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The Rolla Daily News - Rolla, MO
  • Power stayed on 99.9 percent of 2012

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  • Rolla Municipal Utilities kept the electricity coming to you more than 99.9 percent of the time in 2012.
     
    To be precise, the ASAI, or Average Service Availability Index was 99.978862 percent, according to the annual "Reliability Statistics" report prepared for the Board of Public Works.
     
    "We had a very good year," said Operations Manager Tom Parker at Wednesday afternoon's meeting of the board.
    Here are some more statistics:
     
    The CAIDI, Customer Average Interruption Duration Index, which is the average number of minutes interrupted per interrupted customer: 62.91.
     
    The SAIDI (long), System Average Interruption Duration Index (average minutes interrupted per customer for all customers): 111.37.
     
    The SAIFI (long), System Average Interruption Frequency Index (number of long interruptions per customer for all customers): 1.92.
     
    The SAIFI (short), or System Average Interruption Frequency Index (number of short interruptions per customer for all customers): 1.90.
    So each customer, on average, had only about two long interruptions and two short interruptions. The long interruptions lasted, on average 111 minutes. The short interruptions were "blinks."
    There were 111 outages in 2012, not counting the scheduled outages, down from 138 in 2011. Here's what caused them:
     
    Supply to city: 2
     
    Overhead equipment failure: 23
     
    Underground equipment failure: 6
     
    Weather: 34
     
    Birds, animals, etc.: 14
     
    Trees/vegetation: 2
     
    Foreign interference: 3
     
    Unknown; 26
     
    Vehicle: 1.
     
    The number of outages caused by birds and animals was double the 2011 figure. The number of unknown causes was up 136 percent from 11 the year before.
     
    Parker said the "unknown" outages were also likely cause by birds and animals. Most of them occurred in the early morning and there were no reports from the public and no damage found. Most of the time, the power went out briefly and then the system reset itself.
     
    "It was probably squirrels," Parker said. "Or birds."
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