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

\mbox{SAIFI} = \frac{\sum{\lambda_i N_i}}{\sum{N_i}}

where \lambda_i is the failure rate and N_i is the number of customers for location i. In other words,

\mbox{SAIFI} = \frac{\mbox{total number of customer interruptions}}{\mbox{total number of customers served}}

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

  1. ^ Yeddanapudi, Sree. "Distribution System Reliability Evaluation". Iowa State University. http://www.ee.iastate.edu/~jdm/ee653/DistributionReliabilityPredictive.ppt. Retrieved 18 June 2011. 

See also