Anodic protection is used to protect metals that exhibit passivation in environments whereby the current density in the freely corroding state is significantly higher than the current density in the passive state over a wide range of potentials.
In anodic protection potentiostat is used to maintain a metal at constant potential with respect to reference electrode.
Out of three terminals of the potentiostat one is connected to tank to be protected, another to an auxiliary cathode (platinum) and the third to reference electrode.
An anodic protection system includes an external power supply connected to auxiliary cathodes and controlled by a feedback signal from one or more reference electrodes.
[3] Careful design and control is required when using anodic protection for several reasons, including excessive current when passivation is lost or unstable, leading to possible accelerated corrosion.