Measurement sensitivity comparison between cylindrical and rectangular coils above conductive plates

Abstract

Eddy current testing is an important non-destructive testing method in defect detection and material evaluation of conductor. In testing of multi-layer moving conductive plates, the excitation coil is cylindrical and parallel to the conductor, the cylindrical and rectangular coils are placed near the excitation coil serving as pick-up coil respectively. The accurate theoretical expressions of the induced voltage' variation of the pick-up coils are derived, and the coils' sensitivity in varied excitation frequency, conductor thickness and moving speed of conductor are compared, the results are verified with the method of FEM.