Study on Improving Interface Performance of HVDC Composite Insulators by Plasma Etching

High-voltage direct-current composite insulators are faced with various challenges during operation, such as creeping discharge, umbrella skirt damage, abnormal heating and insulator breakage. Among them, the aging of the interface between the core rod and the sheath is one of the important causes of composite insulator failure. In order to improve the electrical resistance of the composite insulator interface, this study uses plasma etching to modify the surface of the glass-fiber-reinforced epoxy resin plastic to prepare the high-voltage direct-current composite insulator core rod–sheath samples. By analyzing the surface morphology of the epoxy resin, static contact angle and surface charge transfer characteristics, the control mechanism of the plasma etching treatment on the interface bonding performance and leakage current of composite insulator core rod–sheath samples were studied. The results show that proper etching time treatment can improve the trap energy level distribution and microstructure of epoxy resin and increase the discharge voltage along the surface; chemical bonding plasma etching can improve the interfacial bonding performance of core rod–sheath samples sheaths, reduce the leakage current of composite insulator core rod–sheath samples sheath specimens and improve their interfacial performance.