Recently, Chinese transformer suppliers on the Internet were fined US$7.1 million by the Nepalese government for using aluminum transformers instead of copper transformers. So what are the facts? The following is the original text of the article: "The transformer they provided to the Nepal Electricity Authority (NEA) was substandard, and NEA terminated a million-rupee procurement project. This case was filed by the Abuse of Power Investigation Commission three years ago. The commission Allegations that the case was conspired by a Chinese manager and the Nepal Electricity Authority. The manager has been fined and sentenced. This incident has become one of the biggest scandals in Nepal. The Abuse of Power Investigation Committee has prosecuted 22 officials and figures of the Nepal Electricity Authority. A Chinese transformer supplier. According to the survey, the transformers provided by the Chinese transformer supplier to the Nepal Electric Power Bureau use aluminum wires instead of copper wires. These transformers lack basic safety features. These transformers can happen even when the grid current is small and unstable. The accident caused an explosion."

Is "substituting aluminum for copper" really feasible?

On the one hand: Will "aluminum replacing copper" cause safety hazards? This is a common question that many are preparing to use aluminum conductor transformers. In this regard, an electromechanical technical engineer said that the safety of distribution transformers cannot simply be judged by the material of copper or aluminum, because all products are produced in strict accordance with national standards, and the quality is based on the production control management of the enterprise decided. Under the specified conditions of use, the application safety of aluminum tape instead of copper tape is the same, because in the distribution transformer with liquid insulation and solid insulation, the aluminum tape conductor will not be oxidized, and its chemical properties will not change. Copper strip is equally safe, and there is no saying that "aluminum strip is worse than copper strip". The country has also issued the "GB/TYST 713-2009 Transformer Aluminum Strip and Foil Standard" which stipulates the standard requirements for aluminum strip in transformer production. It can be seen that the country's application and promotion of copper strip and aluminum strip on transformers is flat. As long as the quality and performance of the product can be guaranteed, whether it is copper strip or aluminum strip, the effect in the transformer is the same. This has further alleviated the lack of copper resources in China.
　　 

On the other hand, it is believed that experts have concluded that it is not appropriate to "substitute aluminum for copper" in the field of power transmission through comparative analysis of various aspects of copper-aluminum-aluminum alloy conductors and cables. According to statistics, 80% of power cable failures occur at the joints. At this point, copper has the unparalleled superiority of aluminum and aluminum alloy. Even if it is oxidized, the copper oxide produced is still a good conductor, which can ensure the electrical connection performance of the joints and terminals; while the aluminum alloy cable has a good construction Process guarantee. After the joints or terminals are oxidized, the alumina produced is an insulator, which will cause the deterioration of the conductivity of the joints or terminals, which will increase the heat of the joints or terminals and make the oxidation more serious.

Many electrical accidents are accompanied by fires. A fire in a general power cable is initially manifested as an abnormal increase in temperature due to excessive Joule heat. The common causes are the increase in the resistance of the cable joint, the aging of the insulation layer, the leakage to the ground or the leakage between the lines, and so on. The increase in the temperature of the cable will aggravate the cause of the temperature, forming a positive feedback, and making the cable very fragile in the face of a fire. Once a cable fire occurs, the fire will be fierce and spread rapidly, and a large amount of harmful gas will be generated during the combustion, which will cause difficulty in fighting the fire. Not only will the fire cable circuit be affected, it will also affect other cables in the cable trench. After the cable burns out, it takes a long time to repair, and the loss is serious.

In short, there are different conclusions about the "aluminum-to-copper transformer". However, according to the current international market, the aluminum strip winding distribution transformers produced by transformer suppliers have become mainstream products in the transformer industry. According to statistics, foreign aluminum strips have been used in substation transformers, dry-type transformer windings, in-screen busbars, dense busbars and other parts. The application proportions are high in Europe, America, Japan and Thailand. Among them, Thai transformers use aluminum. The proportion of belts is as high as 90%. According to the development of this data, it is imperative to replace copper with aluminum on a large scale in China. The transformer aluminum tape has low density, high-precision and burr-free processing on the edges, which can completely replace copper tape in transformer windings and is a very safe transformer material.