Recent Advances in the Application of Fiber-Reinforced Polymers (FRP) in the Insulation Industry

Fiber-Reinforced Polymers (FRP)  is a new composite material with resin as matrix and fiber as reinforcement. It has excellent electrical insulation performance, light weight, high strength, corrosion resistance and low water absorption. It has become the core material to replace traditional porcelain and epoxy insulation parts in power insulation industry, and is widely used in power transmission and transformation, power distribution, electrical equipment and other fields. The traditional high-voltage insulation materials are mainly ceramic and epoxy resin castings. Porcelain insulators have large self-weight, weak impact resistance, easy pollution flashover and ice flashover, and high damage rate during transportation and installation. Ordinary epoxy resin is brittle and has insufficient weather resistance, and it is easy to age and crack in long-term outdoor environment. FRP solves the short board of traditional insulation materials by fiber bearing load and resin wrapping insulation. Commonly used FRP includes glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP). In the field of insulation, GFRP is the most widely used, and carbon fiber is conductive, so it is rarely directly used as main insulation, and is mostly used for composite core load-bearing components. In the field of high voltage transmission, the most typical application of FRP is composite insulator mandrel. The mandrel is made of glass fiber impregnated epoxy resin by pultrusion, which is used as the internal bearing insulation body of the insulator and covered with silicone rubber umbrella skirt. Compared with porcelain insulators, the mass of FRP mandrel is only 1/5 of that of porcelain, and it has high tensile strength and is not easy to break. The surface of the material is hydrophobic, and the lightning voltage of pollution is higher. In coastal and industrial areas where smog, salt fog and industrial dust are serious, the trip accident of the line is greatly reduced. At present, FRP composite insulators are widely used in EHV and EHV transmission lines in China, which is the key component of safe operation of power grid. In terms of insulation structural parts of electrical equipment, FRP can be used to make insulation partitions of switchgear, bus bushings, transformer supports, isolating switch operating rods and so on. FRP sheets and profiles formed by pultrusion and molding have high insulation resistance and low dielectric loss, and meet the electrical indexes such as power frequency withstand voltage and partial discharge. At the same time, FRP has high mechanical strength and can be directly used as a load-bearing insulation support for equipment, which simplifies the structure of equipment and reduces the volume of switchgear. In outdoor power distribution equipment, FRP is resistant to acid and alkali corrosion and will not rust like metal parts, and it will work stably for a long time in wet and rainy environment. In the field of rail transit and new energy, the demand for FRP insulation parts is growing rapidly. FRP insulating members are used for traction converter and cable joint support of high-speed rail, so the light weight of materials can reduce the load of the whole vehicle; The bus insulation bracket and photovoltaic inverter insulation base in the wind power tower can adapt to the temperature difference in the field and avoid insulation aging failure by using the characteristics of FRP resistance to high and low temperatures and ultraviolet rays. There are still some limitations in FRP insulation materials. The matrix resin will gradually degrade at high temperature, and the insulation performance will decrease in long-term high temperature environment; Under the long-term irradiation of strong ultraviolet rays, the surface resin will age and powder, so outdoor products will generally add protective coatings. In addition, FRP materials are refractory composite materials, and it is difficult to recycle waste products, which is the direction that the industry needs to overcome. Generally speaking, FRP breaks the contradiction between strength, weight and pollution resistance of traditional insulating materials. With the development of power system towards UHV and new energy, the formula and molding process of FRP insulation products are continuously optimized, and its application scope in the field of power insulation will continue to expand. It is the core material for the lightweight and high-reliability development of electrical insulation industry.