power cable

Power cables are cables used to transmit and distribute electric energy. In power lines, the proportion of cables is gradually increasing. Power cable is a cable product used to transmit and distribute high-power electric energy in the main line of the power system, including 1-500KV and above power cables with various voltage levels and insulation.

Purpose of power cable

Power cables are often used in urban underground power grids, outgoing lines of power stations, internal power supply of industrial and mining enterprises, and underwater transmission lines across rivers.

Main classification of power cables

According to voltage grade: according to voltage grade, it can be divided into medium and low voltage power cables (35 kV and below), high voltage cables (110 kV and above), ultra-high voltage cables (275~800 kV) and ultra-high voltage cables (1000 kV and above). In addition, it can also be divided into AC cables and DC cables according to the current system. According to insulation materials: 1. Oil-immersed paper insulated power cables are power cables with oil-immersed paper as insulation. Its application history is the longest. It is safe and reliable, with long service life and low price. The main disadvantage is that the laying is limited by the drop. Since the development of non-dripping paper insulation, the problem of drop limit has been solved, and the oil-immersed paper insulation cable has continued to be widely used. 2. The insulation layer of plastic insulated power cable is extruded plastic power cable. Commonly used plastics include PVC, PE and XLPE. The plastic cable has simple structure, convenient manufacturing and processing, light weight, convenient laying and installation, and is not limited by the laying drop. Therefore, it is widely used as medium and low voltage cables and has the trend of replacing viscous impregnated oil-paper cables. Its biggest disadvantage is the existence of dendritization breakdown, which limits its use at higher voltage. 3. The insulating layer of rubber insulated power cable is made of rubber plus various additives, which are fully mixed and extruded onto the conductive core, and then vulcanized at elevated temperature. It is soft and flexible, suitable for occasions with frequent movement and small bending radius. Rubber materials commonly used for insulation include natural rubber - styrene-butadiene rubber mixture, ethylene-propylene rubber, butyl rubber, etc. Divided by voltage grade: 1. Low-voltage cable: suitable for fixed laying on transmission and distribution lines with AC 50Hz and rated voltage of 3kv and below for power transmission. 2. Medium and low voltage cables: (generally 35KV and below): PVC insulated cables, PE insulated cables, XLPE insulated cables, etc. 3. High voltage cable: (generally 110KV and above): polyethylene cable and cross-linked polyethylene insulated cable, etc. 4. Ultra-high voltage cable: (275 ～ 800KV). 5. UHV cable: (1000KV and above).

Basic structure of power cable

The basic structure of power cable is composed of four parts: core (conductor), insulation layer, shielding layer and protective layer. 1. Wire core is the conductive part of power cable, which is used to transmit electric energy and is the main part of power cable. 2. The insulation layer is an indispensable part of the power cable structure, which electrically isolates the wire core from the earth and the wire cores of different phases to ensure the transmission of electric energy. 3. Shielding layer: power cables of 15KV and above generally have conductor shielding layer and insulation shielding layer. 4. The protective layer is used to protect the power cable from the invasion of external impurities and moisture, and to prevent external forces from directly damaging the power cable.

China's wire and cable market space

The sustained and rapid growth of China's economy has provided a huge market space for cable products. The strong attraction of the Chinese market has made the world focus on the Chinese market. In the short decades of reform and opening up, the huge production capacity formed by China's cable manufacturing industry has impressed the world. The wire and cable industry is the second largest industry in China after the automobile industry, with product variety satisfaction rate and domestic market share exceeding 90%. In the world, China's total output value of wires and cables has surpassed that of the United States, becoming the world's largest producer of wires and cables. With the rapid development of China's wire and cable industry, the number of new enterprises has been rising, and the overall technical level of the industry has been greatly improved. The huge production capacity formed by China's cable manufacturing industry has impressed the world. With the continuous expansion of the scale of China's power industry, data communication industry, urban rail transit industry, automobile industry and shipbuilding industry, the demand for wires and cables will also grow rapidly, and the wire and cable industry has huge development potential in the future.