American Transmission Co.

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Madison substation event

At 7:39 a.m. on Friday, July 19, 2019, an American Transmission Co. transformer caught fire at Madison Gas & Electric’s Blount Street Substation in Madison, Wisconsin. A short time later a second fire occurred at the East Campus Substation. The substations are electrically connected by an underground transmission line. Both fires were extinguished by approximately 9 a.m.

ATC thanks Madison’s Fire and Police departments for the quick response to maintain public safety. We also thank officials from the city of Madison and the community for their patience as we worked with Madison Gas & Electric to restore power as quickly and safely as possible that same day.

Environmental cleanup

ATC continues to work in coordination with and under the direction of the Wisconsin Department of Natural Resources to manage the environmental cleanup following the transformer fire.

There are two main areas of focus:

Insulating fluid – ATC’s transformer had approximately 18,000 gallons of dielectric insulating fluid that helps to insulate and cool electrical equipment. Some of the fluid burned in the fire, some was safely pumped from the transformer, and our environmental contractor used a skimming method to separate the dielectric fluid from water used to put out the fire. The city installed booms at the outlets to Lake Monona and the Yahara River to ensure no insulating fluid from the transformers made it into those waterways. The insulating fluid does not contain PCBs, and there is no evidence that insulating fluid made its way into the lake or river. A significant portion of the insulating fluid was recovered and collected into tanks for recycling under the direction of the DNR.

PFAS – The Madison Fire Department used water and a firefighting foam to extinguish the fire at Blount Substation. The DNR asked ATC to test for concentration levels of PFAS — a chemical used in firefighting foam. Test results confirmed the presence of certain PFAS compounds in very low concentrations. ATC is working with the DNR and the City of Madison to treat recovered water to remove PFAS and determine a location to discharge the treated water.

Additional environmental monitoring and coordination with the DNR will continue to determine if further action may be needed.

Information about environmental activities to date can be found on this DNR webpage.

Substation restoration

ATC has been working to get the transmission equipment at Blount Substation back to working order. A new transformer sits on a new concrete pad in the substation, and the 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, ATC made immediate transmission repairs at the East Campus Substation to make it operational. More permanent repairs are planned for 2020.

Cause investigation

ATC investigated the cause of the transformer fire with assistance from an expert from the Electric Power Research Institute. EPRI is an independent, nonprofit organization that conducts research in the electricity sector.

Together, ATC and 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.

As previously shared, prior to the fire ATC had been closely monitoring a component on the Blount transformer because of observed anomalies. ATC consulted with the component manufacturer, conducted additional inspections July 15, 16 and 17, and made plans to take the transformer out of service for a detailed internal inspection on Monday, July 22.

While the transformer suffered considerable damage in the fire, the inspection and teardown showed that the failure originated in the voltage regulating component due to mechanical failure, generating combustible gases and resulting in a fire.

Failures like this are extremely rare, and ATC is conducting internal reviews and consulting industry peers to identify if any changes in work practices are necessary.


ATC Media Relations

Last Updated: October 2, 2019