Aging state assessment of 110kV XLPE cable based on IRC and AE

To evaluate the aging condition of 110kV XLPE cables accurately, this paper employs the isothermal relaxation current (IRC) method and the activation energy (AE) method, discussing the relationship among the aging factor, the activation energy and the aging condition of cable insulation. The results show that compared with unaged cables, the cables under accelerated thermal aging have 0.348 more on the aging factor and their activation energy is generally lower. Besides, compared with the cables running for 14 years, the cables running for 25 years have 0.327 more on the aging factor, 15.05kJ/mol less on the activation energy and 30.6 years less on the remaining life. All these show that increasing of the internal trap's number, deepening of the internal trap's depth and the disintegration of chemical bonds are major microeconomic performances on cable aging. The differences in batching system and production technology system of cables can change the chemical structure in XLPE molecules. And assessment results are in line with expectations. Microscopically, evaluating the aging condition by IRC and AE has the accuracy and validity, which provides an effective method for the evaluation of XLPE cable's aging condition from electrical and chemical aspects, and guides the maintenance and planning of cables.