In early 2019, a Dissolved Gas Analysis (DGA) was performed on all three single-phase 500 kV: 115 kV transformers at Tono Substation. One of the transformers was identified as nearing its end of life due to increased gassing to high levels After PSE’s need assessment and solution report were completed, planning and engineering worked on a design that led to the procurement of a new, state-of-the-art, transformer at the end of 2020.
Two and a half years later, after traveling several thousand miles across the country from Memphis, Tennessee via train and truck, the massive transformer arrived in Centralia, WA, in June 2023. PSE took delivery of the new three phase 500kV:115kV transformer, one of the largest on the West Coast.
In July when the new transformer was energized, PSE Director of Operations, Ryan Murphy Director of Operations, Ryan Murphy’s remarks included, “The efforts required to design, procure and install this Extra High Voltage (EHV) transformer are truly remarkable.”
Much attention is rightly given to the design, manufacturing, installation and commissioning of EHV transformers. The processes and practices PSE crews used to prepare the new pad site, ensured that active component connections are correct and that the transformer protection and monitoring systems are operational were “truly remarkable”. But Murphy’s statement was also about the final transporting, handling and delivery of the massive transformer to the Tono Substation job site.
Transformer Shipping
The manufacturer worked with PSE and provided a transport plan for the 450,000 lb. transformer core. This included multiple methods of transportation during its journey. Transit logistics included traveling via rail and multiple interchanges from the transformer manufacturing facility in Memphis, Tennessee to the rail siding in Centralia, WA. PSE crews were trained and ready. The transformer was offloaded from railcar and loaded onto a heavy haul trailer.
The transformer traveled over road for less than a mile to its final destination. It was then offloaded via jack and slide method onto the substation foundation pad. Additionally, eight truckloads of accessories (bushings, radiators, auxiliary transformer, arrester towers, etc.) arrived onsite after the transformer core was delivered.
It was critical to the life of the transformer that surface moisture was removed from transformer insulation. Final assembly included placing the transformer under vacuum for removing surface moisture and air pocket. Afterward, the transformer was filled with approximately 32,000 gallons and two oil circulations were then performed. The entire process lasted 6 days, nonstop around the clock.
Puget Sound Energy (PSE), headquartered in Bellevue, Washington, is Washington state's oldest local energy company. The 3,300-plus employ utility began service as Seattle Gas Light Company to the “Washington Territory” in 1873. Today PSE service approximately 1.2 million electric and over 900,000 natural gas customers primarily in the Puget Sound region of Western Washington.
The new transformer will help maintain the reliability, resiliency, and integrity of the substation and the electric grid system in South Thurston County.
Hector Gonzalez is a Project Manager with Puget Sound Energy, and has been in the Major Projects department for 6 years. While working in this role, Hector has been involved in multiple substations, transmission line, gas main, and internal facility projects. Hector’s background includes a BS in Construction Management and over 13 years of gas and electric project experience. When he’s not working, Hector enjoys spending time in nature and hiking with his wife and young sons.
