Eddy Current Standard Probes
When a coil of conductive wire is excited with an alternating electrical current an alternating magnetic field is produced. The magnetic field oscillates at the same frequency as the excitation source. When placed near a conductive material, currents opposed to the ones in the coil are induced in the material. These are referred to as eddy currents. In the case of variations in the electrical conductivity and/or magnetic permeability causes a change in eddy current. Additionally, the presence of defects will precipitate a change in phase and amplitude that can be detected as a measurable change in the impedance. Eddy Current testing is generally used on conductive materials to detect surface defects.