Power cables have long been widely used in our lives. The safety of their operation is related to our normal life and the safety of life and property. Therefore, the maintenance of cables is a vital work. The following small series will analyze what we need to know about the correct use of power cables.
1、 Test, acceptance and operation of power cable
In addition to handover test and preventive test, insulation test shall also be conducted for power cables during construction to identify and inspect cable quality and process quality in all links of construction. Test on the cable reel before laying to identify the quality of the cable; Conduct tests after and before laying to identify whether the cable is damaged during laying; Test shall be conducted after the construction of cable head to identify the quality of cable head; Tests shall be conducted before and after cable maintenance to identify the maintenance quality. The main contents of the inspection are as follows:
1. The cables shall be arranged neatly, the fixing and bending radius of the cables shall comply with the design drawings and relevant regulations, the cables shall be free of mechanical damage, and the signboards shall be installed completely, correctly and clearly. The terminals and intermediate joints of oil immersed paper insulated cables and oil filled cables shall be free of oil leakage;
2. There shall be no sundries in the cable trench and tunnel, the cover plate of the cable trench shall be complete, and the lighting, ventilation, drainage and other facilities in the tunnel shall meet the design requirements;
3. The marker pile of directly buried cable shall be consistent with the actual path and the spacing shall meet the requirements. The signs shall be clear, firm and durable;
4. Signs and night lighting devices on both banks of underwater cable line and in anchor prohibition area shall meet the design requirements;
2、 Precautions for cable line operation
1. Do not overload or overheat for a long time. Therefore, do not ignore the monitoring of cable load current, external temperature and joint temperature;
2. Cable line feeder protection shall not be put into reclosing. Most cable line faults are permanent faults. If reclosing action, it will inevitably expand the accident and threaten the stable operation of power grid;
3. After the feeder of the cable line trips, do not ignore the inspection of the cable. Focus on checking whether the cable path is excavated and whether the wire is damaged. If necessary, further inspection and judgment shall be made through test;
4. Special attention shall be paid during the operation inspection of directly buried cables: the ground near the cable path shall not be excavated casually; Heavy objects, corrosive substances and temporary buildings are not allowed to scale on the ground near the cable path; Cable path marker posts and protective facilities shall not be moved or removed at will;
5. After the cable line is out of service, it must be retested before it can be put into use;
3、 Cable line maintenance
The operation and maintenance of cable line is important to do a good job in three aspects: load monitoring, cable metal sleeve corrosion monitoring and insulation monitoring. The main items include: patrol inspection of cable line, cable preventive test, prevention of cable external force damage, analysis of cable fault causes, cable fault detection and wire fault repair. If the cable is damaged, It is necessary to completely eliminate the cause of the fault before repairing or replacing the cable.
When replacing the cable, it can be selected according to the fault causes or environmental characteristics. For example, YJV cross-linked polyethylene cable can be used in places with strong corrosion, high humidity and high temperature. The cross-linked polyethylene insulated power cable has the characteristics of high mechanical strength, good environmental stress resistance, excellent electrical performance and chemical corrosion resistance. In addition, its mechanical strength can be enhanced by adding armor, Make it suitable for tunnels, cable trenches and other environments or directly buried underground.
Although the maintenance work is cumbersome, it is the guarantee for the normal operation and use of the cable. After all, maintenance is always more effective than mending after an accident. Cable failure may not only affect our daily life or work and production, but also cause major safety accidents and life losses, which are irreparable. Therefore, the maintenance of power cables must not be ignored.