Repair of Rainbow Project Unit Number Eight

by Marcus Crahan, Power Engineering, United States,
Lorne W. Brotherton, Power Engineering, United States,
William O'Keefe, Power Engineering, United States,
William T. Rhoads, Power Engineering, United States,

Document Type: Proceeding Paper

Part of: Waterpower '91: A New View of Hydro Resources


This is a case history that discusses diagnosis and correction of a AC synchronous generator problem. The problem involved loss of mechanical integrity between the generator's rim assembly and its rotor spider following a load rejection and transient overspeed. The loss of mechanical integrity caused severe vibration during operation which threatened failure of the generator rotor. A series of noise and vibration tests performed on the generator suggested that loss of mechanical integrity involved wearing of the rim to spider interface. The tests identified that the laminated rotor rim had loosened from its cast steel spider. A unique repair was designed and implemented that did not require generator disassembly. The repair fully restored the rotor's mechanical integrity. In January 1990, Unit Number Eight was returned to commercial service without restrictions. The unit has been producing electric power since this time. Several problems associated with hydro-electric machinery designed and manufactured at the turn of the century are discussed. In some cases, these problems can be resolved. Economic benefits of returning this Unit to service are also discussed.

Subject Headings: Rainfall | Case studies | Transient loads | Electric power | Hydro power | Power plants | Electrical equipment | Diagnosis

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