In an impressed current system, which terminal of the DC power source is the protected structure connected to?

In an impressed current system, the protected structure is connected to the negative terminal of the DC power source. This configuration is utilized to prevent corrosion of metal surfaces that are exposed to corrosive environments. By connecting the structure to the negative terminal, it becomes the cathode in the electrochemical reaction that occurs in the surrounding environment.

This approach effectively reduces the oxidation of the metal structure, as the impressed current prevents the loss of electrons from the metal surface. The relationship between the negative terminal and the metal structure enhances its protection by facilitating a continuous flow of electrons to the structure, thereby displacing any corrosive processes that would typically occur.

The function of the other terminals, such as the positive terminal or neutral terminal, does not provide this protective effect, as they do not facilitate the necessary flow of current that counters corrosion processes. Therefore, the connection to the negative terminal is critical in fulfilling the intended purpose of the impressed current system.