Major Rotor Damage Extends Outage at Four Corners Power Plant

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Researched by Industrial Info Resources (Sugar Land, Texas). Arizona Public Service’s (APS) Four Corners Generating Station has extended a current maintenance outage for an additional five weeks due to extensive damage discovered in the low pressure (LP) rotor. The 755-megawatt Unit 05 was originally forced offline on March 12, 2007, due to turbine vibration issues. Under further inspection, engineers have discovered damage to the diaphragm, stationary blades, and the buckets of the LP rotor. Engineers are expecting repair times to last well into the latter part of April. Plant officials are expecting that this issue will affect the start time of the planned outage for Unit 04, which was slated to begin in early April. At this time, the plant is undecided on when Unit 04 will begin its spring outage, depending on the progress of Unit 05 repairs.

The Four Corners Power Plant is located in Fruitland, New Mexico, about 25 miles west of Farmington. The majority of the Four Corners Power Plant is owned by Arizona Public Service Company (APS), with the remaining stakes belonging to Southern California Edison, El Paso Electric, PNM), Salt River Project (SRP), and Tucson Electric Power (TEP). The station consists of five coal-fired units with a maximum capacity of 2,040 megawatts. The station provides power to about 300,000 residents in New Mexico, Arizona, California, and Texas.

APS is an electric utility subsidiary of the public company, Pinnacle West Capital Corporation (NYSE:PNW ) (Pinnacle West), serving customers in 11 counties mainly in northern and central Arizona. Incorporated in 1985, Pinnacle West owns all of the outstanding equity securities of its major subsidiary, APS. APS is a vertically integrated electric utility that provides retail and wholesale electric service to most of Arizona. Pinnacle West's other significant subsidiaries are SunCor Development Company, which is engaged in real estate development and investment activities, and APS Energy Services Company, Inc., which provides energy services and products in the western United States. Pinnacle West Energy Corporation formerly owned and operated unregulated generating plants. Pinnacle West has three principal business segments: the regulated electricity segment; the real estate segment, and the marketing and trading segment.

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