There is little difference in performance, power, and service life between copper and aluminum wire coils used in motor installation.
However, aluminum wire coils have lower overload capacity and magnetic efficiency than copper wire coils. Therefore, for an aluminum wire coil vibratory motor to achieve the power of a copper wire coil vibratory motor, the core volume must be larger than that of a copper wire coil core; otherwise, it will easily overheat. The two can be distinguished by weight and color. Copper has a higher specific gravity than aluminum. Copper is reddish-yellow, while aluminum is silvery-white.
The resistivity of copper wire coils in motors is 0.017, while that of aluminum wire coils is 0.028. The interchangeable cross-sectional area ratio of copper to aluminum wire is 0.79:1, meaning that 6 square millimeters of copper wire is equivalent to 10 square millimeters of aluminum wire. Therefore, the diameter of the aluminum wire used must be thicker than that of the copper wire, and aluminum wire will not fit in the same stator slot. The current per unit area will also differ; copper wire can carry approximately 5-8A of current per square millimeter, while aluminum wire carries significantly less, approximately 3-5A.
Besides the differences in cross-sectional current capacity and material between copper and aluminum wires, the main differences are: aluminum wire is lighter and relatively cheaper, but has lower mechanical strength. Aluminum wire oxidizes easily at the connection points, leading to overheating, poor contact, and potentially circuit failures (power outages or wire breaks). Additionally, aluminum is difficult to weld, has low strength, a low melting point, is prone to oxidation, overheats, and has high energy loss. How can we identify the type of coil used in a motor without disconnecting the wires? Actually, understanding the operating principle makes it easier to determine:
1. Unlike copper wire, aluminum wire cannot be drawn into very thin wires due to its physical properties. Therefore, aluminum wire is generally slightly thicker for motors of the same power.
2. Because the resistance of aluminum wire of the same cross-sectional area is higher than that of copper wire, in order to obtain the same current, the cross-sectional area of aluminum wire must be increased, that is, the diameter must be larger.
3. To produce a motor with the same power, the diameter of the aluminum wire needs to be increased, which requires more windings. The original slots in the silicon steel sheets are no longer sufficient for the windings to be embedded. Therefore, the slots must be enlarged, and the only way to do this is to increase the outer diameter and thickness of the stator.
In summary, to distinguish between copper/aluminum coil motors, you only need to check the thickness of the winding wires, whether the stator is relatively heavy, or measure the wire resistance.
