There are several reasons and treatment methods for the insulation breakdown of wires and cables:
One is mechanical damage. Due to heavy objects hitting the wires and cables, the excavator accidentally injured the cables, the cables were bent over during laying, and the insulation was injured. The cables were severely squeezed during shipment and the insulation and protective layer were damaged. The direct buried cables suffered excessive tension due to the sinking of the bottom layer. And so on, all cause insulation damage, and even pull the cable. Overhead cables can be used to avoid mechanical damage to the cables. If the cables are laid along the wall, they should be covered, and the burial should be clearly marked, and timely stop taking soil near the cable line.
2. Improper construction can also cause wires and cables. Due to poor construction methods and poor quality of materials used, the cable head and the weak links in the middle failed, resulting in breakdown of the insulation layer. To prevent this phenomenon, the installation quality of the cable head should be improved. During the production and installation of the cable head, the insulation bag should be tight and no gaps should appear. Before epoxy resin and quartz powder, strict drying treatment should be carried out to prevent bubbles and moisture from entering the cable head, and strengthen the insulation treatment of the edge of the lead sheath.
Third, the insulation is damp. Due to the poor construction process of the wire and cable head, moisture can penetrate into the cable, or the inner sheath of the cable is damaged and moisture can enter. Lead-clad cables are laid near the source of the earthquake, causing fatigue cracks due to long-term vibration. The cable sheath is corroded to produce cavities. Due to poor manufacturing quality, there are small holes or cracks in the lead package. In view of these situations, the maintenance of the outer layer of the cable should be strengthened, and a layer of asphalt should be applied to the outer protective layer regularly.
The fourth is overvoltage. The insulation layer is broken down due to atmospheric overvoltage or internal overvoltage, especially the internal overvoltage of the system will cause multiple cables to be broken down at the same time. In this regard, lightning arresters should be installed to improve the technological level of automatic protection of the system.
Post time: Jul-29-2020