How do glass fiber and epoxy resin enhance the mechanical strength of transformer windings? ​

In the power system, epoxy resin three-phase dry-type transformers play a vital role, and the quality of their performance is directly related to the stability and reliability of power supply. As one of the core components of the transformer, the mechanical strength of the winding has a profound impact on the overall performance of the transformer. The close combination of glass fiber and epoxy resin is like building a solid armor for the winding, giving it excellent mechanical strength, and becoming a key factor in ensuring the stable operation of the transformer.
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From the perspective of material properties, glass fiber has the significant advantages of high strength and low density. Glass fiber is made of glass wire drawing, and its internal structure presents an orderly arranged fiber shape. This microstructure gives it extremely high tensile strength. When glass fiber is introduced into the transformer winding, it can play the role of reinforcing the skeleton like steel bars in concrete. Epoxy resin is a polymer material with good bonding and curing properties. In a liquid state, epoxy resin can fully infiltrate the glass fiber and the copper wire part of the winding, and then transform into a hard and tough solid through a curing reaction. This cured epoxy resin not only firmly bonds the glass fiber and copper wire together, but also fills the gaps between them to form a uniform and dense overall structure. ​

During the winding manufacturing process, the combination of glass fiber and epoxy resin is very delicate. First, the glass fiber is wound on the already wound copper wire winding in a specific way. The winding angle, number of layers and distribution density of the glass fiber are carefully designed to ensure that the winding can be provided with the best mechanical support in all directions. For example, in some large transformer windings with extremely high mechanical strength requirements, the glass fiber will be wound in multiple layers, which can effectively enhance the deformation resistance of the winding in different force directions. After the glass fiber is wound, the strictly pre-treated epoxy resin is poured onto the winding in a vacuum environment. The role of the vacuum environment is to eliminate bubbles in the epoxy resin and the air between the winding and the glass fiber, avoid the formation of defects such as air gaps during the curing process, and ensure that the epoxy resin can achieve perfect and tight bonding with the glass fiber and copper wire. During the curing process of epoxy resin, parameters such as temperature and time need to be precisely controlled to ensure that the epoxy resin can be fully cured and achieve the best performance state. ​

The excellent mechanical strength of the winding given by the close combination of glass fiber and epoxy resin plays an extremely critical role in the operation of the transformer. When the transformer encounters a short-circuit current shock, a strong electric force will be generated. According to Ampere's law, the electric force generated by the short-circuit current in the winding is proportional to the square of the current, and its value may be as high as hundreds or even thousands of times that of normal operation. Such a strong electric force will produce huge pressure and tension on the winding. If the mechanical strength of the winding is insufficient, it is easy to deform, twist or even break. Serious damage such as fracture. The winding reinforced with glass fiber and epoxy resin can effectively resist this strong electric force impact with its solid structure. The glass fiber bears most of the tensile stress, while the epoxy resin, through its good adhesion and toughness, tightly bonds the glass fiber and the copper wire together to resist the action of the electric force, thereby ensuring that the winding can maintain the integrity of the structure during a short-circuit fault, providing a solid guarantee for the transformer to quickly resume normal operation after the fault is cleared.​

In addition, in the daily operation of the transformer, due to the frequent changes in load and fluctuations in ambient temperature, the winding will be constantly affected by thermal expansion and contraction. Under this thermal cycle state for a long time, ordinary windings are prone to mechanical performance degradation due to material fatigue. The windings combined with glass fiber and epoxy resin can effectively alleviate the internal stress caused by thermal expansion and contraction because the thermal expansion coefficient of glass fiber is close to that of copper wire. At the same time, the toughness of epoxy resin can also absorb and disperse these stresses, reduce the occurrence of material fatigue, further extend the service life of the winding, and improve the stability and reliability of transformer operation. ​

In epoxy resin three-phase dry-type transformers, the close combination of glass fiber and epoxy resin is the core technical means to improve the mechanical strength of the winding. Through the carefully designed material selection, sophisticated manufacturing process and the excellent performance brought by the synergy of the two, a solid guarantee is provided for the stable and reliable operation of the transformer in a complex power operation environment. With the continuous development of power technology and the increasing requirements for transformer performance, the technology of combining glass fiber and epoxy resin will continue to innovate and improve, and continue to contribute to the efficient operation of the power system. ​