With the development of the national economy, cities are becoming larger and more prosperous, with dense populations and clusters of high-rise buildings. In the urban network renovation, it is stipulated that 110kV lines enter the urban substation, so 110kV transformers are arranged. Taking Beijing as an example, within the Third Ring Road, a substation with a power supply radius of 1.5km is generally equipped with three transformers ranging from 50000 kVA to 63000 kVA. So many large transformers are like time bombs in the city center, especially in the politically charged city of Beijing. Therefore, people have begun to pay attention to high ignition point oil transformers and SF6 gas insulated transformers.
At present, transformers are mainly developing in two directions. One is to develop towards ultra large ultra-high voltage, with voltage levels shifting from 220V, 330V, and 500KV to 750KV and 1000KV. These transformers are generally used in large power plants or power transmission, and their reliability is crucial. Therefore, manufacturers have taken many measures to improve the performance and distribution of electricity, magnetism, heat, and force. The process and assembly involved in iron core manufacturing should minimize the processing coefficient of no-load loss of transformers. Currently, the silicon steel sheets used are all high-quality silicon steel sheets taken from cold-rolled lattice, and the sheet shape is becoming thinner and thinner. 0.35mm has been phased out, and generally 0.3mm, 0.27mm, and 0.23mm thick silicon steel sheets are taken from industrial transformers. To reduce unnecessary working hours and losses during lamination, the manufacturer has adopted the non overlapping yoke process. Iron core binding is generally done manually with non woven glass adhesive tape, which results in insufficient and uneven binding force. Currently, some manufacturers use iron core binding machines to achieve good binding effects and should gradually promote their use. The process and tooling involved in coil manufacturing must ensure low load loss, high ability to withstand short circuit mechanical forces, and good potential dissipation performance. Currently, electrolytic copper rods are rarely used for electromagnetic wire drawing, and mostly oxygen free copper rods with low resistivity and good surface quality are used. However, some small factories still use electrolytic copper. For large products, semi hard wires can be used to improve mechanical strength. To ensure the tightness of the coil during winding, the amplitude dimension of the coil should be as close as possible to zero tolerance, especially the impedance error requirements of the converter transformer are very strict. Therefore, a vertical winding machine or a horizontal winding machine with tension, amplitude, and axial compression devices should be selected. When drying the coil, pressure drying or constant pressure drying should be used as much as possible. This greatly improves the ability of the coil to withstand short circuit mechanical forces. Many manufacturers do not attach importance to the processing of insulation parts, and the insulation workshop environment is not good, which makes it difficult to ensure the insulation strength of the coils. Even some small businesses share the same equipment for insulation processing and metal processing. Should achieve constant temperature and humidity.
Insulating cardboard * It is better to use high-density cardboard, otherwise it also needs to undergo densification treatment, which most manufacturers can achieve. This ensures the performance of insulation, heat dissipation, and resistance to mechanical forces. The support bar cushion block must be treated with deburring and chamfering, and if conditions permit, insulation processing center equipment should be added. Lead wire, in the quality accidents that occur in transformers, insulation and mechanical accidents caused by lead wire problems are more common, so special attention should be paid to lead wire processing. The welding of leads is currently commonly done using flame needle welding or resistance brazing with copper welding machines. Some large enterprises use cold pressure welding, while most foreign countries use cold welding or high-frequency brazing. Currently, high-frequency brazing is still blank in China. Secondly, for large enterprises, especially for products above 220KV, to ensure reliable operation, most of them adopt the current advanced vapor phase drying technology. Some 110KV manufacturers are also using vapor phase drying technology, but there are still a considerable number of 110KV manufacturers using household variable pressure or hot air circulation technology. The fully automatic vapor phase drying equipment developed by Shen Bian is currently the most advanced and first-class equipment in China that can ensure performance. Oil tank processing, currently the phenomenon of oil leakage in oil immersed transformers in China is still quite serious. The main issue is the sealing surface, and the sealing material is not satisfactory. Recently produced acrylic ester has better sealing performance, and some manufacturers have pre treatment of steel plates and shot blasting treatment of oil tanks. The cleanliness of the production environment, especially the production workshop for high-voltage products, is crucial and directly affects the electrical performance. At least a dustproof room is required for the coil winding and body assembly areas. Large enterprises in China generally have the conditions to ensure electrical performance, but their management is not strict, and some even cannot meet the requirements. They should achieve a daily dust reduction of less than 20mg/m2, while large foreign companies have basically achieved full factory dustproof. In this regard, we have a significant gap compared to foreign countries, excerpted from: Industrial Transformers. The second is to develop towards energy-saving, miniaturization, low noise, high impedance, and explosion-proof types. These products mainly focus on small and medium-sized products, such as the new S9 distribution transformer recommended for urban and rural power grid renovation, which is the seventh generation energy-saving product. There are also coil core transformers, amorphous alloy transformers, fully sealed transformers, combination transformers, dry-type transformers, high ignition point oil transformers, SF6 gas insulated transformers, etc. The production process of these transformers can basically borrow the production process of the above-mentioned large transformers, and there are different process characteristics according to different products. For example, for coil iron core transformers, currently produced hazardous iron core transformers are enclosed with multi-stage and R-type iron cores. This requires the installation of coil iron core machines, special winding machines, and core annealing furnaces, otherwise it is difficult to produce coil iron core transformers. For example, in order to achieve the goal of less maintenance for products, the corrugated oil tank type fully sealed transformer needs to be equipped with a corrugated oil tank production line. Currently, China's simple corrugated oil tank production line can also meet production requirements. Amorphous alloy transformers, due to the extremely thin and brittle amorphous strip material, are generally difficult for manufacturers to process into iron cores. Therefore, they usually purchase ready-made iron cores from industrial transformers.
With the rapid development of China's national economy, the demand for electricity is also increasing day by day. As the main equipment in the transmission and transformation system, transformers have also made significant progress. To adapt to and meet market demand, many manufacturers have made unremitting efforts in exploring new processes and materials by continuously improving product structure and enhancing product performance by introducing advanced production technologies and equipment from abroad. The development of transformer manufacturing technology mainly combines the characteristics of new products and structures to research and develop corresponding processes, and focuses on the development and application of new materials and equipment to continuously improve the quality and reliability of products. However, the research and development of these new processes require a large amount of bonus investment and an increase in production costs. Currently, there is an oversupply of transformers in China, and price competition is extremely fierce. The first choice for users in bidding activities is price factors, so it is difficult for manufacturers to make a large amount of investment. As a result, production processes cannot develop, product quality cannot improve, quality cannot improve, and prices will not be high, resulting in a vicious cycle without profits. In the future, the development direction of transformers in our country will still be energy-saving, low noise, fireproof and explosion-proof, and high reliability. Therefore, some of the processes mentioned above still need to be promoted and widely used. In addition, high-quality and low loss magnetic materials can be selected. For large products, laser irradiation or grooved silicon steel sheets can be used. Advanced production equipment such as winding machines with axial amplitude compression devices, vapor drying equipment, and stepper transverse cutting lines should be widely used. Insulation material processing should be uniformly processed by professional manufacturers as much as possible, gradually increasing the use of emerging solid insulation materials such as injection molded parts. Laser cutting is used for insulation component processing in foreign countries, and China may also develop the use of less light to process insulation components. In addition, great efforts should be made to study the quality of the transformer, such as the surface treatment of the fuel tank, the type of paint, etc., to make the fuel tank as beautiful as possible.
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