Power cable is the transmission or distribution of high-power power cables in the power system. With the development of petrochemical industry in the world, plastic insulated power cable is an important variety in low-voltage power cable because of its simple manufacturing process, convenient construction and maintenance.

      However, in the plastic insulation extrusion process will inevitably have impact, scraping, compression, breakdown and other defects, in order to ensure the fixed-length production, reduce waste, while ensuring that the electrical performance of finished cable to meet the standard requirements, the need to find suitable insulation damage repair methods.

1 Hot Welding Repair method Thermal welding is the use of a power to the appropriate electric iron, with the heat of the solder to fuse insulation.

　　 1.1 Low-voltage PVC insulated Cable PVC material belongs to thermoplastic material, which should be used as thermal welding form when the cable insulating layer is damaged and repaired.

In order to ensure and enhance the electrical and mechanical properties of the repair place, the insulating tape is used to overlap the single layer of the repair place, and the wrapping should be flat.

1.2 Low-voltage XLPE insulated Cable The crosslinked polyethylene material belongs to the thermosetting material, and after silane crosslinking, the insulating molecule is meshed and cured. The insulation breakage repair is repaired by hot welding before the water crosslinking process of the insulated core. Then use the Scotch tape to the repair place around the bag, to prevent the repair from falling off; After the insulation core boiled water crosslinking process, the insulating layer breakage should first adopt the hot welding method patching, then uses the pressure grade for the 35kV high pressure self adhesive tape carries on the overlapping wrapping,

and ensure that the high-pressure tape around the package must be flat.

2 Heat shrinkable Pipe Repair method

　　 Heat-Shrinkable Pipe repair method is to fit the size of the heat-shrinkable tube to the defect point, heating shrinkage and tightness defects.

Whether the insulating materials are thermoplastic polyvinyl chloride or thermosetting crosslinked polyethylene, the nominal section is less than 10mm2 insulation core, should be used to repair heat shrinkable pipe, heat shrinkable pipe repair, with insulating tape for winding.

3 Comparison of repair methods

Hot welding repair by means of soldering iron and other tools to repair, insulating layer performance to achieve complete cable level, but the repair process is relatively complex, requiring operators to have a higher level of technology.

For the small section of the core, if the use of thermal welding repair, not easy to ensure the quality of repair, should be used heat-shrinkable pipe repair method. In order to ensure that the electrical properties of the insulation core after patching meet the standard requirements, the insulating layer spark test, the finished product voltage 3.5kv/5min withstand pressure test must be carried out. The above repair method is only suitable for the small range of insulation damage, for scratches, compression, injury and other serious defects, in order to ensure product quality, not to be repaired.