425 / 2022-03-15 21:27:07

Plasma Rejuvenation of Insulation Crack Defects for Cable Accessories

cable accessory,defect repair,plasma,electrical performance,insulation

As an important component for the transition and connection of the cable lines, the cable accessories are the vulnerable spots in the cable lines. Because of its complex structure and prone to scratches and cracks during manual installation on site, the failure of cable accessory accounts for 85.5% of 110 kV cable accidents, which brings hidden dangers to the safe operation of the power system. The replacement of the cable accessory will consume a lot of manpower and material resources, so it is a more reasonable choice to repair the defects caused by the installation in a small area. In recent years, the research on the surface modification of insulating materials by plasma technology has gradually increased. The effect of plasma rejuvenation on the insulation properties of cable accessories was studied by depositing thin films on the cracks. The experimental samples are Silicone Rubber (SIR) and Ethylene-Propylene-Diene Monome (EPDM) insulation taken from cable accessories, with a size of about 50 × 50 mm² and a thickness of about 1 mm. A scratch with a length of about 4 mm was artificially simulated on the surface of the insulating sample. Tetraethyl Orthosilicate (TEOS) and Butyl Methacrylate (BMA) are selected as two different precursors in plasma processing, and the processing time for defect samples is 2 min, 4 min and 6 min, respectively. The resistivity, flashover voltage and breakdown field strength of the insulation samples before and after repair were tested respectively.

The volume resistivity of the SIR insulation samples repaired by plasma with TEOS is significantly improved compared with the samples with cracks. The volume resistivity of the samples repaired for 2 minutes is close to that of the intact samples. The breakdown strength of the samples repaired for 4 minutes is slightly higher than that of the intact samples. The volume resistivity of the EPDM insulation samples repaired by plasma with TEOS is significantly higher than that of the cracked samples, which increases with the increase of repair time, and the breakdown strength also has a certain degree improvement. The rejuvenation effect with BMA is not as good as that with TEOS. After plasma repair with TEOS as the precursor, the electrical properties of SIR and EPDM insulation are improved significantly, and the volume resistivity and breakdown strength are close to perfect insulation.