From the electrothermal characteristics, XLPE and EPM are also the best. The dielectric loss of PVC is too high to be used in high voltage systems. The thermal resistance of PVC is also high, which affects the heat dissipation of cables.
As the material of cable insulation and heat shrinkable pipe, cross-linked polyethylene and ethylene propylene rubber are widely used at present, especially cross-linked polyethylene, which has the most development prospects. PVC insulation is still used in 1-6 kV power cables and other low voltage cables. Due to the poor thermoelectric performance of PVC, the conductor cross section of PVC insulated power cable must be increased compared with XLPE at the same current carrying capacity. If used in 1 kV power cable, the cross section of conductive core should be increased by 15%-20%, and 20%-30% when used in 6 kV power cable. It can be predicted that besides being used for low voltage flame retardant and other special occasions, PVC insulated power cables will always be replaced by XLPE insulated power cables in the future. The cost of XLPE power cables can be reduced by 20% to 30% compared with other common power cables when the same power is transmitted. In the modern production of power cable in our country, we must actively promote it.
At present, the price of other polymer insulating materials such as thermoelastic rubber (TPE) is higher, while fluoroplastics (PTFE) and silicone rubber (MQ) can only be used when high temperature insulation is required. This paper mainly introduces the design and production of XLPE power cable.
Ethylene-propylene rubber insulated cables have been widely used in fire-resistant, flame-retardant and atomic radiation-resistant cables. Ethylene-propylene rubber insulation is also often used in large-length underwater cables such as 35kV river crossing and sea crossing. It has better flexibility and water tree prevention characteristics than XLPE cable.
PVC cables have good flame retardancy and are widely used in low voltage cables below 1kV, multi-core control cables and indoor wiring.
At present, more than 500 kV ultra-high voltage polymer insulated power cables are being developed, and 275 kV and below XLPE insulated power cables have been put into the market.