First, consider the mechanical properties of insulation -- insulation material performance is the key
1, PVC than polyethylene soft, high mechanical strength, good wear resistance, from this point should be preferred PVC. Gb12527-90 standard provisions, PVC tensile strength for 12.5MPa.
The measured tensile strength of PVC cable material reaches about 20 MPa. The tensile strength of polyethylene is stipulated in the standard 10MPa, lower than PVC, the measured value is only about 14MPa, much lower than the measured value of PVC.
2, in the erection of the line, the cable in the ground, PVC cable is not easy to be broken and raised, and polyethylene, on the contrary, is easy to be broken and raised.
In contact with the metal under pressure and tree trunk leaves contact friction, PVC due to high mechanical strength and not easy to be crushed and worn.
Second, consider the atmospheric aging properties - crosslinked polyethylene molecular structure determines the performance
In the process of crosslinking, the linear state of polyethylene molecules is transformed into a network structure through cross-linking agent bypass. The macromolecular chains are closely connected with each other, enhancing the resistance to external force damage. In addition, with the functions of light screening agent and antioxidant, the ability of cross-linked polyethylene to resist atmospheric aging is no longer concerned.
Summary of selection of low-voltage overhead cable:
(1) low voltage overhead polyethylene insulated cable
Although it has excellent insulation performance, it has poor mechanical performance, poor flame retardant performance and poor heat resistance, especially in the aspect of environmental stress cracking resistance and lack of longer time test and experience accumulation for the overlaying, it is suggested that it should be extended after long-term test and research on the laying.
(2) low voltage overhead crosslinked polyethylene insulated cable
Excellent insulation, mechanical properties, heat resistance and deformation. However, due to the high price, it is suggested that under the current economic conditions, it is more suitable for special occasions.
(3) low-voltage overhead PVC insulated cable
Through theoretical analysis and long-term laying practice for more than 30 years, it has been proved that it has the advantages of good atmospheric aging resistance, high mechanical strength, resistance to support, abrasion resistance, fire resistance, etc., as well as insulation ability and water resistance, which can meet the requirements of low-voltage power grid. Therefore, it should be the first choice for the transformation of low voltage power grid.