A transformer is an electrical device that utilizes the principle of electromagnetic induction to transfer electrical energy and convert voltage. Aluminum and copper are commonly used conductor materials in transformer coils. So, when choosing a transformer, should we choose an aluminum core transformer or a copper core transformer?

In terms of volume: under the same rated power and technical standards (such as loss level and insulation level), due to the much higher conductivity of copper than aluminum, aluminum wires require a larger cross-sectional area to achieve the same conductivity as copper wires. This makes the winding, iron core window, and shell/oil tank volume of aluminum core transformers larger than those of copper core transformers; Typically, aluminum core transformers have a volume 10% -25% larger than copper cores, and the larger the power, the greater the volume difference may be.

In terms of weight, the specific gravity of aluminum is 2.7, while that of copper is 8.9. By comparing the weight on the transformer nameplate (which is usually not falsified) with copper core transformers and aluminum core transformers of the same model, it can be distinguished.

In the transformer model, if there is an L symbol, it indicates an aluminum core transformer; if not, it indicates a copper core transformer. If it is a dry-type transformer, the wire cutting cut can also be seen. If the coil cut is silver white, it is aluminum core, and if the cut is gold, it is copper core. At the same time, further identification can be carried out through scratch testing to eliminate interference factors.

In terms of cost difference, the cost of aluminum core transformers is usually lower than that of copper core transformers. This is because the price of raw material aluminum is much lower than that of copper, and the total manufacturing cost of aluminum core transformers in processing is also 15% -35% lower than that of copper core. However, copper core transformers have lower maintenance costs throughout their entire lifecycle compared to aluminum core transformers.

Copper as a conductor has excellent conductivity (100% IACS) and oxidation resistance, while aluminum's conductivity is about 61% of copper's (35-38% IACS), which means that copper has lower energy loss. Considering long-term energy loss, copper core transformers are more cost-effective. In terms of mechanical strength, copper core transformers are usually more favored due to their higher strength and corrosion resistance. If the daily usage load is low and the budget is limited, then choosing an aluminum core transformer is more economical.

In terms of humidity control, aluminum core transformers require an ambient humidity of ≤ 60%, while copper core transformers can withstand an environment with a humidity of ≤ 70%. Aluminum core transformers are more popular in certain application areas, such as budget sensitive and load factor<60% scenarios, mobile substations that require weight reduction, or areas with milder climate conditions or indoor use. Copper core transformers are more commonly used in applications that require higher performance, such as high corrosion environments along the coast, and long-term projects that require minimizing lifecycle costs.

Aluminum core transformer connectors need to be tightened and coated with anti-oxidation grease every 6 months for inspection, while copper core transformers can be inspected annually. The maintenance requirements for aluminum core transformers and copper core transformers are similar, but there are certain differences in their lifespan. Normally, the lifespan of copper core transformers is longer than that of aluminum core transformers because copper has stronger corrosion resistance and oxidation resistance, and can reach 30-40 years under normal maintenance conditions. The problem of joint oxidation in aluminum core transformers is more prominent, and there is a higher risk of electrochemical corrosion in humid environments, requiring strengthened sealing protection. However, this is also influenced by specific usage conditions, manufacturing processes, and maintenance conditions.

Aluminum core transformers and copper core transformers each have their own advantages and application areas. When making a choice, it is necessary to comprehensively consider specific needs, budget, and environmental conditions. Whether it is an aluminum core or copper core transformer, proper maintenance and upkeep are key to ensuring its long-term stable operation.