enameled aluminum wire vs enameled copper wire used in motors
The biggest difference between enameled aluminum wire and enameled copper wire for single-phase induction motors is also caused by the poor conductivity of aluminum. Therefore, the wire diameter of enameled copper wire has to be reduced to 0.12. The same motor specifications as enameled aluminum wire can be reached by about mm. On the contrary, if the single-phase induction motor that originally used enameled copper wire is changed to enameled aluminum wire, the wire diameter must be somewhat larger. To increase, it can reach the specifications required by the original motor. Therefore, the motor will need more space to accommodate the increased wire diameter, but this more space is often the most difficult to provide among the motors.
The silver-white coil on the left side of the figure below is a single-phase induction motor using enameled aluminum wire, and the right side is a traditional enameled copper wire motor. The test method is based on the comparison parameters of the motor performance standard of enameled aluminum wire, and only the enameled wire is changed. The wire diameter of the copper wire is measured by how much the wire diameter of the enameled copper wire has to be reduced before it has the same motor size as the enameled aluminum wire.
In order to solve the problem of increasing wire diameter space when using enameled aluminum wire, it is better to replace it with a motor that does not need to consider the slot full rate. A few motors have such special values, among which the stator field coils of general motors This is an example of this. As shown in the figure below, the test conducted this time is based on the same specification of wire diameter and number of turns.
From the comparison of the above enameled copper wire and enameled aluminum wire, it is obvious that the efficiency, torque, speed and output power are greatly reduced, so simply use the same wire diameter and number of turns to replace it. If it is not feasible, it is necessary to re-plan and design a new wire diameter and number of turns to achieve the same number and output specifications.
The use of enameled aluminum wire as a replacement material for enameled copper wire failed and was not adopted in the use of motors. The difference in use between aluminum and copper, wire tension and spot weldability were the main rejected materials. reason.
The failure of the development of enameled aluminum wire did not hinder the development of replacing copper with aluminum. Instead, copper-clad aluminum, which is more convenient to use, was introduced. The outer ring uses 15% copper to cover the inner 85% aluminum. Such a composite method will greatly improve the applicability, and the acceptance and possibility of substitution will increase.
Due to the addition of copper, the performance of the wire can be improved, but the composition of aluminum is still as high as 85%, and the decrease in conductivity is still an unavoidable problem. It is also necessary to increase the wire diameter to solve the difference in material. It must be used in a structure with sufficient space Among the motors, the technology of using enameled copper-clad aluminum wire has been very mature. Considering cost and product competitive advantages, the number of manufacturers used has increased significantly, and there is a trend of full replacement.
Although the conductivity of aluminum is lower than that of pure metal materials such as silver, copper and gold, its conductivity is still in the excellent range, and it is suitable as a conductive conductor material, and the content of aluminum in the earth is higher than that of the first three. The materials silver, copper and gold are easy to come by. They are the highest proportion of pure metal materials, about 7.45% of the total mass of the earth’s crust. Therefore, the price of aluminum is cheaper than the first three materials. Comparing copper with aluminum, it can be seen that the density of aluminum is 2.7 g/cm3 less than 8.9 g/cm3 of copper, which is 1/3, so the weight will be greatly reduced, but the conductivity of aluminum is only about 62% of copper. Under the design of conducting the same amount of current, the required cross-sectional area of ??aluminum is about 1.6 times larger than that of copper. Therefore, copper conductors are used as the main conductor in applications such as power source and signal wires with conductive efficiency, while aluminum wires can be used. In applications that do not focus on performance and are aimed at weight or cost requirements, such as earphones, audio, etc., aluminum also has the characteristics of reducing vibration parts and can obtain better transient performance.
Observed from the motor characteristic measurement data, in fact, there is still a small drop in the number of specifications, but it is very close, the difference is about 2%, so it can be accepted in practical applications.
Shaded pole motor is a type of single-phase induction motor. It is a motor with simple structure but low output power. It has poor working efficiency and is suitable for occasional actions such as vending machines. The appearance is shown in the figure below. It shows that the black part is the motor coil, which is simple to wind and has no space limitation. Therefore, enameled copper-clad aluminum wire can also be used to reduce production costs.
Because the characteristic efficiency of the shaded pole motor is not good, and in fact, the output performance of the shaded pole motor modified with enameled copper-clad aluminum wire is still slightly reduced. However, in actual work, it is impossible to feel the difference, so it still has Ability to replace.
Conclusion
Today, when raw materials continue to rise, the price of copper is an unsolvable problem faced by motor factories. This alternative material for copper-clad aluminum is one of the solutions. Copper-clad aluminum wire has essential defects in any case, and it is difficult to compare performance with copper wire. However, as long as it is used properly, the difference can be greatly reduced. It still has excellent market value and can bring new things to the motor. The cost and additional lightweight competitive advantage.
