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Vol. 26 (2023 year), No. 4, DOI: 10.21443/1560-9278-2023-26-4

Petrova R. M., Gracheva E. I., Valtchev S., Miftakhova N. K.
Methods for assessing the reliability of in-shop power supply

Research activities in the field of development of electrical power and electrical equipment include the development of new approaches to assessing the reliability indicators of electrical equipment elements and in-house power supply systems in general. The study has examined methods for assessing the reliability of electrical equipment in intra-shop power supply systems using the example of a workshop network section, including its main elements: power transformer, low-voltage cable lines, distribution points, circuit breakers, magnetic starters, contactors, switches. The reliability parameters of the circuit are calculated relative to the distribution cabinet of the power (DCp) and the distribution point of the power (DPp); regarding each connection of DCp and DPp. The methods under consideration are recommended to be used to clarify the frequency and timing of maintenance and repairs of electrical equipment of the in-shop power supply system, as well as to analyze the reliability of operation and identify the least reliable sections of network diagrams. The presented calculation using the logical-probabilistic method by constructing a fault tree is advisable to use to estimate the frequency of power loss of DCp and DPp, as well as individual connections. For the studied circuits, graphical dependences of the probability of failure-free operation of electrical equipment and the occurrence of a failure over time have been constructed.

(in Russian, стр.15, fig. 10, tables. 4, ref 17, AdobePDF, AdobePDF 0 Kb)

Vol. 27 (2024 year), No. 4, DOI: 10.21443/1560-9278-2024-27-4

Petrova R. M., Gracheva E. I.
Assessment of reliability parameters of in-plant power supply schemes with two-transformer substations

In the process of designing in-plant power supply systems, it is necessary to determine their rational redundancy. The reliability of the power supply system has been established for the following variants of the circuit of two-transformer 10/0.4 kV substations: without redundancy; with redundancy (when installing a sectional switch); with double redundancy (when installing a sectional switch and a backup jumper for 0.4 kV). The calculation data have shown that the reliability of the circuit without redundancy is 1.87 times lower compared to the circuit with redundancy and 3.17 times lower than with the circuit with double redundancy. Graphic dependencies of the mean time between failures of power supply circuits with two-transformer substations from different rated capacities of shop transformers have been obtained for three variants: without redundancy; with redundancy; with double redundancy. The optimal condition is to use a smaller number of transformer substations (respectively, transformers) while maintaining the load factor of 0.8. When comparing the graphs, it has been found that the longest mean time between failures is achieved with double redundancy, and the shortest – with no redundancy. The research results can be recommended for use in the process of designing in-plant power supply systems to assess and improve the reliability and efficiency of equipment operation

(in Russian, стр.13, fig. 9, tables. 2, ref 15, AdobePDF, AdobePDF 0 Kb)