Review of protection protections of rural 0.4 kV electrical networks from single-phase short-circuit faults

The paper considers technical solutions to improve the protection of rural 0.4 kV electrical networks from single-phase short circuits. During the analysis of literature sources it has been revealed that the main technical solutions to increase the protection are the use of additional re-earthing of the neutral conductor, replacement of outdated protective switching equipment with modern ones, sectionalization using fuses, sectionalizing points and multi-contact switching systems. The use of these solutions was demonstrated on the example of a radial rural 0.4 kV electrical network with the most frequently used equipment for power supply of agricultural consumers. The use of technical solutions to improve the protection of 0.4 kV power line was realized on a computer model, which was used to determine the currents of single-phase short circuit and compared with the time-current characteristics of protective switching devices. As a prototype of the rural 0.4 kV electrical network, a 1000 meter long transmission line made with A-35 wire connected to a TM-250/10/0.4 kilovolt Y/Y/Yn transformer was taken. It was revealed that it is possible to increase the protection of 0,4 kV electrical network with the use of 4 additional repeated grounding meters by 0,8-2,15%. Other technical solutions to increase the protection of 0.4 kV electrical network from single-phase short circuits were also considered. It was noted that the most perfect technical solution to improve protection against single-phase short circuits is the use of modern sectionalizing points and multi-contact switching systems, as they in addition to line protection also allow to provide monitoring of electrical parameters and configuration control.