Power cable is the most extensive,the most in demand cable products in the power transmission, distribution and other essential electrical transfer line .
With the social progress and economic development, human depend on electrical energy more and more , the demand for electrical energy is increasing. However, most countries in the world have a problem of uneven distribution of energy and productivity. Therefore, building large-capacity and long-distance power grids has drawn great attention from governments of all countries. In order to reduce the line loss in long-distance transmission, high-voltage transmission technology is required. China is actively developing EHV and UHV transmission and distribution lines. Along with the development of EHV transmission technologies, more and more high demands are placed on power cables, which is an important component of the power grid, and must withstand high voltage and ultrahigh voltage The test. XLPE cable has good electrical performance, large transmission capacity (long-term operating temperature up to 90 ° C, instantaneous short-circuit temperature up to 250 ° C), light weight, less production process, fast production, and manufacturing cycle Short, high drop or vertical laying, easy installation and maintenance, and other advantages of simple structure, has been favored by users, more and more popular in the power sector, its share in the field of high-voltage, high voltage cables continue to increase gradually Replaces the trend of other types of cables. Currently, the international 220KV and below the voltage level of the main high-voltage XLPE cable insulation, 500KV XLPE insulated cables have also been used in the EHV lines.
The long-term operation and experience shows that the aging of the water tree is one of the main factors that lead to the deterioration of the XLPE cable XLPE insulation.The DL / T 1070-2007 standard defines a water tree as "the presence of moisture in the insulation, Electrical stress and certain triggers, such as impurities, protrusions, space charges or ions.When developed into some microchannels. Tubular water trees appear, and bow-tie water trees.
Tubular water trees are water trees developed from insulating shields or conductor shields that are water trees starting from impurities or other defects in the insulation that develop radially toward the insulative shield and the conductive shield.
Water-resistant trees, however, contain cross-linked polyethylene insulation that can retard the development and growth of water-tree insulation, polymer modification or filler.
Reasonable selection of cleanliness assurance, process optimization, etc., the successful development of water-resistant tree performance of the cable.
Water-resistant tree cross-linked cable is mainly through the semi-conductive material resistance to water molecules to penetrate, reducing the depth of water molecules inside the insulation
The probability of improving the molecular stability of insulating materials, and enhance the water-resistant tree growth characteristics of cross-linked cable materials to improve .Water-resistant tree performance. United States Japan Germany from the late 1980s began to study the waterproof function of medium voltage XLPE cable,So that the safety and reliability of the cable doubled. In North America and Europe, water-resistant tree insulation material dominates. Manufacture .Sophisticated cross-linked polyethylene cables can normally be used for an average of 20-25 years, while water-resistant XLPE cables can Use for more than 40 years.
In recent years, some domestic raw materials and cable manufacturers in the water-resistant cross-linked polyethylene materials, products side Face also have started research work.In order to prevent the intrusion of external moisture, UHV cables mainly adopt lead sheath and ultra-clean insulation materials, communication cables
It is mainly the use of aluminum plastic longitudinal package structure, but for the larger amount of medium voltage power cables, the cost of both methods are too
Therefore, the most realistic and effective method to restrain the water tree is to create water tree factors such as micro-gaps, impurities and protrusions,
Specifically, is the use of water-tree insulation materials and clean production technology.
At present, there are not many manufacturers that can independently produce water-resistant tree insulation materials. Zhejiang Wanma is one. According to the document entitled "China Machinery Industry Federation and China Mechanical Engineering Society" (CSL  No. 629) commended the 2011 China Machinery Industry Science and Technology Award project, Zhejiang "Wanma Polymer Materials Co., Ltd." Water tree cable insulation material "won the 2011 China Machinery Industry Science and Technology Award third prize, computer code: 1102072. This is also another award after winning the third prize of Hangzhou Science and Technology Progress Award in 2011. Many honors obtained from water-tree cable insulation materials mean that polymers are at the forefront of the industry in the field of water-tree cable insulation materials research and will also encourage us to devote more efforts to product R & D and innovation in pursuit of more High goals, to create a new height.