| 摘要 |
PURPOSE:To drain off the water entrapped around a runner in a quick manner through centrifugal force, by carrying out drainage with a casing drain pipe in a process of water level depression in addition to drainage by a leaked water drain pipe attached to a bottom ring. CONSTITUTION:At a point where a guide vane 2 comes to the full closing or in close proximity to such a state, an switching valve 8a is opened from a suction pipe 8 for water level depression in a runner chamber and compressed air is fed into the runner chamber, depressing a water level W in the runner chamber down fully to the position where it may not contact a runner 3 being idling. In a process of depressing the water level W, the water entrapped around the runner 3 is discharged to a discharge pipe 4 by means of a conventional bottom ring leaked water drain pipe 10 attached to a bottom ring 11 by a centrifugal force produced by runner's idling and in addition to this operation, drainage is carried out also from a casing drain pipe 12 attached to a casing 1 so that a large quantity of water around the runner may be drained off as quickly as possible. |
