| 摘要 |
PURPOSE:To reduce the cost for water pressure iron pipe and the like by quickly closing a guide vane to a predetermined degree of opening when a water wheel etc. is shut from the load, and slowly closing after passage of a certain while, and thereby suppressing rise of the water pressure. CONSTITUTION:In case load shutoff is made during operation of a Francis turbine or a reversible pump-turbine with a small specific velocity, a guide vane is quickly closed to a certain predetermined degree of opening, which is maintained for a predetermined period of time T. Then the guide vane is slowly closed after passage of time T. Thereby water pressure rise in a water pressure iron pipe is suppressed to reduce cost for water pressure iron pipe etc. It is also made possible to reduce the water pressure drop in a tailrace so as to increase the suction height, so that the amount of excavation for power plant can be lessened to a great extent.
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