The Effect of Dissolved Gases on the Electrical Conduction and Breakdown of Insulating Oil

An experimental study has been made of the effect of dissolved air on the electrical conduction and breakdown of insulating oil. It was found that the breakdown of degassed oil is preceded by an appreciable conduction current which is accompanied by fluorescence of the highly stressed oil. It was shown that both the conduction current and the breakdown voltage, particularly the latter, are affected by the residual oxygen dissolved in the oil. Other observations are concerned with the change in breakdown voltage when the air content of the oil is increased up to its saturation value at atmospheric pressure.