Study on the Generation Characteristics Of Oil-Paper Insulation Bubble Inside High-Voltage Bushing

During the operation of the transformer bushing, due to the long-term superposition of the electric field and conductor heating, many bubbles will precipitate on the surface of the oil-immersed cardboard inside the bushing. When the bubbles migrate to the strong electric field inside the casing, it will cause partial discharge. Therefore, the initial temperature of bubbles over the oil-paper was defined based on liquid physical analysis in this paper. The test platform for bubble observation inside the bushing oil-paper insulation was established, and prepared samples with different moisture content. The rapid heating method was used to study the law of bubble generation, and the law of the initial temperature change of bubble generation was obtained. The results showed that the faster the temperature rise, the lower the bubble formation starting temperature. When the temperature rise rate increases by 4°C / min, the bubble initial temperature drops by about 20 □; While when the temperature rise rate is slower, the bubble generation initial temperature is more dispersive but the results are normally distributed. And as the water content increases, the initial temperature of bubble generation reduced. When the moisture content increased from 2.7% to 6.8%, the bubble initial temperature dropped by 44 □.