Deterioration diagnosis technique of housing rubber for composite hollow insulators

A field test and an accelerated aging test with composite hollow insulators were conducted to evaluate long-term reliability and predict longevity. An 84 kV gas circuit breaker with composite hollow insulators was subjected to field test at Chita substation, Chubu Electric Power Company in 1996. This field test is scheduled for completion in 2004. An accelerated aging test with a small composite hollow insulators was conducted for up to 5,000 hours with the conditions specified in IEC 61109 Annex-C. Appearances, hydrophobicity, and surface deterioration were periodically analyzed. It was found that green algae deposited on the surface of some portions of the housing rubber of field test specimens, but was not associated with significant deterioration. Erosion developed on the housing of the specimens subjected to the accelerated aging test for 4,000 hours, and 5,000 hours. The number of eroded traces increased with time. Slight deterioration was found even on the areas without erosion analyzed by Fourier Transform Infra-red Ray spectroscopy.