Influence of deteriorated porcelain insulator on electric field and potential distribution of insulators strings in 110kV transmission lines

Deteriorated insulators may lead to flashover or power failure in transmission lines, because of degradation in insulators strings' mechanism and insulation level after long periods of performing. By utilizing finite element method, E-field intensity and potential distribution of insulators strings with different resistance in different positions under the same pollution level have been researched. Simulation results indicate that: 1, E-field line distorts most seriously on the joint of deteriorated insulators' porcelain and steel-foot, spreading along the outline of deteriorated insulators, making the insulator looks like equipotential. 2, E-field intensity distorts most gravely on the joint of porcelain and steel-foot as well, the distortion will aggravate as the deteriorated position approaching the high-voltage side. 3, Comparing with normal insulator strings, except the deteriorated position, the voltage of the every one of the rest insulators bears in the deteriorated strings rise, which can rise up to 26.77%, causing normal insulators accelerated aging. The statics above provide some theoretical support for the deteriorated insulators detection according to characteristics.