In the process of selling weak current cables, whether online or offline, many customers will ask about identifying the quality of weak current cables. How to identify:
1. Sheath: On the surface, you can see the regular "irregularity" of the braided mesh inside the compression, indicating that the processing technology is good and there will be no relative sliding. It is a good cable. The appearance is smooth, and the "unevenness" of the compressed braid cannot be seen. If the sheath feels loose when pinched by hand, it is a poor cable.
2. Check the braiding of the shielding layer: whether the number of braids is enough. Check the weldability of the copper braid. Scratch the tinned copper wire to see if there is copper wire inside. The hardness of the aluminum-magnesium alloy wire is obviously greater than that of the copper wire; the braiding is sparse and distributed. Unevenness, loose insulation, etc. are bad cables.
3. Check the core wire: diameter - SYV cable is 0.78-0.8mm, SYWV cable is 1.0mm; recently there has been a SYV75-5 cable with a core wire diameter of 1.0mm. The characteristic impedance of this cable is definitely not 75 ohms. , should not be used in 75 ohm transmission systems.
4. Check the adhesion between the core wire and the insulation layer: cut the insulation layer diagonally and pull the core wire apart according to the peeling direction to see if the core wire and the insulation layer are adhered to the process material; good cables have greater adhesion, poor cables have greater adhesion. The cable is not bonded.
5. Longitudinal tensile test: Take one meter of cable, peel off the core wire, insulation layer, shielding layer and outer sheath in layers, leaving 10 cm long each. The method is: hold the two adjacent layers of the cable with both hands and pull in opposite directions; good cables generally cannot be pulled with force, while poor cables can be easily pulled out without much effort-elevator cables are very important, and many so-called " "Elevator special cables" all have problems in this regard.
