An Attempt at Predicting Cable Breakdown Voltage from Dielectric Measurements

For twenty slightly different ethylene propylene (EP) insulated model cables, an 0.8 correlation coefficient was found between dielectric strength after aging and both tan6 after aging and the change with aging of insulation resistance constant (IRK). Aging consisted of 3.5 months immersion of 60 cable specimens in 90°C water with 2 MV/m 60 Hz electrical stress continuously applied. However, tan6 and IRK measurements made regularly on EP and crosslinked polyethylene (XLPE) insulated 15 kV cables, similarly aged at 2 MV/m in 90°C water, did not predict how long a cable would withstand the aging stresses.