Research on Method to Get Corona Inception Electric-Field Intensity Based on Small Corona Cage

Corona is an important aspect which influences the design of transmission lines and electric equipments. With the increase of altitude and voltage grade, the corona performance of equipments becomes more complex. First, this paper explains electric field distribution around the overhead multiple conductors is consistent to one of multiple conductors in the corona cage; then according to the test data of four different altitude points, we bring up the method to get corona inception electric-field intensity: in AC dry condition, using the tangent method ; in AC rain condition, using the threshold method. And afford the engineering basis to construct EHV and UHV AC project in the west high altitude area.