Determination of Optimal Frequency in Magnetic Eddy Current Testing for Discrimination of Inner Defect or Outer Defect

This paper is a study on the determination of optimal frequency in Magnetic Eddy Current Testing (MEC) for characterizing defects in ferromagnetic steel pipe inspection. Conventional methods have their own limitations so that cannot distinguish between inner defects and outer defects. MEC can overcome the limitations of conventional methods. It can not only detect both inner defect and outer defects, but also distinguish between them. It is important to determine frequency to distinguish two defects in MEC. In this paper, the principle of distinguishing two defects has been explained and appropriate frequency was proposed. By using frequency that makes the phase of signal varies for each defect, two defects can be distinguished. Finite element simulation and experiment were performed. The result shows that the frequency increases, the phase difference between two defects also increases so that it can distinguish two defects through the phase difference of the signals. © 2024 Korean Institute of Electrical Engineers. All rights reserved.