The power cable core is prone to sharp burrs during the pressing process. As the operating voltage increases, the electric field on the conductor surface increases, and the electric field of the burr tip is seriously distorted, causing the main insulation dendritic discharge.
　　1. Water tree branches deteriorated
　　It is the main reason for the XLPE cable accident, accounting for 71% of the accident, mostly in natural deterioration.
　　2. Copper shield tape is broken
　　In the cable with one end of the copper shield, when the copper shield tape is broken, the copper shield tape at the non-grounded end becomes non-grounded, and the copper shield tape will induce a high voltage. If the high voltage causes the discharge to occur at the fracture site, Often cause insulation damage.
　　Copper shield with a broken feature is:
　　(1) single-core cable than the three-core cable accidents.
　　(2) from the operation to the destruction of time, ranging from weeks to years.
　　(3) the conductor resistance at the fracture site is increased to several thousand euros, and the ground flashover of the non-ground side cable can not be protected.