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System Reliability

Xcel Energy is now calculating and tracking reliability performance using methodology provided by the Institute of Electrical and Electronics Engineers (IEEE); this methodology is more commonly used in our industry and incorporating it improves our ability to benchmark Xcel Energy’s performance with other utilities. Please note that while our performance indicators for 2013 reflect our old methodology, the numbers below use the IEEE methodology.

System Average Interruption Duration Index

The System Average Interruption Duration Index (SAIDI) measures the average number of minutes a typical customer was without power in a year.

  • Xcel Energy: 95.59
  • NSPM: 97.31
  • NSPW: 88.14
  • PSCo: 93.88
  • SPS: 100.55

System Average Interruption Frequency Index

The System Average Interruption Frequency Index (SAIFI) measures the average number of power outages that an average customer experienced in a year.

  • Xcel Energy: 0.99
  • NSPM: 0.88
  • NSPW: 0.78
  • PSCo: 1.13
  • SPS: 1.09

Customer Average Interruption Duration Index

The Customer Average Interruption Duration Index (CAIDI) measures the length of the average power outage in a year.

  • Xcel Energy: 96.18
  • NSPM: 110.69
  • NSPW: 113.36
  • PSCo: 83.02
  • SPS: 92.07