Effect of liquid motion on breakdown voltage under divergent electric fields in transformer oil

Conduction current and liquid motion under divergent electric fields in transformer oil were measured, and the effect of polarity on the DC breakdown voltage was clarified. Electric field and space charge density distributions near the breakdown were computed, taking the liquid motion into account. It was deduced that the breakdown occurred due to the field enhancement in front of the plane electrode, and it was demonstrated that the breakdown voltage in the case of the negative sharp electrode was much higher than in the case of the positive one.<>