Satoshi Kobayashi , Yutaka Matsuzaki , Yoshihiro Arashitani , Ryuzo Kimata
Furukawa Electric's composite insulators are characterized by a hermetically sealed structure made by integral molding with a silicone rubber sheath that covers up to the end fittings. Exposure tests on full-size insulators were carried out in Okinawa at 77 kV over a 5-year period to evaluate them under the usage conditions prevailing in Japan. No deterioration was observed, nor was any deterioration observed in accelerated aging tests carried out on full-size insulators in accordance with IEC 61109 Annex C, demonstrating ample reliability. Service life of the composite insulators was estimated by charged exposure tests and accelerated aging tests with leakage current as the parameter. A figure of not less than 34 years was arrived at as the period within which slight deterioration would occur under the severe sea-salt contamination occurring in Okinawa, thereby confirming a sufficiently long period of resistance.