Breakdown Voltage Behavior of CO₂, Air, and Nitrogen under Positive and Negative Impulses: Influence of UV Irradiation.

In the context of finding environmentally friendly alternatives to SF₆ for high-voltage insulation systems, this study investigates the breakdown behavior of three gases — CO₂, Air, and Nitrogen under sphere-plane geometry. Breakdown voltages were measured under both positive and negative lightning impulse voltage, with and without ultraviolet (UV) irradiation. The results highlight significant differences in breakdown characteristics depending on gas type, voltage polarity, and the presence of UV photons. UV irradiation, in particular, affects the inception processes differently for each gas, modifying both the breakdown voltage levels and statistical dispersion. This comprehensive comparative analysis aims to provide insight into the physical mechanisms at play and support the development of sustainable insulation technologies to replace SF₆.