Thermal aging of oil-paper used in power transformers

In this paper, the thermal degradation behavior of the samples mineral oil/craft paper with different content of water was studied. Accelerated thermal aging experiment was performed at the elevated temperature of 140, 150 and 160 centigrade in the oven up to 960 h. The content of CO+CO₂ and 2-furfural dissolved in the transformer oil were detected with gas chromatograph (GC) and high performance liquid chromatograph (HPLC) respectively. The degree of paper polymerization was measured according to GB01548-89 (Chinese standard). The experimental results show, along with thermal aging time and temperature, the content of CO+CO₂ and 2-furfural in the oil was increased, while the degree of paper polymerization was decreased, and the aging of the samples becomes more serious when the water content in the oil was increased. Above experimental results can be applied in evaluating the residual lifetime of power transformers