Performance of Positive Corona in Tree-Shaped Multi-Needle-to-Plane Configurations
M. Abdel-Salam, H. Ziedan, and S. Kamal El-deen
Electrical Engineering Department, Assiut University, Egypt
Abstract- This paper is aimed at investigating the electric field, the positive-corona onset-voltage and current-voltage relationship of tree-shaped multi-needle-to-plane configurations. The configurations include 1, 5, 9, 13 and 17 needles arranged in one, two and three layers. The well-known charge simulation method was used to calculate the electric field in the gap spacing between positively-stressed needle-arrangements and opposite ground plane. Based on the evaluated field values, the onset-voltage was calculated according to the criterion of sustained avalanche process to trigger a streamer within the ionization-zone surrounding the coronating needle. Three needle-arrangements of single, five and nine needles were stressed positively to measure the corona onset-voltage and current-voltage characteristics at different gap spacings. The agreement between the calculated and measured onset-voltage values is satisfactory with a deviation not exceeding 3.96%. For the same applied voltage, the corona current decreases with the increase of the number of needles for the same gap spacing. The obtained results are discussed in the light of discharge physics.
Keywords-Charge simulation, positive corona, streamer theory, tree-shaped electrodes, corona onset voltage