Winding wire—also referred to as magnetic wire or enameled round wire—refers to wire coated with a thin layer of insulation and wound into a coil. It is a key component in transformers and other magnetic equipment (e.g., inductors and motors). While many transformers utilize copper windings, some use aluminum ones. Below, we provide a comparison between the two to serve as a helpful guide for readers that needs assistance choosing the one that is best for their needs.
Overview of Aluminum Wiring
Aluminum wiring is lighter in weight and lowers in cost than copper. However, since it is usually incorporated into bigger and, consequently, heavier transformers, the overall benefits of these qualities are minimal. Additionally, its few advantages are often outbalanced by its many disadvantages. For example:
The electrical conductivity and thermal conductivity of aluminum are less than copper. These qualities make the aluminum windings less efficient, which can lead to higher operating costs, and more prone to high hot spot temperatures, which can lead to shorter operating lives.
Transformers wound with aluminum produce more noise during operation than those wound with copper, which can lead to worse working conditions for system operators.
Overview of Copper Wiring
While copper wiring is heavier than aluminum wiring, it is often used to make smaller and lighter transformers. This is because copper offers higher electrical conductivity levels than aluminum. The resistivity of copper is 0.6 times that of aluminum. Therefore, the cross-section of an aluminum conductor needs to be 1.66 times larger than that of a copper conductor to demonstrate the same amount of resistance. As a result, an aluminum wound transformer would need to be much larger than a copper wound one to handle the same load.
Some of the other advantages copper wiring offers over aluminum wiring include:
Lower losses (due to better electrical conductivity) and temperatures (due to better thermal conductivity)
Greater reliability with regard to the line and load connections
Better manufacturability since the generally smaller-diameters conductors are easier to handle