Influence of co-field and cross field flow of mineral oil with and without additives on conduction current and breakdown voltage in highly nonuniform fields

The paper presents the results of the effect of enforced co-field and cross-field oil flow on the conduction current and breakdown voltage of degassed oil, oil saturated with O₂ and with SF₆ and oil containing 1-methylnaphthalene (MN) and dimethylaniline (DMA) as additives. Direct voltage and a point-to-plane electrode geometry were used and results were obtained for both polarities of the point electrode. A general conclusion from all experiments is that oil flow, whether co-field or cross-field, raises the breakdown voltage and lowers the conduction current. The results also show that with the exception of DMA, all additives both gaseous (O ₂ and SF₆) or solid (MN) raised the breakdown voltage and reduced conduction current, compared with degassed oil, for both polarities of the point electrode. These effects are attributed to the electron-trapping properties of the additives