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IEVref:692-08-03ID:
Language:enStatus: Standard
Term: service unavailability per customer served
Synonym1: system average interruption duration index, CA US
[Preferred]
Synonym2: SAIDI
[Admitted]
Synonym3:
Symbol: UCS
Definition: sum of durations of all interruptions of supply to individual customers served during a time interval, divided by the product of the total number of customers served and the duration of that time interval

Note 1 to entry: If tij is the duration of the ith interruption of supply to customer j during a time interval of duration T, and NS the total number of customers served, then the service unavailability per customer served is given by

U CS = i j t ij N S T MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdi9qqqj=hEeeu0lXdbb a9frFj0xb9Lqpepeea0xd9s8qiYRWxGi6xij=hbba9q8aq0=yq=He9 q8qiLsFr0=vr0=vr0db8meaabaGacmGadiWaaiWabaabaiaafaaake aacaWGvbWaaSbaaSqaaiaaboeacaqGtbaabeaakiabg2da9maalaaa baGaeyyeIu+aaSbaaSqaaiaadMgaaeqaaOGaeyyeIu+aaSbaaSqaai aadQgaaeqaaOGaamiDamaaBaaaleaacaWGPbGaamOAaaqabaaakeaa caWGobWaaSbaaSqaaiaabofaaeqaaOGaamivaaaaaaa@48A3@

Note 2 to entry: Only sustained interruptions are considered.

Note 3 to entry: If the duration of the time interval is expressed in years, the quantity is called the "average yearly downtime per customer served".

Note 4 to entry: The term "customer" represents the end user and not some intermediate distribution system or company.

Note 5 to entry: Service unavailability per customer served can be used to describe past performance or to estimate expected future performance.

Note 6 to entry: This entry was numbered 191-27-03 in IEC 60050-191:1990.


Publication date:2017-12-15
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