American Transmission Co. (ATC) is working on activities relating to the recent fires at the Blount and the East Campus substations in Madison. The company is also providing information regarding the cause, status of the environmental cleanup, and efforts to restore the electrical equipment.
An ATC transformer caught fire at Madison Gas & Electric’s Blount Street Substation in Madison, Wisconsin, at 7:39 a.m. on July 19, 2019. A few minutes later a second fire occurred at the East Campus Substation. The two substations are electrically connected by underground cables.
"We are grateful that no one was hurt during this incident, and we are thankful to the city of Madison, the fire department, and the police for helping to keep everyone safe," said Paul Roehr, ATC vice president of operations. "We apologize for the inconvenience the community experienced for not having power on a hot summer day. We are thankful to Madison Gas & Electric for working with us to restore power safely and quickly that same day."
Cause Investigation Complete
The ATC investigated the cause of the transformer fire with assistance from an expert from the Electric Power Research Institute (EPRI). Together, the ATC and the EPRI performed a visual inspection of the damaged transformer at Blount Substation a few days after the fire and then conducted a controlled teardown of the transformer to disassemble and inspect the condition of various components to better understand the cause.
Prior to the fire, the ATC had been closely monitoring a component on the Blount transformer because of observed anomalies. The company consulted with the component manufacturer, conducted additional inspections on July 15, 16, and 17, and made plans to take the transformer out of service for a detailed internal inspection on July 22.
"Based on our experience and consultation with the manufacturer, we took prudent action in scheduling the outage," said Jim Vespalec, ATC director of asset planning and engineering. "While the transformer suffered considerable damage in the fire, the inspection and teardown showed that the failure originated in the voltage regulating component because of mechanical failure, generating combustible gases and resulting in a fire."
Failures like this are extremely rare, and the ATC is conducting internal reviews and consulting industry peers to identify if any changes in work practices are necessary.
Environmental Cleanup Continuing
The ATC continues to work in coordination with and under the direction of the Department of Natural Resources (DNR) to contain, collect, and properly dispose of the transformer’s insulating fluid and the water used to extinguish the fire. There were approximately 18,000 gal of insulating fluid in the transformer to insulate and cool the electrical components. A significant portion of the insulating fluid was recovered and collected into tanks for recycling under the direction of the DNR.
The DNR also asked the ATC to contain and collect water from the stormwater system that the fire department used to extinguish the fire. With high lake levels at the time of the fire, there is no reason to believe any water was discharged into the waterways. The DNR also asked the ATC to test for concentration levels of PFAS, which is a chemical in firefighting foam used to contain the fire. The ATC is working with the city of Madison and the DNR to treat approximately 180,000 gal of recovered water to remove PFAS.
Additional monitoring and coordination with the DNR will continue to determine if further action may be needed.
New Transformer in Place
The ATC has been working to get the transmission equipment at Blount Substation back to working order. A new transformer is sitting on a new concrete pad in the substation, and necessary electrical connections and tests are being completed with the goal of putting the new transformer in service by mid-October.
Within a week of the fire, the ATC made immediate transmission repairs at the East Campus Substation to make it operational. More permanent repairs are planned for 2020.