Analysis of electric field distribution at air gap defect and its influencing factors in mine-used high-voltage cable insulatio

In order to know influence factors and laws of electric field distribution with air gap defects in cable insulation, taking mine-used high-voltage XLPE cable as research object, ANSYS finite element software was used to establish cable structure model contained air gap defect. Influence of shape, size and location of the air gap and thickness of the insulating layer on electric field distribution in the air gap was simulated and studied based on theoretical analysis of relationship between shape, size and electric field strength of air gap in insulation. Results show that electric field intensity of elliptic cylinder air gap defect is the largest of four different shapes of air gap, and the larger the air gap length in direction of insulation perpendicular to the field strength, the greater the field strength in the air gap. For size of the air gap, the larger the r value, the greater the field strength at the air gap, and change of the air gap size has little influence on the field strength at the air gap. For different radius size of the air gap, the maximum electric field strength at the air gap increases first and then decreases with increasing of distance between the air gap and the conductor shield. For a given size of the air gap, the field strength in the air gap and the insulation increase accordingly with decreasing of thickness of the insulation. These conclusions lay foundation for partial discharge of air gap defects, and also provide technical guidance for cable operation and maintenance.