The three span video monitoring device for transmission lines is developed for overhead transmission line sections that cross high-speed railways, highways, and important transmission channels in the power grid, with the aim of preventingThe research and development aim to prevent major public safety and power grid safety incidents caused by "three spans", such as tower collapse, wire breakage, and string drop accidents, in line with the requirements and corresponding technical specifications of the State Grid Corporation of China's "Major Anti accident Measures for Overhead Transmission Lines with Three spans" proposed in March 2016, effectively improving the level of intelligent management of the power grid.