Identification of dipolar relaxations in dielectric spectra of mid-voltage cross-linked polyethylene cables

A relaxational analysis using Thermally Stimulated Depolarization Currents (TSDC) can yield a lot of information about medium voltage XLPE cables. Nevertheless, it may be difficult to find the cause of a given relaxation because dipolar and space charge relaxations need large electric fields to behave differently. Alternatively, we have used correlation between TSDC and Isothermal Depolarization Currents (IDC) data to determine the cause of a characteristic peak found in the spectra of cable samples. The analysis must assume that the relaxation is dipolar to reach a good fit of IDC data. Finally, the physical mechanism of the relaxation is discussed.