Exploring the electrical properties of pressboard and kraft paper insulation in power transformers: A dielectric spectroscopy and principal component analysis approach

We explored the aging effects on insulating materials used in power transformers through dielectric spectroscopy. Frequency domain spectroscopy (FDS) was conducted for both aged and new Kraft paper and pressboard samples to determine their dielectric properties across a temperature range of 40–100 ℃ for pressboard and 40–70 ℃ for Kraft paper. Principal component analysis (PCA) was employed to classify the data, identify key factors contributing to variance, and elucidate the relationships between different parameters. The analysis revealed positive correlations between conductivity and frequency, as well as between permittivity and tan delta, with distinct differences in behavior observed between aged and new samples at lower frequencies. Additionally, the impact of temperature was evident, with increased temperature leading to an upward shift in dielectric behavior. At lower temperatures, aging had a reduced effect on the materials' properties. These findings provide significant insights into the dielectric behavior and aging mechanisms of insulation materials in power transformers.