SAIDI

The System Average Interruption Duration Index (SAIDI)^[1] 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:

${\displaystyle {\mbox{SAIDI}}={\frac {\sum {U_{i}N_{i}}}{N_{T}}}}$

where ${\displaystyle N_{i}}$ is the number of customers and ${\displaystyle U_{i}}$ is the annual outage time for location ${\displaystyle i}$, and ${\displaystyle N_{T}}$ is the total number of customers served. In other words,

${\displaystyle {\mbox{SAIDI}}={\frac {\mbox{sum of all customer interruption durations}}{\mbox{total number of customers served}}}}$

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^[2]	SAIDI (hours) in 2019^[3]	SAIDI (hours) in 2020^[4]
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

References

1. Yeddanapudi, Sree. . Iowa State University. Archived from the original on 26 December 2011. Retrieved 18 June 2011.
2. The World Bank, Data Bank "World Development Indicators", total population 2020, https://databank.worldbank.org/reports.aspx?source=2&series=SP.POP.TOTL&country=
3. The World Bank, Data Bank "Doing Business", SAIDI index WB 2019, https://databank.worldbank.org/SAIDI-Index-WB/id/dd1d6036
4. The World Bank, Data Bank "Doing Business", SAIDI index WB 2020, https://databank.worldbank.org/SAIDI-Index-WB/id/dd1d6036

External links

• EIA Reliability Metrics video by the U.S. Energy Information Administration on Youtube