Research on the exterior electric field of the ultrahigh voltage post insulator under impulse voltage

Higher technical requirements of post insulator for Ultra-high Voltage (UHV) transmission and transformation project have been proposed. The polluted post insulators on service may flashover as a result of lightning. The electrical field and potential distribution of the post insulator have relations with the flashover. In order to study the character of exterior electric field distribution in UHV post insulator, a finite element computation model is set up by theory analysis. The electric field distribution of 1100kV post insulator for substation operated in standard lightning impulse is computed. Research result can be achieved that the electric field distribution curve changed with time is similar to the excitation source of thunder. The electric field of the first and the last big or small umbrella is large, and the middle umbrella is relative small. The biggest electric field lies in the insulation jacket surface, which is a serious challenge for insulating medium.