Treatment Method for Moisture of XLPE Power Cable
In urban power grid reconstruction projects, cables, especially polyethylene insulated power cables, have been widely used. However, due to the particularity of the cable, there are special requirements for the installation, operation and maintenance of the cable. Cable dampness or water ingress reduces the insulation resistance of the cable, it is a few important aspects that cause the operation accident of cable line.
Causes and hazards of cable flooding:
1.The whole new cable is sealed with a plastic seal at both ends of the cable when it leaves the factory. However, after a section of the cable is used at the construction site according to the actual situation, the remaining part is simply wrapped with a plastic cloth to break the gap. Since it is usually placed in the open air and the seal is not good, it will inevitably have water vapor infiltrated into the cable.
2.When laying a cable, it is necessary to pass through roads, bridges, culverts, etc. Because of the weather or other reasons, a lot of water is often accumulated in the cable trenches. During the laying process, it is inevitable that the cable heads will dip in the water. The water enters the cable due to the loose binding or breakage of the plastic sheeting; In addition, the outer sheath and even the steel armour may be scraped when traction and pipe piercing, especially when mechanical traction is used.
3.After the cable laying is completed, the cable head is not produced in time due to the limitation of on-site construction conditions, so that the unsealed cable breakage is exposed to the air for a long time, even immersed in water, so that the water vapor enters the cable in large quantities.
4.During the cable head making process (including the terminal head and the intermediate joint), the newly processed cable ends sometimes accidentally fall into the accumulated water in the site due to the negligence of the construction personnel.
5.In the normal operation of the cable, if the breakdown occurs for some reason, the water in the cable ditch will enter the cable along the fault point. In civil construction, especially in the construction site where large construction machinery is used, cable breakage or breakdown accidents caused by various human factors are common. When such an accident occurs, the insulation of the cable is seriously damaged, which also causes the cable to enter water. After the cable enters the water, under the action of the electric field, aging will occur, and finally the cable will break down.