The state has explicitly ordered the use of copper cond […]
The state has explicitly ordered the use of copper conductive sub-wires in newly built houses. But the same copper wire, there are also inferior copper wires, the copper core is made of recycled copper, which contains many impurities, and some inferior copper wires are not as conductive as iron wires, which can easily cause electrical accidents. At present, there are many varieties, specifications, and prices of wires on the market, making it very difficult for consumers to choose.
In terms of the price of two copper core wires of 2.5 square millimeters and 4 square millimeters commonly used in home decoration, the price of a coil of the same specification can vary by 20% to 30% because of different manufacturers. As for the quality and length, it is even more difficult for consumers to judge.
According to industry sources, the huge price difference of wires is due to the different raw materials used in the production process. The main raw materials for the production of wires are electrolytic copper, insulating materials and sheath materials. At present, the electrolytic copper in the raw material market is about 50,000 yuan per ton, while the recovered miscellaneous copper is only about 40,000 yuan per ton; the price of high-quality products of insulating materials and sheath materials is 8,000 yuan-10,000 yuan per ton, while defective products The price is only 4000 yuan-5000 yuan per ton, the price difference is even greater.
In addition, the insufficient length and insufficient glue content of the silicone wire insulator are also important reasons for the price difference. The length of each reel is 100 meters for the high-quality products, while the inferior products are only about 90 meters; the insulators contain 35%-40% of the glue content of the excellent products, and the defective products are only 15%. By comparison, it is not difficult for consumers to see that the difference in the sales price of finished wires is caused by the slick material.
Common faults of cable lines include mechanical damage, insulation damage, insulation damp, insulation aging deterioration, overvoltage, cable overheating faults, etc. When the above-mentioned fault occurs in the line, the power supply of the faulty cable should be cut off, the fault point should be found, the fault should be inspected and analyzed, and then repair and test should be carried out. The power supply can be restored after the fault is removed.
The most direct cause of cable failure is breakdown due to insulation degradation. There are:
Overload operation. Long-term overload operation will increase the temperature of the cable and age the insulation, which will cause insulation breakdown and reduce construction quality. Electrical aspects include: the construction process of the cable head fails to meet the requirements, the sealing of the cable head is poor, the moisture invades the inside of the cable, and the insulation performance of the cable is reduced; protective measures are not taken when the cable is laid, the protective layer is damaged, and the insulation is reduced. The civil works include: poor drainage of pipe trenches in industrial wells, long-term water soaking of cables, which damages the insulation strength; too small wells, insufficient cable bending radius, and long-term damage to the external force of extrusion; mainly due to brutal mechanical construction in municipal works and digging injuries Dig the cable. Corrosion; the protective layer suffers from chemical corrosion or cable corrosion for a long time, which causes the protective layer to fail and the insulation is reduced; the cable itself or the cable head accessories are poor in quality, the cable head is poorly sealed, the insulating glue is dissolved, and cracked, causing the resonance phenomenon in the station to be vde electrical The line disconnection fault causes the line-to-phase capacitance and the ground capacitance to form a resonant circuit with the excitation inductance of the distribution transformer, thereby exciting ferromagnetic resonance.