Finite Element Simulation of Pulsed Remote Field Eddy Current Phenomenon

The remote field eddy current (RFEC) effect was first observed when an alternating current was applied to a coil inside a metallic pipe. It is characterized by the energy released from an excitation coil which propagates twice through the tube/pipe wall under inspection before it reaches the pick-up coils/sensors located 2–3 diameters away from the excitation. This technique is routinely used for metallic tube inspection. Distinguishing features include high and equal sensitivity to both OD and ID defects, independence of phase signals to lift-off, approximately linear signal phase to thickness relationship, no restriction with regard to penetration depth, and detection depending on signal-to-noise ratio only. There are also some disadvantages associated with the RFEC technique, primarily, high power requirements and large separation distances between the excitation and sensor coils