January 2012 Capital Investment - National Grid

Exhibit ___ (EIOP-19)Page 51 of 684replacement. Overhead line equipment failures will be managed through the Damage /Failure budget and any Level 1, 2 or 3 issues identified during foot patrols will also beaddressed through the Damage / Failure budget.Table II-19Transmission – Overhead Line Refurbishment ProgramProgram Variance ($millions)CIP FY12 FY13 FY14 FY15 FY16 FY17 Total2011 17.0 19.0 21.3 61.2 70.9 - 189.42012 - 23.2 27.8 46.3 56.9 68.2 222.4Transformer Replacement Strategy (C31656)Power transformers are managed through routine visual inspection, annual dissolvedgas analysis (“DGA”) and electrical testing where required. Transformers with tapchangersare also maintained in accordance with our substation maintenance standards.In the next five years the investment plan is to replace three transformers withanomalous DGA results that have been or are expected to be confirmed as in poorcondition through electrical testing.With the previous exceptions, this Plan utilizes a replace on fail approach with failuresmanaged through the use of strategic spares. In this context, failure means either DGAresults that suggest an immediate need for replacement or actual physical / electricalfailure. Over the next five years, a process has been initiated to ensure sufficientstrategic spares are available to cover the probability of failure for the majority of thefleet. The costs for purchasing these spares are currently included within the Plan inproject C39883 within the Asset Condition spending rationale. Furthermore, projectC31656 within the Damage Failure spending rationale includes funding for any neededemergency replacements between FY14 – FY17 of the Plan.Drivers:In the current Plan period, the purchase of a spare transformer for the Harper Substationis planned since none currently exist and each transformer is in a deteriorated conditionwith obsolete parts that are not stocked by OEM or after market manufacturers. Thepurchase of a spare transformer is an interim measure until a system study can beperformed to determine a long term plan for Harper and the remaining 4kV stations inthe Niagara Falls area.Transformer LTC TRF 3 at Greenbush (C31663) is a 57 years old 115-34.5kVtransformer and DGA results indicate it has had an internal flashover with elevatedacetylene along with active connection heating and possible partial discharginggenerating hot metal gases of ethylene, methane, ethane, and hydrogen. It has issueswith the high side bushings, which are GE type U bushings, and silicon carbide surgearrestors which should be replaced. Power factor testing indicates high deterioration ofthe insulation between the high side and low side windings with lesser deteriorationII-3452