Abstract: Based on the heating issue of conductor diversion plates on tension towers of overhead transmission lines in Beijing, this paper first describes the commonly used methods for repairing heating defects of diversion plates and compares their advantages and disadvantages. Then, it introduces the working principle and structural design of a newly developed defect-repair device, namely the visual electric fastening device, which enables live-line maintenance of diversion plate heating defects at ground potential. Additionally, operators can monitor the precise position of the device in real time through its visualization capability and remotely control its operation, significantly improving repair efficiency while ensuring operator safety and the reliable operation of overhead transmission lines.