Experimental Investigation on the Bubbling Inception Temperature in Kraft Paper Impregnated with Mineral Oil and Synthetic Ester

This paper aims to comprehensively investigate the Bubbling Inception Temperature (BIT) of two insulating fluids. The reason why the BIT is important is that it is a critical parameter to estimate the bubble formation within power transformers during overload conditions. Indeed, with the ever-increasing demand of electricity, transformer overload could be a source of bubble unfolding. The study specifically focuses on Kraft paper impregnated with a mineral oil and a synthetic ester. A specially-designed experimental setup that helps controlling key parameters such as temperature and moisture content, is employed to investigate the BIT. The investigations reveal that the BIT of synthetic ester-impregnated paper is higher than that of mineral oil-impregnated paper. The present study provides valuable insights to prevent bubble formation and enhance the overall reliability of power transformers.