The Spin on Turbines and Generators

The Spin on Turbines and Generators. . , Reaction turbines are used at Saint Anthony Falls. Water flows to, through, and out of a reaction turbine as a liquid column, tightly constrained and carefully directed to capture its force. The column starts at the penstock's intake, positioned just above the floor of the headrace to ensure a constant water supply. The velocity of the water increases as it descends to the turbine, where guide vanes direct the flow to turbine runners., "Water entering the runner is given a whirl by the guide vanes," the 1951 Mechanical Engineers' Handbook explains. "The whirl is taken out by the runner so that the water leaves the runner without appreciable whirl." The "whirl" propels the runners, which don't catch and hold water like waterwheel buckets do. Instead, the runners are curved, like the blades of a propeller. The water's pressure causes a reaction, the runner spins., After transferring its energy to the runners, the water would slow down under normal conditions, creating a backwash that would slow the runners. By a draft tube creates a vacuum at the turbine's outlet, speeding the water to the tailrace, where a more leisurely flow does not interfere with turbine performance., Water flows into the turbine through channels, which are spiral passages created by metal guides. From the guides, the water enters the runners, the space between the metal vanes (also known as buckets). The vanes are also sometimes called runners or wheels. An early twentieth-century book explained the operation of an inward-flow radial turbine: "The waster from the reservoir R enters the guide G which surrounds the wheel W, flowing towards the centre; after passing through the buckets, it is gradually deflected downwards by the curved surface of the part of the wheel, so that it enters the suction-tube T in a vertical direction.", Making the Connection , When Main Street Station was built in 1894, power was transferred from the three turbines to a generator shaft 45' above the turbine by a continuous rope. Leather belts, some 6' wide, connected the generators with other equipment., Frustrated by the loss of power with the inefficient rope system, engineers developing the hydroelectric plant at the Lower Dam looked to a new technology; "direct connection," where a shaft projecting from the turbine's axis spins the magnets in an adjacent generator. The Lower Dam plant was one of the first in the nation to use direct-connected turbine-generator units, which remain the industry standard. The Hennepin Island plant, built in the following decade, also featured direct-connected units., The rope drive linking the turbine and generator is illustrated in this drawing by H.M. Byllesby and Company., The 1911 fire provided an opportunity to retool the Main Street Station. Change was limited, though, by the surviving turbines, which were reused to get the plant back on-line quickly. Also, the plant had to support obsolete power equipment for specific systems, such as arc streetlights, that were still in service. As a result, rope drives were reinstalled between the turbines and the generators. This system remains in place today. Although no longer in use, it is the only example of nineteenth-century rope-driven technology in the state and one of the few in the country., Generators connected to rope and belt drives filled the generating room of the Main Street Station before the 1911 fire. The generators were powered by three hydraulic turbines and by steam turbines in a neighboring building (no longer standing.), Volts x amps = watts , Atoms consist of a nucleus and electrons. When electrons separate easily from the atoms in a material, such as copper, that material is a good conductor of electricity. Generators use electrons, which carry a negative charge, to create electricity. Turbines spin magnets around coils of copper wire, which activates electrons and generates electrical current. The strength of the current is measured in amps, the force of the moving current in volts, and the amount of power produced in watts. Your electric bill is based on how many watts you have used.