An improved method of detection and concentration of methanol in oil-paper insulation

This paper presents an improved method for detecting methanol and the concentration of methanol in transformer oil-paper. Acetonitrile is used as an extractant, and methanol is detected by gas chromatography-mass spectrometry. Experiments show a linear correlation coefficient of this method that reaches 0.99 and the minimum detected concentration of methanol in transformer oil can be as low as 5.57 μg/L. In order to investigate the relationship between the methanol concentration and the degree of aging of insulating paper, an oil-paper insulation simulation system is designed. The experiment shows that there is a linear relationship between the logarithm of methanol concentration and the degree of polymerization, the linear correlation coefficient is greater than 0.94. An actual oil sample from a transformer is used to show that the method can be used to further study the methanol concentration.