Nova Scotia Power filed responses to two rounds of information requests (IR-1 to IR-29) justifying an urgent $1,093,699 U&U work order to purchase a spare transformer for the Kempt Road substation following two failures in 2010.

M03715 · CI# 40425 - P-510 - NSPI WO - Kempt Road Transformer - $1,093,699Zero dollars spent to date

AI summary

NSPI explained the project was filed as an Unforeseen and Unbudgeted (Capital Expenditures) work order rather than through the 2011 ACE Plan because two of three 138-25 kV transformers at the Kempt Road substation failed in February and September 2010, leaving the Halifax Peninsula at risk of significant unsupplied load (up to 54 MVA at peak) if the sole remaining in-service unit (installed 1976) failed (IR-1, IR-29).
Root cause investigations attributed the failures to transformer 'through faults' caused by distribution system faults — such as tree contact — near the high-fault-level substation; NSPI's primary corrective measure, implemented after the September 2010 failure, was setting reclosers to single-shot reclosing prior to significant wind events (IR-5, IR-18).
NSPI compared alternatives including underground feeder construction (estimated well over $1,000,000) and overhead street feeders (~$150,000/km plus >$1,000,000 in termination costs), concluding that purchasing an energized spare transformer at $1,093,699 was the lowest-cost option; rebracing the at-risk third transformer (104H-T62) was estimated at ~$950,000 and would not eliminate future failure risk (IR-14, IR-19).
To mitigate immediate System Reliability risk, NSPI temporarily relocated a transformer from the not-yet-commissioned Dartmouth Crossing Substation to Kempt Road, but this left Dartmouth Crossing without a unit, creating additional reliability exposure and reinforcing the urgency of the new purchase (IR-16, IR-29).
Several system planning documents, substation single-line diagrams, and supplier identity information were filed confidentially or redacted due to security concerns and commercial sensitivity; NSPI's spare transformer adequacy methodology was adapted from Hydro One guidelines, with the new unit designated as a permanently energized spare (T-64) once 104H-T61 is returned to service (IR-12, IR-16, IR-25).

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What was filed

Documents filed on this day

N-2 Responses to Information Requests IR-1 to IR-14 1/27/2011 exhibits
N-3 Redacted Responses to 2nd Set of Information Requests IR-15 to IR-29 3/29/2011 exhibits
06426 2nd Set of Information Requests (IR-15 to IR-29) 2/21/2011 other_documents