1. Common faults of empty overhead cable lines
1. Overhead line failure
①Short circuit and damage of wires. The reasons that cause short circuit and damage to the wire are:
a. The distance between the wires and wires is small, and the flatness of the three-phase wires is different. It is very easy to cause color collision and short circuit when the wind blows, and the wires are burned.
b. Tree technology and internal metal objects falling on the line; accidentally touching the line when the crane is working also cause the wire to be short-circuited and damaged.
c. Long-term erosion by harmful substances in the surrounding environment, with a reasonable cross-section reduction. The damage to the wire is not very serious, and the method of laying wire maintenance can be considered as appropriate to solve it.
2. The wire connector is overheated. The reasons that lead to the over-temperature of the wire connector are:
a. The load current of the wire exceeds the larger specified value of the wire cross section.
b. The quality of the construction work of the wire connector is not good.
c. The circuit has been blown by rain and wind for a long time, and air oxidation and erosion have become more and more serious: the resistance of the connector loop increases: the hazard is hot. Department is
If the wire is overheated, you can try to reduce the load. Monitor the operation again, and allocate and solve it according to the development trend.
2. ABC Cable line failure
In terms of conditions, common cable faults include mechanical equipment damage, lead (aluminum) cracking, bursting, environmental pollution of terminal equipment heads, explosion of terminal equipment heads or intermediate connectors, insulation penetration, and metal material protection wire Common faults such as sleeve erosion holes. For this reason, common cable faults include damage by external force, chemical corrosion or electric erosion, lightning strikes, water immersion, improper construction of plant diseases and insect pests ↓Improper maintenance and other common faults. Common cable faults and avoiding methods are as follows:
① Water seepage of the plastic cable: Once the plastic is invaded by water, it is very easy to cause embrittlement of the insulation layer, especially when the temperature of the conductor is high, the infiltration and embrittlement caused by the water in the conductor is more serious. Therefore, no water seepage is allowed in the transportation, storage, laying and operation of plastic cables.
②Cable overload operation: The safety factor of cable operation is not so much related to the current carrying capacity of the cable. Overloading may increase the failure rate of the cable, and at the same time, it will continue to reduce the service life of the cable. The cable damage caused by overload is mainly in the following aspects:
a leads to the destruction of the wire contacts;
b. Speed up the embrittlement of the insulation layer of the cable maintenance;
c. Make the lead bag of the cable swell and even crack, such as the fatigue, cracking, and cracking of the lead bag caused by the long-term overload of the cable with poor quality of production and poor installation standards;
d. The cable terminal equipment head is swollen and cracked by the bituminous insulating rubber.
③Destroyed by external force: Some of the safety accidents of the cable itself are caused by the destruction of mechanical equipment under external force. According to the investigation, the damage of mechanical equipment caused by external force caused by improper municipal management methods and improper construction of the project is about It accounts for 50% of cable safety accidents. Therefore, when cables are transported, hoisted, and laid through regenerated buildings, care must be taken to avoid the harm of external forces. During the construction of the surrounding engineering of the cable line, it is necessary to remind the construction workers to pay attention to this point and implement safeguard measures when necessary.
④Environmental pollution of the waterproof casing of the cable terminal equipment head: The key method is to clean the waterproof casing on time, and it is best to carry out complete cleaning under the power-off standard: in the area with serious pollution, the waterproof casing of the cable terminal equipment head should be coated Stain-resistant architectural coatings, or moderately improve the flame retardant grade of waterproof casing.
⑤The water seepage of the outdoor terminal equipment head explodes: mainly because of unreasonable operation and maintenance, the condensed water of the terminal equipment head will accumulate in the cable head, and finally cause the insulation layer to penetrate back and cause an explosion.
⑥The cable’s middle connector exploded: most of the cases were caused by the over-loading of the insulating rubber in the connector box and the shell swelling, or the poor conductor connection caused the connector to overheat and explode.
⑦The inspection of outdoor cable terminal equipment head has the following aspects:
a. Whether the waterproof casing at the end of the cable is cracked, and whether the electrode connecting wire clamp of the grounding wire of the transformer is heated:
b. Whether the insulating glue in the cable terminal equipment head becomes soft, overflows, lacks, and whether there is moisture on the surface:
c. Whether each sealing part of the cable terminal equipment head leaks oil;
d. Is the wire connector good?