Since protection identification methods based on travelling waves for switch onto faulted line are imperfect, the paper analyzes the characteristics of travelling waves caused by breakers asynchronous closing.

The found and dealt with the defaults of non-synchronous closing in phase-to-phase for 5033 circuit breaker at 500 kV Fanchang station;

Based on modeling of a three-phase transformer,the physical process of three-phase non-synchronous closing is analyzed,the changes of flux in the closing of transformer is calculated,and the closing situations which result in the maximum flux is also analyzed,as well as the influence of leakage reactance on flux,which is found to be non-negligible in analysis of inrush.