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    Assessment of Reliability Indicators of In-Plant Power Supply Systems with Two-Transformer Substations
    (Institute of Electrical and Electronics Engineers Inc., 2024) Valtchev, Stanimir; Miceli, Rosario; Petrova, Renata Maratovna; Gracheva, Elena Ivanovna; Çolak, İlhami; Kurokawa, Fujio
    The proposed article is devoted to the evaluation of reliability indicators of in-plant power supply systems with dual-transformer substations 10/0.4 kV. The paper considers the reliability of the system for the following variants of power supply schemes: without redundancy; with redundancy when installing a sectional circuit breaker; with double redundancy: when installing a sectional circuit breaker and a redundant jumper at 0.4 kV. © 2024 IEEE.
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    Assessment of Reliability Indicators of Power Supply Systems with Two-Transformer Substations During Technical and Economic Calculations
    (Institute of Electrical and Electronics Engineers Inc., 2024) Valtchev, Stanimir; Miceli, Rosario; Petrova, Renata Maratovna; Gracheva, Elena Ivanovna; Çolak, İlhami; Kurokawa, Fujio
    The proposed article is devoted to the assessment of reliability parameters of in-plant power supply systems with 10/0.4 kV double-transformer substations. The paper studies the reliability of the power supply system for the following variants of two-transformer substation schemes: without redundancy; with redundancy when installing a sectional switch; with double redundancy: when installing a sectional switch and a redundant jumper at 0.4 kV. The graphical dependences of operating time to failure of power supply schemes with two-transformer substations on different rated capacity of shop transformers for three variants have been obtained: without redundancy; with redundancy; with double redundancy. The optimum condition is the use of a smaller number of transformer substations, and, accordingly, transformers, while maintaining the value of load factor 0.8. When comparing the graphs, it was found that the longest MTBF is achieved with double redundancy, and the shortest - with no redundancy. The results of the research can be recommended for use in the process of designing systems of in-plant power supply to assess and improve the reliability and efficiency of equipment operation. © 2024 IEEE.
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    Investigation of Cable Line Heat Mode Parameters in Power Supply Systems
    (Institute of Electrical and Electronics Engineers Inc., 2024) Valtchev, Stanimir; Miceli, Rosario; Gracheva, Elena Ivanovna; Petrov, Almaz Radikovich; Tsitson, Ivan Ivanovich; Çolak, İlhami
    The paper develops regression models of dependences of the estimated service life of cable line insulation on the load factor in various operating conditions. The study of thermal modes using approximation functions of the obtained results is carried out. The temperature parameters of the cable line with different types of insulation have been obtained. The results can be used to clarify the temperature modes of cable lines when selecting their cross-sections at the stage of design of electrical engineering systems. © 2024 IEEE.
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    Method for Estimating Power Losses in Low-Voltage Networks
    (Institute of Electrical and Electronics Engineers Inc., 2024) Valtchev, Stanimir; Miceli, Rosario; Petrov, Almaz Radikovich; Gracheva, Elena Ivanovna; Çolak, İlhami; Kurokawa, Fujio
    In the proposed work, the study of a section of the shop network of an industrial enterprise with the determination of the equivalent circuit resistance. The calculation method presents the errors in the failure to take into account each of the considered parameters of the network. Causes and main damages of switching devices for voltage 0.4 kV are given. The main factor that influences in determining the equivalent resistance of the investigated circuit is the resistance of low-voltage switching devices. Determination of the type of empirical dependence of the resistance of devices depends on the current flowing through the contact connections. The error at non-calculation of this parameter for the mixed section of the power supply scheme reaches 77.15 %. Neglecting the heating temperature of conductors when calculating the equivalent resistance also has a significant impact and leads to an error of 5.6 %. Also neglecting the line loading factor and ambient temperature in determining the circuit resistance leads to an error of 3.17 % and 2.4 %, respectively. The results of the study can be used to assess the level of power and energy losses in low-voltage shop networks, which will significantly increase the reliability of the data obtained. © 2024 IEEE.