Analysis of Defects in the Conductor Shielding of Interconnected Power Cable
Introduction
The cable shield has an important function in power cables, which is to protect the inner conductor from external electrical fields. At the same time, the shield can strengthen mechanical strength and reduce the noise radiation of the cable. Shielding for power cables is mainly composed of an uninsulated metal tube (a copper tube in the case of copper cables), a semi-conductive material layer and other components (such as fillers). When the cable is laid at a certain distance, a certain electric field will be generated between the two electric conduits, and thus a certain amount of current flows between the two electric conduits. When using the electric cable in the current-carrying electric field, if the conductor shielding layer is not provided or there is a defect, the current caused by the electric field between the two electric conduits will increase. This will cause interference of various signals overhead, exacerbating external noise and affecting the safety of power supply system. Therefore, the detection of the defect of the shield should be taken seriously for power cables.
Overview of Interconnected Power Cable Shield Defects
Power cable shielding defects are mainly caused by leakage of water, seepage, cracks and other factors. The main types of these defects are:
1) Water leaks, seepage and cracks in the metal casing of the electric conduit: If there are water leaks, seepage or cracks in the metal casing of the conduit, when current flows in the electric field, it will cause the current to leak from the metal casing. The current will flow to the ground from the water in the casing or the soil around the cables, causing grounding of current and affecting the normal voltage of the cable.
2) Defective grounding of the electric connector: The connectors of the cables should be firmly grounded. When the grounding is defective, it will also cause current leakage, which will cause problems such as increased voltage and interference of external signals.
3) The shielding layer is affected by heat, corrosion and other reasons: Deterioration of the electromagnetic wave absorption function of the shielding layer will cause excessive interference of external signals and will affect the normal operation of the power supply system.
Analysis of Defects in Interconnected Power Cable Shield
Interconnected power cable shields must ensure good shielding performance and physical properties, so as to guarantee the normal operation and safety of power cables. In order to ensure the effective detection of the defects in the shielding of cables and guarantee the safety of power supply, the relevant departments shall take the following measures for inspection and processing of the defects.
1) Pay attention to the protection of the cable itself: When the power cable is laid, attention should be paid to the protection of the cable itself, such as keeping the environment and soil clean, avoiding the penetration of rainwater or corrosive substances, carefully checking the grounding protection of connectors, and doing a good job in the construction of waterproof and moisture-proof. In addition, the construction in other process steps should be standardized, not arbitrary construction.
2) Strengthen the testing of the shielding layer and metal casing: After the construction of the power cable is completed, the electric cable and metal casing should be tested in a professional field, to check whether there are defects in the shielding layer and metal casing. If there are any defects, they should be repaired in time to ensure the shielding performance of the power cable.
3) Increase the identification of connecting terminals and connections: The connecting terminals and connections of the cables should be checked frequently to ensure that the electrical connection does not become loose and the surface does not corrode, so as to ensure that the grounding performance at the connecting terminals is intact and meets the requirements.
4) Always focus on the functionality assessment and testing of the cable shield: Regular maintenance or functionality assessment should be carried out to check the shielding performance of the shield, to confirm that the normal voltage is maintained and there is no effect on the external environment.
Conclusion
In summary, defects in the interconnecting power cable shielding layer can cause problems in the power supply system such as grounding of current, increased voltage and interference of external signals. Therefore, it is necessary to pay attention to the protection of the power cable during laying, strengthen the shielding layer and metal casing testing, increase the identification of connecting terminals and connections, and conduct regular maintenance and functionality assessment of the shielding layer to prevent and mitigate defects in the shielding layer of the power cable and ensure the safe operation of the power supply system.
