MADISON, WISCONSIN – American Transmission Company has identified the part that caused a 138 kV transformer to explode leading to fire in a Madison substation last summer.
On July 19, transformer explosion at a Madison Gas & Electric substation at 722 E. Main St. left some 13,000 homes and businesses without power Downtown and on the Isthmus. American Transmission Co. announced it had identified the part that had failed and caused the explosion.
According to the findings, a load tap changer within the transformer failed and ignited combustible gases at about 7:40 a.m. on July 19, reports Kenosha News.
ATC’s spokeswoman, Anne Spaltholz, said that an annual sample of gases taken from the transformer in June showed changes, so ATC ordered a follow-up test in July, consulted an industry expert and made additional inspections on July 15, 16 and 17. The company had planned to shut down the transformer for a more detailed inspection on July 22.
Spaltholz said the part had been in service for about 35 years and had a life expectancy of 50 to 60 years. She said ATC is conducting internal reviews and consulting industry peers to determine if any work practices should be changed.
“This is an extremely rare event,” Spaltholz said. “We’ll continue to take a look at anything surrounding this event to see if there’s anything we can do differently.”
Spaltholz said a replacement transformer has been moved into the substation and is expected to be in service by mid-October.
Source: Kenosha News