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Seattle substation upgrades make West Coast grid more reliable

Seattle City Light is installing a new, 480,000 pound transformer as part of upgrades at the East Pine Substation that are designed to make the facility stronger during an earthquake and more reliable as it helps to transmit power from Canada to the West Coast of the United States.


From the first hydroelectric facility on the Cedar River, to the massive concrete arc of Boundary Dam, City Light is founded on a tradition of big and bold engineering.

Residents of the Central District and Capitol Hill are currently getting a peek at that tradition, as workers and contractors work on massive upgrades of the East Pine substation. The work is designed to make that facility stronger during an earthquake and more reliable as it helps to transmit power from Canada to the West Coast of the United States.

20150801_060044_resized_1The most visible part of that project happened last week. Between Aug. 1 and Aug. 8, contractors moved a 30-foot-long, 22-foot-tall, 480,000-pound transformer from its staging location near the Port of Seattle, all the way to the substation at 1501 22nd Ave.

The machine replaces an older, smaller transformer that has served its operational life. It was manufactured in Korea by the Hyosung Corporation. It arrived by ship at the Port of Tacoma and was barged to Seattle this summer.

Moving it from the port to its final location has been a logistical odyssey. It is so heavy and unwieldy that it had to be transported in two trips, from the port to a staging area in a tandem trailer, and from there to the station in a relatively smaller rig.

P1030383Over the weekend, the transformer was slipped into position with the help of pneumatic pistons and metal rails. It will be fully assembled and filled with oil so it can go into service in November.

The rigs and moving equipment may be the most visible part of the project, but what’s under and around the new transformer is perhaps the most important.

The new transformer will sit on a base of pendulum bearings. These bearings serve as shock absorbers, allowing the transformer to glide back and forth during an earthquake. By transferring movement for force, the bearings help to keep the transformer upright and connected. It will be the third transformer in the entire United States – and the second at City Light – to use this new technology.

pedestalIn addition to the gliding bases, the transformer and the equipment around it will be supported by new metal structures designed and custom built by City Light engineers and steel workers to be stronger and more resilient during an earthquake.

The structures include supports and tall pedestals shaped like mini Eiffel Towers that will hold solid conductors. They resonate at a different range of frequencies than the motion of an earthquake, so that they won’t rattle apart during ground shaking.

“To the equipment, it will feel like everything is fixed directly to the ground,” said Robert Cochran, the civil engineer who designed the new structures.

All these upgrades will make the substation more reliable. This is a critical issue for our city and the entire West Coast. The East Pine Substation supplies power to all the major hospitals on First Hill and to parts of downtown. It is also part of the Bulk Electric System that moves power from Canada all the way down to California.