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The article considers an important scientific and technical problem of determining the transient resistance in the “rail - ground” system, which is of critical importance for ensuring the safety and efficiency of railway transport. The subject of the study is the mechanism of electric current spreading through the ballast layer, taking into account the features of the contact interaction between the rail and the crushed stone. The purpose of the study is to develop a comprehensive methodology for calculating the electrical parameters of a railway track. To achieve this goal, an analytical modeling methodology is applied that takes into account the mechanical characteristics of the system, the resistivity of materials and the influence of the water layer. In the course of the work, a mathematical model was developed that allows taking into account various configurations of crushed stone contact with the rail, including lateral contact and clamping under the rail. Special attention in the study is paid to the analysis of the influence of mechanical stress in the contact zone, surface and volume conductivity, as well as the effects of contamination and moistening of the ballast layer. As a result of the research, methods for calculating transient resistance have been developed, taking into account various factors, and graphs of resistance dependence on key system parameters have been constructed. The practical significance of the work lies in the possibility of applying the results obtained to predict the electrical characteristics of railway tracks, optimize their operation and increase electrical safety. The developed technique makes it possible to take into account the key factors affecting the transient resistance: the condition of the crushed stone surface, volume and surface conductivity, and mechanical stress in the contact zone. This makes it possible to more accurately assess the electrical characteristics of a railway track and make informed decisions on its maintenance and repair. The study showed that surface conductivity (due to contamination and water film) often has a more significant effect on the overall resistance of the system than the bulk conductivity of the material.

In this article, the object of the study is the power supply cables for non-traction railway consumers. The electrical parameters of the insulated conductor are determined. Primary parameters of the aluminum shell of the main power supply cable are obtained. As a result of solving the problem, the transient resistance of an isolated conductor is determined. From the boundary conditions, the propagation constant of the metal shell of the power supply cable in the polymer insulating coating is determined. As a result, the values of the transition resistance obtained by different methods are the same.

The article analyzes the change in the strength properties of structural materials used in the production of current collectors of electric rolling stock, proposes a method for calculating the reduction of resource indicators of elements of a system of moving frames of electric current collectors made of hardened aluminum alloys as a result of the thermal effect of the flowing current. The features of heating the levers of the current collector during laboratory tests are considered. The most heat-stressed units and elements bearing a mechanical load are installed. The dependence of the thermal degradation of the levers of a system of moving frames at various temperatures is determined. The nonlinear conversion function is calculated for calculating the integral value of thermal wear. A method is proposed to increase the reliability and performance of current collectors, based on the use of permanent temperature control of its key elements.

The article shows that the replacement of concrete poles should be based on their actual corrosion state. Authors propose a new method for determining the corrosion state of the contact system concrete poles underground part, which allows to carry out measurements on the two poles at the same time. In this case, second pole acts as a current electrode. There is a formulas for determining the resistance of concrete, resistance and capacity of «steel - concrete» interface region. This algebraical expressions are results of the transient process analysis for the contact system poles equivalent circuit. The values of these parameters define the corrosion state pole in the underground part. Using of the proposed method will significantly reduce the time and labor costs of diagnostic procedures.

The article is about defining corrosion state of overhead structures underground part. Specially designed concrete models are used for experiments and calculations. These models are made with the fabric technology of overhead structures creation. «Steel - Concrete» interface region parameters are calculated with a help of transient process which situated when DC power supply is connected to the scheme. There is a formulas and a methodic for calculation needed parameters. In the end of the article theoretical curve is located. It exactly coincides with an experimental curve.

Nowadays a frequency-controlled externally excited synchronous motor intensively uses in highly automated high-power electric drives. Earlier there were less reliable and more carefully maintained electromechanical direct current systems in these applications. At the same time, setting up of the closed-loop automatic control systems with subordinate regulation of the synchronous machines is the more difficult task. This is because a synchronous machine is a more complex control object. The purpose of this work is a comparative analysis of transients. In this case, saturation is taken into account according to the magnetic flux in the air gap. The coordinates of the machine are regulated by two different automatic control systems. The first system is typical, which uses field-oriented control of the magnetic field of the stator, the second system is upgraded, it selects the law of control of the magnetic field depending on the static load. Special attention in the current article is paid to the method of accounting for the saturation of the magnetic system of the motor and the construction of a mathematical and simulation model convenient. This article substantiates the feasibility of synthesizing more complex automatic control systems are ones with variable structure. The choice of the magnetic field control law in such systems avoids the negative effect of saturation of the machine's magnetic system on the quality of transients. The models presented in the current work can be used in the design of real controlled synchronous electric drives operating under high loads.