Test procedures and lifetime data analysis for electro-thermal endurance characterisation of EPR-insulated cables

The endurance of EPR-insulated cables is investigated by means of laboratory tests on cable models aged by thermal and electrical stresses, single or combined. The thermal and multi-stress life lines obtained by tests carried out according to a factorial procedure are reported. A significant contribution to plot the life lines is provided by the combined analysis method, which allows the electro-thermal life surface to be drawn. Indices for electrical, thermal and combined-stress endurance characterisation can thereby be supplied. The test results give high values of electrical, thermal and multi-stress endurance coefficients for the tested cables. This confirms the good electrical and thermal behaviour of EPR-insulated cables. Finally, a comparison of the results with a life model, able to provide life estimations, is made, obtaining good data fitting