Impressed Current Cathodic Protection Systems

Due to the high currents involved in many seawater systems it is not uncommon to use impressed current systems. Impressed current systems use anodes of a type that are not easily dissolved into metallic ions, but rather sustain an alternative reaction,
oxidization of the dissolved chloride ions.
2Cl^- => Cl₂ + 2e^- Power is supplied by an external DC power unit..

Figure 2: Impressed current cathodic protection system in seawater

by: Richard Baxter, Jim Britton
Source: http://www.cathodicprotection101.com/