. Development and electrical distribution of water power . draft tubes join about 20 feet from the unit, but are heredivided by a vertical wall, the discharge outlet into the tail-race ofeach unit being composed of two passages, each 13 feet wide and15 feet high. This arrangement of the draft tubes, since they areconstructed of solid concrete, necessitated very complicated form-work, especially since it was necessary to have easily curvingsurfaces which would offer little or no resistance to the flow ofwater. The exciters are located in the centre of the power-housewith five main un
. Development and electrical distribution of water power . draft tubes join about 20 feet from the unit, but are heredivided by a vertical wall, the discharge outlet into the tail-race ofeach unit being composed of two passages, each 13 feet wide and15 feet high. This arrangement of the draft tubes, since they areconstructed of solid concrete, necessitated very complicated form-work, especially since it was necessary to have easily curvingsurfaces which would offer little or no resistance to the flow ofwater. The exciters are located in the centre of the power-housewith five main units on each side of them. The intake conduitsand draft tubes for them are 6 feet square in section. Each turbine is set in the concrete chamber without the usualsteel or iron casing. Each chamber can be closed independentlyof all the others, and after being closed by the gates in front of the MCCALL FERRY PLANT 221 intake conduits and the stop-logs at the ends of the draft tubes, can bedrained through outlets leading to pumps installed for that Below the power-house floor runs a chamber parallel to thelength of the power-house in which will be installed the pumps for 222 DEVELOPMENT AND DISTRIBUTION OF WATER POWER draining the wheel chambers and the turbine-driven oil pumps forsupplying the thrust bearings with oil. The turbines are of the vertical shaft, inward and downwardflow, Francis type. There are 10 main units each capable ofdeveloping 13,500 under a head of 53 feet with the gates open80 per cent at 94 Each turbine when run at its rated loadwill take about 2,700 cubic feet of water per second. Each tur-bine has two separate wheels mounted on the same shaft, the latterbeing of forged steel, 20 inches in diameter. The upper wheeldischarges through a steel casing leading to the draft tube whilethe lower wheel is set immediately over the draft-tube pit, and dis-charges into it without the medium of a casing. The wheels areabout 10 feet in diameter. The
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