Articles techniques et présentations

A critical element in understanding the pre-breakdown and breakdown mechanisms in gas/solid insulation systems is the triple point. This point is where two dielectric materials and a conductor intersect. Understanding these mechanisms at the triple point is crucial for designing systems that require hybrid insulation, such as those found in electrical engineering, space solar power stations in spacecraft, and particle accelerators. In this paper, the dynamic mode of the electric current module in COMSOL® Multiphysics is used to assess the electric field, within a 2D geometry representing the hybrid insulation (gas/polymer), commonly found in electrotechnical equipment. The objective is two fold: firstly, it aims to determine the characteristic time of the voltage impulse at which the electric field ceases to be governed by the permittivity of the insulators and instead is governed by conductivity. Secondly, it seeks to estimate the quantity of charges needed to be deposited on the surface of the polymer in order to push the electric field lines towards the gas volume, thus avoiding surface breakdown of the polymer. In order to determine the characteristic time, a field-dependent conductivity, obtained experimentally, is integrated into COMSOL®. For charge estimation, a comprehensive parametric study involving permittivity, electrical conductivity and surface charge density is undertaken. Identifying both characteristic time and charge density are crucial for the design of electrotechnical equipment.

Keywords: electric current, charge density, impulse voltage, electrotechnical equipment design