Dielectric strength of insulating liquids in a continuously circulating system

THE electrical properties of liquid dielectrics have been studied by theoretical and experimental physicists for a long time. Of the various properties one of the most important, and probably the least understood, is the mechanism of electrical breakdown. To become acquainted with the voluminous literature in this field one must read not only monographs^1–4 but also more recent important summaries and experimental contributions.^5–13 One of the important concepts in the past has been that breakdown is initiated by ionization in gas bubbles thrown out of solution or suspension in the liquid. As a new experimental approach to this problem we set up a closed system in which the liquid could be continuously circulated through the dielectric strength cell with filters, dryers, and a degasifier in series in the system so that solid particles, moisture, and dissolved gas could be removed.