Average Service Availability Index

The Average Service Availability Index (ASAI) is a reliability index commonly used by electric power utilities. ASAI is calculated as

${\mbox{ASAI}}={\frac {\sum {N_{i}\times 8760}-\sum {U_{i}N_{i}}}{\sum {N_{i}\times 8760}}}$

Or in relation to SAIDI (when the annual SAIDI is given in hours)

${\mbox{ASAI}}=1-{\frac {\mbox{SAIDI}}{8760}}$

where $N_{i}$ is the number of customers and $U_{i}$ is the annual outage time (in hours) for location $i$.

See also

• ASUI
• SAIDI
• SAIFI
• CAIDI
• CAIFI
• MAIFI