Surface Charging Affecting Metal Particle Lifting Behaviors Around Epoxy Spacer of HVDC GIL/GIS.

In this article, the mechanisms of surface charging and surface modification of epoxy spacer affecting the lifting voltage and the motion trajectory of spherical metal particles in a downsized dc gas insulated transmission line (GIL) are investigated by simulations and experiments. Results show that the lifting voltage can be predicted with much accuracy by calculating the electric field distribution under the capacitive condition. Prestressing leads to a 27% decrease of lifting voltage, which is traceable to that surface charging making a major contribution to the enhancement of electric field force. Direct fluorination is proven as an effective modification method to improve the insulation performance of epoxy spacer again. The lifting inclination is significantly inhibited after treatment because of less surface charge accumulation and more rationalized electric field distribution. The trajectory simulation results indicate that more serious surface charging can activate more metal particles to lift up and drive them to more collisions. The lifting probability and velocity of metal particles around the epoxy spacer are markedly decreased by fluorination, which is a promising treatment for dc GIL/gas insulated switchgear (GIS) application. [ABSTRACT FROM AUTHOR]