日本久久99成人网站,国产69精品久久久久孕妇,亚洲国产激情另类小说区,婷婷综合缴情亚洲狠狠

Power cables and accessories are the key products for transmission and distribution of electric energy in the trunk lines and distribution network lines of the power system, mainly including AC power cables and accessories with rated voltages of U0/U0.6/1kV-290/kV of all voltage levels. Among them, the rated voltage of 1.8/3kV and below is low voltage power cable, 3.6/6kV-26/35kV is medium voltage power cable, 66kV~110kV is high voltage power cable, and 220kV and above is ultra-high voltage power cable. In recent years, China has promoted the development and application of flexible DC cables, including DC power cables and accessories of all voltage levels within the rated voltage Uo10kV~525kV.

Power cables are basically classified according to the types of insulating materials. Extruded fixed insulation power cables, represented by XLPE insulation materials, have been widely used. At the same time, there are a small number of oil impregnated paper insulated ("MI cable" for short) power cables and oil filled ("OF cable" for short) paper insulated power cables. During the 13th Five Year Plan period, superconducting power cables and GIL gas insulated lines have also been continuously developed and applied in engineering. PP (polypropylene) thermoplastic insulation material with environmental protection characteristics is called a new type of power cable, which is under development and engineering demonstration application in China.

Power cables are divided into land cables and submarine cables according to the use scenarios. In recent years, submarine cables have been rapidly developed and widely used, especially the development of offshore renewable energy (wind power), which has promoted a large demand for submarine cables.

6kV and above power cables need to be equipped with cable accessories of corresponding voltage levels. Cable accessories include terminals and intermediate joints, including wrapping, molding, cold shrinkage, heat shrinkage, prefabrication, combination and other forms.

The characteristics of power cables, whether land cables or submarine cables, AC cables or DC cables, are as follows: the voltage level ranges from lkV to 500kV, and the current voltage level tends to be higher; The specification range is wide, from 1.5 mm to 3500 mm, and now tends to be larger conductor cross-section. Power cable is not only widely used in distribution network, but also an important foundation and indispensable product for power transmission of backbone network. The transmission capacity is becoming larger and larger, and the operation safety and reliability are becoming more and more important. People not only pay attention to the quality improvement and technical improvement of power cables and accessories, but also study the reliability of power cable system operation, including the electrical factors, mechanical factors, temperature and environmental factors of the system, as well as the mutual integration and coordination; It also pays more attention to the economy and durability of the power cable system operation, including the transmission capacity, loss, maintenance cost of the cable system and the rapid recovery capability in emergency. Therefore, the power cable system is faced with the challenges of quality improvement, operation economy, reliability and durability, involving material innovation, structural innovation and manufacturing process innovation. Faced with the new requirements of social progress, urban development and environmental coordination, the challenges of long-distance transmission underground cabling involving large capacity, low loss, easy laying, operation and maintenance, and intelligent control, as well as the challenges of the development and application of marine resources and new energy, and the reliability of safe transmission of electric energy in complex environments such as the seabed.

In recent years, China's cable industry has made great progress in the above areas, but there is still much room for improvement, perfection and promotion. In the field of manufacturing, the integration of fine management, informatization, equipment automation and digitalization of power cable manufacturing is still on the way to achieve high-quality intelligent manufacturing and development. In the application field, the construction of high-voltage, high-capacity, long-distance underground and undersea power transmission networks, the development and application of corresponding materials and high-end equipment still have a big gap compared with the international technical level.