Topic:"System Reliability" in M03715

Why do this project? Currently there are three 138-25 kV transformers at Kempt Road Substation that supply area load. Since 2001 there have been four transformer failures at Kempt Road. Most recently there have been two transformer failure...

AI summary Three 138-25 kV transformers at Kempt Road Substation have experienced multiple failures since 2001, with two recent units removed for rewinding. The remaining transformer is at risk of failure due to high fault levels in the area, prompting a proposal to purchase a spare transformer to prevent extended power outages.

NON-CONFIDENTIAL 1 Request IR-1: 2 3 On page 4 of 20, under "Why do this project now?", NSPI states this project is being 4 advanced at this time to reduce the probability of loss of load due to a transformer failure. 5 Please provide spec...

AI summary NSPI justifies submitting a transformer replacement project as a U&U work order rather than part of the 2011 ACE Plan, citing a 2010 failure of two Kempt Road substation transformers, leaving only one aging unit operational. The project aims to prevent potential load loss if the remaining transformer fails.

NON-CONFIDENTIAL 1 Response IR-4: (cont'd) 2 3 If NSPI were to lose the most heavily loaded of the 3 transformers at 104H Kempt Road, NSPI 4 could do the following transfers of load: 5 6  transfer 20 MVA on a short-term basis onto the mob...

AI summary NSPI outlines contingency plans for handling transformer failures at the Kempt Road substation, detailing load transfers between transformers and mobile units. The response includes specific MVA redistribution strategies for single and dual transformer outages, ensuring continued service under emergency conditions.

CI # 40425 Kempt Road Transformer $1,093,699 Board staff issued Information Requests ("IRs") on December 24, 2010 and February 21, 2011, to which responses were received by the Board on January 27 and March 29, 2011, respectively. The Boar...

AI summary The Board approved NSPI's request for funding to purchase a fourth transformer for the Kempt Road Substation to improve power supply reliability in downtown Halifax. The Board expressed concerns about insufficient project details and the outdated status of the spare transformer report, but accepted the request due to urgency and alignment with Hydro One guidelines.

IR-1: On page 4 of 20, under "Why do this project now?", NSPI states this project is being advanced at this time to reduce the probability of loss of load due to a transformer failure. Please provide specific information to support the abo...

AI summary NSPI's project aims to reduce transformer failure risks by advancing the work now. The Board requests justification for submitting this as a U&U work order instead of the 2011 ACE Plan and details on the 2010-2011 work schedule. Additional queries focus on substation configurations and contingency capacity.

IR-18: With reference to the response to IR-5: - a) When were the investigations noted in IR-5 (a) completed? - b) When did NSPI start to use the procedure described in IR-5 (b)? - c) Please describe any measures taken to limit the magnitu...

AI summary The document contains four questions related to the completion of investigations, the implementation of procedures by NSPI, fault current mitigation measures, and unimplemented options. These questions reference prior inquiries (IR-5) and are part of a regulatory proceeding (IR-18).

IR-28: Please provide and discuss assumed transformers' failure rates, and probabilistic risk assessments of the reliability of power supply to customers in the downtown Halifax area, for the following transformer configurations at the Kem...

AI summary The document requests probabilistic risk assessments and failure rate analyses for transformer configurations at Kempt Road Substation across six timeframes, including pre-2009, post-2010, and scenarios with spare transformers. It also asks for economic analyses comparing urgent transformer purchase versus delayed purchase, referencing prior IR-5(b) responses.

CI # 40425 Kempt Road Transformer $1,093,699 Board staff issued Information Requests ("IRs") on December 24, 2010 and February 21, 2011, to which responses were received by the Board on January 27 and March 29, 2011, respectively. The Boar...

AI summary The Board approved NSPI's request to purchase a fourth transformer for the Kempt Road Substation to improve power supply reliability in downtown Halifax, despite concerns about insufficient project justification and outdated transformer requirement reports. The Board also requested an updated report on spare power transformers.