The onset voltage of coronas on bare and coated conductors

This paper concerns theoretical and experimental investigations of the effect of a conductor coating on the onset voltage of a corona on overhead transmission-line conductors. The onset voltage for a self-maintained discharge on the basis of discharge physics is evaluated. This calls first: for accurate calculation of the electrical field in the vicinity of a coated conductor and its correlation to the field values near a bare conductor of the same radius. The well-known charge simulation technique is used for field calculation. The calculated electrical field values are utilized in evaluating the onset voltage of positive and negative coronas an bare and coated conductors. The onset voltage increases with a conductor coating. The calculated onset-voltage values agreed satisfactorily with those measured for laboratory models and full-scale test lines.