Switching Overvoltage Flashover Characteristics of Full-Scale AC 500 kV Transmission Tower with Composite Cross Arms

Overhead transmission line has always been the major approach for large capacity power transmission over long distances, which takes a great deal of steel and land source. Therefore, composite cross arms are introduced to a full-scale AC 500 kV model tower, which could save the transmission corridor by 10
^%
• The switching overvoltage flashover characteristics of the air gaps are investigated. Three flashover paths are observed and the flashover processes are recorded. Also, the influence of air humidity and air density is considered. And the test results are corrected to standard conditions. By comparison with other air gaps, the switching overvoltage withstand ability of composite cross arm is slightly higher than the typical V -string line insulators, which totally meets the requirement of AC 500 kV transmission tower.