[Technology Exchange] How to transform a high-loss distribution transformer into a low-loss distribution transformer?

Abstract: Distribution transformers will be scrapped due to high loss during long-term use, which is also a serious waste of resources. If we can reuse the used transformers, it will not only effectively reduce the waste of resources, but also It can also improve the utilization of distribution transformers, and it also has very important significance for protecting the ecological environment. This article mainly introduces the relevant measures and measures for transforming high-loss transformers into low-loss transformers for reference.

Keywords: transformer; high-loss and low-loss retrofit; core winding

First, the transformation analysis of high loss transformer

In the process of rapid development of China's electric power industry, the total installed capacity of electric power has also reached the world's leading position, and the achievements made in electric power projects are not only obvious to all, but also made important contributions to China's social and economic development. In the power system, the transformer is a very important power equipment. Power plants, substations, and transmission networks all need to be adjusted by transformers. In China, relevant regulations for transformer use were made in 2006, and corresponding regulations for high-loss transformers were also made. It was stated that high-loss transformers will gradually be replaced. In the 1980s, the Chinese government began to gradually replace low-loss transformers with high-loss transformers. This will not only effectively reduce the transformer's resource consumption, but also contribute to environmental protection. The use of large-scale low-loss ground-breaking transformers is also being gradually carried out, in which urban and rural power grids are transformed to increase the efficiency of the use of low-loss transformers. After the new low-power transformers were put into use, the no-load loss was reduced by about 8%-15%. At present, China's high-loss transformers for distribution transformers are also gradually introduced in China's market. Many new energy-saving transformers have also become mainstream products on the market. Especially in recent years, the transformation of power grids in various regions of China has gradually transformed high-loss transformers, which is also an important basis for the development of China's power industry.

However, if the high-loss transformers that have been eliminated have not been processed, the copper, silicon steel sheets and various materials contained therein will cause great pollution to the environment, and such industrial pollution will also affect the ecological and natural environment. The pollution generated by the random deposition of solid waste and the dismantling of waste gas, waste water, and other substances into river water and land is very serious. This is what we must pay attention to at present.

However, in the process of continuous development of the transformer industry, the use of new transformers for waste transformer materials can also reduce the environmental pollution caused by transformers. In China, thousands of high-consumption transformers are gradually replaced every year. Remanufacturing high-consumption transformers also brings great pressure on the market, but there are also great challenges. If the used transformers and materials can be recycled, high-consumption transformers can be gradually transformed into low-loss transformers. Reusing them can not only save a lot of resources, but also effectively reduce the loss of electrical energy. Our country’s environmental protection will also make a very important contribution.

Second, the high loss transformer transformation of low loss transformer measures

Transformers for high-loss transformers usually use several different methods, including partial and complete replacement transformers, so that the transformer can effectively reduce the consumption of resources after replacement. At the same time, there is load loss of the transformer, etc. If the transformer is reformed, then the winding in the transformer must also be better, so that the original and original conductors of the transformer need to be replaced and adjusted in time. The aluminum conductor in the transformer must be replaced with a copper conductor. If there is no fault in the core of the transformer, then after use, the density of the silicon steel sheet in the transformer will be used to meet the standard requirements.

The main process flow for transforming a high-loss transformer into a low-loss transformer is to first test the SL7, S7 or S9 high energy-consuming transformers that need to be retrofitted to test their no-load losses, and to reduce the silicon steel according to the no-load losses of each transformer. The magnetic flux density of the chip, the number of turns of the transformer winding, and the capacity of the transformer are reduced, and the transformer to be reformed is redesigned so that it satisfies various performance indexes of the S11 low-loss transformer.

The dismantled materials are processed in the following manner: the old copper wire removed is processed by fire and used for the production of other products; the old transformer oil is used for lubrication of lathes in machining shops; The old transformer oil tanks are scrapped according to the difference in the degree of corrosion, or processed for derusting, pickling, painting, etc., and then used in transformers after remanufacturing; if the dismantling old silicon steel sheet is of poor quality or is in operation Severely burned, it will be scrapped. If it is of good quality, it must be used to transform the transformer after removing the rust and adding new silicon steel sheets. After signing with the user the technical agreement for the transformation of the transformer contract and transformation, the specific transformation plan is as follows: First, according to the transformation of the transformation of the transformer transformer calculation sheet, design transformation of the transformer high voltage winding, low voltage winding drawings, according to the new transformer The manufacturing process involves transformer body assembly, leads, and assembly. After the completion of the final assembly, the factory-built test is performed according to the requirements of the newly-manufactured transformer, and the various properties of the transformer after the transformation are verified. After the requirements of the national standards are met, the products are allowed to leave the factory. For cores of high-loss distribution transformers, since K0 and GFe are fixed values, to reduce the no-load loss P0, the Pw must be reduced, and the Pw value is related to the magnetic flux density of the silicon steel sheet. Since the core is not replaced after the modification, the voltage and frequency are not changed. Therefore, the no-load loss should be reduced, and only the way to reduce the magnetic flux density in the iron core can reduce the Pw value of the silicon steel sheet. In practical engineering applications, in order to make better use of the iron core, when the distribution transformer that needs to be modified is tested under the original 匝 potential, the no-load loss can not meet the requirements of the current low-loss distribution transformer, and when temporary no-load is adopted, temporary The method of adjusting the number of turns of the low voltage winding by the line turns is to measure the no-load loss until it can meet the no-load performance index specified in the current GB/T6451-2008 standard.

[Technology Exchange] How to transform a high-loss distribution transformer into a low-loss distribution transformer?

Third, the transformation of transformer windings

The basic principle of the transformation of the distribution transformer windings is derived from the transformer load loss formula. The resistance loss of the coil accounts for the largest proportion in the load loss value of the transformer.

In the process of transforming the transformer, if the wire is a copper wire, the value of P0 and Pk of the transformer must be reduced. Only by increasing the number of turns of the low voltage coil of the transformer, due to the limited window height and window width of the transformer, the transformer can only be modified for derating. When the original material of the transformer is an aluminum wire, the transformer can be modified with equal capacity based on the calculation result. Since the ratio of resistivity of copper to aluminum at 75°C is 0.02135/0.0357=0.598, the ratio of load loss is reduced after copper conductors are used in place of aluminum conductors, and the cross section can be reduced to approximately 70%. It can be seen that this method can not only increase the number of turns and reduce the no-load loss, but also make it possible to use conventional methods to make the transformer meet the needs of transformation without reducing the capacity.

The method of transforming a high-loss power distribution transformer from which the power grid is put out of operation into a method of transforming an old transformer core with new coils, new insulation, new leads, and new components into an S11 low-loss distribution transformer that satisfies the requirements of the national standard. Transformer copper, silicon steel, transformer oil and other materials are fully utilized. After such transformation, not only can these materials avoid environmental pollution, but they can also reduce the use of silicon steel sheets, copper and other materials, save a great deal of raw material consumption each year, and make its own contributions to the country's currently advocating conservation-oriented society.

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