Influence of Moisture and Temperature on Relaxation Function of Oil-Paper Insulation in Traction Transformers

Relaxation function can well reflect the microscopic polarization mechanism of dielectric. In order to analyze the influence of moisture and temperature on relaxation function of oil-paper insulation, building a physical model of the oil-paper insulation system containing moisture and obtaining the expression of relaxation function. Setting up a testing device for the oil paper insulation dielectric spectroscopy in the laboratory, the parameter values of relaxation function expression were obtained according to test result by Fourier inverse transformation. The results show that the relaxation function containing three relaxation factors are more suited for the relaxation of oil-paper insulation containing moisture content and microscopic polarization mechanism, moisture and temperature have a significant effect on relaxation function.