The Variation of Electric Field on the Conductor Surface Characterized by Space Charge Density

Abstract

The accuracy of surface electric field (SEF) is important for the research of corona discharge phenomenon, both in numerical simulation and actual application. However, it is widely considered that the SEF is invariable after corona occurs (Kaptzov’s assumption). This theory makes corona study more convenient, but slightly inconsistent with the actual situation. In this work, SEF for the negative corona discharge in a coaxial cylinder’s model is investigated through the space charge density. Space charge density is measured by sound pulse method, which is a non-contact measurement method. It can avoid the introduction of interference in the study of SEF. By selecting the maximum charge density (charge density around the conductor) closely related to the SEF as the research objective, the variation of SEF intensity can be obtained. Results show that the values of charge density increase with the rise of applied voltage and the diameter of the conductor. Through the maximum charge density near the wire, the variation formula of SEF can be obtained. It shows that SEF is not a fixed value and not equal to the onset field intensity, and it has a decreasing trend with the applied voltage rising after corona initiates.