Influence of accelerated water tree aging on insulation of XLPE cables

The influence of water tree aging process on physical, chemical and dielectric properties of insulating material in 10kV ross-linked polyethylene (XLPE) cables was studied. It was found that with the increase of aging process, the chemical structure of outer insulating layer was changed while the crystallinity and density were decreased. In addition, the temperature difference of TG loss between inner layer and outer layer was enhanced, and the melting temperature was lowered. A new dielectric loss peak was found in the low frequency range with the water tree aging process. It is suggested that the aging process take place from outer insulating layer, and by the combination of electrical force and mechanical force, The experimental results show that microstructure defects are introduced in the insulating material. A physical and chemical process is suggested to clarify the influence of water tree aging process on the insulation of XLPE cables. Cross-linked polyethylene (XLPE) has been extensively used as an electrical insulation for medium and high voltage power cables because of its excellent physical, chemical and electrical properties. However, it is well known that degradation under service condition may change its chemical composition and physical morphology. The influence of water tree aging process on physical, chemical and dielectric properties of insulating material in 10kV XLPE cables was studied in this paper. It was found that with the increase of aging process, the chemical structure of outer insulating layer was changed while the crystallinity and density were decreased. In addition, the temperature difference of TG loss between inner layer and outer layer was enhanced, and the melting temperature was lowered. A new dielectric loss peak was found in the low frequency range with the water tree aging process. It was suggested that the aging process take place from outer insulating layer, and by the combination of electrical force and mechanical force, microstructure defects was introduced in the insulating material, which can be shown in the experimental results. A physical and chemical process was suggested to clarify the influence of water tree aging process on the insulation of XLPE cables.