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:

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

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

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

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.

See also

• SAIFI
• CAIDI
• CAIFI
• MAIFI
• ASAI
• ASUI