First, the electrical resistivity of the Aluminum Wire and the Copper Wire are different;
Second, this is the most critical, that is, the aluminum wire is easily oxidized in the air, forming a layer of oxide on the surface, and the hardness of aluminum is smaller than that of copper, which greatly increases the connection between the aluminum wire and the copper wire. The contact resistance, when the current is passed through the connection, the contact resistance will be hot. If it is a large current, the heat will be very serious and the connection will be burnt.
Third, according to the safe operation rules, the aluminum wire cannot be connected to the copper wire.
(1) The copper wire is connected with the aluminum wire, and the electrical corrosion will occur at the connection. Generally, the aluminum wire is corroded first, causing the phase loss to damage the electrical equipment. This is caused by the electrochemical reaction of two different materials. If there is no copper-aluminum joint, copper joints for copper wire and aluminum joints for aluminum wire, but do not connect directly, be sure to fill a layer of zinc skin as a transition layer in the middle, because copper and zinc do not produce electric corrosion, aluminum zinc No electrical erosion is produced, which solves the problem of electrolytic corrosion of copper and aluminum.
(2) Copper-aluminum joints: one end is a copper joint and one end is an aluminum tube. In the past, it was welded on a copper-aluminum extrusion butt welder. Now there is an advanced copper-aluminum flash butt welder. Of course there are other processes.
(3) The molecular structure changes after welding, and the aluminum is not lost in the original metal, thus eliminating the phenomenon of electric corrosion.
Solution: (Because the external line is charged, the operation is extra careful)
1) riveting the aluminum wire and the copper wire together by riveting;
2) soldering the aluminum wire and the copper wire together by soldering;
3) The best thing is to replace the incoming wire with copper wire.
