Overvoltages during Single-Phase Earth Fault in Neutral-Isolated Networks (10÷35) kV

Aims: The purpose of the article is to analyze networks with zero insulation (10 ÷ 35) kV, which have disadvantages that adversely affect the insulation of operating equipment, as a result of which, in modern conditions, it is desirable to improve the operating modes of such networks.

Place and Duration of Study: Department of Electromechanics (Electrical and electronic engineering).

Methodology: To limit the surges that occur in such networks, an arc quenching coil is used, the operation of which is based on two processes: a coil that compensates for the capacitive current, a sharp decrease in the voltage recovery rate in the arc range.

Results: In connection with the above, by carrying out accurate calculations, it is necessary to solve a number of issues on grounding the neutral with active resistance in networks (10÷35) kV: effective grounding of networks, ensuring safety, limiting the impact on communication lines, limitation of emerging surges, ensuring normal operation of switching devices, etc.

Conclusion: 1. Due to the difficulty of obtaining an accurate adjustment when earthing the neutral through an arcing coil, and even under normal conditions, overvoltages in the phases are likely as a result of the displacement of the neutral. 2. Networks with zero insulation (10÷35) kV have disadvantages that adversely affect the insulation of operating equipment, and in modern conditions it is desirable to improve the operating modes of such networks.3. In networks with an isolated neutral (10÷35) kV, the connection of the neutral to earth with active resistance allows you to significantly limit the extreme voltages that may occur in the network.