. The Street railway journal. Circa 1150 hp su 20-ft. Actinghead a 130 r. p. m. La capacità delle turbine varia come radice quadrata del cubo della testa di azione. C'è una velocità qualsiasi testa data a cui corrono alla più alta economia, thisspeed che varia con la radice quadrata della testa. Così, su 17^-ft.head la potenza del cavallo sarebbe 1150 X f (-**) r 20.0/ o 940, e la velocità più economica 121.6. Se sulla testa ijl/2-IT viene utilizzata una velocità superiore o inferiore, la capacità di potenza del cavallo della turbineè materialmente inferiore. A 190 r. p. m. la capacità di potenza del cavallo isnaught. L'oggetto del tu
2237 x 1117 px | 37,9 x 18,9 cm | 14,9 x 7,4 inches | 150dpi
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. The Street railway journal . approximately 1150 hp on 20-ft. actinghead at 130 r. p. m. The capacity of the turbines varies as thesquare root of the cube of the acting head. There is one speedon any given head at which they run at highest economy, thisspeed varying with the square root of the head. Thus, on 17^-ft.head the horse power would be 1150 X f (-**) r 20.0/ or 940, and the most economical speed 121.6. If a higher or lower speedis used on ijl/2-it. head, the horse power capacity of the turbineis materially less. At 190 r. p. m. the horse power capacity isnaught. The object of the turbine governor is to provide a speed of130 revolutions, given any head and any load which may be on thegenerator. This is done by a centrifugal governor which controlsthe turbine gate opening or water inlet. The efficiency and capac-ity of the turbine do not change materially from full gate downto eight-tenths, but below eight-tenths gate both are materiallyreduced. The turbines are set about half-way between the elevation of. FIG. 4.—CROSS SECTION THROUGH LOWER STATION 14 ft. to 16 ft. above the river bed. Below the superstructure thereis a 3-ft. base of concrete, 33 ft. wide. This base is especially wellreinforced by a rubble rock and concrete dyke construction inthe sand rock below the crest line of the dam and again at the toeof the dam. This will prevent undermining. The face of the damis perpendicular. The down-stream side is so shaped or sloped asto ease the momentum of the water and discharge it horizontally, thus preventing an undertow which might prove fatal to the struc-ture. The main structure is of limestone from the quarries on the east water in the head and tail-race. The pressure above the turbinerunner and the suction from the draught tubes together form thehead on the turbine. Should the normal elevation of water in thehead race increase 2 ft. during a common spring or fall flood i-»enormal elevation of water in the tail-race would make a corre-sponding incr
