PVC sheath On the surface, the regular "unevenness" of […]
On the surface, the regular "unevenness" of the braided net can be seen in the compression, indicating that the processing technology is good, and there will be no relative sliding, and it is a good cable. The appearance is smooth, the "unevenness" of the compressed braid is not visible, and the sheath is loose when pinched by hand, which is a bad cable;
Check the shielding layer network. Is the number of edits sufficient? Check the solderability of the braided copper wire. Scratch the tinned copper wire to see if it is copper wire. The hardness of the aluminum-magnesium alloy wire is obviously greater than that of the copper wire; cable;
Check the core wire
Diameter-SYV cable is 0.78-0.8mm, SYWV cable is 1.0mm; a SYV75-5 cable with a core diameter of 1.0mm has appeared. The characteristic impedance of this cable is definitely not 75 ohms and should not be applied to 75 ohms. In the transmission system;
Check the adhesion of the core wire and the insulating layer. Cut the insulating layer obliquely, and pull the core wire in the stripping direction to see if the core wire and the insulating layer are bonded with the process materials; the good cable has a larger bonding force, and the poor cable does not bond;
Longitudinal tensile test. Take one meter of cable and strip 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 two hands and pull them in opposite directions; a good cable can’t be pulled with strength, and a bad cable can be easily pulled out without a lot of effort-the elevator cable is very important, many so-called "Elevator cables" all have this problem.