gui chao cable news: video line appearance
from：guichao author：admin click： 329 addtime：2017-04-13 16:03:36
visual appearance identification:
1 pvc sheath:
the surface can be seen inside the compression of the network has a regular "roughness"",
it shows that the processing technology is good, it will not produce relative sliding.
the appearance of smooth, can not see the compression of the network "roughness",
with the hand pinch sheath is loose, is poor cable;
2 check the shielding layer network:
is that enough? copper wire mesh, check solderability,
tinned copper wire scraping inside is not copper,
the hardness of al mg alloy wire is obviously larger than that of copper wire;
sparse distribution, uneven distribution,
and the insulation layer is not tight, such as cable;
3 check the core:
diameter syv cable is 0.78-0.8mm,
sywv cable for 1.0mm;
a cable with a syv75-5 core diameter of 1.0mm has been developed recently,
characteristic impedance of the cable,
definitely not 75 ohms,
not applied to 75 ohm transmission system;
4 check the bonding force between the core and the insulating layer:
the insulating layer is cut obliquely, and the core line is opened according to the peeling direction,
see the core line and the insulation layer has no bonding process materials;
the good cable has a large adhesion force, and the differential cable does not match;
5 longitudinal tensile test:
take one meter cable, delamination core line,
insulating layer, shielding layer, outer cover,
each stay 10 cm long.
the method is that two hands are respectively holding two adjacent layers of the cable,
pull in the opposite direction;
good cable general force pull,
poor cable can not easily pull out vigorously,
elevator cable is very important,
many so-called elevator cable are the existence of this problem.