Framing With Composite Insulators
Framing for overhead transmission lines has conventionally relied on designs based on pole-top cross-arms or davit arms. More recently, however, composite line post insulators, which are more flexible and handle dynamic mechanical loads better than porcelain, are being used for this framing function, also allowing reduced structure costs and right-of-way widths. This presentation explains how line post insulator selection should consider combined in-service vertical and longitudinal cantilever loads as well as transverse compression and tension loads from wind and line angle. Combined Load Curves then correlate combined OHL design loads to a 50% value of the insulator’s specified cantilever load to prevent damage.