Regarding cathodic protection, what is the defining technical difference between a sacrificial anode system and an impressed current system in terms of the required external power source?

The defining technical difference between a sacrificial anode system and an impressed current system lies in the requirement for an external electrical power source to drive the protective current. A sacrificial anode system, often called galvanic protection, relies entirely on the natural electrochemical potential difference between two dissimilar metals. In this setup, a more reactive metal, known as the anode, is electrically connected to the protected structure,....