Experimental Studies on Synergistic Effects, Electrode Erosion, and Decomposition Characteristics of SF₆ Admixture in Divergent Fields

Sulfur hexafluoride (SF6) gas is a potent greenhouse gas, and there has been research into more environmentally friendly gases as a replacement to SF6 in HV equipment. The research into alternative gases has shown that SF6 admix have a promising dielectric property as comparable to pure SF6. In this article, the synergistic effects of adding a dopant gas (SF6) to nonelectron affinity gases such as N2, dry air, and Ar are tested with varied volumetric concentrations of SF6 by using a HV co-axial sparkgap (SG) switch under partial discharge (PD), that is, point-plane topology. The experimentation is carried out with doped gas concentration varying from 5% to 50% for operating pressure levels of 0.0345–0.172 MPa with interelectrode distance of 0.4 cm. The binary mixture of SF6 with N2 and dry air exhibits a higher synergism with $\varphi $ (SF6) ~5%. Furthermore, in SF6/N2 and SF6/dry air, the synergistic effects exhibit a saturated behavior with rise in $\varphi $ (SF6). Unlike SF6/N2, the growth rate of breakdown voltage (BDV) in SF6/Ar is greatly reduced at higher pressure with low % by vol. of SF6. Apart from breakdown study, the decomposition characteristics and electrode erosion rates of SF6/N2 has been investigated. The comprehensive experimental investigations reported herein present the application feasibility of these admixtures as a replacement to SF6.