Diagnostic Testing and Repair of Grand Rapids Generating Station's Unit Four

Crahan, Marcus; Gusberti, Gary A.; ,

Diagnostic Testing and Repair of Grand Rapids Generating Station's Unit Four

by Marcus Crahan, Power Engineering, Mission Viejo, United States,
Gary A. Gusberti, Power Engineering, Mission Viejo, United States,

Document Type: Proceeding Paper

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

Abstract:

This paper is a case history that discusses diagnosis and correction of a variable pitch propeller type (Kaplan) hydraulic turbine problem. The turbine problem involved fatigue failures of its guide bearing. Diagnostic testing performed in Oct. '89 suggests a self excited, subsynchronous hydraulic whirling vibration caused the fatigue failures. Hydraulic whirling was caused by not operating the turbine at peak efficiency. The self excited vibration was eliminated in Dec. '89 by adjusting the governor's blade angle and wicket gate control system. A turbine bearing has not failed since governor adjustment. Besides eliminating turbine equipment failures, power oscillation, guide bearing temperature, noise and draft tube surges were also reduced. Several relationships between variable pitch propeller turbine vibration and efficiency are discussed. Methods to measure and analyze turbine vibration and relative efficiency are also discussed. Finally, economic benefits associated with improved hydraulic efficiency are discussed.

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