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News Analysis

Fortnightly Magazine - March 15 2000

SAIDI, and other familiar acronym-named calculations for utilities in Ontario, where electric retail competition is set to kick off in November. In Ontario, the link between deregulation and increased reliability oversight is a direct and overt one, for the restructuring legislation strengthened the language giving the energy board mandate to protect the consumer, allowing the board to come up with what senior communications officer Lee Wilson calls "a very strict code of conduct."

To Wilson, the link between deregulation and reliability is clear. "They're starting to go hand-in-hand, quite frankly," she says, "because the consumer is saying 'what are you going to do for me now.' It's consumer driven."

Lori A. Burkhart is contributing legal editor, Carl J. Levesque is associate editor, and Bruce W. Radford is editor-in-chief at Public Utilities Fortnightly.

 

Apples and Oranges?

Why comparing utilities on reliability is a dicey business.

Different states prefer different means of measuring reliability, so an index in one state may vary slightly from the same index in another.

In Illinois, utilities such as Commonwealth Edison and Illinois Power use three indices: CAIDI (Customer Average Interruption Duration Index), CAIFI (Customer Average Interruption Frequency Index), and SAIFI (System Average Interruption Frequency Index).

California prefers SAIDI (System Average Interruption Duration Index), MAIFI (Momentary Average Interruption Frequency Index), and SAIFI, as required by that state's 1996 decision adopting annual reliability reporting requirements (Decision No. 96-09-045, Sept. 4, 1996, (Cal.P.U.C.).

As ComEd points out in its 1998 reliability report, when comparing reliability calculations for utilities, analysis should include such variables as the weather experienced by each utility and the type of load (urban, rural, or suburban) they serve. And even more care, ComEd says, should be taken when comparing statistics of utilities from different states since, for example, some state commissions require that interruptions lasting more than five minutes be included in calculations, while other states require inclusion of interruptions lasting as little as one minute. In the case of the two following states, at least in their SAIFI calculations, California uses a five-minute threshold, while Illinois uses a one-minute threshold.

Apples and Oranges?

Why comparing utilities on reliability is a dicey business.

Different states prefer different means of measuring reliability, so an index in one state may vary slightly from the same index in another.

In Illinois, utilities such as Commonwealth Edison and Illinois Power use three indices: CAIDI (Customer Average Interruption Duration Index), CAIFI (Customer Average Interruption Frequency Index), and SAIFI (System Average Interruption Frequency Index).

California prefers SAIDI (System Average Interruption Duration Index), MAIFI (Momentary Average Interruption Frequency Index), and SAIFI, as required by that state's 1996 decision adopting annual reliability reporting requirements (Decision No. 96-09-045, Sept. 4, 1996, (Cal.P.U.C.).

As ComEd points out in its 1998 reliability report, when comparing reliability calculations for utilities, analysis should include such variables as the weather experienced by each utility and the type of load (urban, rural, or suburban) they serve. And even more care, ComEd says, should be taken when comparing statistics of utilities from different states since, for example, some state commissions require that interruptions