Views:0 Author:Site Editor Publish Time: 2021-12-10 Origin:Site
Overhead insulated conductors have an extra layer of insulation and have better insulation performance than bare conductors, which can reduce the distance between lines, reduce the insulation requirements for line supports, and increase the number of circuits erected on the same pole.
Overhead Insulated Wires are less oxidized and corroded than bare wires due to the insulating layer on the outer layer, and have stronger corrosion resistance, which can prolong the service life of the circuit.
Although the insulated wire lacks a steel core, it is tough, so that the mechanical strength of the entire wire meets the requirements of the stress design.
There are two types of overhead insulated wires: aluminum core and copper core. In the distribution network, aluminum cores are used in many applications, mainly because aluminum is lighter and cheaper, and has low requirements for line connectors and support parts. In addition, the original distribution lines are mainly steel core aluminum stranded wires.
The aluminum core wire is used to facilitate the connection with the original network.
In actual use, aluminum core wires are often used. Copper core wires are mainly used as down conductors for transformers and switchgear.
There are two types of insulation protection layers for overhead insulated wires: thick insulation (3.4mm) and thin insulation (2.5mm).
The thick insulation allows frequent contact with trees during operation, and the thin insulation allows only short-term contact with trees.
The insulation protection layer is divided into cross-linked polyethylene and light polyethylene, and the insulation performance of cross-linked polyethylene is better.
This erection method is to use the current conventional cement poles, iron accessories and ceramic insulator accessories with bare conductors, and erect according to the erection method of bare conductors, which is more suitable for the area where the old lines are reconstructed and the corridors are sufficient. For single laying, special insulating brackets are used to suspend the wires. This method can increase the number of circuits to be erected, save the line corridors, and reduce the cost of line units.
Lines erected by bare conductors, in areas with a lot of trees, often create great shields for the erection and maintenance of lines and greening and forestry. The use of overhead insulated wires can reduce tree felling (early erection and operation and maintenance stages), solve many problems, and reduce conflicts with greening, forestry and other departments, protect the ecological environment, beautify the city, and reduce the line Ground Fault.
1. Used in areas where there is a lot of metal dust and pollution. In old industrial areas, metal processing companies often have metal dust flying in the wind due to environmental protection failures. In the polluted areas of thermal power plants and chemical plants, short circuits and ground faults in overhead distribution lines have been caused. The use of overhead insulated wires is a better way to prevent short-circuit grounding of 10 kV distribution lines. Suitable for salt spray areas.
2. The salt spray corrodes the bare wires very seriously, which greatly reduces the tensile strength of the bare wires. In the event of wind and rain, the wires will break, causing short circuit grounding accidents and shortening the service life of the wires. The use of overhead insulated wires can better prevent salt spray corrosion. Because there is a layer of insulating layer protection, it can reduce the corrosion of the salt spray to the conductor, delay the aging of the circuit, and extend the service life of the circuit.
3. Suitable for areas with more lightning. Overhead insulated wires have a layer of insulation protection, which can reduce line lightning, even if there is lightning, the impact will be much smaller. In minefields, lines built with bare conductors generally have a relatively rapid decline in line insulation, and burst grounding accidents often occur. After replacing the overhead insulated wire, the power outage time of the ground fault can be reduced.
4. It is suitable for the renovation of the old city. As the overhead insulated wire can withstand a voltage of 15kV, the minimum vertical distance between the insulated wire and the building is 1m, and the horizontal distance is 0.75m. Therefore, replacing the low-voltage mains with 10kV overhead insulated wires and directly sending them to the load center, shortening the radius of the low-voltage power grid is an effective power distribution method for the transformation of old cities.
5. Conducive to typhoon prevention. Due to the poor typhoon resistance of overhead bare-conductor lines, the line trips one after another as soon as the typhoon arrives. With the use of overhead insulated wires, instantaneous contact between the wires will not cause a short circuit, reducing faults, and greatly improving the line's ability to withstand typhoons.
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