Dynamics of water drops on metal and insulator surfaces submitted to AC voltage

This paper reports an experimental study of the deformation of water drops on both conducting and dielectric solid surfaces under ac voltage stress. The discharge activities between water drops and between a conducting water drop and a small rod electrode on a flat hydrophobic insulator are investigated. It´s shown that the electric field applied to the drop surface is controlled by the electrode geometry and spacing between water drop and the electrode. The inception electric field strengths of partial discharges for rod electrode provide relevant inputs for the field inhomogeneity used in the simulation of the deformation of aligned water droplets. The discharge current characteristics of water drops on dielectric solid surface made of silicone rubber (SIR), under ac voltage stress are also measured. It´s shown that the length of a discharge between droplets or between a single droplet and a small rod electrode is reduced through a particular type of its distortion. This is visually characterized by a water filament or thin film between the water drops along the insulator surface.