| 摘要 |
PURPOSE:To enable discharge operation to be carried out under any condition by providing a high signal selection circuit which selects the higher signal out of control target needle opening signals from a tracking cam to advance and retreat a needle and an overflow water amount setter. CONSTITUTION:In the case of stopping a Pelton wheel due to any fault, a control target needle opening of a tracking cam 1e which interlocks with the turning movement of a deflector 1b to be closed is lower than the needle opening before the deflector 1b is closed. The control target needle opening signal from an overflow amount setter 101 is kept constant unless a necessary discharge amount changes. Therefore the output from a high signal selection circuit 100 shifts, smoothly to the control target needle opening from the overflow water amount setter 101 from the time when the control target needle opening from a tracking cam 1e is lower than that from the overflow water amount setter 101. It is thus possible to continue discharge operation under any stoppage condition and to control a needle 1a in response to the change of water level.
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