Effect of Nitrogen Fine Bubbles on Negative Lightning Impulse Breakdown Voltage and Discharge Propagation Characteristics of Pure Water

Authors focused on pure water as an ultimate liquid insulating material that is harmless to the environment and has the potential to be used as an alternative to electrical insulating oils. Since the part of insulation properties of pure water, such as volume resistivity and dielectric dissipation factor, are inferior to that of insulating oils, it needs to be improved. It has already been reported that nitrogen fine bubbles (N2 FBs) have the potential of increasing the volume resistivity of pure water. In this paper, authors report the experimental results related to the effect of N2 FBs on negative lightning impulse breakdown voltage (NLI BDV) and discharge propagation characteristics of pure water. Some of the experimental results suggest that N2 FBs may not adversely affect the NLI BDV, discharge current, and time from the camera trigger to strong light emission occurring due to spark discharge of pure water.