The process is to make polyethylene (PE) material with linear molecular structure form cross-linked polyethylene with three-dimensional network branching structure through specific processing methods, so that the long-term allowable working temperature is increased from 70 ℃ to 90 ℃ (or higher), and the short-circuit allowable temperature is increased from 140 ℃ to 250 ℃ (or higher), which greatly improves the actual service performance on the premise of maintaining its original excellent electrical performance.

Cable accessories are widely used because they solve the problem of cable tapping in the transformation of overhead line to cable and have the characteristics of full insulation, full sealing, maintenance free and flexible installation and combination. Crosslinked cables are most commonly used in 10kV distribution network. The cable accessories used in matching refer to the terminal head, middle head and cable junction box. In the early days, the traditional oil paper insulated cable terminal head is now rarely used. At present, the most commonly used are heat shrinkable cable head, cold shrinkable cable head and cold shrinkable middle head. The cold shrinkable cable head and cold shrinkable middle head are also called prefabricated cable accessories, which are widely used in the cable distribution network. Because of full insulation, full sealing and full shielding, prefabricated cable accessories are suitable for all kinds of harsh environments, reliably ensure equipment and personal safety, and greatly improve the reliability of power supply. Therefore, they are the direction of future development.

Cross linked polyethylene (XLPE) insulated power cable (hereinafter referred to as cross-linked cable) will produce dendritic discharge channels under the action of electric field and water, which is called water tree. Water tree will continue to grow with the development of time, and eventually lead to insulation breakdown, which has become an important cause of early damage of power cables.

The production and application of ordinary cross-linked cable has a history of nearly 30 years. It has excellent electrical and mechanical properties in dry environment, but in practical application, the cable laying environment is usually bad. The cable often needs to be immersed in water for a short time or a long time, or in an environment with high moisture and humidity, while the ordinary cross-linked cable has no water tree resistance at all, Under long-term use, the insulation will gradually absorb the water in the environment. Due to a large number of small voids in the cable insulation, the micropores will be filled with water, and the water filled micropores can produce water trees under very low voltage. Under the long-term action of electric field, a large number of water tree will be caused in the cable insulation layer, and the aging of water tree will crack the insulation molecules; When the water tree in the micropore reaches the saturation state, the electrical and mechanical properties of the insulation will decline sharply. The conductive water tree (electric tree) will lose a lot of electric energy and eventually cause the breakdown of the cable insulation layer, which will greatly reduce the service life of the cable.