1. The main features of overhead insulated conductors (ABC cables) have good insulation performance.
Overhead insulated conductors have an extra layer of insulation and have superior 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 (ABC) cable uses and characteristics-Jianzhenda Cable|Jianzhenda Wire and Cable|Jianzhenda-Jianzhenda Cable has good insulation performance. Overhead insulated conductors have an extra layer of insulation and have superior 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. Good corrosion resistance.
2. The specification core of the overhead insulated wire. There are two types of overhead insulated wires: aluminum core and copper core. In the distribution network, aluminum core applications are more, 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 wire is mainly used as the down conductor of transformers and switchgear. Insulation Materials. 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 insulating protective layer is divided into cross-linked polyethylene and light polyethylene, and the insulating properties of cross-linked polyethylene are better.
3. The laying method of overhead insulated wires is a single conventional laying method.
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 bare conductor erection method, which is more suitable for the area where the old line is reconstructed and the corridor is sufficient. A special insulating bracket is used to suspend the wires for single laying. This method can increase the number of circuits erected, save the line corridors, and reduce the cost of the line unit.
4. The application area of overhead insulated wires is suitable for places with many trees.
Lines erected by bare conductors are often shielded by the erection and maintenance of lines and greening and forestry in areas with many trees. 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 and forestry departments, protect the ecological environment, beautify the city, and reduce the line Ground Fault. 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 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. 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.
5. Design and construction of ABC conductors. The insulated wires and the steel core aluminum stranded wires are in the same specification, and the current carrying capacity of the insulated wires is smaller than that of the bare wires. After the insulated wire is added with the insulating layer, the heat dissipation of the wire is poor, and its current-carrying capacity is almost a grade lower than that of the bare wire. Therefore, when designing and selecting, the insulated wire should be selected a larger gear. At the same time, the strain clamp is directly clamped on the wire insulator. In order to prevent excessive wire tension from cracking or peeling of the insulation layer, the maximum working stress of generally insulated wires is about 41N/mm2. Wire arrangement and pitch. The conductor arrangement of overhead insulated lines is basically the same as that of bare conductor lines, which can be divided into: triangular, vertical, horizontal, and multi-loop erection on the same pole. The span of overhead insulated lines should be controlled at 50m. The distance between phases of insulated wires. Due to the good insulation performance of overhead insulated wires, the distance between phases is smaller than that of bare conductor lines, but the distance between vertical and triangular arrangements is not less than 0.3m; the distance between horizontal arrangements is not less than 0.4m. The vertical and horizontal distances of two circuit lines erected on the same pole shall not be less than 0.5m. The clearance distance between the jumper, the down conductor and the adjacent lead wire and low-voltage line, and the clearance distance between the overhead insulated wire and the pole wire or frame shall not be less than 0.2m. Connection of insulated wires. The connection of the insulated wire is not allowed to be twisted, and the insulated wire should not be connected within the span as much as possible. It can be connected when the tension rod is jumper. If you really want to connect within the span, within a span, each wire cannot exceed one socket, and the distance between the connector and the fixed point of the wire should not be less than 0.5m. Insulated wires of different metals, different specifications, and different twisting directions are strictly forbidden to make load-bearing connections within the pitch. The connection point of the insulated wire should be wrapped with an insulating cover or self-adhesive insulating tape. Sag of insulated wire. After the conductor is erected, considering the influence of plastic elongation on sag, the sag reduction method should be used to compensate. The percentage of sag reduction is 20% for aluminum or aluminum alloy core insulated wires and 7% to 8% for copper core insulated wires. When the wire is tightened, the insulated wire should not be overdrawn. After the wire is tightened, the sag of each phase wire in the same gear should be consistent. Fixing of insulated wires. Insulated wire and insulator are fixed with insulated wire. For pin-type or rod-type insulators, the straight rod adopts the top groove tying method, and the direct angle rod adopts the side groove tying method, which is tied to the side groove of the outer corner of the line. The screw-type insulator is bound in the side groove, and the insulating wire and the contact part of the insulator should be wound with insulating self-adhesive tape. Construction and erection of insulated wires. The construction and erection of insulated wires is different from overhead bare wires. It does not allow the wires to damage the insulation layer during the construction process. Pay attention to the protection of the insulation layer during construction, and try to avoid contact and friction between the wire insulation layer and the ground and tower accessories. Overlap of insulated conductors and drop wires. The connection of jumper wires and drop wires of insulated wires is different from that of bare wires, because insulated wires need special wire strippers to strip the insulation layer. The process is more complicated and the requirements are stricter. The jumper connection can be connected by a parallel groove clamp or a connecting pipe. The lead wire can be connected with a parallel groove clamp or a T-shaped clamp. At the same time, wrap the interface with an insulating cover or insulating self-adhesive tape. Coordination of ordinary fittings and insulated wires. Overhead insulated wires have special line fittings, which can insulate the entire line. Considering the cost of the circuit, ordinary accessories can also be combined to reduce the cost of the circuit. Since the insulated wire has an extra layer of insulation, the wire diameter is larger than that of the bare wire. When using ordinary fittings, the wire fixing fittings and connecting fittings should be enlarged. The tension clamp should be clamped together with the protective layer of the wire to prevent the overhead insulated wire from peeling off, which affects its mechanical and insulation properties.
The use of insulated wires instead of bare wires is a technological advancement measure to achieve insulation of distribution lines, which can better improve the reliability, stability and safety of power supply, save line maintenance and management costs, and help improve the economic benefits of power supply enterprises. Compared with overhead bare wires, overhead insulated conductors have better performance, and the cost is not too high. In rural power grids, depending on local conditions, it is beneficial to use overhead insulated conductors in some areas.
