Assessing new SF6 replacement gases through Pulsed Townsend experiments

The topic of SF6 replacement is still lively discussed in the high voltage community. Especially in the last years, research was intensified to find an alternative gas or gas mixture with similar or better insulation properties but lower global warming potential than SF6. Due to the almost unlimited number of possible gas mixtures, the high voltage laboratory at ETH re-initiated the search by using very efficient methods. One of the key elements is a highly automated Pulsed Townsend experiment with which the swarm parameters of gases and gas mixtures are measured. Traditionally, in high voltage engineering the voltage withstand strength of gases is determined by breakdown experiments. With our Pulsed Townsend experiment we have chosen a different way to determine the insulation properties…