Aerial cable (also known as overhead insulated cable) is a specialized cable manufactured using a production process similar to cross-linked cables, which is a new transmission method between overhead conductors and underground cables. Aerial cables are all single core and can be divided into hard aluminum wire structure, hard drawn copper wire structure, aluminum alloy wire structure, steel core or aluminum alloy core support structure, and self-supporting three core laminated structure (the wire core can be hard aluminum or hard copper wire) according to their different structures. It has the main characteristics of high power supply reliability, good power supply safety, convenient installation and maintenance, and reasonable economy. Its main technical parameters include weather resistance, insulation level, inner and outer semi conductive shielding layers. Aerial cables are widely used in power transmission both domestically and internationally.
Classification of overhead cables
Aerial cables are not ordinary oil paper insulated cables or cross-linked insulated cables directly hung on overhead towers, but a specialized cable manufactured using a production process similar to cross-linked cables.
Generally, overhead cables are single core and can be divided into hard aluminum wire structure, hard drawn copper wire structure, aluminum alloy wire structure, steel core or aluminum alloy core support structure, and self-supporting three core laminated structure (the wire core can be hard aluminum or hard copper wire) according to their different structures.
The hard aluminum wire structure is lightweight, with moderate tensile strength, easy to bend cables, convenient installation, and low engineering cost. It can be easily installed on existing towers and is commonly used in renovation or new construction projects.
The structure of hard drawn copper wire is relatively heavy, but it has a high tensile force and strong resistance to external forces. Even when the tower is broken, the cable can still be energized. The aluminum alloy wire structure is lightweight and has high tensile strength, mainly used in large-span tower systems with a span of 100m.
Steel core or aluminum alloy core support structures are generally used in 35kV voltage systems with large spans. Square insulation components are used to separate the support wire (bare wire) from the three insulated phase lines. The support wire can be used as a lightning rod, and its biggest advantage is that the sag is small, and the arc weight is only about 2.4% of the span.
The self-supporting three core twisted structure is used in systems with medium span. The disadvantage of this type of cable is that the manufacturing length of the three core cable is shorter than that of a single core, there are more joints, and there is an outer semi conductive shielding layer. The terminal head or stress cone structure should be installed at the end of the cable like ordinary cables.
main features
Key Features
1. High power supply reliability
The use of overhead cables can greatly reduce various types of short circuit faults (especially common flashover faults in overhead bare conductors), and the failure rate is 4-6 times lower than that of overhead bare conductors.
2. Good power supply safety
The use of overhead cables significantly reduces accidents of electric shock injuries and fatalities
3. Easy to install and maintain
Aerial cables can be installed on any type of tower or along walls. In special cases, they can also run through trees and be directly fixed to tree poles with metal fittings. It can be installed in a single circuit or multiple circuits on the same pole without requiring a wide electrical corridor. It can be easily installed on the original overhead line, utilizing the existing cross arms and porcelain bottles, or using a complete set of supporting hardware and accessories. According to the actual situation on site, manufacturers can also customize or make some special fittings, making construction extremely convenient. Aerial cables do not require specialized inspections, and there is no need for short circuit tripping accidents caused by branches flashing, residents littering, or accidental collision of crane arms, which greatly reduces the maintenance and repair work of the line
4. Economically reasonable
Although using overhead cables is more expensive than using bare overhead conductors, it is cheaper than ordinary underground installation cables. Therefore, although the one-time investment of using overhead cables is slightly higher, considering other factors, its operating cost will be significantly lower than that of overhead bare wires.
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