What are the issues to pay attention to in the construction of power cables

1. It is an eddy current problem caused by high current power cables

During the construction of power cables, some use steel supports, some use steel protective tubes, and some use cable clamps and overhead laying. Any steel (iron) closed circuit formed around the power cable may generate eddy currents, especially in high current power cable systems where eddy currents are even greater. During the construction of power cables, measures must be taken to prevent the formation of a steel (iron) closed loop around the cable and prevent the occurrence of eddy currents caused by the cable.

2. It is a mechanical damage problem caused by the turning of power cables

Due to the large outer diameter of power cables, transportation and laying are difficult, and the requirements for turning radius of power cables are also quite strict. During the construction of power cables, if the turning angle is too large, it may cause mechanical damage to the inside of the conductor. Mechanical damage is caused by a decrease in the insulation strength of the cable until a fault occurs. During construction, a cable head fault was discovered. During the production of the cable head, the lengths of the three cable heads were the same. When connected to the equipment, due to terrain limitations, the middle phase cable head was too long and became arched, causing damage and discharge at the root of the cable head. Afterwards, measures were taken to appropriately shorten the length of the middle phase cable head connection in the equipment connection, so that the three-phase cable heads are not subjected to external forces. Practice has proven that the operation effect is good. From this, it can be seen that during the cable construction process, it is necessary to minimize the torque on the cable as much as possible. When turning and leaving room for the cable, the cable should be naturally bent to prevent internal mechanical damage.

3. It's a moisture-proof issue with power cables

Operating experience has shown that most of the faults in medium and low voltage power cables are caused by faults in the middle joints and terminals of the cables, while faults in the middle joints and terminals are mostly due to poor sealing and moisture intrusion, resulting in a decrease in insulation strength. However, medium and low voltage power cable networks often use dendritic power supply methods, with a large number of cable terminals. Therefore, sealing and sealing the cable terminals and middle joints is one of the important measures to ensure the safe and reliable operation of the cables.

4. It is a grounding issue for medium and low voltage power cables

In public medium and low voltage power cable networks, due to the unequal three-phase loads, if cables with metal protective layers are used, the grounding of the metal protective layer must be considered, and the normal induced voltage at any non grounded point of the metal protective layer must not exceed 100V. I believe that in medium and low voltage cable networks, grounding (grid) should be installed at all cable joints, and the metal protective layer should be reliably grounded.