Electric Field Simulation Study of Zero-Value Defects in 110kV Transmission Tower Insulator Strings

Ceramic insulators are susceptible to the influence of complex environmental factors during long-term operation, easily leading to zero-value insulators and causing flash over or breakdown phenomena. In severe cases, these issues can result in power outages, grid failures, and even fires, short circuits, and equipment damage with significant consequences. In this paper, the 110kV straight-line cathead tower insulator string is selected as the simulation object, and the finite element calculation method is employed to analyze the spatial electric field measurement results under different operating conditions. The research findings indicate that the outer surface of ceramic insulators exhibits an asymmetric “U”-shaped distribution of the spatial electric field. Additionally, it was observed that the spatial electric field variation caused by degraded insulators decreases as the measurement distance increases. Considering the three-dimensional spatial electric field, the degradation of insulators has a close correlation with the position of the degraded insulator within the insulator string. When a zero-value insulator is present at the high voltage end of the insulator string, the electric field value of the entire string is significantly higher than the normal value. Furthermore, the impact of multiple degraded insulators in succession has the most significant effect on the rate of spatial electric field change. The research results provide theoretical support for the detection of substandard insulators, offering valuable references for further improving and optimizing insulator design, maintenance, and management.