Browsing by Author "Meleshko, V. V."

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    Comparative Analysis of Experimental and Calculation Methods for Determination of the Traction Current Harmonics Distribution in Rails
    (Дніпровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2018) Havryliuk, Volodymyr I.; Meleshko, V. V.
    EN: The purpose of this work is to perform the comparative analysis of experimental and calculation methods for determination of the distribution of traction current harmonics in rails. To investigate the distribution of traction current in the rails, the special marks ("flags") were set up at a certain distance (100, 300 and 500 m) from the point of measurement along the track. The moments of passing the train past the "flags" were recorded in a computer due to a sound signal from the train, as well as visual observation. The train was moving in the measuring section in a quasistationary mode with an average speed of about 48 km/h. Traction current was measured in circuit of the interthrottle jumper with using an inductive contactless sensor and registered using computer. The distribution of the return traction current harmonics in rails for AC feeding systems were modeled by using the multiconductor transmission line (MTL) model. Some discrepancies in the results of experimental and calculation methods were observed. One of main reason of measurement errors were an inaccuracy in determining distances from the train to the measurement point. Calculation errors were related mainly with using inaccurate electrical parameters of track in model, in particular, the track ballast resistance and the ground resistances. However, in general, the considered model can be used for investigation of the traction current harmonic propagation in rails from train, and their influence on the track circuits receivers for different cases including the variation of the track circuits electrical parameters, as well as the number of rolling stock units in the feeder zone. Such analysis of harmonic in rails is important for revealing the causes of failures in railway signalling system operation under simultaneous affecting on it several factors adverse to safe operation.
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    The Comparative Analysis of Main Calculation Methods of Matrix Elements' Impedance of 1520 mm Rail Track Gauge in Audio Frequency Range
    (Днепропетровский национальный университет железнодорожного транспорта имени академика В. Лазаряна, Днепропетровск, 2014) Havryliuk, Vladimir I.; Meleshko, V. V.
    EN: With the aim of comparative analysis of main calculation methods of series impedance matrix for 1520 mm rail track gauge in audio frequency range a brief mathematical formulation revue of two methods for calculation of traction rails' impedance with consideration of earth return current has been carried out. The applicability of Carson's method and complex depth of earth return method for calculations of impedance of 1520 mm track gauge in frequency range 1005 Hz have been con-firmed. ..10 The observed differences of calculated results and measured data may be eliminated by correct choice of parameters in the calculation formulas.
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    Improving the Positioning Accuracy of Train on the Approach Section to the Railway Crossing
    (Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпропетровськ, 2016) Havryliuk, Volodymyr I.; Voznyak, Oleg M.; Meleshko, V. V.
    EN: Purpose. In the paper it is necessary to analyze possibility of improving the positioning accuracy of train on the approach section to crossing for traffic safety control at railway crossings. Methodology. Researches were performed using developed mathematical model, describing dependence of the input impedance of the coded and audio frequency track circuits on a train coordinate at various values of ballast isolation resistances and for all usable frequencies. Findings. The paper presents the developed mathematical model, describing dependence of the input impedance of the coded and audio-frequency track circuits on the train coordinate at various values of ballast isolation resistances and for all frequencies used in track circuits. The relative error determination of train coordinate by input impedance caused by variation of the ballast isolation resistance for the coded track circuits was investigated. The values of relative error determination of train coordinate can achieve up to 40-50 % and these facts do not allow using this method directly for coded track circuits. For short audio frequency track circuits on frequencies of continuous cab signaling (25, 50 Hz) the relative error does not exceed acceptable values, this allow using the examined method for determination of train location on the approach section to railway crossing. Originality. The developed mathematical model allowed determination of the error dependence of train coordinate by using input impedance of the track circuit for coded and audio-frequency track circuits at various frequencies of the signal current and at different ballast isolation resistances. Practical value. The authors propose the method for train location determination on approach section to the crossing, equipped with audio-frequency track circuits, which is a combination of discrete and continuous monitoring of the train location.