ASUI

The Average Service Unavailability Index (ASUI) is a reliability index commonly used by electric power utilities. It is calculated as

${\mbox{ASUI}}={\frac {\sum {U_{i}N_{i}}}{\sum {N_{i}}\times 8760}}=1-{\mbox{ASAI}}$

where $N_{i}$ is the number of customers and $U_{i}$ is the annual outage time (in hours) for location $i$. ASUI can be represented in relation to SAIDI (where annual SAIDI is given in hours) as

${\mbox{ASUI}}={\frac {\mbox{SAIDI}}{8760}}$