What type of current should be superimposed for testing galvanic current blocking?

When testing for galvanic current blocking, the most effective method is to use AC superimposed on the DC current. This approach is particularly useful because it allows for the detection of small AC currents that may be present in a galvanic corrosion scenario, which typically occurs in the presence of dissimilar metals in an electrolyte.

Using AC superimposed on DC helps to differentiate between the DC components that may represent overall corrosion tendencies and the AC components that indicate dynamic changes or specific conditions that can influence galvanic action. This technique captures not only the continuous flow of DC but also allows for the measurement of any fluctuations and irregularities that might affect the overall assessment of galvanic current presence and its blocking effectiveness.

Other current types, like simple DC or constant current, do not provide the necessary information as they lack the dynamic characteristics provided by alternating current. Pulsed DC, while offering some variation, also does not replicate the conditions required to properly assess galvanic influences as effectively as AC superimposed.