Experimental investigation of dielectric properties of alternative insulation gases for medium voltage switchgear

Abstract:
Due to its high dielectric strength, SF6 is the most common insulation gas in medium and high-voltage applications, however, its high global warming potential causes a search for SF6-free solutions. This paper investigates the dielectric properties of several alternative insulation gas mixtures with lower or no global warming potential for the use in medium voltage switchgear. The results are obtained from generic configurations and resin insulators in test vessels as well as a primary and a secondary distribution medium voltage switchgear. The dielectric strength of a large number of test configurations, including various gas mixtures, arrangements, pressure levels and switching positions of the systems is determined in a reproducible and comprehensible manner. The tests are carried out using standard lightning impulse voltage of positive and negative polarity.