The Production Secret of Amorphous Alloy Transformers

Materials required for the production of amorphous alloy transformers Amorphous alloy strips Amorphous alloy strips are the core materials for manufacturing amorphous alloy transformer cores, and their performance directly determines the energy-saving effect of The Transformer. Amorphous alloys are a metal material prepared by rapid solidification technology. The atoms are arranged in disorder, there are no grain boundaries, high magnetic permeability and low coercivity, and excellent soft magnetic properties. The common components of amorphous alloys are iron (Fe), boron (B), silicon (Si), cobalt (Co), etc. The ratio of different elements will affect the magnetic properties, mechanical properties and corrosion resistance of amorphous alloys. For example, increasing the iron content can increase the saturation magnetic induction intensity; the addition of boron and silicon elements can help reduce the magnetic crystal anisotropy of the material and improve the magnetic properties. Amorphous alloy strips are usually very thin, generally around 20 to 30 microns, and the width is determined according to production requirements, usually 100 to 200 mm. Insulating materials Insulating materials play a vital role in non-ferromagnetic alloy transformers. They can isolate conductive components and prevent leakage current and short circuits. Commonly used insulating materials include insulating cardboard, insulating varnish, polyester film, etc. Insulating cardboard is mainly used to make winding skeletons, interlayer insulation and interphase insulation of transformers, and has good mechanical strength and insulation properties; insulating varnish is used to impregnate windings, which can improve the electrical insulation, moisture resistance and heat dissipation performance of windings; polyester film has high electrical strength and heat resistance, and is often used in conjunction with insulating cardboard to enhance the insulation effect. In addition, in some high-end non-ferromagnetic alloy transformers, high-performance insulating materials such as polyimide films are also used to meet higher insulation requirements and high temperature resistance. Conductive materials: Conductive materials are key components of transformer windings and are used to transmit electrical energy. At present, the commonly used conductive materials for transformer windings are high-purity electrolytic copper or aluminum. Copper has excellent electrical conductivity, thermal conductivity and mechanical properties, and has a low resistivity. It is an ideal conductive material, but its cost is relatively high; aluminum has a low density and low cost, and is also widely used in some cost-sensitive applications. However, the resistivity of aluminum is slightly higher than that of copper, and the cross-sectional area of ​​aluminum windings needs to be larger at the same current carrying capacity. During the production process, the conductive material is processed into round wire or flat wire, and wound into different turns and structures according to the capacity and voltage level of the transformer. Non-ferrous alloy transformer production process Amorphous alloy strip processing First, the amorphous alloy strip is processed. Due to the low hardness and high brittleness of amorphous alloy strips, they are prone to slight damage during transportation and storage, and these damages may affect the magnetic properties. Therefore, it is necessary to inspect and clean the surface to remove impurities such as oil, dust, and oxide film on the surface. Then, according to the design size of the core, the amorphous alloy strip is sheared into a suitable length and width using high-precision shearing equipment. The dimensional accuracy must be strictly controlled during the shearing process to avoid dimensional deviations causing air gaps during core assembly, thereby increasing magnetic resistance and loss. Core Manufacturing Amorphous alloy transformer cores usually adopt rectangular or involute structures. The manufacturing process of rectangular cores is to stack the cut non-ferrous alloy strips in a certain lamination method, usually by overlapping or butting to ensure the continuity of the magnetic circuit and lower magnetic resistance. During the stacking process, appropriate pressure should be applied to make the strips fit tightly and reduce the air gap. The manufacturing process of involute cores is more complicated. First, the non-ferrous alloy strips are wound on a special mold to form an involute-shaped core cake, and then the core cakes are assembled into a complete core through a special assembly process. After the core is made, annealing treatment is required to eliminate the internal stress generated by the strip during the cutting and stacking process, and to restore and optimize the magnetic properties of the amorphous alloy. The annealing process is usually carried out under vacuum or inert gas protection, with the temperature controlled at 300-400℃, and slowly cooled after a certain period of insulation. Winding production: According to the design requirements of the transformer, after the conductive material is processed into wires of corresponding specifications, the winding production begins. The winding usually uses a winding machine to wind the wire onto the insulating skeleton according to the designed number of turns and winding method. During the winding process, the winding tension must be strictly controlled to ensure that the winding is tight and uniform, and to avoid loose wires or over-tightening. At the same time, the insulating material should be laid between the winding layers and turns according to the prescribed insulation process to ensure good electrical insulation performance. After the winding is completed, insulation testing and DC resistance testing are required to check whether the insulation and conductivity of the winding meet the design requirements. Core and winding assembly: Assemble the manufactured core and winding. First, install the winding on the core column of the core. Then, use fasteners to fix the core and winding together to ensure a firm structure. During the assembly process, pay attention to maintaining the accurate relative position of the core and winding to avoid magnetic circuit and circuit abnormalities due to improper assembly. After the assembly is completed, the overall electrical connection of the transformer is carried out, including the connection of the winding leads and the installation of the tap changer. Transformer body processing and assembly The assembled core-winding components (i.e., transformer body) need to be further processed. For oil-immersed transformers, the transformer body needs to be vacuum dried to remove moisture and humidity in the body and improve insulation performance. After the drying process is completed, the transformer body is placed in the transformer oil tank and filled with qualified transformer oil. The oil filling speed and oil temperature should be controlled during the oil filling process to prevent bubbles and poor insulation. For dry-type transformers, heat dissipation devices and protective shells need to be installed to ensure heat dissipation and protection requirements during the operation of the transformer. Testing and inspection After the transformer is assembled, it needs to be fully tested and inspected. The test items include no-load test, load test, insulation test, short-circuit test, etc. These tests are used to check whether the performance indicators of the transformer meet national standards and design requirements. For example, the no-load test is used to measure the no-load loss and no-load current of the transformer to evaluate the performance of the core; the load test is used to measure the load loss and short-circuit impedance of the transformer to evaluate the performance of the winding. Only non-ferromagnetic alloy transformers that pass all test items and have qualified indicators can be finally packaged and shipped and put into use on the market. The production of amorphous alloy transformers has extremely high requirements for material properties and production processes. Each link directly affects the performance and quality of the transformer. With the continuous advancement of technology and the development of materials science, amorphous alloy transformers are expected to play a greater role in the field of energy conservation and contribute to the sustainable development of the power industry.