Why is copper used instead of aluminum in power transformers?

Power transformers are the core of all modern power systems. Without electricity, the world cannot operate, and without transformers, the power system cannot be imagined.

Do you know what the core of these transformers is?

Yes, you guessed it right! It is the winding of a transformer, without which the transformer cannot work. These windings are made of copper or aluminum, however, copper windings are superior to aluminum windings because they are better and superior in many aspects. Let’s discuss what makes copper more popular than aluminum in transformers.

Why do you prefer copper over aluminum in transformers?

1. Lower creep level – Copper has much lower creep than aluminum. Under extreme loads and high temperature conditions, the creep rate of aluminum can reach up to 25 times, making aluminum wound transformers more prone to faults than copper wound transformers.

2. Durable and long-lasting termination – Copper termination is more durable than aluminum because the formation of oxides during its service life is different. Copper oxide is soft and conductive. It is also easy to decompose. However, alumina is the opposite of it. It is very tough because it clanks strongly on the terminals and it is difficult to remove their formation and accumulation. Most importantly, the aluminum oxide formed on the terminals is also electrically insulated. Aluminum requires a layer of tin, copper, or nickel to prevent you from making non mechanical connections such as welding.

3. No current effect – Copper has no current effect when terminating copper. Therefore, in the case of copper windings, the termination of the transformer allows for copper to copper termination on the transformer terminals. Connectors are usually made of copper or copper alloys (such as brass). Therefore, there is no danger of current action during termination. However, when aluminum comes into contact with copper or copper alloy during the termination process, it will lose material through the action of current, leading to contact loosening or complete loss of contact.

4. Harder, sturdier, and more ductile – Copper is harder, sturdier, and more ductile than aluminum, all of which cause copper to expand less and not flow at the terminals, thus preventing regular inspections and other maintenance such as tightening connections or inspecting terminals. Aluminum is weak and will flow out of the terminals during tightening. If not tightened properly and left unchecked for a long time, it can lead to loose connections, sparks, or device fires.

5. High short-circuit resistance – Compared to aluminum, copper has excellent mechanical properties such as yield strength or elastic modulus. This leads to the use of copper damaged transformers specifically when it comes to transformers with a high probability of short circuits, such as electric arc furnaces. Frequent short circuits can worsen the system, significantly weakening the transformer and its terminals, thereby reducing the reliability of the transformer and the entire system.

6. Smaller and Lighter – Copper winding transformers are smaller, lighter, and more compact than aluminum transformers of the same rating. Compared to aluminum, copper has a lower resistivity. It is only 0.6 times that of aluminum, and if it is an aluminum wound transformer, the required conductor cross-section is 1.66 times higher than that of copper. This leads to a larger overall size of everything used in transformer manufacturing, such as transformer oil tanks, oil, iron cores, contacts, insulation, etc. All of these have led to the increasing weight of transformers, requiring larger and more sturdy installation areas.

7. Less metal fatigue – If high-voltage windings are composed of copper, they are less susceptible to metal fatigue than aluminum windings, as the fatigue life of aluminum conductors is much shorter than that of copper. This makes it easier for aluminum transformers to malfunction after the windings become loose during operation for a period of time

8. High performance – Copper wound transformers have higher performance, better efficiency, and lower lifecycle costs because they have lower energy loss and are precious to consumers’ pockets, rather than drilling holes like aluminum transformers, where maintenance costs, operating costs, installation costs, and other operating expenses are much higher than copper wound transformers.

9. Better current distribution – The current distribution in copper conductors is better than that in aluminum because it has higher conductivity and metallurgical properties. This can prevent nonlinear loads from causing additional losses like aluminum wound transformers, making copper wound transformers a better choice.

10. Low manufacturing cost – Compared to aluminum transformers, copper wound transformers are cheaper to manufacture because they require fewer conductor materials and cross-sectional areas. It requires smaller machines and other facilities, such as smaller powder coating settings, smaller quality control laboratories, fewer storage areas, etc. During the manufacturing process, it is necessary to make it more feasible than aluminum damaged transformers.

Kvtester Electronics Technology Co.,Ltd. is a high-tech enterprise specializing in power testing, testing, research and development, production, and sales of testing equipment. It has been engaged in the electrical testing industry for many years, and its products are of high quality. We welcome customers to come and purchase.