Environmental friendly high voltage testing equipment with synthetic air

The replacement of sulfur hexafluoride (SF₆) has become imperative to ensure compliance with the new EU F-gas Regulation (EU) 2024/573 applicable to the electrical industry. Synthetic air

(synAir) has emerged as a potential alternative; however, its adoption introduces significant challenges in the design and development of next-generation high-voltage equipment.

A reliable testing system must operate under actual industrial site conditions and withstand mechanical shocks during transportation, as well as multiple electrical breakdowns of the test specimen, to enable accurate and comprehensive diagnostic procedures.

The dielectric strength of synAir under atmospheric conditions is approximately one third of that of SF₆. Increasing the gas pressure enhances the dielectric performance of synAir; however, the relationship between pressure and dielectric strength is non-linear and eventually reaches a saturation point. From a mechanical standpoint, elevating the pressure in gas-insulated equipment significantly increases costs and necessitates additional safety measures due to sealing requirements and structural constraints. Consequently, an optimal insulation design must determine the appropriate pressure level and equipment geometry to satisfy electrical, thermal, and mechanical requirements.

This paper presents initial results and operational experience with gas-insulated test components utilizing synAir. It is noteworthy that the load cycles of these components remain identical to those of SF₆-insulated systems. To date, a gas-insulated reactor employing synthetic air has been qualified for test voltages up to 340 kV, along with a gas-insulated loss measurement system rated for 100 kV. We are committed to transitioning all gas-insulated testing technologies to synthetic air in the coming years.