The influence of booster sheds on AC flashover performance of ice-covered 750 kV class tension insulator strings

By comparing the differences of electric field distribution and 50% flashover voltage between common arrangement insulator string and adding booster shed every four insulators (ABSEFI) arrangement insulator string during the melting period, this study explores the influence of booster sheds on ice-covered 750kV class tension insulator strings. Computer simulations and artificial icing flashover tests were used for the comparative analysis. Numerical simulations were done by the use of the finite element method (FEM). The simulation results show that the electric field strength at insulator steel-feet, which booster sheds have little impact on, is much higher than that in other places. Therefore, compared with common arrangement, there is no obvious improvement in the potential distribution after booster sheds being added on the tension string. Artificial icing flashover tests were carried out to compare the 50% icing flashover voltage of these two arrangements in different pollution severities. In addition, the flashover process of these tests was analyzed to study the influence of booster sheds to icing flashover. The experimental results show that, under the condition of 10 mm thick icing, the booster sheds increase the icing-flashover voltage of tension insulator strings by about 7%. The improvement is irrelevant to pollution severities.