To investigate the characteristic parameters of dielectric response phenomena of cross-linked polyethylene（XLPE） cable insulation aging

we experimentally investigated the cable samples by accelerating the aging for water tree. The polarization and depolarization current（PDC） tests were performed on the samples with different aging degree. The experimental data were analyzed. The peak time τ3 of the third branch and dielectric loss factor were extracted as aging characteristic parameters by the theory of It-lnt curves and extended Debye model. The relationship between the characteristic parameters and aging degree was studied. The results show that the current curves are affected by the cable length and cannot directly reflect the actual state of cable insulation. With the prolongation of aging degree

the peak value of the third branch shifts rightwards

and the loss factor curves shift upwards at lower frequencies（0.001～0.5 Hz）. It is considered that the water tree interface continues to expand with the prolongation of aging time. The trap depth is increased and the dielectric loss factor gradually increases during the polarization process. Therefore

the peak time τ3 and dielectric loss factor at lower frequencies can be used for determining the aging extent of the cables.