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The article presents a method for determining the thyristor shoulders of the rectifier-inverter converter (inverter) of an electric locomotive, on which the control pulses are passed. The method is based on the analysis of the duration of the current switching of the thyristors of the inverter shoulders and the rate of rise of the rectified current in the inverter circuit of the electric locomotive. The implementation of the method is carried out by refining the software of the microprocessor control system of the electric locomotive. The simulation of electromagnetic processes of rectifier inverter Converter of AC locomotive series 3es5k "Ermak" in the mode of regenerative braking during emergency operation is carried out on the example of missing control pulses on thyristor shoulders VS2 and VS7. As a result of modeling, data are obtained that confirm the effectiveness of the method proposed by the authors

The question of the possibility of using concrete foundations support of a contact network as earthing. The analysis of the impact of the construction of the foundation for the spreading re-sistance. The results of the calculation of spreading resistance of the anchor bolt foundation metal support on the proposed formula.

The article considers the issue of providing protection for the contact network when removing 3.3 kV traction substations from the Nazivoye direction of the Omsk power supply distance of the West Siberian Railway. When the 3.3 kV switchgear is brought out to repair, the protection zone for connection of the contact network of adjacent traction power supply system objects (traction substations, sectionalizing stations, parallel connection points) increases. To ensure the protection of the DC contact network, lowered settings for the operation of high-speed circuit breakers are introduced, which inevitably limit the capacity of the section for the passage of freight trains. Considered the existing order of withdrawal of equipment for repair with the inclusion of a traction substation post section. The limitations of skipping freight trains during the implementation of the existing scheme are estimated. Short circuit currents are also calculated and the settings for the protection of high-speed circuit breakers are selected when the sectioning station is switched off and the sectional disconnectors of the station are switched on. It was found that the condition for selecting the protection settings is not fulfilled when detaching from the minimum value of the short-circuit current. To reduce the limitations, a prototype of a short-circuit contactor of a direct current 3.3 kV grid has been developed. The use of a short-circuit-breaker allowed the protection of the contact network, for the time of the withdrawal of the switchgear equipment for repair, without transferring to lower settings for the operation of circuit breakers. Also in the article are given the technical characteristics and features of the proposed device design. The results of a test of a short-circuit of a 3.3 kV direct current contact network in the Dragunskaya-Novokievskaya-Lubinskaya section are presented. The main directions for further work are determined.