The power supply of the fired cable should be cut off first if a fire occurs in a high-voltage cable , and then the fire should be quickly extinguished. The cause of the overhead cable fire should be found later, and the fault point should be found and repaired quickly. If you want the quality of the high-voltage cable, you can identify it by checking the shielding layer netting, checking the core wire, and checking the adhesion between the core wire and the insulating layer, and you can also perform a longitudinal tensile test.
1. Sheath: On the surface, the regular "unevenness" of the braided net in the compression can be seen, 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;
2. Check the shielding layer weaving: whether the number of weaves is enough for the copper material to weave the mesh, check the solderability, scratch the tinned copper wire to see if it is copper wire inside, the hardness of the aluminum-magnesium alloy wire is obviously greater than that of the copper wire; Uneven, not tightly wrapped with the insulating layer, etc. is a bad cable
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 diameter of 1.0mm. The characteristic impedance of this cable is definitely not 75. Ohm, not applied to 75 Ohm transmission system;
4. Check the adhesion force between the core wire and the insulating layer: cut the insulating layer diagonally, and pull the core wire in the peeling direction to see if the core wire and the insulating layer are bonded to the process materials; good cables have greater adhesion, but poor The cable is not stuck;
5. Longitudinal tensile test: Take one meter of control cable, strip the core wire, insulation layer, shielding layer, and outer jacket 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; good cables generally cannot be pulled by force, but poor cables can be easily pulled out without much effort.