Verification and Analysis of Lumped-Circuit Approximate Models of Twisted-Stranded Cables for High-Speed Railway Signaling Systems

Abstract

To evaluate the transmission characteristics, anti-electromagnetic interference performance, and cable channel fault detection of multi-core twisted-stranded cables used in high-speed railway signaling systems, this study established a model for accurate twisted cable physical simulations. With the LEU-BSYYP cable, the finite element method (FME) software constructed a one twisted cycle length model and calculated the per-unit-length (pul) distribution parameters of the cable under high-frequency pulses. The purpose is to simulate long-distance twisted cables physically and analyze the factors affecting the transmission quality and transmission distance of high-frequency signals quantitatively by constructing a lumped equivalent circuit comprising cascaded T-type circuits. Additionally, by analyzing the relationship between the working frequency and the characteristic impedance error, where the characteristic impedance error is the difference in characteristic impedance between a lumped equivalent circuit and a lossy uniform transmission line, the number of T-type cascaded circuits that fulfill the accuracy requirements of the physical simulation is determined. Finally, the model output is compared with the measured waveforms using a 500 m LEU-BSYYP twisted pair cable as an example to verify the correctness of the equivalent modeling of the lumped circuit in the paper.