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Enormous electrical transformer maneuvered into place following cross-continent journey

After making a long cross-continent journey, a 110-ton power grid transformer arrived at the East Pine Substation in the wee hours of Sunday, Feb. 12. Similar in weight to a Boeing 757 airplane, Seattle City Light’s newest transformer has an expected lifespan of 40 to 50 years. It replaces a decades-old transformer, improving power reliability and load capacity and allowing for greater control and monitoring capabilities.

The transformer maneuvering through the main gates.

“Aside from our hydro-generators, transformers like this one are the largest and most expensive pieces of equipment in Seattle City Light’s electrical system,” said Hans Gutmann, electrical power systems principal engineer. 

The East Pine Substation houses four transformers powering Seattle’s Central District, First Hill, and Capitol Hill, including area hospitals. The new transformer is part of a multi-year project to expand and upgrade the brick-walled substation, which came online in 1967 and was designated a Seattle Landmark in 2019 due to its award-winning architectural design.

Transformers are large-scale pieces of electrical equipment that play a key role in power distribution. They convert high-voltage electricity carried from power generation sites to substations and lower the electric voltage level, ensuring safe power transmission to customers’ homes or businesses.

“Transformer replacements are one of the largest single projects undertaken by our stations’ personnel, taking many months of planning, preparation, and execution and thousands of labor hours,” Gutmann explained.

The delivery and installation of a transformer requires careful coordination, and City Light had a game plan leading up to the transformer’s arrival on Super Bowl Sunday.

A photo from an SDOT’s traffic camera showing the transformer’s slow progress through Seattle’s streets.

In late 2022, the transformer was loaded onto a rail car in Montreal, Canada, and traveled to Vancouver, Wash. On Feb. 8, the oversized load hit the road traveling up Interstate 5 on a 185-foot-long heavy hauler escorted by a convoy of support vehicles over the course of four nights. (Heavy-haul transportation permits restrict travel to night.)

Workers help guide the transformer precisely through the main gates of the substation.

Late in the evening of Feb. 11, the caravan exited the freeway at Martin Luther King Jr Way South and carefully maneuvered through city streets to the East Pine Substation. Our Seattle Department of Transportation colleagues tweeted the final overnight leg of the transformer’s long journey to the substation.  

The final blocks of the transformer’s trip had been extensively surveyed in advance. With parking restrictions and designated hold points for traffic in place, the transformer was ready to be offloaded at the substation. At daylight on Feb. 12, workers used a system of hydraulic jacks and rails to carefully coax the transformer through the substation’s main gate – just wide enough for the enormous piece of equipment to pass through – with pinpoint precision. The jacks allowed the transformer to move up to 18 inches per interval between the pin locks that secured the transformer to the rails.

With the transformer in place (a super feat on Super Bowl Sunday!) City Light will continue to deliver reliable energy to our customers.