High quality and stable cable is the guarantee to ensure the safety of power transmission and transformation. What should be paid attention to in the construction of power cable.

1. Cable eddy current.

The so-called eddy current causes. In the construction of power cables, some use steel supports, some use steel protective tubes, some use cable clamps and overhead laying. If a steel (iron) closed circuit is formed around the power cable, eddy current may be formed. This phenomenon will not only cause the continuous consumption of electric energy, but also cause the rising of metal temperature and the burning of cables Fire.

Especially in the high-voltage cable system, the eddy current is larger. During the construction of power cable, measures must be taken (which measures will be further discussed in the future articles), so that the steel (iron) closed circuit can not be formed around the cable to prevent the occurrence of eddy current caused by the cable.

2. Mechanical damage caused by power cable turning.

Due to the large outer diameter of power cable, it is difficult to transport and lay, and the requirements for turning radius of power cable are also strict. In the construction of power cable, if the turning angle is too large, it may cause mechanical damage inside the conductor, and the mechanical damage is caused by the decrease of the insulation strength of the cable until the failure occurs. A cable head failure is found in the construction. When the cable head is made, the length of three cable heads is the same. When connecting with the equipment, due to the limitation of the terrain, the middle phase cable head is too long and becomes an arch. The cable head Root damage discharge. After that, measures should be taken to properly shorten the connection length of the middle phase cable head so that the three-phase cable heads are free from external forces. The practice has proved that the operation effect is good. It can be seen that in the process of cable construction, the torsion on the cable should be reduced as much as possible. When the cable turns and is reserved, the cable should be in natural bending to prevent internal mechanical damage.

3. Cable moisture-proof.

The operation experience shows that most of the faults of the medium and low voltage power cables are the faults of the cable intermediate joints and terminal heads, while most of the faults of the intermediate joints and terminal heads are caused by the poor sealing and the moisture intrusion, which leads to the decrease of the insulation strength. However, the branch power supply mode is often used in the medium and low voltage power cable network, and the number of the cable terminal heads is large, so the cable terminal heads and intermediate joints shall be plugged properly Leakage sealing is one of the important measures to ensure the safe and reliable operation of the cable.

4. Grounding problems of medium and low voltage cables.

In the public medium and low voltage power cable network, since the three-phase load is not equal, if the cable with metal sheath is used, the grounding problem of metal sheath must be considered, and the normal induced voltage at any point of the metal sheath at the ungrounded place shall not be greater than 100V. The author believes that in the medium and low voltage cable network, all cable joints should be equipped with grounding electrodes (Network), and the metal sheath should be reliably grounded.