Dielectric strengths of CO/sub 2/ and N/sub 2/ containing SF/sub 6/ under alternating voltage in non uniform field

摘要

At present work AC breakdown strengths of N/sub 2/, CO/sub 2/, SF/sub 6/ and the mixtures of SF/sub 6/+N/sub 2/ and SF/sub 6/+CO/sub 2/ containing 20, 10, 1% of SF/sub 6/ in non uniform field were experimentally studied. The rod-plane of 5, 15 and 25 mm gap spacing was used as an electrode system. The relative gas pressure was varied within the range of 100-500 kPa. The experimental results have shown that addition of SF/sub 6/ to CO/sub 2/ and N/sub 2/ can significantly increase the AC breakdown voltage with respect to CO/sub 2/ and N/sub 2/. Especially within the pressure range of 150-300 kPa, the breakdown voltages of some of the SF/sub 6/+CO/sub 2/ mixtures are higher than that of pure SF/sub 6/. For example, the breakdown voltages of 20, 10% SF/sub 6/ mixtures for 25 mm gap spacing are about 2.4 and 2.8 times those of CO/sub 2/ and N/sub 2/ respectively at a pressure of 200 kPa. In the case at 25 mm gap spacing mixtures with 1% of SF/sub 6/ content have breakdown levels same as the corresponding values in pure CO/sub 2/ and N/sub 2/ gas pressure in excess of 400 kPa and 350 kPa respectively.