Abstract
The authors investigated the partial discharge characteristics of SF6 gas wedge gap against the AC and the impulse voltages. It was clarified that the impulse partial discharge voltage (impulse PDIV) is higher than the AC partial discharge voltage (AC PDIV). The ratio of impulse PDIV to AC PDIV is 1.5-1.8 for lightning impulse or 1.4-1.8 for switching impulse.
We calculated the breakdown voltage of gas wedge gap provided that gas wedge gap satisfies Pashen's Law, and compared it with the experimental results. As a result, the AC PDIV has very good agreement with the calculated breakdown voltage in low gas pressure, but in high gas pressure the AC PDIV is lower than the calculated value. On the contrary, impulse PDIV is higher than the calculated value in all experimented gas pressure range,
It is clarified that these phenomena is explained by the lack of initial electrons in gas wedge gap in low gas pressure and by the residual charge in gas wedge gap in addition to the lack of initial electrons in higher pressure.
