Optimization of the Electric Field Structure at the Isolation Sites of Environmentally Friendly Cabinets Based on the Polarity Effect of Uneven Electric Fields

In high-voltage electrical insulation structures, extremely uneven electric fields are often present. During discharge, the differing polarity effect under high field strength result in varying characteristics of corona inception voltage and breakdown voltage across the gaps for electrodes of different polarities. This paper focuses on a certain 12kV environmentally-friendly gas cabinet as the research subject. Based on preliminary experiments, data were obtained and combined with the use of simulation software to analyze the electric field at the isolation gap, calculating the coefficient of electric field non-uniformity. Subsequently, optimization was performed on the isolation knife, isolation static contact base, and isolation knife screw. The coefficient of electric field non-uniformity decreased from 14.54 to 9.77 after optimization. Furthermore, in the prototype tests conducted post-optimization, the difference in breakdown voltage between positive and negative polarities decreased from 15.1% to 8.4%, thus demonstrating the feasibility and rationality of the optimization.