Gases released by surface flashover of insulators

Abstract

The gases released by surface flashovers on alumina ceramics, glass, and quartz, using 20-μs voltage pulses, were investigated using an ion-pumped metal vacuum system. Appreciable quantities of gas were measured (approximately 10−6 Torr liter or 1013 molecules). The composition of this gas differed significantly from the background gas. The dominant species in the surface flashover gases were CO2, CO, and H2; a modest amount of CH4 was observed, along with lesser quantities of N2 and H2O. The dominant gas in the system background was nitrogen, accompanied by (in decreasing amounts) H2, H2O, CO/CO2, Ar, CH4, and He. We concluded that the gas released by flashovers on the surface of the insulators was not adsorbed system background gas, but was gas adsorbed during the handling and processing of the insulator.