Turbines, Generators, Control Board
When you tour the powerplant's grounds, you will see the massive General Electric transformers, each capable of conducting 800 to 11,000 volts of electricity, and the forebays and canal system that brought the water from the dam.
The units at Folsom, called reaction turbines, have a series of blades mounted on the turning element, or runner. Water is admitted through a series of fixed guide vanes and strikes all the blades simultaneously. When the water enters through the guide vanes, the direction of its flow is at right angles to the shaft of the turbine; the water is deflected and leaves the runner nearly parallel to the shaft. The great force exerted on the blades as the water flow changes direction turns the shaft and drives the connected generator shaft.
When the Folsom plant was in operation, the water was directed to the turbines by inlet pipes each eight feet in diameter. The four pairs of McCormick turbines were run under a head (water pressure) of 55-feet of water and at a speed of 300-revolutions per minute. Waterflow through the turbines was regulated to match the fluctuating demand for electric energy, by opening or closing valves at the turbine-inlet. The turbines are directly connected to the six-inch armature shafts of Folsom's generators. In 1895 these units were reported to be the largest three-phase dynamos ever constructed. Each stands 8-feet, 8 1/2 inches and weighs 57,877 pounds. Their combined capacity is 3,000 kilowatts. Brought to California by ship around Cape Horn, the vintage generators are still in place at the powerhouse. The control switchboard at Folsom, faced with Tennessee marble, is another part of the original equipment that is still intact.