Theoretical investigation of the onset voltage of negative corona on stranded conductors is described in this paper. The method of calculation is based on the criterion developed for the formation of repetitive negative corona Trichel pulses. This calls at first for an accurate calculation of the electric field in the vicinity of stranded conductors. The investigated gap is a three-dimensional field problem. To solve this problem, a new modification of the charge simulation technique is presented, where the simulation charges are helical of infinite length. Laboratory measurements of the onset voltage on stranded conductors are carried out to check the accuracy of the present calculations. The effects of varying the field nonuniformity on the onset voltage values are investigated. The calculated onset voltage values for stranded conductors agree satisfactorily with those measured experimentally.

No abstract

No abstract

The study presents a detailed experimental and numerical analysis of the corona characteristics of a proposed 'trielectrode system' for electrostatic separation applications. The system consists of an ionising wire, a movable auxiliary wire and a non-ionising cylinder, having the same voltage and placed parallel above a grounded plate. A computational technique coupling the method of characteristics and the charge simulation method is developed to model the corona governing equations of the proposed configuration. Influence of the auxiliary wire's position on field modulation of the ionising wire, corona onset and switching on/off of the discharge is established both numerically and experimentally. Dependence of the spatial distributions of the electric field and current density on the system's geometrical characteristics is evaluated and assessed. The study includes a physical model of the corona discharge of this particular electrode arrangement and demonstrates the configuration's specific features and advantages as compared with the earlier designs. The computed results compared favourably well with experiments.

No abstract