At present, the cable in the wire and cable market can be said to be true and false, and the copper clad aluminum wire and copper clad aluminum magnesium wire are new products just listed in recent years, which gives a lot of black merchants the opportunity to use various illegal channels to pursue windfall profits. The current price of oxygen-free copper wire is around 50,000 yuan per ton, while the price of copper-clad aluminum is only 25,000 yuan per ton. (Note: oxygen free copper specific gravity 8.9, aluminum specific gravity 2.7). So, as a customer, when we go to buy a product, we can't just believe what others say. We have to shut them down ourselves. How can you tell a copper-clad aluminum cable apart?
Specifically, we can identify it in the following five ways:
First, look at the appearance
The cable depends on the copper. Qualified copper cores should be purple, shiny and soft to the touch. The copper core of false copper wire is purple black, yellow or white, impurities, poor mechanical strength, poor toughness. They break with a little pressure, and they often break. To check, just peel off one end of the wire 2cm, and then gently rub a piece of white paper on the copper core. If there is black material on the white paper, the copper core is more impurities.
Second, look at the cross section
Because the thicker wires are copper-clad aluminum, it's easy to see. So the general copper clad aluminum is flexible wire, composed of a lot of small filaments and a lot of strands. But you can identify the material by cutting through the cross section and looking at the white (the color of aluminum).
Three, fire method
Just burn it with a lighter, and look at the phenomenon of burning and the result after burning. When the flame hits the wire, the conductor of the copper clad aluminum and copper clad aluminum magnesium wire will sag straight, not easy to burn out. After combustion, the conductor color is gray or darker; Because aluminum has a lower melting point than copper. Difference: copper clad aluminum after burning, with a finger twist, the conductor will break, more brittle, will break into many segments. If the bare copper wire without oxygen burns into balls, it is copper wire. With different thickness of copper wire burning results are not the same, fine wire melting, coarse silk.
4. Scrape with a tool.
Tinned copper wire turns yellow when scratched, so it's copper. Bare oxygen free copper wire is still raw and copper after scratch. And copper - clad aluminum wire and copper - clad aluminum magnesium aluminum show snowflake point white. Or you can rub silk on a concrete floor to get the same effect. Copper-clad steel wires can also be identified by this method or by magnets.
5. Test with instruments
The copper conductor of the cable is made of anaerobic copper wire. In addition to smooth surface and no defects, its dimensions, mechanical and physical properties and electrical properties should also meet the requirements of (GB/T3953-2009 electrical round copper wire). In particular, conductor resistance (rate) is a key index to measure the quality of conductor materials. In order to distinguish the advantages and disadvantages of copper conductors, we often use the bridge method to measure the conductor resistance, and according to its cross section into the resistivity of the conductor.
1)GB/T3048.2-2007 "Electrical performance test method of wire and cable Part II: Resistivity test of metal conductor materials" (IEC60468:1974, MOD).
2) Electrical hard round copper wire (Ty3.0mm) at 20℃ resistivity (no more than):0.01777ωmm2/m;
3) Electrical soft round copper wire (TR) at 20℃ resistivity (no more than):0.017241ωmm2/m