SF6 contaminated by SO2: Dielectric strength and influence on sealing materials

This work investigates the influence of the presence of SO
₂
in SF
₆
regarding its breakdown voltage. A test chamber was built to accommodate a gas pressure of 2 bar, with a pair of electrodes inside, separated by a variable distance. The SO
₂
concentration in SF
₆
was 0,5 and 500 ppm. Preliminary results indicate that the influence of the presence of SO
₂
in SF
₆
regarding the breakdown strength is minimal. The effect of SO
₂
was also investigated on the switchgear sealing. For this purpose a metal chamber was designed and built to test pure SF
₆
and mixtures of SF
₆
and SO
₂
under 20 bar pressure, at 120 °C, for two months with different sealing materials, in order to evaluate the relative degradation of these materials. Preliminary results indicate that these mixtures can affect the mechanical resistance of the sealing material.