PURPOSE: To effectively prevent water life from entering into a water-intake passage by using an electric screen.
CONSTITUTION: Rod or plate electrodes 3 in parallel, in stages and in opposition are arranged on the wall faces 2 on both sides of a water-intake passage 1 which has a wider upper face and a narrower bottom and sectionally shaped in a reverse trapezoid to apply between pairs of opposite electrodes 3 voltage which is gradually higher toward the water surface side and lower toward the bottom. Pairs of opposite electrodes 3 are connected to a common electric screen forming power supply 6 via electric resistors using water in the water- intake passage 1 so that the electric resistors 5 can be gradually smaller in value toward the water surface side and larger toward the bottom.
MAEHATA HIDEHIKO
ARAI HIROSHIGE
TSUKAHARA MASANORI