220 kV Power Transmission Lines Unexplained Tripped Accident Analysis

Due to the advantages of light weight,good anti-pollution performance,etc.,composite insulator has been widely used in the power system.With the increase of the running time and usage quantity of composite insulator,unexplained regular accidents occur frequently.Combining with a typical 220 kV transmission lines unexplained trip accident in Changsha area,the scene of the accident situation is combined with the theoretical analysis and calculation.The factors of composite insulator umbrella shed structure,hydrophobic and surface field distribution for the composite insulators flashover reason caused by Guano dropping.The preventing measures of birds trouble,improving the shed structure,increasing the silicone rubber shed and adding anti-bird pedal is proposed,as well as the calculation for the increase of the protecting scope of the silicone rubber sheds is performed.