Duke Energy officials say they are working to find out why winterization efforts failed at one of their Triad-area plants.
Power reductions at the Dan River Combined Cycle Power Plant and two other North Carolina facilities led to rotating outages just before Christmas.
At a Tuesday briefing before the North Carolina Utilities Commission, Duke Energy officials said the natural gas-powered Dan River plant has an operating capacity of approximately 700 megawatts. But when lines froze during the cold snap, the plant moved from full power to about half its capacity.
Sam Holeman, vice president of transmission systems planning and operations for Duke Energy, said during the commission briefing that the equipment that froze was part of a cold weather protection program and was insulated.
“And yet the weather was able to overcome those circuits," he said. "We have some evaluation work to do to figure out why that happened on those particular pieces of instrumentation and didn't happen on others.”
The problems at the Dan River site and two other locations in Person County led to rotating outages just before Christmas.
Duke Energy apologized Tuesday for the interruptions.
The current Dan River facility in Rockingham County has been in operation since 2012. It replaced a former coal-burning facility that has since been demolished.
In 2014, nearly 40 tons of coal ash at the site spilled into the Dan River after a rupture in a containment pond.