In industrial systems, cables are used to connect various pieces of equipment. Diagnosing soft faults in cables is a consistent step to ensure the system's stable operation. The bottleneck with existing diagnostic methods is locating and evaluating multiple faults in a cable with low error. In this article, a novel fault diagnosis method is proposed to locate multiple faults and estimate their reflection coefficients; the latter is used to assess the level of the fault. First, the reflection coefficient spectrum (RCS) (the data to be processed) is modeled, the relationship with faults is elaborated, and cable model parameters are estimated. Second, a matched filter matrix is constructed to analyze the RCS to locate faults. Third, the compensation model based on the cable transfer function is constructed to compensate for the attenuation of the signal and then estimate the reflection coefficients. Finally, sidelobe analysis is performed to improve detection accuracy, and multiple reflection analysis is performed to elaborate on the complex reflection phenomenon between multiple faults and filter out their interference in detecting real faults. Experimental results show that the proposed method locates multiple faults, estimates reflection coefficients with low error, and exhibits good robustness in the presence of noise.

Soft faults in cables may trigger short circuits and open circuits in time, in that, they ought to be detected and thus eliminated at an earliest possible stage, as to ensure safe and stable operation of the cables. A method called the time-reversal multiple signal classification (TR-MUSIC) had been proposed in the literature, which has been demonstrated to be an effective technique for locating soft faults in cables, owing to its high resolution and excellent noise robustness. However, traditional TR-MUSIC relies on a vector network analyzer for measuring the scattering matrix of cables, which adds cost and complexity to its implementation. In this regard, a new way of acquiring the desired scattering parameters is herein proposed. An arbitrary function generator is used to inject incident signals into the cable under test, and an oscilloscope is used to collect the reflected signals. After post-processing, the phase of scattering parameters can be obtained. There’s another key issue in the image of the detection results, ghost traces caused by the periodicity of Green’s function severely impact the vision saliency of the actual fault location, which limits the performance of the fault location. A step frequency variant of TR-MUSIC has been proposed, therefore, to mitigate ghost traces. Experimental results show that the fault location error of the proposed approach is smaller than 0.33% for a 51-m long coaxial cable. Moreover, in the case of introducing noise, the proposed approach can operate in situations with signal-to-noise ratios as low as –6 dB.

This work proposes a new method to evaluate the electrical contact performance of aviation connectors by in-situ measurement of broadband impedance. The broadband impedance of the wire-connector under corrosive environments is measured using an inductive coupled measurement scheme, which can be conducted under operating conditions. By observing variations in the inductance and resonant frequency of measured impedance, the degradation of the connectors can be assessed more accurately and intuitively. Experiments reveal a quasi-linear degradation correspondence between the impedance of connectors and corrosion duration. Moreover, the impedance of connectors is more sensitive to corrosion-induced degradation compared to resistance, which means that potential damage to the connector can be detected earlier through the proposed in-situ impedance measurement, allowing for better-informed risk management and timely repair or replacement, particularly in safety-critical situations.

This work presents an inductive coupling method for detecting soft faults in cables. The scattering parameter S₁₁ 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.

The gasketed seam is a critical factor affecting the shielding effectiveness of the enclosure. To accurately simulate the shielding effectiveness of the enclosure, it is necessary to model the gasketed seam. However, due to the complex microstructures on the contact surface of the gasketed seams, directly measuring and modeling the gasketed seams is challenging. To address the issue, this work puts forward an equivalent modeling approach. Based on the constraint that the transfer impedance is constant, the gasketed seams are modeled as isotropic regular structures instead of modeling the geometrical details. The transfer impedance can be made identical under different modeling conditions by establishing a connection between the key parameters (including the geometric and material-related ones) and the measured transfer impedance of the gasketed seam. This ensures that the electromagnetic field leakage through the gasketed seam remains consistent, ultimately achieving equivalent shielding effectiveness. In this way, modeling and simulating gasketed seams become straightforward and practical while keeping calculations accurate. Experimental results confirm the effectiveness of the equivalent modeling approach.

The wear of the contact surface caused by relative sliding can degrade the electrical contact performance of the aviation electrical connector. This work mimics contact surface wear through repeated plugging and unplugging experiments. A non-contact in-circuit impedance measurement method using a dual inductive probe technique is employed to continuously measure the impedance of the circuit under test, which comprises the connector and connecting wire, across the 1 MHz to 150 MHz frequency range during the experiment. Subsequently, the electrical parameters of the degraded connector are determined by combining a lumped transmission line model of the connecting wire with a broadband impedance model of the connector, based on the measured impedance of the circuit under test. The experimental results indicate that as the number of plugging and unplugging cycles increases, the resonant frequency observed in the broadband impedance measurements decreases. This phenomenon is primarily attributed to an increase in the contact capacitance of the connector due to wear on the contact surfaces. After 2000 test cycles, the resonant frequency of the circuit under test decreased by 1.25 MHz. Parameter identification revealed that the contact capacitance of the connector increased from 11.6 pF to 48.9 pF, a 4.22-fold rise. Meanwhile, the DC contact resistance increased by only 1.15 times over the same period. These findings suggest that contact capacitance is a more sensitive indicator of early degradation than DC contact resistance.