Topic:"Asset Management" 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.

Why do this project now? This project is being advanced at this time such that the probability of loss of load due to a transformer failure is reduced. In addition, favorable pricing is available from the manufacturer on this transformer.

AI summary The project is being advanced now to reduce the probability of load loss from transformer failure and capitalize on favorable manufacturer pricing for the transformer.

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 Request IR-3: 2 3 On page 2 of 20 of the submission it is stated that the new unit would be connected as an 4 energized spare at Kempt Road and would be utilized in the event of a failure "of the 5 existing three transfo...

AI summary The document discusses a request (IR-3) for information about the Kempt Road substation's transformer configuration. The response states the current setup includes three operational transformers, with one recently rewound and another relocated. A fourth transformer will be added as an energized spare, altering the substation's configuration.

NON-CONFIDENTIAL 1 Request IR-15: 2 3 On page 4 of 20 of the submission it is stated that the two recent transformer failures 4 occurred on July 5, 2009, and September 4, 2010. According to page 4 of 5 of the CI# 5 39723 submission, 104-T6...

AI summary The document addresses a request (IR-15) pointing out discrepancies in dates related to transformer failures. The response clarifies that a July 2009 date was incorrect, correcting it to February 2010, and confirms other failures in February 2010 and September 2010.

CONFIDENTIAL (Attachment Only) 1 Request IR-16: 2 3 With reference to the response to IR-3 (b), it is stated that a transformer was taken from 4 another location and placed in-service at Kempt Road: 5 6 (a) Where was this transformer taken...

AI summary NSPI's response to IR-16 details that a transformer was moved from the non-operational Dartmouth Crossing Substation (expected to be in-service by December 2011) and specifies its voltage and MVA rating. The response does not address future relocation plans or energized spares criteria.

CONFIDENTIAL (Attachment Only) 1 Response IR-17: (cont'd) 2 - 3 (d) The unit located at Onslow is the only system spare capable of being connected to 138-25 - 4 kV. Date Filed: March 29, 2011 NSPI (UARB) IR-17 Page 2 of 2

AI summary The document states that the Onslow unit is the only system spare capable of connecting to 138-25 kV. Filed by NSPI (UARB) on March 29, 2011, as part of IR-17, this technical detail highlights infrastructure limitations relevant to regulatory proceedings.

NON-CONFIDENTIAL 1 Request IR-18: 9 on the levels of risk for failure of this unit, before and after the implementation of 10 the procedure described in the response to IR-5 (b). 11 12 (c) Based on investigations of the two faulted transfo...

AI summary The document discusses the risk levels of a transformer unit before and after implementing a procedure, steps to reinforce the integrity of a transformer, and the cost comparison between enhancing an existing transformer and replacing it with a new one. It also mentions the limitations of current testing methods and the lack of historical data for comparison.

IR-5: In its approval request (page 4 of 20) NSPI states that since 2001 there have been four transformer failures at Kempt Road: - a) Please describe the findings of the investigations into the root cause of these failures;

AI summary NSPI has requested approval and highlights four transformer failures at Kempt Road since 2001. The document asks for an explanation of the findings from the investigations into the root causes of these failures.

- b) Which corrective measures and/or procedures have been developed by NSPI to decrease the probability of future transformer failures at this substation? 1 IR-6: 2 On page 4 of 20, under "Why do this project", NSPI states: 3 4 It is expe...

AI summary The document outlines a series of inquiries regarding corrective measures and procedures developed by NSPI to reduce the likelihood of future transformer failures at the Kempt Road substation, including requests for documentation, transformer age and life expectancy, spare transformer availability, cost breakdowns, and alternative solutions.

IR-15: On page 4 of 20 of the submission it is stated that the two recent transformer failures occurred on July 5, 2009, and September 4, 2010. According to page 4 of 5 of the CI# 39723 submission, 104-T63 Transformer Refurbishment, this u...

AI summary The text requests clarification regarding discrepancies in dates related to transformer failures (July 2009, September 2010) and damage from a February 2010 storm, as noted in submission pages and CI# 39723.

IR-16: With reference to the response to IR-3 (b), it is stated that a transformer was taken from another location and placed in-service at Kempt Road: - a) Where was this transformer taken from? - b) What is the rating of this transformer...

AI summary The IR-16 inquiry seeks details about a transformer's relocation, its specifications, future placement, single line diagrams, and NSPI's policies on energized spares and planning criteria.

IR-17: With reference to the response to IR-4: - a) As it relates to the hypothetical loss of all three transformers at the Kempt Road Substation, how much of the stated 54 MVA could not be transferred to the Armdale and Water Street subst...

AI summary IR-17 requests detailed technical information about transformer capacity limitations, substation diagrams, mobile transformer capacity, and spare equipment availability following a hypothetical loss at Kempt Road Substation. Questions focus on transfer capacity constraints, documentation requirements, and equipment specifications.

IR-19: With reference to the response to IR-6: - a) Describe any test results regarding the integrity of this third transformer. - b) On page 4 of 20 of the submission NSPI states: liThe remaining unit has been exposed to similar condition...

AI summary IR-19 queries NSPI on test results for a third transformer's integrity, risk assessment of a unit post-procedure, reinforcement measures for transformer integrity, and cost comparison between enhancements and replacement.

IR-20: With reference to the response to IR-7: - a) What is the remaining life expectancy of the two transformers that were or will be rewound and refurbished? - b) It is noted that 104H-T61 was rewound in 2010. Please elaborate on this pr...

AI summary The IR-20 inquiry seeks details on transformer life expectancy, the 2010 rewind of 104H-T61 including Board approval dates, and the history of 104H-T63 rewound in 2001 and 2010, including technical specifications and locations. This relates to NSPI's infrastructure maintenance and capital approvals.

IR-22: With reference to the response to IR-10: - a) NSPI states that the winding configuration of the spare transformer located in Onslow is such that it cannot be paralleled with the existing units without taking an outage. Please furthe...

AI summary IR-22 requests clarification from NSPI on the winding configuration of a spare transformer in Onslow, specifically why it cannot be paralleled without an outage and the required duration. It also asks if NSPI plans to acquire an additional mobile transformer, including availability and rating details.

IR-27: Please explain, using transformer 104H-T62 as an example, how NSPI determines an optimum replacement age for a substation transformer.

AI summary The proceeding requests NSPI to explain its methodology for determining the optimum replacement age of substation transformers, using transformer 104H-T62 as an example. The focus is on NSPI's technical approach to infrastructure lifecycle management.