SAIDI

The System Average Interruption Duration Index (SAIDI) is commonly used as a reliability indicator by electric power utilities. SAIDI is the average outage duration for each customer served, and is calculated as:

$\text{SAIDI}=\frac{\sum U_i{N}_i}{N_T}$

where $N_i$ is the number of customers and $U_i$ is the annual outage time for location $i$, and $N_T$ is the total number of customers served. In other words,

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

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; the share of renewable energy (gross electricity consumption) is also given:

Country	Population (million)	SAIDI (minutes)	Renewable energy share (%)	Year (2013 if not named)
USA	328	280	23	2019
Luxembourg	0.5	10	5.8
Denmark	5.6	11.25	43.1
Switzerland	8.1	15	19
Germany	83.2	12.2	49.3	2020
Netherlands	16.8	23	10
Austria	8.5	33.96	68
Belgium	11.2	34.75 with major e.	12.4
Italy	59.8	42.27	31.3
Great Britain	64.1	54.71	13.8
Spain	46.6	58.2	36.7	2011
Slovenia*	2.1	60	33.1
France	63.9	68.1	16.8
Hungary	9.9	67.21	6.6
Sweden	9.6	70.77	61.8
Lithuania	3	72.67	13.1
Ireland	4.6	82	20.8	2010
Portugal	10.5	88.7	49.1
Greece	11.1	96	21.2
Czechia	10.5	98.01	12.8
Slovakia	5.4	110.9	20.8
Finland**	5.4	138 with major e.	30.9
Norway*	5.1	144 with major e.	37.4
Cyprus	1.1	148	6.6	2012
Croatia	4.3	176.1	42.2
Poland	38.5	254.9	10.7
Malta*	0.4	360	1.6
Estonia	1.3	378.5 with major e.	13
Latvia	2	621	48.8
Romania	21.3	635	37.5	2009

*, ** = Alternative SAIDI (e.g. T-SAIDI)

See also

• Average Service Availability Index (ASAI)
• ASIDI
• ASIFI
• ASUI
• CAIDI
• CAIFI
• CTAIDI
• MAIFI
• SAIFI