Theoretical Analysis of Electric Heating Field and Insulation Accident of High Voltage AC Basin Insulator

Abstract

Basin insulator is widely used in GIS equipment. It is an important insulating part to realize electrical isolation between central conductor and grounding flange. In this paper, the insulation properties of the materials used for the basin insulator are analyzed experimentally, and the distribution of the electric field of the basin insulator is obtained through the electro-thermal coupling analysis process, and the relationship between the hottest spot temperature and the current carrying capacity is calculated. The heating curve of the basin insulator is obtained by using the theoretical model, and the basin insulation accident is analyzed by using the curve. Considering that the basin insulator is in the SF6 gas atmosphere for a long time, the local temperature rise caused by overheating fault of the basin insulator, and then the variation law of SF6 gas pressure and density caused by the overheating fault of the basin insulator are theoretically analyzed in this paper. Research shows: there is significant non-linear relationship between the insulation performance parameters of the basin body and the temperature. The eddy current field and harmonic field analysis method based on the finite element method can effectively calculate the heating of the center guide rod and the basin body under the power frequency condition. The maximum electric field intensity appears at the interface between the basin and the center conductor, with the value of 6.033kV/mm. The maximum temperature is near center conductor side of the basin, with value of 0.033kV/mm. When the current carrying capacity is higher than 1.5 times of the rated value, the thermal breakdown phenomenon of sudden temperature rise occurs. The calculation process of thermal electric coupling proposed in this paper provides way for verification of thermal electric performance of basin insulator design scheme, and also provides theoretical guidance for its on-site maintenance and accident analysis.