Breaking Characteristic of a Gas-Insulated Fast-Acting Switch in Synthetic Air under Inductive Load

The search for ecologically friendly alternative gases leads to new challenges for the design of gas-insulated switchgear. Synthetic air as one of the non-fluorinated gases is a viable option for the use in high voltage disconnectors and earthing switches. Due to the lower switching capacity compared to sulfur hexafluoride, a higher operating pressure or additional methods to support are extinction might be required. This work deals with the breaking of inductive loads and the corresponding characteristics of synthetic air. For this purpose, a test device utilizing a plain break design, as typically used in earthing switches designed for sulfur hexafluoride, is tested with regard to its breaking capacity at different pressures with and without the transient recovery voltage in accordance with IEC 62271-102. The results show a rise in the breaking capacity with increased gas pressure. The tests conducted with the transient recovery voltage show two distinct patterns, in which the successful interruption of the current occurs exclusively either at the first current zero crossing or exhibits multiple reignitions before arc extinction.