1. Look at the model on the transformer inscription. If it is an aluminum coil transformer, there should be an L symbol, but there is no such symbol for a copper coil transformer.

2. From the appearance, the aluminum coil transformer should be slim (thin and tall), while the copper coil transformer should be short and fat. And the total volume should be larger.

3. Also, it is identified by weight. Because the specific gravity of aluminum is 2.7 and that of copper is 8.9. Take the weight on the transformer nameplate (generally, this data will not be false). To compare with the weight on the copper coil transformer samples of other manufacturers.

4. In fact, if the product is produced by a regular large factory, the reputation and quality should be trustworthy. In addition, from a technical point of view, the aluminum coil for dry-type transformer cast with epoxy resin will not have a problem, but it is better. Because the expansion coefficient of aluminum is closer to that of epoxy resin than that of copper, it is better for the reliability of transformer. Therefore, in Europe, most epoxy cast transformers use aluminum coils. As long as the manufacturing quality is qualified, there will be no problem in the use of aluminum coil transformer.