A frequency-domain detection method for railway signal cable faults

Fault detection of railroad signal cables is of great significance for ensuring the safe operation of railroad systems. To address the most common high-resistance fault problem in railroad signal cables, the inhomogeneous characteristics of cable structures are analyzed by measuring the electrical parameters of multiple 1 m cable segments. Based on these measurements, a normal model of inhomogeneous cable parameters is constructed, followed by the establishment of an inhomogeneous high-resistance fault simulation model for railroad signal cables. The feasibility of the frequency-domain reflectometry (FDR) method for locating high-resistance faults in railroad signal cables is then verified. Furthermore, a dedicated hardware system based on the FDR method is independently designed. This system transmits a 0.1 MHz to 5 MHz swept-frequency signal into the cable and collects the reflected signals required for FDR analysis through an intermediate-frequency detector. The collected data are subsequently processed on a host computer to realize the localization of high-resistance faults with resistance values of 0.1 MΩ and 0.5 MΩ within a cable length of 1000 m. Experimental results confirm the effectiveness and accuracy of the FDR method for detecting and locating high-resistance faults in railroad signal cables.