Composite insulators are a special type of insulation control that can play an important role in overhead transmission lines. Composite insulators are also known as synthetic insulators, non-porcelain insulators, polymer insulators, rubber insulators, etc. The main structure is generally composed of an umbrella skirt, FRP core rod, and end fittings. The umbrella skirt is generally made of organic synthetic materials such as ethylene-propylene rubber, high temperature vulcanized silicone rubber, etc.; the FRP core rod is generally made of glass fiber as reinforcing material and oxidized resin as base material; the end fittings are usually carbon steel or carbon structural steel coated with hot zinc aluminum.
Composite insulators consist of at least two insulating materials; one of them for the task of providing electrical properties and the other for the task of providing mechanical properties.
For high-voltage circuit breakers, composite insulators are increasingly used instead of ceramic insulators. Indeed, composite insulators are lightweight, resilient, do not explode under shock, have good seismic properties, and withstand contamination well.
Flang end Fitting
Composite insulators used in HV circuit breakers generally comprise composite tubes, metal flanges, and elastomeric silicon sheds. The composite is made of glass fibers and epoxy resin. The sheds are made out of silicone rubber.
The core of a composite insulator consists of a composite bar, which consists of a matrix and reinforcing fibers. The substrate is made of epoxy resin and alkali-free glass reinforcing fibers and consists of glass fibers running parallel and isotropic throughout the rod. The core composite quadrilateral depends on the design of the insulator and the tensile load it has to withstand and is made in different diameters.
However, the range of figures mentioned by different manufacturers can be set between 14 mm and 70 mm. The fibers in the composite insulator core have two main tasks, one being the main insulating member and the other being the task of carrying the mechanical load. The composite core construction is accomplished by a process of extrusion molding. In general, pultrusion is a process used to produce continuous composite profiles (e.g., rods, tubes).
In this process, glass fibers are fed from the fiber feeder to the resin impregnation and enter the die after passing through the preform. In the heat-treated form, impregnation and curing of the resin occur and the contours form the cross-sectional shape of the mold. The advantages of assembled parts include lighter weight, lower maintenance costs, and greater corrosion resistance; the most important advantage of strength (rigidity relative to weight) is relatively high due to the high percentage of fibers and their continuity in the structure of these components. It should be noted that there are other methods used to produce composite cores, including manual warping and filament winding techniques, but due to the highest strength obtained and the highest mechanical properties of the pultrusion process, this method of pultrusion molding is the preferred alternative method.
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