A Parametric Study of Evaluation of Damage into Solid Dielectrics Due to PD Activity Using a Kinetic Model

A kinetic model based on Particle in Cell - Monte Carlo Collision (PIC-MCC) model is used for parametric study of the damage due to partial discharges activity into the surroundings dielectrics of a narrow channel encapsulated within the volume of a dielectric material. The parameters studied are applied electric field, channel dimensions and gas pressure. After application of an electric field across a dielectric material which contains a narrow channel, repeated ionization process starts in the gaseous medium of narrow channel. Charged particles, especially electrons, gain energy from the electric field across narrow channel and cause damage into dielectric surfaces of narrow channel on impact. The dependence of the electron energy distribution function (EEDF) on the applied electric field is studied. These estimations are performed based on the number of C-H bond-scissions produced by the impacting electrons of a single PD pulse. Based on this technique, the consequent damage into the solid dielectric and the time required to increase surface conductivity is computed. The formation of acid molecules due to interaction of PD pulse with polymer surface in presence of air and humidity causes changes in the surface conductivity of the surrounding dielectrics of the narrow channels. It is observed that the extent of damage caused by a PD is primarily determined by the total number of impacting electrons capable of producing bond-scission at the dielectric. Parameters that effectively cause an increase in the number of energetic electrons increase effective damage as well as surface conductivity of surrounding dielectrics.