Satoshi Kobayashi, Yutaka Matsuzaki, Hiroshi Masuya, Yoshihiro Arashitani, Ryuzo Kimata
The United States is leading a world-wide trend toward replacing ceramic and glass insulators with composite insulators that are lighter in weight, as well as being superior in pollution withstand voltage characteristics and resistance to impact (to counter vandalism). In the early 1990s, Furukawa Electric developed composite insulators for use as 66/77-kV inter-phase spacers, and subsequently has extended applications to include 275-kV inter-phase spacer insulators and 154-kV and 66/77-kV class transmission line suspension insulators. The IEC, an international standards organization, has tested this kind of composite insulators for electrical and mechanical performance and has confirmed their reliability, but the use of organic material as the insulating material has aroused reservations about long-term aging. Accordingly work has been going forward on outdoor long-term loading cycle exposure tests and indoor accelerated aging tests.