Eddy Current Generation

Description

The eddy current method is based on the principle of generating circular electrical currents (eddy currents) in a conductive material. This is achieved by the use of a coil connected to an alternating current generator driving an alternating magnetic field (primary field). The current flow induced by this primary field within the conductive material will itself produce a magnetic field (secondary field) in opposition to the primary field according to Lenz’s law. This reaction can be measured as a change of the impedance of the coil/sample arrangement (change in amplitude and phase of the voltage related to the generator current driving the coil). A coil in air is not influenced by eddy currents, but moving the coil towards an electrical conductive sample results in a signal, which can be used for distance measurement, e.g. measurement of non-conductive coating thickness on electrical conductive material.