SAIFI
The System Average Interruption Frequency Index (SAIFI)[1] is commonly used as a reliability indicator by electric power utilities. SAIFI is the average number of interruptions that a customer would experience, and is calculated as
[math]\displaystyle{ \mbox{SAIFI} = \frac{\sum{\lambda_i N_i}}{N_T} }[/math]
where [math]\displaystyle{ \lambda_i }[/math] is the failure rate, [math]\displaystyle{ N_i }[/math] is the number of customers for location [math]\displaystyle{ i }[/math] and [math]\displaystyle{ N_T }[/math] is the total number of customers served. In other words,
[math]\displaystyle{ \mbox{SAIFI} = \frac{\mbox{total number of customer interruptions}}{\mbox{total number of customers served}} }[/math]
SAIFI is measured in units of interruptions per customer. 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 1.10 interruptions per customer.
References
- ↑ "Distribution System Reliability Evaluation". Iowa State University. Archived from the original on 26 December 2011. https://web.archive.org/web/20111226034249/http://www.ee.iastate.edu/~jdm/ee653/DistributionReliabilityPredictive.ppt. Retrieved 18 June 2011.
See also