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AI-generated summary · Application · 10/28/2010

NSEB directs Nova Scotia Power to adopt a six-year relay testing cycle, rejecting NSPI's proposal to extend to ten years

M03232 · P-401.32 - Nova Scotia Power Inc. (NSPI) -  Relay Testing Report - 2009Review of Report
AI summary
  • The Board reviewed NSPI's 2009 Relay Testing Report (Matter No. M03232), which covered 325 relays tested during the year, with 10 (3%) replaced or repaired for serious functional failures, 53 (16%) recalibrated, and 259 (80%) found acceptable.
  • Over the full three-year cycle (2007–2009), total program costs reached approximately $440,000, with 2009 alone costing $92,200; failure rates across the cycle averaged approximately 2%.
  • NSPI requested Board approval to extend its relay testing schedule from a three-year to a ten-year cycle, citing low failure rates, the existence of backup protection for failed units, and the argument that physical testing itself creates single-contingency risks during the testing period.
  • The Board accepted that the three-year cycle had served its purpose of establishing relay integrity but was not persuaded that a jump to a ten-year interval was appropriate.
  • By letter dated October 28, 2010, the Board directed NSPI to implement a six-year testing cycle for 69 kV and 138 kV system relays, and to continue filing annual reports in the current format; relays classified as Bulk Power System Elements remain subject to a four-year cycle.

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What was filed

Documents filed on this day

  • 05589 Board Letter giving directions other_documents