Effect of bubble flow on partial discharge under non-uniform AC electric fields in FC-72

The focus of this study is on thermal bubbles which limits the application of phase-change cooling technology in high electric fields. In order to investigate the impact of the boil-induced bubble flow on the partial discharge (PD), a PD test chamber is set up which is modified to adjust the intensity of the bubble flow. PD signals and characteristics of the bubble flow are recorded under different heating conditions and electric fields. It is found that thermal bubbles have negligible impact on the PD characteristics under a non-uniform field, but the discharge frequency decreases as the boiling intensity increases. A deviation occurs in the trajectory of bubbles, which makes discharge in bubbles impossible. It is also found that the heat induced fluid affects the density of dielectric liquid and ionization coefficient of the discharge environment, which reduces PD frequency.