Mitigation of Aging Product Generation in C4F7N-Based SF6 Alternatives: A Holistic Approach

C4F7N (2,3,3,3-tetrafluoro-2-(trifluoromethyl) propanenitrile) gas mixtures have emerged as a promising ecofriendly replacement for SF6, the most global-warming-potent and widely used industrial gaseous dielectric in power grids. However, aging products of C4F7N gas mixtures with potential toxicity have also raised concerns. In this work, we demonstrate that by properly exploiting the heterogeneous characteristics of C4F7N aging, both its solid and gaseous aging products generated due to electric discharges can be effectively mitigated. With CO2 as the buffer gas to prevent carbonization, FKM fluoroelastomer rubber as the gasket to hinder the polymerization, and 4A molecular sieves as the adsorbent to further fixate the residual aging products, benign C2F6 and CO at sufficiently low concentrations become the only aging products detected after the electrical aging of C4F7N gas mixtures. This work showcases effective abatement strategies of C4F7N aging products, thus facilitating the transition toward SF6-free green power grids.