Yelm Hydroelectric Turbine Generator Refurbishment
Built in 1930, the facility consists of a diversion dam located on the Nisqually River near the town of McKenna, a nine-mile long power canal that crosses the prairie north of Yelm, and a power house located two miles west of Yelm. The facility has 208 feet of head feeding two seven-foot diameter penstocks. Units 1 and 2, both 3 MW Westinghouse vertical Francis generators, share one penstock while unit 3, a 6 MW Westinghouse vertical Francis generator, is fed solely by the other penstock. After power generation, the water is returned to the Nisqually River several miles downstream from the diversion dam.
NAES Power Contractors supplied supervision, labor, equipment, and materials for the project.
- Performed pre-teardown readings and inspections, and checked shaft alignment
- Complete disassembly and inspection of turbine/generator components
- Performed electrical tests on stator and rotor, and prior and post cryogenic cleaning, drying, epoxy repair on windings, varnishing, and painting
- Ultrasonically tested all thrust and guide bearings for delamination and verified dimensions met required clearances
- Rebabbitted bearings that didn't meet the NDE visual and UT inspection requirements
- Off site machining of new stationary seal rings, head cover erosion repair, turbine modifications, wicket gate repair, new bronze wicket gate bushings, spare shear linkages, and replaced turbine shaft seal sleeves
- Installed high pressure oil lift systems
- Complete reassembly of generator/turbine components; conducted post alignment and runout checks
- Startup and commissioning support