Pulsed Eddy Current Method: an Overview

As the name implies, the pulsed eddy current (PEC) method uses a transient excitation of an eddy current probe, as opposed to the continuous-wave (CW) excitation used in conventional eddy current inspection. The PEC approach offers several advantages over the conventional method. First, because the transient field is related, by means of a Fourier transform, to the CW field at multiple frequencies, a single PEC measurement is equivalent to multiple CW measurements as a function of frequency. PEC instrumentation is, however, much simpler and less expensive, and PEC data acquisition is much faster than multiple CW measurements. The transient method also offers the possibility of time-gating, which enables the user to distinguish signals originating from deep within a specimen from signals originating nearer the surface.