T&D World Magazine

2008 Electric Reliability Performance Report

This report presents Department of Public Service Staff’s (Staff) assessment of electric reliability performance in New York State. As a means of monitoring the levels of service, utilities are required to submit detailed interruption data to the Public Service Commission (Commission). Staff relies on two primary metrics to measure reliability performance: the System Average Interruption Frequency Index (SAIFI or frequency) and the Customer Average Interruption Duration Index (CAIDI or duration).1 By compiling the results of individual utilities, the average frequency and duration of interruptions can be reviewed to assess the overall reliability of electric service in New York State.

The statewide interruption frequency for 2008, excluding major storms, was considerably better than that recorded in 2007, where all companies except Orange and Rockland Utilities, Inc. (Orange and Rockland) showed improvement. The statewide duration in 2008 was slightly worse than in 2007. The year 2008 was the second-most affected by storms in five years and had 35 more storms than in 2007. Staff attributes some of the 2008 improvement in frequency to the high number of major storms (excludable events). Typical weather patterns result in less severe weather that lead to minor storms, which are included in the measures and thereby increase performance measures. Similar overall patterns exist for frequency and duration when analyzing the reliability data excluding Consolidated Edison Company of New York, Inc (Con Edison) performances....

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