Insulation Test of the Nitrogen Blanket Transformer under Sudden Temperature Drop

During the transformer operation, it is a common condition that the oil temperature decreases due to sudden rainstorms. Because the nitrogen layer is set to contact the transformer oil in the nitrogen blanket transformer directly, the influence of nitrogen dissolution and precipitation on the insulation characteristics is very important. In this paper, the effect of nitrogen is analyzed. First, the electrical field under the nitrogen bubble effect is simulated. Second, the sudden temperature drop situation is developed based on the reformed transformer. Last, the insulation changes are analyzed by partial discharge data. According to the analysis, the sudden temperature drop won’t influence the transformer operation.