In this paper, an analysis of degradation processes influence on the increase of polar products and charge carriers concentration, and the values and forms of absorption/resorption currents curves are presented. Based on their values, the polarization index and conductivity factor are determined and lifetime duration curves are drawn. Finally, it is shown that the obtained lifetime values are very close to the ones determined using the mass loss method, and the possibility of the absorption/resorption (A/R) currents use to estimate lifetime values for composite insulations of high power electrical machines is also discussed.

Keywords: Insulation systems, Absorption/resorption currents, Lifetime