The characteristics of insulation resistance of transformers

It has been demonstrated that a double-layered dielectric model could approximately describe and explain the absorption phenomena of the oil-paper insulation of a transformer after data measured with a Megger-meter was fitted to curves. Some insulation is shown to have high insulation resistance but low absorption ratio (R/sub 60"//R/sub 15"/) owing to its long absorption process. In this case, the polarization index (R/sub 10'//R/sub 1'/) is recommended as a better criterion.<>