Wilson Dam & Hydroelectric Plant, Turbine & Generator Unit, Spanning Tennessee River at Wilson Dam Road (Route 133), Muscle Shoals, Colbert County, AL
Significance: At Wilson Dam, two manufacturers, Westinghouse and General Electric, each supplied 4 of the dam's first turbine and generator sets to the 18 unit-capacity powerhouse. Illustrated here is one of the original GE generators with its correlative "Francis" turbine built by the Newport News Shipbuilding & Dry Dock Co. Named after its originator, James B. Francis, the Francis, or inward-flow, turbine has distinctly American roots that lead back to its first application in the textile mills of Lowell, Massachusetts in 1849. By the time of Wilson Dam, the Francis turbine had grown in size and efficiency to become one of the standard prime movers in modern hydroelectric plants. Such increases in runner size were in tandem with an increase in the size of generators and their electrical output. In 1900, General Electric generators at Niagara Falls were producing 5,000 horsepower per unit. 25 years later, Wilson Dam was called the "Niagara of the South," with each GE generator set producing 35,000 h.p. Maximum efficiency in hydroelectric generation is dependent upon the integration of both dam and turbine design. The type and size of the runner dictates the design of the dam's penstock, scroll case and draft tube. At Wilson Dam, these sub-structural features utilize massive concrete formwork to create the perfect turbine setting. Flowing through three penstocks and into a single scroll case (spiral distributor), the water of the Tennessee River enters the turbine inwardly through guide vanes, flows into the side of the Frances runner and is discharged axially through the center of the turbine into the draft tube, in this case a unique design known as the Moody spreading draft tube. To maintain consistent electrical frequency throughout changes in river level, and hence, changed in turbine speed, flow of water into the runner is controlled by a Lombard hydraulic governor linked to a collar of 20 wicket gates that surrounds the turbine.
Unprocessed Field note material exists for this structure: N165
Survey number: HAER AL-47-A
National Register of Historic Places NRIS Number: 66000147