When laying a variety of plastic power cables, will be subjected to a variety of mechanical external forces, such as bending, stretching, torsion, positive pressure, shock and vibration. All mechanical external forces, imposed on the cable will cause some damage to the cable. In order to protect the integrity of the cable structure and electrical properties and improve the service life of the cable, it is necessary to add an armor layer to the outer sheath of the cable.
There are usually two types of cable armor, steel armor and steel armor.
In order to allow the cable to withstand radial pressure, the use of double steel strip, the gap around the package process, known as steel tape armored cable; cable into the cable wrapped around the core, and then extruded plastic sheath. The representation of such cable models such as control cable KVV22, plastic cable VV22, communication cable SYV22, and so on. The two Arabic numerals in the subscript of this type of cable, the first: "2" means double steel tape armor; the second: "2" means a polyvinyl chloride sheath, such as a polyethylene sheath to "2 "To" 3 "can be. This type of cable is generally mainly used in the bearing pressure than the larger occasions. For example: cross the roads, squares and vibrations relatively large side of the road, the railway side, suitable for buried, tunnels and pipe laying.