Unit 4 at the 2,000 MW Colstrip coal-fired power plant in Montana will be under repairs for at least six months, according to NorthWestern Energy and PPL Montana. The remaining units continue to operate at full power.
The 740 MW unit tripped offline on July 1. NorthWestern Energy, which owns a 30 percent share in the unit along with four other companies, said damage was apparent to the stator or rotor assembly and was consistent with a ground fault. PPL Montana, which operates the unit, developed the six-month repair schedule.
Under the companies' Reciprocal Sharing Agreement, each party equally shares costs to operate, maintain and repair the unit as well as its allocation of the output from operating units. The repairs are expected to cost $30 million, and NorthWestern’s share will be about $4.5 million.
PPL has property damage insurance and may file a damage claim. If they do, the deductible would be $2.5 million. NorthWestern Energy has already purchased replacement power.
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