| 摘要 |
PURPOSE:To enable the independent control of corrosion protective current on a propeller blade, by connecting an input terminal for protective current feedback to a DC power source device to a grounding circuit between the shaft of the propeller blade and the shell of a hull, and providing a variable resistant element in the proper position of said circuit. CONSTITUTION:A variable resistant element 9 is provided in the grounding circuit 8 in the position nearer the shell 1 side of a hull than the junction of an input terminal 4c for protective current feedback. The detection signal for the protective condition of the shell from a reference electrode 3 provided to the shell 1 is compared with a set value through a signal input terminal 4a, and a DC power source device 4 supplies required electric current from an output terminal 4b to the insoluble anode 2 provided to the shell 1 in accordance with the result of the comparison. If the protective current for the shell 1 is decreased by the automatic control and causes the deficiency in the protection of a propeller blade 6 during protection, the resistance for the element 9 is increased to a required value to control the feedback protective current from the shell 1 to the terminal 4c, whereby the protective current from the anode 2 is fed back to the terminal 4c through the blade 6 and the shaft 7 and the protective current for the blade 6 is increased to a required value. |
