The study on the relationship of frequency domain spectroscopy of oil-paper insulation with degree of polymerization and tensile strength

Frequency domain spectroscopy (FDS) has been widely applied to the detection and assessment of oil-paper insulation condition with the prominent advantages of non-destructive and precise evaluation. The degree of polymerization (DP) and tensile strength (TS) are taken as the direct representation of the mechanical performance of insulation paper/pressboard. This paper established aging experiment and FDS test platform and measured the dielectric spectroscopy of oil-immersed pressboard as well as the DP and TS. With the help of mathematical analysis, an exponential quantitative relation between dielectric loss and DP as well as the TS is put forward. And when the frequency reaches 0.001Hz, the result proves to be the best fit. Combined with the quantitative relationship achieved in this paper, the DP and TS can be obtained without the outage of transformer, thus realizing the accurate diagnosis and evaluation of the aging condition of transformer insulation system.