Bubble Formation and Motion Characteristics in the Transformer Oil-Paper Insulation System Under the Extremely Inhomogeneous Electric Field

Under the combined effect of the electric and temperature fields, bubbles will be formed on the transformer oil-paper insulation system, which will seriously endanger the insulation strength. However, the current study usually divided the formation and motion of bubbles into independent parts, lacking research on the whole process of bubble evolution. This article experimentally investigated and theoretically analyzed the whole process of the formation, deformation, and motion of bubbles in the oil-paper insulation system and explored the influence of the extremely inhomogeneous electric field (EIEF) on bubbles evolution. The results show that with the enhancement of the electric field, the bubble inception temperature (BIT) and bubble size increase significantly, while the number of bubbles decreases. Under the stretching and pushing effect of the electric field force, the bubbles will deform and move toward the low electric field region. In addition, this article studies the influence of bubbles on the transformer electric field distribution through multiphysical field simulation.