| 摘要 |
In a system for protecting a metallic vessel 10 containing corrosive fluid from corrosion, by anodic polarization, apparatus for detecting <PICT:0977135/C6-C7/1> malfunction of a standard reference electrode 32 of the system comprises a second reference electrode 34 and means for comparing the potential differences between the reference electrodes and the vessel and for giving an alarm signal when the deviation between the compared potential difference exceeds a pre-determined value. In Fig. 2 the electrodes 32, 34 are connected to a device 30 which includes a mechanical vibrator which alternately places the electrodes in circuit with the vessel 10 so that when a deviation occurs an output voltage of square wave form results. The device 30 converts this output voltage to alternating current which passes via a capacitor 39 to an amplifier 36. The amplified A.C. is converted in a convertor 40 and supplied to a signal device 42. An electronic chopper circuit may be used instead of the mechanical vibrator. In an alternative arrangement, Fig. 3 (not shown), the electrodes and the vessel are connected to a bridge circuit which produces an output when the potential differences differ. Fig. 4 (not shown) illustrates an arrangement in which a timing motor periodically connects the second reference electrode to the detecting apparatus at such times as no anodic current is being passed between the vessel 10 and the inert electrode of the system which includes an "on-off" controller for controlling the anodic current. Fig. 5 (not shown) illustrates an arrangement in which the system includes a proportional controller continuously controlling the magnitude of the anodic current. This arrangement also includes a timing motor for periodically connecting the second reference electrode. |
