Absolute Eddy-Current Measurement of Electrical Conductivity

摘要

By a through-transmission technique, absolute eddy-current measurements can be made of electrical conductivity. The through-transmission technique induces current in the same directions as does the regular eddy-current test, and the primary standard is small enough to be carried into the field. The measured magnitude and phase shifts can be compared with calculations based on theoretical analysis and computer programs written in the late 1969s. A careful analysis of errors caused by variations in the coil and sample dimensions, edge effects, and misalignment of the coils has been performed by computer calculations and dimensional analysis. The experimental equipment has the sensitivity and stability to measure the conductivity to within 0.05%, and measurements on samples compared with dc standards have given errors of less than 0.5%. (ERA citation 07:060130)