Study on the breakdown characteristics of conductor-plane gap under vegetation fire condition based on the combustion features

摘要

The frequent forest fires become a serious threat to the performance of transmission lines’ external insulation, therefore, researches on the breakdown characteristics under flame conditions is of great significance for the transmission lines' construction and safe operation. In order to study the breakdown characteristics of the gap under forest fire, the discharge tests of conductor-plane gap were carried out by the simulation forest fire experiment platform here, and typical vegetation causing the line tripping out easily were selected to simulate the forest fire. The influences of combustion features such as flame temperature, height, conductivity, and heat release rate were analysed too. The results show that the effect of different types of vegetation flame on breakdown characteristics of gap is obviously different, especially under the fir branches flame, the average breakdown voltage gradient drops to 10% of that of the pure air gap. The flame temperature has a minimal impact on the gap breakdown characteristics, while the conductivity has a significant influence on the insulation strength of the gap.