Calculation of Coulomb Force to a Conductor Based on the Analysis of Electric Field Strength

Vibration of a transmission-line conductor is set up by corona discharge on water drops hanging beneath the conductor under rainy weather. This corona-induced vibration of a transmission-line conductor has become more serious problem owing to the rise of transmission voltage. To make the mechanism of coronainduced vibration clear theoretically, it is important to investigate force to a conductor. As the first step, calculation of coulomb force caused by space charge is described in this paper. The calculation model is the co-axial cylindrical electrodes, and the inner conductor has a knife edge which shames hanging water drops. In computing coulomb force, the analysis method of electric field strength is used. The calculation of electric field strength is performed with the method of successive approximation. In general, it is difficult to determine boundary conditions in calculation of corona electric field. Therefore, in order to determine the boundary condition for the space charge density, we adopted electric field strength in the vicinity of the tip of the knife edge. Using electric field strength at the surface of the inner conductor, which is calculated in the manner described above, it is able to compute coulomb force working the conductor. Coulomb force was calculated under various conditions such as applied voltage, diameter of a conductor, and length of projection. As a result, it was showed to be able to treat of force to a conductor quantitatively. And we obtained a guide to analyse corona-induced vibration theoretically.