AC Breakdown Characteristics of Low Pressure Air With Variable Oxygen Content

This paper presents the investigation on the impact of oxygen content changes on the AC breakdown characteristics of air insulated gaps at low pressure. As the oxygen content decreases, the insulating performance of low pressure air gaps improves slightly. When the electrode radius is larger than 1.0 cm, the streamer criterion provides a good prediction of the breakdown voltages for the air gaps with low pressures and different oxygen contents. McQuarrie method is employed for correcting the relative pressure, then an empirical formula is proposed to estimate the breakdown voltage of air gaps under low pressures. This formula accounts for variations in oxygen contents, electrode radii and gap distances.