Experiment and Simulation of Pressboard Barrier Effect on the Streamer Propagation in Natural Ester During Positive Pulsed Voltage

In this study, the effect of the pressboard barrier (PB) on streamer pattern in natural ester under the non-uniform electric field is investigated by experiment and simulation. The propagation patterns and characteristics of the streamer in the oil with/without a pressboard barrier are obtained by the shadowgraph technique. The mechanism of the pressboard barrier effect on the streamer pattern and propagation is revealed using a multi-streamer branch simulation method. Results show that the positional relationship between the needle electrode and the pressboard barrier significantly affects the streamer propagation and branching. The barrier effect of the pressboard, the distribution of space electric field affected by the pressboard barrier, and the image force of charge on the pressboard surface are all critical factors for affecting the propagation and branching of the streamer. The greatest threat to the pressboard failure is the z-axis streamer or those branches close to the z-axis that is severely inhibited by other streamer branches. It raises the risk of insulation failure caused by the breakdown of the insulating pressboard.