SAN DIEGO — For the first time, researchers from the Idaho National Laboratory tested a full-scale 230-kilovolt three-phase power transformer, a keystone of the U.S. grid, under simulated earthquake conditions.
INL subjected one of the largest, heaviest and hardest-to-replace components of the U.S. grid to a realistic earthquake simulation at the University of California, San Diego’s Large High-Performance Outdoor Shake Table, the world’s most powerful earthquake simulator. A damaged transformer can take five years or more to replace. But until now, no one had subjected a full-scale 230-kV transformer — including oil, bushings, radiators and conductors — to real seismic conditions.
Power transformers step voltage up and down as electricity moves from generation units to homes, hospitals and emergency services. “We’re trying to protect a critical, hard-to-replace piece of equipment that keeps the power on during a disaster,” said Bjorn Vaagensmith, INL’s principal researcher on the project. “If the transformer goes down, so does the hospital, the water system, everything downstream of it.”
The project brought together industry, the private sector and the U.S. government. INL served as the technical lead, and contributors included W.E. Gundy & Associates Inc. (WEGAI) Research; UC San Diego; the University at Buffalo; dozens of utilities; the Department of Energy Office of Cybersecurity, Energy Security, and Emergency Response’s (CESER) natural hazards program; and the DOE Office of Electricity’s (OE) Transformer Resilience and Advanced Components program.
INL’s CESER- and OE-funded seismic testing work aligns with President Donald Trump’s executive order “Achieving Efficiency Through State and Local Preparedness,” which aims to make U.S. infrastructure, communities and the economy resilient to dynamic global threats and hazards.
“For decades, the committee responsible for seismic substation design has raised concerns about seismic damage to power transformers, which are often the most vulnerable substation components and the most common earthquake casualty,” said Jon Bender, principal engineer at WEGAI Research. “Even so, this experimental work wasn’t possible until INL, CESER and OE joined the team.”
“Safeguarding America’s critical energy infrastructure against all hazards, including cyber and physical, is central to CESER’s mission,” said CESER Director Andrew McClure. “This groundbreaking testing gives us essential empirical data to strengthen high-voltage grid components before a major earthquake strikes.”
Replacing a damaged full-scale transformer can take years, and a major earthquake hitting multiple substations could leave communities without power for months. Utilities in earthquake-prone regions, from the U.S. West Coast to Chile and Japan, are watching closely.
“The faculty and staff at UC San Diego were pleased to work with the project team to test the seismic response of this transformer,” said John McCartney, principal investigator at the Large High-Performance Outdoor Shake Table. “We believe that the shake table’s six-degree-of-freedom motion capabilities, 20 meganewton payload capacity and roofless outdoor setting provide unparalleled opportunities for this type of testing.”
The test targeted three questions current standards don’t address:
Can we predict transformer behavior during an earthquake? The leading theory behind frequent bushing failures is dynamic resonance. If engineers can predict that condition, they can optimize designs and build the knowledge into seismic specifications for high-risk projects.
Can a decoupler save the bushings? Bushings — the insulators carrying electrical connections through the tank — are a major failure point. The test included a new decoupler system meant to ease that stress, bridging the gap until resilience is built into transformers from the start.
Does base isolation work at this scale? No one has tested base isolation on a full-scale 230-kV transformer before, though evidence suggests it could sharply cut seismic risk across vulnerable components, including bushings.
Results will be published through DOE’s Office of Scientific and Technical Information and in peer-reviewed journals, with the goal of making the data public to support future industry standards.
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