Nondestructive Detection of Cracks for a Distribution Line, Using Eddy Current Test

We report experimental results of an eddy current test. When an excitation coil is brought close to a conductor, an eddy current is induced in the conductor. If there is a crack in the conductor, the eddy current will avoid that area, causing variation in the magnetic field generated by the eddy current. We examined how effectively the differential motion method could be used to detect the magnetic field change through the output voltage difference between two coils. We report characteristics of detecting coil output voltage and phase difference characteristics between excitation current and the output voltage and frequency characteristics of the detecting coil output voltage.