Elimination of Coil Liftoff from Eddy Current Measurements of Conductivity

The construction of eddy current conductivity meters is based on developing a method to effectively eliminate the distance effects between the surface of the coil and the workpiece under test in conductivity measurements. As a result of numerous experiments, it was observed that each actual measuring coil can be replaced by the one that is characterized by only two parameters. Following this procedure makes it possible to use only one universal mathematic formula for each of the coils. Appropriate calculations are provided to certify the theory. This paper describes the method of determining the equivalent parameters of the coil, a scaling method for a conductivity meter based on the elimination of liftoff on conductivity results, and a proposition for an effective method to measure the conductivity of rough elements.