AI-generated summary
· Application · 10/19/2010
Nova Scotia Power filed responses to Board Information Requests IR-1 through IR-3 regarding its 2009 Relay Testing Report (P-401.32)
AI summary
- NSPI confirmed that as of end-of-2009, 1,223 mechanical relays at 138kV and 69kV remain in its transmission test program, with 1,408 tested over the three-year cycle; 185 relays were removed from the program due to Npcc Bulk Power System reclassification, retirement, or protection upgrades (IR-1 response, p. 1).
- One relay could not be tested during the three-year cycle because removing it from service posed too great a risk to system stability; NSPI stated it will be tested at the next scheduled major maintenance outage (IR-1 response, p. 2).
- Total program costs over the three years were $440,340, declining from $188,689 (2007, 653 relays) to $159,441 (2008, 430 relays) to $92,210 (2009, 325 relays), with per-relay costs ranging from $284–$371 depending on substation configuration and relay density (IR-2 response, p. 1).
- NSPI proposed extending the relay testing cycle from three years to ten years, citing a low ~2% failure rate over the completed cycle, the presence of backup protection for all failed units, and the paradox that testing itself introduces single-contingency risk by temporarily removing protection equipment from service (IR-3 response, p. 1).
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What was filed
Documents filed on this day
- N-2 NSPI (NSUARB) IR-1 to IR-3