ATC, contractor crews work to restore power for thousands following severe storms
Two massive storm systems and several tornadoes rolled through ATC’s service area on Aug. 28, creating eight transmission line outages and impacting nearly 40,000 retail customers across 12 Wisconsin counties.
ATC operators in Cottage Grove and Pewaukee were paying close watch to the weather radar prior to the arrival of both storms. As the first storm moved through south central Wisconsin, several 69,000-volt lines were fiercely impacted causing a succession of outages that trickled east.
From the operations centers, operators are usually able to assess exactly where in the line a fault is occurring. If those assessments through high-speed data communications can’t be made remotely, ATC relies on crews from our local distribution companies like Alliant Energy and We Energies to be the boots on the ground and provide observations from the field. In this weather event, many of those inspections were initially hindered by the sheer depth of the water from rainfall that was blocking roadways.
The most common reason that an outage occurs on transmission lines is due to lightning. When the electrical current strikes a line, it will typically trip and re-close. In some cases, it does not – which is when onsite inspection must occur. In the case of the storms on Aug. 28, other unique impacts occurred. The wind fractured many trees and branches, dropping them onto the lines and forcing outages. On a pair of lines east of Fond du Lac, a piece of metal blown off a nearby structure became embedded into the pole arms and conductors. More than 20 poles along a line north of Lomira snapped in the wind, taking the line down. And although some of the transmission lines impacted were 138-kV lines, most were 69-kV lines – which are typically carried on wooden poles.
Despite the number of outages and the 25 crew members dispatched, most of the transmission lines were restored after the water subsided. Many of ATC’s maintenance and engineering staff worked through the night on Aug. 28 to help crew members restore all but one transmission line – which is still undergoing repairs. Meanwhile, operators’ switching efforts restored power to support customer and system needs on ATC’s transmission grid.
As a precaution, ATC also flew aerial patrols over the storm-damaged areas, which revealed 16 different instances of leaning trees or poles. For safety and reliability reasons, the most severe cases were immediately addressed.
During extreme weather conditions or on a clear, calm day, our goal is always the same – to keep the lights on, businesses running and communities strong.