Interfacial phenomena in composite hollow insulator

Long term reliability has been an issue in the practical use of composite hollow insulators for many years and much basic research and numerous field tests have been conducted. However, very little research on the reliability of interfaces between the FRP core and silicone rubber housing of composite hollow insulators has been reported in comparison with extensive research on pollution proofing on the surface. Although a six- or seven-year field test on composite hollow insulators demonstrated that they satisfied practical requirements through electrical and mechanical tests, decreased interfacial adhesion strength was observed. This paper describes the results obtained from an accelerated deterioration test with samples simulating the interface between the FRP core and silicone rubber housing. They confirmed that the expected lifetime of interfacial adhesion of the composite hollow insulator exceeded 25 years. The decline in dielectric performance due to the ingress of rain or moisture into the interface was assumed to be a consequence of degraded interfacial adhesion. However, the thermal and electric simulations revealed that the resistance of the interface retained a sufficient level even with the ingress of water or moisture. Therefore, the composite hollow insulator could maintain its required dielectric strength for much more than 25 years.