In the cross-linked insulated wire and cable, the main cross-linking method is inert gas (nitrogen) cross-linking, warm water cross-linking, irradiation cross-linking three kinds, for the production of 10-500KV 70mm2 or more large cross-section, high voltage level of the cable, the main use of inert gas cross-linking (dry chemical cross-linking) to complete. The inert gas crosslinking is made of polyethylene insulating material with peroxy compound crosslinking agent. After three layers of co-extrusion, the conductor shielding layer -- insulation layer -- insulation shielding layer is extruded, and the sealing crosslinking pipe filled with high temperature and high pressure nitrogen is continuously and evenly formed. The heat transfer medium is nitrogen (inert gas), the crosslinked polyethylene has excellent electrical performance, and the production scale can reach 500KV.


The test shows that nitrogen meets the technical requirements of GB3864 industrial nitrogen, and is used as the heating medium in the production of cross-linked cables, which can improve the quality of cross-linked cables, save investment and have a high degree of automation. It requires nitrogen purity ≥ 99.5%; Nitrogen pressure 1.2 ~ 1.6MPa; Dew point ≤-40 ℃.


In the past, most cross-linked production line manufacturers selected bottled nitrogen, but because most bottled nitrogen is the by-product gas of other manufacturers' cryogenic oxygen production devices, the purity of most bottled nitrogen is not good, and oxygen and water indicators often overspend. If the water content of the medium is too high, water vapor occurs when the temperature is too high, forming bubbles contained in the plastic state of PE, which will make PE age early. Therefore, the selection of nitrogen gas source required for dry cross-linked production line is very important.


The nitrogen making machine uses pressure swing adsorption (PSA) nitrogen production principle, which has the characteristics of simple process flow, normal temperature production, low energy consumption, high degree of automation, easy to start and stop, less maintenance, product nitrogen purity can be adjusted with gas volume, etc., is an efficient on-site nitrogen production system.