Longhui Xiong

May 31, 2023 | mdpi.com | Yanbo Zhang |Xiubo Liu |Longhui Xiong |Zhuo Chen

2.3. Eddy Current TestingDue to the principle of electromagnetic induction, alternating current in a coil sensor creates a changing magnetic field, which will produce an eddy current on the rail surface. The eddy current will produce a new magnetic field, the direction of which is opposite to that of the initial magnetic field. Thus, when defects exist, the fluctuation in difference between the two magnetic fields will cause variation in the impedance and electromotive force [91,92].