Multiple Structure Cathodic Protection System

Abstract

The invention is a multiple-structure cathodic protective system that includes multiple voltage-controlled outputs to protect multiple structures with a common ground bed, or a single structure with multiple anode ground beds. Each output feeds an individual cable that is powered by independent pulse-width-modulated voltage power supplies. Current through the cables is monitored and the PWM control compensates to maintain the correct amount of current for maximum protection and long life.

1 ) A computerized voltage-controlled multiple-output cathodic protection unit  11  used to inhibit corrosion in multiple metal structures, comprising a main computer  13 , said computer comprising an input power converter  17 , one or more output power supply cards  31 ,  33 ,  35  which fit into the main computer  13 , and each power supply card providing constant current to respective metal structure Z 1 , Z 2 , Z 3  through common anode bed  19 . 
     
     
         2 ) A computerized voltage-controlled multiple-output cathodic protection unit  11  used to inhibit corrosion in a metal structure Z 4 , comprising a main computer  13 , said computer comprising an input power converter  17 , one or more output power supply cards  31 ,  33 ,  35  which fit into the main computer  13 , and each power supply card providing constant current to a metal structure Z 4  through multiple anode beds  51 ,  53 ,  55 . 
     
     
         3 ) A method of protecting multiple metal structures from corrosion by
 a) converting an input power source  17  to one or more DC voltage buses suitable for powering a computer  13  and one or more power supplies  31  of at least 30 W;   b) powering one or more independent power supplies  31  from the DC voltages  17 ,   c) connecting each of the positive terminals of the independent power supplies to a buried anode bed, and   d) connecting each negative terminal of the independent power supplies to a respective metal structure to be protected; and   e) adjusting the output voltage of the independent power supply so an optimal current flows through the structure to be protected.   
     
     
         4 ) A method of protecting a single metal structure from corrosion by
 a) converting an input power source to one or more DC voltage buses with an input power converter  17 , the outputs suitable for powering a computer and one or more power supplies  31  of at least 30 W;   b) powering one or more independent power supplies  31  from the DC voltages,   c) connecting each positive terminal of the independent power supplies to an independently located buried anode bed  51 ,  53 ,  55 , and   d) connecting each negative terminal of the independent power supplies to a metal structure to be protected Z 4 ;   e) adjusting the output voltage of the independent power supplies  31  so an optimal current flows through the return line from the structure to be protected.   
     
     
         5 ) A method as in  claim 3 , with the additional steps of:
 a) providing an alarm when a short has developed such that current above a user-set level is flowing through an independent power supply; and   b) shutting down the outputs of one or more independent power supplies when an alarm sounds, and then after a preset amount of time or an operator reset of the system;   c) returning each power supply to service.   
     
     
         6 ) A method as in  claim 4 , with the additional steps of:
 a) providing an alarm when a short has developed such that current above a user-set level is flowing through an independent power supply; and   b) shutting down the outputs of one or more independent power supplies when an alarm sounds, and then after a preset amount of time or an operator reset of the system;   c) returning each power supply to service.