Analysis on Blackout of 220kV Caoqiao Substation of Beijing Power Network in China on March 21,2008

In this paper the process of blackout occurred in 220kV Caoqiao substation of Beijing power network in China on March 21, 2008 is presented. By means of detailed investigation and analysis on the configuration and operation condition of the power equipments relative to the fault, the conclusion is drawn that in the gas chamber of cable terminal the incorrect connection of the noumenon of gas insulated switchgear (GIS) with cable terminal which touches off destruction of insulation is the main reason leading to this accident. In view of the vital function of high voltage switchgears in power network, the field installation of high voltage switchgears is an important link to ensure the overall performance of GIS, thus strict quality control should be applied to this link. Finally some suggestions and reform measures to prevent this kind of accidents are proposed.