Abstract
Purpose. The work is intended to investigate the electromagnetic processes in impedance bond in order to improve noise immunity of track circuits (TC) for safe railway operation. Methodology. To achieve this purpose the methods of scientific analysis, mathematical modelling, experimental study, a large-scale simulation were used. Findings. The work examined the interference affecting the normal performance of track circuits. To a large extent, part of track circuit damages account for failures in track circuit equipment. Track circuit equipment is connected directly to the track line susceptible to traction current interference, which causes changes in its electrical characteristics and electromagnetic properties. Normal operability, performance of the main operating modes of the track circuit is determined by previous calculation of its performance and compilation of regulatory tables. The classical method for determination of track circuit parameters was analysed. The classical calculation method assumes representation of individual sections of the electrical track circuit using the quadripole network with known coefficients, usually in the A-form. Determining the coefficients of linear element circuit creates no metrological or mathematical difficulties. However, in circuits containing nonlinear ferromagnets (FM), obtaining the coefficients on the entire induction change range in the cores is quite a difficult task because the classical methods of idling (I) and short circuit (SC) are not acceptable. This leads to complicated methods for determining both the module and the arguments of quadripole network coefficients. Instead of the classical method, the work proposed the method for calculating the track circuit dependent on nonlinear properties of ferromagnets. Originality. The article examines a new approach to the calculation of TC taking into account the losses in ferromagnets (FM), without determination of equivalent circuit quadripole network coefficients. When building the FM reversal model in parallel magnetic fields, the most accurate methods are the approximation ones that take into account not only the changes in values and over time, but also their derivatives. The development of computer hardware and software makes real the mathematical methods for calculating TC with significant change in ferromagnetic inductance, including the saturation areas. Herewith, it is important to search for approximating analytical expression that describes the dynamic limit hysteresis loop (HL). Practical value. The changes in the electrical parameters of the same TC were analysed using the classical and the new calculation methods, the difference made less than 10%. The work introduced some measures to increase operational noise immunity of TC.
Highlights
Experience has shown that certain conditions and operating modes of the power network create a powerful influence of the traction current noise on the work of electric track circuits (TC)
It results in increased leakage currents into the open-line track of AC electric traction lines, causing magnetization of impedance bonds and track transformers, and disruption of short track circuits; 2) In the areas of AC electrified railroads the ice on the contact network collectors creates an electric arc, accompanied by electrical transients in the power circuit of an electric locomotive
Stant component of this current at the rail line asymmetry causes saturation of ferromagnets; 3) Switching on the locomotive main switch in a certain voltage phase of the circuit power line leads to transition process with the consequences given above; 4) When a laden electric locomotive enters the neutral section on the current collectors there are several electric arcs repeated aperiodically; this leads, as mentioned above, to the occurrence of transients and failures of TC
Summary
Experience has shown that certain conditions and operating modes of the power network create a powerful influence of the traction current noise on the work of electric track circuits (TC). Stant component of this current at the rail line asymmetry causes saturation of ferromagnets; 3) Switching on the locomotive main switch in a certain voltage phase of the circuit power line leads to transition process with the consequences given above; 4) When a laden electric locomotive enters the neutral section on the current collectors there are several electric arcs repeated aperiodically; this leads, as mentioned above, to the occurrence of transients and failures of TC From the above it follows that improvement of track circuit noise immunity in the signalling systems in conditions of permanent reverse traction current influence is an actual scientific and technical problem
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