Investigation of a number of power accidents by the discovery of distribution transformer "to aluminum instead of copper" problem has been repeatedly banned. Because this phenomenon is hidden, it is difficult to identify the appearance of the finished product and the terminal after the production, and it is difficult to find the test items stipulated in the existing standards. At the same time, suspension core disassembly inspection is a destructive method, more difficult to carry out, but also not economic. Transformer fraud, replacing copper with aluminum, especially distribution transformer users distributed in industrial manufacturing, real estate, high-speed rail, transportation, new energy power generation and other fields, user knowledge of transformers and Information asymmetry of transformer manufacturers. A large number of cases show that many aluminum instead of copper transformers have entered the market through a variety of means, including access to large cities such as Shanghai, leaving potential safety hazards.

01 transformer "aluminum instead of copper" and harm transformer "aluminum instead of copper" refers to distribution transformer winding with aluminum, aluminum alloy or copper-clad aluminum and other materials instead of copper, but not in the name plate of the phenomenon. One,"replace copper with aluminum"transformer is not specific or most people's life, body or property safety. From the perspective of Criminal Law, it is a crime of endangering public security and a serious criminal act. Dry-type transformers are commonly used in high-rise buildings, commercial buildings, libraries, airports, data centers, factories and other public and public places, it will inevitably lead to great damage to people's lives and property. The explosion of a large oil-immersed transformer is a major disaster. II. Implementation of the strategy of "replacing copper with aluminum" transformer to endanger China's Belt and Road. In the construction of the Belt and Road, there have been scandals in Nepal over the use of aluminum instead of copper transformers, and the people involved have been sentenced by Nepalese courts. If this happens again and again, it will be a devastating blow to China's manufacturing reputation, especially since China's contract power projects have become a bright spot in the Belt and Road. "replacing copper with aluminum" transformers is a major threat to China's development as a manufacturing power. It is impossible to build a manufacturing power on the basis that Chinese manufacturing can not hold to even the most basic baseline and that fake medicines, fake food, fake industrial products and piracy are rampant. It's only a matter of time before the beach starts to collapse. Therefore, the fight against fake industrial products and industrial fraud must be an important part of the construction of China's quality power. 4. "replacing copper with aluminum" transformers caused severe depreciation of the assets of industrial enterprises and new energy projects. If the enterprise's assets are aluminum instead of copper transformer, it is a substantial depreciation of the assets, is bound to bring high-risk assets, is sooner or later something will go wrong. If such assets enter the balance sheet of any project or enterprise in large quantities, they are a significant potential threat to the enterprise and the project.

02 How to identify transformer "aluminum instead of copper" through the following table can be seen, high and low voltage winding all aluminum transformer than the total weight of copper transformer is 55 kg higher, this is mainly because of its body weight, the weight of the oil, the weight of the fuel tank, the body volume and so on have increased. The same is true for transformers where the high voltage conductor is aluminum and the low voltage conductor is copper.

In theory, a transformer from the same manufacturer can be measured and statistically analyzed to determine whether it uses aluminum windings. However, in practice, due to the differences in manufacturing methods, designs, techniques and materials used by various manufacturers, there are various situations such as high-pressure windings replacing copper with aluminum, low-pressure windings replacing copper with aluminum, copper-clad aluminum, etc. , there is no corresponding data as a reference, judgment is difficult. As a transformer user, the post-test is passive. Once a transformer is replaced with aluminum, the disposal cost is high. The best method is to test and consult before purchasing, avoid purchasing aluminium instead of copper transformers. Industry experts believe that under what price conditions may be aluminum instead of copper manufacturers, which manufacturers may be aluminum instead of copper, which enterprise transformer quality guarantee, can give users advice. In addition, the Power Grid Company, as a professional customer of transformer procurement, has a lot of mature experience of transformer quality management, to other industry transformer users have a good reference. The survey also found that many users of the transformer procurement contract is very simple, once a transformer to replace copper with aluminum event without the basis of the contract claims and compensation for the calculation of losses, resulting in difficult claims, heavy user losses. Some in the industry have suggested that if a corresponding compensation clause is added to the transformer purchase contract, the liability for compensation should be increased and the amount of compensation increased, iNCLUDING: direct losses, indirect losses, loss of profits, attorney's fees, transportation fees, testing fees, court litigation and execution fees, daily loss due to stoppage of production, replacement costs, labor costs due to claims, etc. , if the above-mentioned losses are not easily estimated, they may be stipulated in the contract in terms of the amount of experience plus increased liability. The suppliers, intermediaries, contractors and manufacturers concerned shall be subject to unlimited joint and several liability for the replacement of copper with aluminum if it is found that the transformer has been replaced with aluminum throughout its life cycle. In addition, in the event of replacing copper with aluminum, the contract may stipulate that the legal representative of the transformer manufacturer shall be liable for life-long and unlimited compensation. 03 Is it possible to replace copper with aluminum in power transmission? According to the research report on the strategic planning of the application of copper and aluminum resources in the power cable market issued by the Resource and Environment Policy Institute of the Development Research Center of the State Council, the conclusion is drawn that it is not appropriate to replace copper with aluminum in the field of power transmission through the Comparative Analysis of copper-aluminum Alloy conductors and cables. The operation experience of power network shows that 80% of the faults of power cable occur at the joint. In this regard, copper has the incomparable advantage of aluminum and aluminum alloys, even if oxidized, the resulting copper oxide is still a good conductor, can ensure the electrical connection performance of joints and terminals, and aluminum alloy cables even if there is a good construction process guarantee, in the joints or terminal parts of the oxidation, the resulting aluminum oxide is an insulator, will lead to joint or terminal conductivity deterioration, which will increase the joint or terminal heating and thus more serious oxidation. Many electric power accidents are accompanied by fire. A fire in a power cable typically begins with an abnormal increase in temperature due to excessive joule heat. Common Causes of Cable Junction Resistance Increases, insulation layer aging, leakage to the ground or between the lines, and so on. And the cable temperature increase will aggravate the cause of temperature, forming a positive feedback, leading to the cable in the face of fire is quite vulnerable. Once the cable fire occurs, the fire is fierce, spread quickly, in the burning will occur a large number of harmful gases, resulting in difficulties in fighting. Not only will the ignition of the cable circuit be affected, it will also affect other cables in the cable trench. After the cable burns out, the repair time is long, the loss is serious. In a word, the problem of replacing copper with aluminum in transformers is considered by many people in the industry merely as a result of the low price of industrial products, but its essence is a major social problem, and its harm degree is far beyond people's expectation. As fake medicine and fake food, must not sit back or wait until "big head doll" born or enterprise, residential high-rise transformer explosion caused serious consequences before the introduction of severe sanctions. 

Source: Electrical Technology