PURPOSE: To prevent the artesian condition of a water introducing passage by carrying out drainage when the water level in an upper part water tank reaches the set water level at the start of drainage, because of the gushing-out water in a water introducing passage tunnel during the stop of the taking-in of water for a long period and completing drainage when the water level becomes less than the set value at the completion of drainage.
CONSTITUTION: Through, during the stop of taking in water, the inflow of water from a water taking-in gate 21 stops, the water level in an upper water tank 23 is gradually increased by the gushing-out water in a water introducing passage tunnel 22. Then, a controller 24 detects that the water level in the tank 23 reaches the set water level at the start of drainage during the stop of a water wheel power generator 26. Then, the water wheel of the power generator 23 is applied with a brake so as not to be revolved by the splash of the water stream which is generated by a deflector. The needle installed at the top edge nozzle of a hydropressure steel pipe 25 is opened up to the set value of the drainage opening degree, and water is discharged into a drainage passage 27. Further, when the water level in the water tank 23 lowers to the water level at the completion of drainage, the needle is perfectly closed to complete drainage, and brake is released. Accordingly, drainage can be carried out automatically, and the artesian condition in the water introducing passage tunnel can be surely prevented.
MAKINO MASAMICHI
TANAKA MASAHIRO
CHUBU ELECTRIC POWER