Effect of temperature and time on the dissipation factor of power cable junctions

Systematic measurements of dielectric constant and dielectric absorption of field-assembled power cable junctions aged by temperature cycling over a wide range have been performed. Experimental results on dielectric properties for power cable junctions in the frequency range 10^-4 Hz to 1 Hz are reported. Evidence of decreasing dissipation factor with time for short aging time and increasing dissipation factor after a long aging time is presented. Results show that the measurement of the dissipation factor and the relaxation frequency in the low frequency region is useful way to estimate the degradation of the power cable junctions. The chemical and physical changes which can occur because of the aging of the polymer seem to affect the complex dielectric constant at low frequency