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Date submitted2021-02-20
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Date accepted2021-10-18
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Date published2021-12-16
Thermal protection implementation of the contact overheadline based on bay controllers of electric transport traction substations in the mining industry
The article presents the principle of thermal protection of the contact overheadlineand substantiates the possibility of practical implementation of this principle for rail electric transport in the mining industry. The algorithm for the implementation of modern digital protection of the contact overhead line as one of the functions of the controller is described. A mathematical model of thermal protection is proposed, which follows from the solution of the heat balance equation. The model takes into account the coefficient of the electrical networktopology, as well as the coefficient of consumption of the current-carrying core of the cable, which determines the reduction in the conducting section from contact erosion and the growth of oxide films. Corrections for air flows are introduced when receiving data from an external anemometer, via telemechanics protocol. The mathematical model was tested by writing a real thermal protection program in the C programming language for the bay controller, based on the circuitry of which is the STM32F407IGT6 microcontroller for the microcontroller unit. Verification tests were carried out on a serial bay controller in 2020. The graphs for comparing the calculated and actual values of temperatures, with different flow rates of the current-carrying conductor of the DC cable, are given. To obtain data, telemechanics protocols IEC 60870-104 and Modbus TCP, PLC Segnetics SMH4 were used.
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Date submitted2020-10-05
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Date accepted2021-03-30
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Date published2021-06-24
Improving the efficiency of relay protection at a mining and processing plant
The paper presents the results of constructing effective relay protection in the power supply system of a mining and processing plant (MPP). A brief description of the MPP is given, the power supply and substitution circuits used to calculate the short-circuit currents are given. A statistical analysis of failures in the electric network of the MPP has been carried out, which makes it possible to draw conclusions about the nature of failures ranges. Analysis of the registered faults shows that a significant part of them are line-to-earth faults, which in most cases turn into multiphase short circuits, which are interrupted by overcurrent protection. In order to improve the efficiency and reliability of the relay protection, the power supply scheme of the MPP was refined and analyzed. The calculation of the short-circuit currents was made, which made it possible to calculate the settings of the relay protection and give recommendations on the place of its installation and adjustment in order to ensure the normal operation of electricity consumers. To reduce the number of failures to the cable insert on the line leaving the administrative and household complex (AHC), and to increase the reliability of power supply to consumers, it is advisable to divide the capacities of the existing 10 kV line into two parallel ones by laying a second line. It is recommended to install a current cut-off on the line outgoing to the AHC, the feasibility of the installation of which was shown by calculations. This will reduce the chance of failures to the cable gland. Data on the setting currents of overcurrent protection and current cut-off are given on the selectivity card.
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Date submitted2015-08-23
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Date accepted2015-10-26
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Date published2016-04-22
Low-voltage electrical apparatus
- Authors:
- S. M. Apollonskii
- Yu. V. Kuklev
The article describes the main trends in the development of low-voltage electrical appliances and related accessories, as well as issues of efficiency, reliability and safety. According to the authors, the main trends in the development of low-voltage apparatus can be considered: the transition from the use of certain devices to the system devices, unified by the process of installation and running in standard modules and comply with all the functional requirements of control systems; improving the standardization and normalization of the EA on an international scale; unification of constructive elements of the EA; increase the volume of production of complete device management and contactless application logic control systems and specialized computers for management purposes; increase the proportion of contactor relay equipment DC, performs a variety of control functions. Improved security service low voltage, through the use of low voltage (24 V DC, 110 V AC), voltage presence signaling devices; increase the proportion of and the use of combined control and protection devices as well as devices for the automation of recruitment and duty cycles of machines: differentsequencer, track control devices, relays, pulse counting, and so on. n.