The insulation system of low-voltage circuit breakers includes the circuit breaker base and cover, which are made of SMC and BMC insulation materials with good insulation, flame retardancy, and mechanical strength. This not only improves the breaking capacity of the circuit breaker, but also ensures its mechanical and electrical life. SMC and BMC insulation materials are made by using unsaturated polyvinyl chloride resin as the adhesive, glass fiber as the reinforcement material, and adding some fillers to make unsaturated polyvinyl chloride glass fiber reinforced molding plastics.
SMC and BMC low-voltage circuit breaker insulation components have superior electrical insulation properties. Good flame retardancy, arc resistance and leakage resistance, high mechanical strength, excellent performance such as good moisture and moisture resistance, corrosion resistance, and reliable dimensional stability. During the SMC/BMC molding process, not only the appearance of the material has changed, but also the structure and properties of the material have undergone fundamental changes. However, the reinforcing materials remain largely unchanged, with resin being the main source of change. Therefore, it can be said that the molding process is to use the characteristics of each stage in the resin curing reaction to achieve the process of product molding. When the molded plastic is added to a mold that has been heated to a certain temperature, the resin in the mold is heated and melted into a sticky state with a certain fluidity. Under pressure, it can wrap the fibers and flow together until it fills all parts of the mold cavity, which is called the "sticky flow stage" of the resin. Continuing to increase the temperature, the resin undergoes chemical cross-linking when heated, resulting in an increase in molecular weight and branch chain density. When a network structure appears in the molecular cross-linking, the fluidity quickly decreases until it exhibits a certain degree of elasticity. Continue heating and the resin crosslinking reaction continues. The cross-linking density further increases, and then the fluidity is lost. The resin changes from gel state to insoluble and unmelted body structure, reaching the "hard solid stage". The above stages in the molding process occur continuously without obvious boundaries, and the entire reaction is irreversible. Therefore, the molding pressure required by the compression molding process is higher than that of other process methods, and it is used for high-pressure molding. Therefore, it is required that the molds formed by compression molding have high strength, high precision, and high temperature resistance. The molding method has high production efficiency, difficult to determine product dimensions, smooth surface, and is suitable for large-scale production. Products with complex structures can be formed in one go, and the appearance and size of the products have good repeatability.
The main disadvantage of SMC and BMC molding technology in producing circuit breaker insulation parts is the complexity of mold design and manufacturing, high initial investment, and susceptibility to equipment limitations. Therefore, SMC and DMC materials are ideal insulation materials for manufacturing circuit breaker insulation components in large-scale production.
Ningbo Huayuan provides the molding and processing of SMC and BMC circuit breaker insulation parts. As one of the pioneers of resin based composite materials in China, Huayuan has accompanied the vigorous development of China's composite materials industry, from scratch to brilliance. The resin based composite materials, SMC materials, BMC materials, outdoor power communication boxes, power electrical insulation components, rail transit, high-speed railway special equipment and other products developed and produced have replaced traditional materials and products such as metals, cement, plastics, and wood in more and more fields, and are widely used in multiple industries and fields such as power, communication, rail transit, high-speed railways, automobiles, and municipal engineering. Huayuan provides core structural components and insulators such as medium and low voltage air circuit breakers, vacuum circuit breakers, and contactors in the power and electrical industry. It is an important partner and supplier of the Fortune 500 circuit breaker manufacturers worldwide.
