Impact of Resistive Neutral Grounding on Arcing During Single-Phase Faults in Low-Voltage Electric Networks

This article considers the safety improvement possibilities of low-voltage three-phase electric networks by grounding their neutral through a high-value resistor. The safety of an electric network is primarily determined by single-phase fault processes. Arcing faults are the most dangerous type of such processes. The conducted research showed that low-voltage grounding arcs are unstable. Arc duration does not exceed half of the free current period of the single-phase fault. Such arcing faults result in overvoltages and heat production at the insulation damage location. This paper considers the features of arcing in low-voltage electric networks with neutral grounded through a resistor. These features were studied in physical experiments. During the experiments, the authors recorded the electric arc current and voltage oscillograms. The obtained oscillograms were used to assess the power and maximum current surges of the grounding arc. The authors studied the impact of three-phase electric network parameters like the impedance of the resistor connected to the neutral, phase capacitance, and voltage value on the power of the arc. Experiments were conducted on a physical model of an electric network with voltages of 220 V and 380 V. The results were compared with similar research on electric networks with an insulated neutral and showed. This showed that high-value resistor grounding of the neutral can be effectively used to improve the safety of low-voltage electric networks.