ポリプロピレン系新規絶縁材料の電力ケーブルへの適用(1)

Abstract

Crosslinked polyethylene(XLPE) has been widely adopted as insulating material for high voltage power cables up to 500kV. Further improvement of electrical and thermal properties on insulating material is required in order to increase cable operation efficiency. Therefore, the development of novel insulating material possessing high thermal properties will be necessary. Recent progress of catalysis technology contributes to obtain new polymeric materials which may be applied to electrical insulation. The authors investigated the basic properties of newly developed stereoregular syndiotactic polypropylene(s-PP) which is synthesized with homogeneous metallocene catalyst. Though recycling of crosslinked polymers such as conventionally used XLPE may be difficult because of its poor heat deformation, the s-PP which is not crosslinked must be suitable for recycle. A series of experiments on its physical and electrical properties gave following results.(1) S-PP has sufficient flexibility compared with isotactic polypropylene (i-PP).(2) Both AC and Lightning Impulse breakdown strength of s-PP in spite of no cross-linking are superior to those of XLPE in the range of temperature 25°C to 90°C.(3) Degradation by copper of s-PP is less than i-PP.(4) S-PP/VLDPE blend shows sufficient brittleness temperature for use.These results suggested that s-PP would be available as insulating material for power cable at higher temperature operation.