Critical electric field needed for the propagation of surface discharges on water

The core objective of this study was to investigate the behavior of electric discharge exited in air over water and to study the way in which the lightning impulse is conducted into a water body. During the experiments, standard lightning impulses from -550 kV to 350 kV have been directed on water surfaces and surface discharges has been photographed using two cameras. The conductivity of the water has been varied from 41.5 μS/cm to 51.5 mS/cm. Analysis carried out in the study revealed that the current rather travels along the water surface than into the water when the conductivity of the water is low. A logarithmic variation was observed between the calculated electric field and the conductivity. For this variation a saturating trend could be observed and it appeared as if there is a critical value for the electric field below which no penetration will occur at any level of conductivity. Based on the experimental results of this study it can be estimated that to be less than 1.5×105 V/m for the positive breakdown and -5.0×105 V/m for the negative breakdown.