Eversource says standard transformers cost millions as PURA probes upsizing decisions and alternatives

Authority engineers and counsel questioned Eversource distribution witnesses about substation transformer replacements and project alternatives. Angela Soldman (manager, distribution asset management) and Dave Glady (VP, distribution engineering) explained Eversource’s practice of using standardized bulk transformer sizes—62.5 MVA and 40 MVA are common on the system, with smaller 25–40 MVA and padmount 5–10 MVA units used where appropriate.

Soldman said a standard 62 MVA bulk transformer is "approximately $3.5 million," and the full project cost depends on related equipment (foundations, relays, switches and oil containment). When asked whether the company would upsize a legacy unit that is worn but not projected to exceed capacity in the short term, witnesses said they evaluate capacity and condition together, considering a roughly 40‑year asset life so as not to replace an asset only to see capacity constraints arise shortly thereafter.

Project CS00533 (Salisbury) drew scrutiny because the company replaced a 13 MVA, 70‑year‑old unit with a 40 MVA standard unit; Eversource said the original vintage unit was aging, industry supply constraints and standardization drove the selection, and alternatives (including temporary 25 MVA mobile units during work) were considered. Staff requested a late‑file exhibit with the alternatives evaluated, the incremental costs for each option (transformer and associated foundation/containment costs), 90/10 noncoincident peak forecasts, N‑1 contingency loadings and the substations’ firm capacities before and after projects. The company agreed to provide alternatives costs and a table of standard unit material prices by the late‑file deadline.

Authority staff pressed for evidence the company considered non‑asset options (demand reductions, flexible interconnections) and noted that transformer purchases have recently spiked in cost. The company acknowledged transformer pricing trends had materially increased capital estimates and that some supplement requests were prompted by rising transformer prices.