Electrical Breakdown and Recovery of Water and Propylene Carbonate

Polar liquids, especially water, offer the advantages of high permittivity, a high dielectric strength and a fast dielectric recovery. These benefits make them appealing dielectrics for use in high-energy storage systems and as high-power switching media. In certain applications, however, the use of water is limited by its relatively high freezing point of 0degC and low boiling point 100degC. In comparison, propylene carbonate (C⁴H⁶O³) has a freezing temperature of -55degC and boiling point of 243degC in addition to its high permittivity of 65. The dielectric strength was found to be 2.3 MV/cm, slightly higher than that of water tested under the same conditions. As an alternative to water in high repetition rate systems we studied the dielectric recovery of propylene carbonate after breakdown. We found the recovery time to be more than one order of magnitude longer than for water. Moreover, the breakdown in propylene carbonate gives rise to a polymer formation in the liquid.