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Impressed Current

A means of providing corrosion protection for metallic underground storage tank and piping systems.

The typical cathodic protection system involves use of sacrificial anodes buried in the soil near the tanks or piping to be protected. At some installations, those where tanks and piping are poorly coated, a similar, but slightly different system is more desirable.

An impressed current system, instead of relying on sacrificial anodes to provide the protective flow of electricity, relies on electricity provided by an outside power source. The electricity is brought to the site through utility transmission lines. There, through use of a rectifier, it is converted from alternating current to direct current.

This direct current is channeled to anodes buried near the structure to be protected. The current flows from the anodes to the structure, protecting it from corrosion.

See also Cathodic protection.