Research on Damp Aging Evolution of Cable Joints based on PDC method

Damp has been identified as one of the most harmful factors of insulation of cable joints. In order to study the evolution pattern of electrical characteristics of cable joints with dampness, time and frequency domain parameters of 10kV XLPE cable joints were measured by PDC (polarized depolarized current) method. Results show that the multiple interfaces in the cable joints have little effect on the number of Debye relaxation branches. The Debye third-order exponential model can well reflect the internal polarization / depolarization process of the cable. Varieties of characteristic parameters such as time constant, electrical conductivity and aging factor A were extracted and analyzed based on Debye model. The affecting factors and sensitivity of each characteristic parameter are summarized. It is found that the second branch time constant has a large mean interval and strong resolution on each aging stage. The third branch time constant has strict monotonicity and high accuracy, but tends to be saturated with the increase of moisture time.