Cable Soft-Fault Detection Method Based on Single-Inductive Probe Coupling Measurement

This work presents an inductive coupling method for detecting soft faults in cables. The scattering parameter S<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> of the cables is measured using a clamp-on inductive probe in conjunction with a vector network analyzer, eliminating the need for direct physical contact between the cable and the test equipment. The measurement results obtained through this method are comparable to those of traditional techniques, thanks to the de-embedding of the probe’s response. An electromagnetic time reversal technique, based on the scattering parameters, is employed to detect soft faults, enabling not only fault location but also the estimation of the reflection coefficient associated with the fault. Experiments conducted on coaxial cables, RVV cables, and twisted pairs show that the proposed method can accurately locate soft faults. The location error is limited to no more than 0.96%, even in cases where the impedance mismatch at the fault is only 4%. Moreover, in the presence of noise, the proposed method maintains high accuracy in fault location, even when the signal-to-noise ratio (SNR) of the scattering parameters is as low as -20 dB.