A Systematic Search for Insulation Gases and their Environmental Evaluation

Abstract

The high global warming potential of SF₆ makes it essential to search for substitutes with lower environmental impact. This paper presents a systematic approach to searching and evaluating gaseous SF₆ substitutes for insulation and switching applications in electrical power equipment. the procedure consists of three steps. Firstly, a structured set of criteria is defined which accounts for the functional requirements, environmental effects and safety aspects. Secondly, a comprehensive search strategy for candidate gases is defined which combines combinatorics and chemical systematics. the third and final step an evaluation of the integral environmental impact of a functional unit of equipment redesigned for a substitute gas. It is found that only air/nitrogen fulfill all relevant criteria both for insulation and switching but that they exhibit a much lower performance than SF₆.