In 2018, Hydro One hired us to perform engineering and design services for its Stanley Substation Refurbishment Project. The original 115/13.8-kV substation, placed in-service in 1958, was supplied by two 115-kV circuits. Much of the equipment in the yard and control house had reached the end of its useful life and needed to be replaced to maintain reliable service.
The project scope included the replacement of two 13.8-kV 75‑MVA (dual secondary winding) transformers, installation of a new 13.8-kV switchgear within a new precast building, and the large-scale replacement of all 115-kV and 13.8‑kV protection in a new control room. Also covered was the replacement of all existing roll-in 13.8-kV switchgear breakers as well as the relocation of the transmission termination lattice structure for both circuits.
Because the substation supplies critical load within southern Ontario, the equipment being replaced required a recall time of eight hours or less. To deliver such critical project updates without interrupting service, we developed a detailed construction sequencing plan for the overall project. This comprehensive plan, which required more than 20 phases and close coordination with Hydro One stakeholders, incorporated company-specific requirements while considering the physical limitations of the site. It also identified circuit transfers, developed by our team, to maintain energization of transformer and distribution feeders during construction.