Northern States Power d/b/a Xcel Energy (NYSE: XEL) told the Minnesota Public Utilities Commission in a June 21 update that the coal-fired Sherburne County (Sherco) Unit 3, offline since November 2011, should be back in service in early September.
“We continue to make good progress on our restoration efforts and continue to expect Unit 3 to return to service in early September, as noted in our last update in this docket on June 6, 2013,” Xcel said. “We also note that we have received the final root cause analysis report, and we will be reviewing the report with our partner, Southern Minnesota Municipal Power Association (SMMPA), in the near future. We will provide additional information about the report in our next update.” That next update is due in early July.
The 884-MW Unit 3 went off-line in November 2011 while being restarted after a repair shutdown. During the testing procedure after unit restart, specifically the overspeed test, the turbine and generator instrumentation showed vibration levels significantly above normal, and the unit was shut down. The vibration damaged many of the steam, oil, and hydrogen seals in the turbines and generator, and caused a fire.
Sherco is a three-unit, 2,400-MW plant. It burns low-sulfur Western coal from mines in Montana and Wyoming. The plant normally burns more than 9 million tons of coal a year. Westmoreland Coal (NasdaqGM: WLB) is a major supplier out of its Absaloka strip mine in Montana.