The design of reliable high voltage equipment remains a challenge nowadays. The surface charge accumulation at gas/solid interface is a major problem of HVDC GIS/GIL. The electric field can be distorted and the dielectric strength of the system can be thus reduced dramatically due to surface charges.

The development of HVDC networks leads to an increasing need of Gas Insulating Substations (HVDC-GIS). When an insulator is subjected to high thermoelectric dc DC stress, space charge accumulation can induce local increases of the electric field, which must be known and taken into account for the equipment design when the fields exceed several kV/mm.

This paper is aimed at the study of the propagation of discharge at the surface of solid insulator and the development of an analytical model of flashover in air.

This paper is aimed at the comparison of breakdown voltages of SF6 and mixtures at different concentrations of Fluoronitriles in CO2. The experiments are conducted in different electrodes geometries under DC and lightning impulse voltages.

This paper is aimed at the breakdown characteristics of Fluoronitriles – CO2 gas mixtures in different experimental conditions; these mixtures constitute promising substitutes to SF6 gas in high voltage applications especially gas insulating switchgear (GIS).

Charge accumulation on solid insulator in Gas Insulated Substation (GIS) is one of the major issues under Direct Current (DC). A specific device has been developed in order to assess the origin of such charges within SF6, in a coaxial geometry.

This paper is aimed at the experimental study of creeping discharges and flashover of cylindrical epoxy solid insulators with and without barrier.

HVDC (High Voltage Direct Current) technology is particularly suitable for the transmission of high-power energy over long distances. However, some technical/technological problems have to be addressed/managed when passing from HVAC to HVDC due among others to the fact that the electric field distribution in gas insulated systems (GIS) operating under DC stress is very different from AC conditions.

This paper is aimed at the propagation of discharges over a surface of insulator and the development of an analytical flashover model in air at atmospheric pressure. The experimental results show that the critical conditions of flashover are over the half of creeping distance.

Dimensionning of DC isulation is relatively complexe and need to take into account must more effects and parameters than in AC. This paper presents simulation methodology to applied for DC GIS and GIL.