Charge deposition and insulator flashover in SF6 under impulse voltages

In compressed-gas-insulated equipment, the weakest point in the system is often at the interface between the gas (usually SF₆) and the solid spacers used to support the conductors. In the present work a study was made of impulse flashover of model spacers under varying conditions. An important feature of the study was that, in all cases, the surface charge density was measured before and after each impulse-voltage application; the equipment was designed so that the complete surface of the spacer, including both triple-junction regions, could be scanned by a charge probe