| 摘要 |
1478728 Hydraulic pumps and turbines ALLIS-CHALMERS CORP 24 Oct 1975 [30 Dec 1974] 43753/75 Headings F1C and FIT An hydraulic turbine, pump or pump-turbine includes an arrangement to prevent syphoning of water through an overflow passage 28 from penstock 23 to draft tube 26 when the water level in the latter is depressed by air-pressure supplied to the runner housing via pipe 27, e.g. during spinning reserve of the turbine or starting in the pumping mode. The anti-syphon arrangement comprises a pipe 32 supplying air-pressure to the top of overflow passage 28 from the draft tube 26 or other source. The air-pressure in passage 28 may be reduced when required by a suction pump (38), Fig. 2 (not shown) in pipe 32. The air-pressure in the runner housing and draft tube 26 is controlled by a float 34 which admits more air when the float rises beyond a predetermined level. While runner 8 is rotating in air, cooling water is admitted to seals 16, 17 via pipes 18, 19 respectively. During normal runner operation, valve 31 closes overflow passage 28 and penstock valve 24 and wicket gates 22 are open.
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