Preliminary study on icing and flashover characteristics of inverted T-type insulator strings

Insulator icing flashover has always been one of the important factors influencing the safety of power grids in winter. Due to the limitation of tower structure and distance between the conductor and the ground, the existing anti-icing flashover method has certain effects but still cannot fully meet the safety requirements of power grids. Based on the idea of changing the ice coverage and discharge path of insulator string, a brand-new insulator string that arranged as inverted T-type is proposed in this paper to achieve the purpose of reducing ice coating and increasing the ice flashover voltage. The icing and flashover experiments are simulated in an artificial climate room. The experiment results show that the ice amount of inverted T-type insulator is smaller than that of the same type and same creepage distance of suspension I-string, and the inclined portion of the inverted T-type arrangement is basically free from bridges under glaze and mixed-phase ice conditions. In the case of the same creepage distance, dry-arc distance, the same degree of contamination, and the ice-covering condition of the same type of insulator, the melting flashover voltage gradient E-50 of the inverted T-type string is 14.8-16.3% higher than that of the suspended I-string. The results show that after the insulator adopts inverted T-type arrangement, the ice coating can be significantly reduced and the ice flashover voltage can be increased. The conclusions of the study provide a new solution for the anti-icing flashover treatment and design of the overhead lines.