The hysteresis character of corona formation

YEARS ago in studying the nature of corona losses occurring from a small high-voltage laboratory line the cathode ray tube was used to observe the cyclic relation of corresponding instantaneous values of line voltage and charge.¹ It was found that the sides of the resulting diagrams were practically parallel, causing them to resemble hysteresis cards. The significance of this was not recognized at the time. More recently two items were encountered that have called for a critical study to be made of these same diagrams: (1) the value of the power lost through corona from a transmission line closely approximates that given by the product of the charging current and the voltage in excess of the critical voltage; (2) the dominating importance of the crest voltage in relation to corresponding corona loss. These items clearly indicated the hysteresis character of corona formation.