| 摘要 |
910,460. Automatic control systems for cathodic protection arrangements. SABINS, R. C. May 5, 1959 [May 9, 1958; June 2, 1958], No. 15338/59. Class 38 (4). In a system for the cathodic protection of a ship's hull in which current from an external source is passed between an anode and the hull, and the current is regulated in accordance with the output of a silver/silver chloride half cell mounted near the hull, the half cell is intermittently or continuously depolarized by current from another external source. In one embodiment, a rectifier 81 supplies direct current between an anode 14 and the hull 16. The output of the rectifier 81 is controlled by a saturable reactor 64 in turn controlled by the output of a photo-cell 37 via a self-saturating magnetic amplifier 39. The photo-cell 37 may be illuminated by a lamp 34 through a hole in the face of a millivoltmeter 26 connected between a selected silver/silver chloride half cell 21 and the hull. The meter 26 is adjusted by an external resistance (not shown) so that at the required potential between half cell and hull, the meter pointer obscures the photo-cell 37. Movement above this value is prevented by a stop. If the potential falls, the cell is illuminated and passes a greater current, which after amplification causes the full output of the rectifier 81 to be applied between anode 14 and hull. Four half cells 21 are provided and these are sequentially connected by a motordriven switch 23 to the control system meter 26, to an auxiliary depolarizing source 92, to an idle rest position, and to a potential recorder 103. In a modification, Fig. 3 (not shown), only one cell is provided and it is permanently connected to both the meter and, through a high resistance, to the depolarizing source. Specification 868,819 is referred to. |
