa State University. Archived from the original on 26 December 2011. Retrieved 18 June 2011.</ref> is commonly used as a reliability index by electric power utilities. SAIDI is the average outage duration for each customer served, and is calculated as:
<math> \mbox{SAIDI} = \frac{\sum{U_i N_i}}{N_T} </math>
where <math>N_i</math> is the number of customers and <math>U_i</math> is the annual outage time for location <math>i</math>, and <math>N_T</math> is the total number of customers served. In other words,
<math>\mbox{SAIDI} = \frac{\mbox{sum of all customer interruption durations}}{\mbox{total number of customers served}}</math>
SAIDI is measured in units of time, often minutes or hours. It is usually measured over the course of a year, and according to IEEE Standard 1366-1998 the median value for North American utilities is approximately 1.50 hours.
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:
| Country | Population
(million) in 2020<ref>The World Bank, Data Bank "World Development Indicators", total population 2020, https://databank.worldbank.org/reports.aspx?source=2&series=SP.POP.TOTL&country=</ref> |
SAIDI
(hours) in 2019<ref>The World Bank, Data Bank "Doing Business", SAIDI index WB 2019, https://databank.worldbank.org/SAIDI-Index-WB/id/dd1d6036</ref> |
SAIDI
(hours) in 2020<ref>The World Bank, Data Bank "Doing Business", SAIDI index WB 2020, https://databank.worldbank.org/SAIDI-Index-WB/id/dd1d6036</ref> |
|---|---|---|---|
| Austria | 8.9 | 0.7 | 0.6 |
| Belgium | 11.5 | 0.7 | 0.4 |
| Croatia | 4.0 | 4.8 | 3.3 |
| Cyprus | 1.2 | 0.3 | 0.6 |
| Czechia | 10.7 | 0.5 | 0.5 |
| Denmark | 5.8 | 0.5 | 0.5 |
| Estonia | 1.3 | 0.3 | 0.3 |
| Finland | 5.5 | 0.6 | 0.2 |
| France | 67.6 | 0.2 | 0.4 |
| Germany | 83.2 | 0.2 | 0.3 |
| Greece | 10.7 | 1.9 | 1.6 |
| Hungary | 9.8 | 2.8 | 2.6 |
| Ireland | 5.0 | 0.3 | 0.8 |
| Italy | 59.4 | 0.5 | 1.3 |
| Latvia | 1.9 | 1.0 | 1.0 |
| Lithuania | 2.8 | 0.4 | 0.4 |
| Luxembourg | 0.6 | 0.4 | 0.4 |
| Malta | 0.5 | 0.6 | 0.8 |
| Netherlands | 17.4 | 0.8 | 0.8 |
| Norway | 5.4 | 0.7 | 1.5 |
| Poland | 37.9 | 1.3 | 1.1 |
| Portugal | 10.3 | 0.6 | 0.5 |
| Romania | 19.3 | 2.1 | 3.1 |
| Slovakia | 5.5 | 1.0 | 0.9 |
| Slovenia | 2.1 | 0.6 | 0.1 |
| Spain | 47.4 | 0.5 | 0.5 |
| Sweden | 10.4 | 0.6 | 0.6 |
| Switzerland | 8.6 | 0.2 | 0.2 |
| United Kingdom | 67.1 | 0.3 | 0.3 |
| United States | 331.5 | 1.2 | 1.3 |
