Electric field distributions and space charge behavior in nitrobenzene under low frequency alternating voltage

It has been shown that the electric field distribution and, consequently, the space charge distribution, in a liqUid insulant are different under direct and low frequency alternating voltage and that both differ from ideal distribution predictable from geometry. It has been recently shown that in commercial insulating liquids the breakdown is controlled by space charge.² For lack of more substantial information, however, authors⁷ have obtained the breakdown field strength at 60 Hz in an insulating liqUid by measuring the breakdown voltage and calculating field from the electrode geometry. It is shown here that even with plane parallel electrodes the field can differ markedly from the ideal case because the electric field in a liqUid insulator is defined by both the electrode geometry and by the space charge dynamics within the fluid.