POLYMER SP INSULATOR

A polymer SP insulator comprising an FRP core 1 , a sheath 2 having a plurality of sheds 6 provided on outer periphery of FRP core 1 , and metal-end-fittings 3, 4 crimped to upper and lower ends of FRP core 1 , in which a flat plate 11 for adjusting the overall length dimension after crimping the metal-end-fitting 4 is assembled in the inner bottom of the metal-end-fitting 4 , and the overall length dimension is uniformly adjusted by the thickness of the flat plate 11 . Further, a stress concentration portion such as cross groove is provided in the outer bottom of the lower Metal-end-fitting 4 , and prevents instability by deformation of flange 8 when crimping the Metal-end-fitting 4 . In this configuration, in spite of the structure of crimping metal-end-fittings at upper and lower ends of the FRP core, the overall length tolerance, parallelism and eccentricity can be suppressed. In order to assure the flashover distance economically, preferably, the diameter of sheds of at least highest position and lowest position is larger than the diameter of intermediate shed.