ATC restarting electric system in Michigan’s Upper Peninsula
PEWAUKEE, WI — American Transmission Co., owner and operator of the electric transmission system in Michigan’s Upper Peninsula, is working to bring the transmission grid in the UP back on line following an apparent lightning strike to two key 138,000-volt transmission lines at approximately 3:30 this morning between Oconto County, Wis. and Dickinson County, Mich. As a result, the western two-thirds of the UP experienced an electrical system outage as a 345,000-volt transmission line that also serves the UP was out of service for a planned outage. Subsequently, the instability of the system triggered the automatic shutdown of Presque Isle Power Plant in Marquette, Mich., to protect the system.
ATC and local utilities have been coordinating the methodical restart of the electric system today including restoring the transmission system and bringing generating units at Presque Isle Power Plant back on line. ATC expects the transmission system to be fully operational by early this afternoon, which will enable local utilities to return electric service to customers. Some customers already have had service restored.
ATC continues to conduct helicopter and foot patrols to inspect transmission lines.