Electrical Properties of Organic Insulating Liquids Containing Fluorescent Solutes

A new phenomenon is reported which is concerned with the excitation of fluorescent solutes in organic liquid dielectrics when high electric fields are applied. The characteristics of the emitted light have been studied and related to the pre-breakdown conduction current and the electric strength. Dielectric liquids showing this effect have been synthesized by dissolving known concentrations of fluorescent materials in simple organic liquids. These have confirmed the exeprimental results obtained with more complex transformer oil. Also, experiments are described which show that even highly degassed liquids exhibit a pressure dependence of electric strength if brought into a state of super-saturation by applying tension to the liquid.