Photoelastic measurements of mechanical stresses induced in XLPE during electrical aging

The mechanical response of cross-linked polyethylene (XLPE) to a cyclic stress induced by oscillating electrostatic forces could be an important factor with regard to long-term degradation. To demonstrate the presence of mechanical stresses induced by high electric fields in XLPE, the authors performed photoelastic measurements. These measurements were conducted on tip-plane-geometry XLPE samples to estimate the distribution of the internal mechanical stress resulting from the application of a 5-kV, 1-kHz AC voltage for up to 3000 h. The results obtained show a time-dependent photoelastic pattern suggesting some structural change in the area located at the tip of the electrode.<
>