Three methods of XLPE cable cross-linking process

DATE: 2017-6-27 16:38:02 | HITS:270

XLPE cable is the use of XLPE (cross-linked polyethylene) material as insulating layer of the cable, In the production process, the physical  or chemical method is used to change the molecular structure of XLPE (cross-linked polyethylene) from linear molecular structure to network linear structure. After changing the molecular structure of XLPE material, The long-term working temperature of the cable is increased from 70 DEG C to 90 DEG C centigrade or above, when it is short circuited the temperature is allowed to increase from 140 DEG C to 250 DEG C or above. The cable has greatly improved its application range and performance under the condition of maintaining the original electrical performance;


Figure 1:YJV22-26/35KV-3*300mm2 XLPE cable

At present, the process of cable cross linking can be divided into three categories:

First kind   chemical cross-linking of silane;

Second kind   Peroxide chemical cross-linking, including saturated vapor cross-linking and inert gas cross-linking, molten salt cross-linking , silicone oil cross-linking, in China, second kinds of cross-linking methods are used, i.e. dry chemical cross-linking;

Third category   Irradiation cross-linking;

1、Chemical cross-linking of silane;

Chemical cross-linking of silane is also called warm water cross-linking and wet cross-linking. Warm water cross-linking adopts adding silane cross-linker material,

Through the extrusion of 1+2, the extrusion of the outer shield layer - the insulating layer - the insulating shield layer is completed, The insulating wire core which has been cooled and loaded with a cable reel is dipped in 85-95 DEG hot water to hydrolyze and crosslink, The moisture content in the insulating layer will be affected by wet cross-linking. Generally the highest voltage level is only 10KV.

2. Inert gas cross-linking

Polyethylene cross-linked material added with peroxide cross-linking agent in dry chemical cross-linking process,After the extrusion of the three layer extrusion of the conductor shielding layer insulation layer and the insulating shield layer, the cross-linking process is carried out continuously and uniformly through a sealed cross-linked pipe filled with high temperature and high pressure nitrogen. The heat transfer medium is nitrogen (inert gas). XLPE has excellent electrical performance and Production range up to 500KV grade.


 Figure 2:  YJLW03-Z-290/500KV-1*2500mm2  XLPE cable

3. Irradiation cross-linking

Irradiation cross-linking is also called physical cross-linking. The modified polyethylene insulation material is used for physical cross-linking, Through the extrusion methods of 1+2, the extrusion of the outer shield layer - the insulating layer - the insulating shield layer is completed,The cooled insulated wire core is uniformly irradiated by a scanning window of a high-energy electron accelerator. The irradiation cross-linking process does not adding cross-linking agent, and the high-energy electron beam produced by the high-energy electron accelerator penetrates the insulating layer effectively during cross-linking, and produces cross-linking reaction through energy conversion,

Because the High-energy electron band has very high energy and evenly passes through the insulating layer, therefore, the formed cross-linked bond has the advantages of high energy and good stability. In the process of using, the heat resistance of the cable is better than that of the chemical cross-linking cable. However, due to the limitation of the energy stage of the accelerator (generally less than 3.0Mev, the effective penetration thickness of the electron beam is below 10mm.). Considering the geometric factor, the voltage level of the production cable can only reach 10KV, and the advantage is below 6KV.

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Date: Tuesday, June 27, 2017

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