In order to investigate the inhibition effect and its mechanism of prior rejuvenation for water trees in XLPE cables in service

the prior rejuvenation cable samples were prepared by injecting siloxane liquid into the core of new cables with a pressure. New cable samples and the prior rejuvenation cable samples were subjected to accelerated aging experiment using the water-needle electrical method. By optical microscope

the water trees in the cable samples were observed and the lengths of water trees were measured at different aging times. Meanwhile

molecular structures and microstructure of the water tree areas in XLPE cable samples were observed and analyzed by infrared spectrometer（IR）

scanning electron microscope（SEM） and energy disperse spectroscopy（EDS）. The results indicate that the average length of water trees in the untreated cable samples is 0.4 times longer than that in the prior rejuvenating cable samples after aged 4 weeks. By SEM and EDS

few micro pores but a large amount of white particles comprised of silicon were observed in the water tree area of the prior rejuvenation cable samples. It is proposed that the rejuvenation liquid was able to diffuse into the insulation; it reacted with water molecule during the accelerated aging experiment and generated organic particles that filled micro pores in water tree. Therefore

it can inhibit water tree growth in XLPE cables.