VARIATION OF SURFACE FLASHOVER VOLTAGE IN SF6 WITH PRESSURE

Surface flashover characteristics of solid spacers in a rod-plane conf iguration have been investigated in SF6, at pressures to 400 kPa, for switching impulse voltages to determine the effect of spacer, spacer m aterials and polarity of applied impulses. The effect of spacer materi al on the flashover voltage is not significant. For negative polarity impulses, the influence of the spacer is also insignificant. But for p ositive polarity impulses, at pressures < 200 kPa, the spacer efficien cy becomes > 1.0. On the other hand, at pressures > 200 kPa, the prese nce of spacer drastically reduces the flashover voltage of the system. At about atmospheric pressure also, the spacer efficiency in air has been found to be > 1.0, with the same electrode geometry.