Average Service Availability Index

The Average Service Availability Index (ASAI){{cite web

|url=http://www.ee.iastate.edu/~jdm/ee653/DistributionReliabilityPredictive.ppt

|title=Distribution System Reliability Evaluation

|first=Sree

|last=Yeddanapudi

|publisher=Iowa State University

|accessdate=18 June 2011

|url-status=dead

|archiveurl=https://web.archive.org/web/20111226034249/http://www.ee.iastate.edu/~jdm/ee653/DistributionReliabilityPredictive.ppt

|archivedate=26 December 2011

}}{{cite book|last=Pham|first=Hoang|title=Handbook of reliability engineering|url=https://books.google.com/books?id=Xe6Z4wKQFMoC&pg=PA514|accessdate=21 July 2011|date=8 April 2003|publisher=Birkhäuser|isbn=978-1-85233-453-6|pages=514}} is a reliability index commonly used by electric power utilities. ASAI is calculated as

$\backslash mbox\{ASAI\}\; =\; \backslash frac\{\backslash sum\{N\_i\}\; \backslash times\; 8760\; -\; \backslash sum\{U\_i\; N\_i\}\}\{\backslash sum\{N\_i\}\; \backslash times\; 8760\}$

where $N\_i$ is the number of customers and $U\_i$ is the annual outage time (in hours) for location $i$. ASAI can be represented in relation to SAIDI (when the annual SAIDI is given in hours, 8760 is the number of hours in a year)

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