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line post insulator
Polymer Line Post Insulator
Author:composite insulators   time:2/24/2010 5:28:41 PM  read:2935times

Structure
Mainly consist of an FRP Core, a Silicone Rubber Housing and Metal End Fittings. In many cases, polymer line post insulators are mounted to a supporting structure (wooden or steel pole, tower, etc.) through an additional base. The FRP Core is the internal insulating member designed to ensure the mechanical characteristics. The Silicone Rubber Housing is the external insulation, which provides the necessary leakage distance and protects the core from the weather. Metal End Fittings are assembled to the both ends of the core for the purpose of transmitting mechanical loads to the core. A base adapts the end fitting for mounting to a supporting structure.
Materials
Housing (Weathershed & Sheath) is 100% silicone rubber before adding fillers. The sheath and the weathersheds are formed at the same time from the same rubber mass by compression molding. The best mixture of base polymer, fillers, and additive agents achieves an effective contamination, weather resistant, anti-tracking, and anti-erosion performance.
Core is high quality pultruded FRP (Fiber Reinforced Plastic) rod. The rod is made with excellent alignment and distribution of fibers within an Epoxy resin.
End Fittings are ductile iron in accordance with ASTM A536. All surfaces of the end fittings to be exposed to environmental conditions are galvanized in accordance with ASTM A153.
Failure Modes
Two potential failure modes of a polymer LP insulator are mechanical failure and sealing failure. A sealing failure allows the invasion of moisture inside the polymer insulator. Moisture inside the insulator leads to internal electrical puncture. A mechanical failure would be the result of a post that has been overloaded to the point that a component has fractured. It is important that both mechanical failure and sealing failure be considered as fatal failure modes for polymer insulators when choosing appropriate loading limits.
A polymer LP is a unique application compared with the other conventional insulators. Unlike porcelain, glass, and even polymer suspension insulators, only a polymer post is used in service while visibly deformed by an applied load. When insulators other than polymer posts are deformed due to their service load, generally those insulators have failed. The deformation of a polymer post can cause the seal to fail at a lower cantilever load than the ultimate mechanical failing load. Consequently, the failing load of the seal and the mechanical failing load do not necessarily correspond in the case of polymer posts.
line post insulator
 
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