An insight into thermal life testing and characterization of EPR-insulated cables

Conventional and analytical procedures for thermal endurance characterization of insulating materials, described in IEC Standards, are applied to EPR-insulated cable models. Close results are obtained by the two procedures, provided that the diagnostic properties, the end points and the test temperatures are carefully chosen. Moreover, the thermal endurance indices do not vary using either the Arrhenius model, assumed by IEC 216, or the Eyring model. However, modifications of the life models are required in order to take into account the compensation effect, which has been observed for the diagnostic properties and the end points considered for thermal endurance characterization. The comparison of the values of the thermal endurance indices obtained for EPR-insulated cable models with those derived in the past for XLPE cable models shows that the tested EPR has slightly better thermal endurance characteristics.