How Much Do You Know About High Voltage Overhead Cable Insulated Cable?

In the 1960s, rubber wires (BX series) were used for low-voltage 380V overhead lines in my country. The insulation life of this type of wire was less than 2 years. Later, plastic wires (BV series) were used, and the life span could be extended to about 8 years, but it was still not satisfactory. In fact, these two types of wires were treated as bare wires. Before the 1980s, bare wires were still used for 10kV lines in my country. With the development of urban construction and power grids, safety issues have become increasingly severe. In the transformation of power grids in rural, mountainous and forest areas, some overhead insulated cables are needed, especially in forest areas, because bare wire transmission is one of the causes of forest fires. In short, overhead insulated cables are often used in the following 6 places:

1. Suitable for places with many trees

For lines with bare wires, in areas with many trees, the construction and maintenance of lines often have great conflicts with greening and forestry. The use of overhead insulated wires can reduce the felling of trees (in the initial stage of construction and operation and maintenance), reduce conflicts with greening, forestry and other departments, protect the ecological environment, beautify the city appearance, and reduce line grounding faults.

2. Suitable for areas with lots of flying metal dust and pollution

In old industrial areas, metal processing enterprises often have flying metal dust flying in the wind because environmental protection does not meet standards. In polluted areas of thermal power plants and chemical plants, overhead distribution lines are short-circuited and grounded. The use of overhead insulated wires is a better way to prevent short-circuit and grounding of 10kV distribution lines.

3. Suitable for salt fog areas

Salt fog corrodes bare wires severely, greatly reducing the tensile strength of bare wires. When encountering wind and rain, it is easy to cause wire breakage, resulting in line short-circuit and grounding accidents, shortening the service life of the line. The use of overhead insulated wires can better prevent salt fog corrosion. Because there is a layer of insulation protection, the corrosion of salt fog on conductors can be reduced, and the aging of lines can be delayed.

4. Suitable for areas with more lightning

Overhead insulated wires can reduce line lightning induction because of a layer of insulation protection. Even if there is lightning, the impact will be much smaller. In the minefield, the lines erected with bare wires generally have a faster decline in line insulation, and burst grounding accidents often occur. After replacing the overhead insulated wire, the power outage time of ground fault can be reduced.

5. Suitable for the reconstruction of old urban areas

Since 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 trunk line with a 10kV overhead insulated wire and directly sending it to the load center to shorten the power supply radius of the low-voltage power grid is an effective distribution method for the reconstruction of the old city.

6. It is conducive to typhoon prevention

Since the overhead bare wire line has poor typhoon resistance, the line trips one after another when the typhoon arrives. After the use of overhead insulated wires, the instantaneous collision of the wires will not cause a short circuit, which reduces faults and greatly improves the typhoon resistance of the line.

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