Due to major shortcomings observed in the first generations of bare overhead low-voltage power lines, there was a technical and security need to create a new technical solution, which after several experiments and trial solutions was adopted as a power network constructed with low-voltage insulated aerial bundled cables – LV ABC. Thanks to its great advantages in relation to the old power networks, LV ABC has become a dominant technical solution on almost all continents of the world. Three basic types of LV ABC have emerged as basic versions:
LV ABC with neutral messenger
Self supporting LV ABC
LV ABC with bare neutral messenger
LV ABC is generally produced in cross sections from 16mm2 to 240mm2;
Harmonized standard for production of LV ABC is HD 626;
Conductor insulation is made of cross-linked polyethylene;
Phase conductors are made of aluminum;
Neutral messenger conductors are generally aluminum, steel reinforced conductors and are usually 54.6mm2 and 71.5mm2;
Power networks constructed with LV ABC can be mounted on concrete, wooden and lattice steel poles. Simultaneously with the development, testing and consideration of all aspects of new generations of insulated power networks, the accessories needed to install them have also been developed. It is very important to know that an overhead system, as well as an underground cable system, is the weakest and most endangered at the places where it forks, terminates, branches or joints, which disrupts the continuity of the conductor. Therefore it is very important to have LV ABC accessories of high quality, reliable over a long period of time and easy and simple to install.
LV ABC accessories are basically devided into the following groups:
- Accessories for mounting and fixing LV ABC on the poles, they have a primarily mechanical role and they include Tension clamps PA, Suspension clamps PS, different types of Brackets CA , CS , CA – CS and cluster mounts, as well as cable fixing clamps BRF
- Accessories for jointing and termination of LV ABC, they have a role to extend the main line, i.e to joint two main lines and they include Pre-insulated joints MJPB and MJPT and Insulated piercing connectors, CPTAU cable lugs , End caps
- Accessories for branching LV ABC, they have both mechanical and electrical role and they include Insulated piercing connectors, MJPB joints, Pre-insulated mechanical joints, Adapters and similar technical solutions
- Accessories for protection and safety during electrical works in construction of LV ABC networks and protection from overvoltage and electric shocks, they include devices like PMCC and similar devices
- Each of the above listed groups has its irreplacable role in proper and safe construction of LV ABC power network. All accessories are standardized and according to standard EN 5048 which is legally and technically advanced, the successor to standard NF C 33. Pole Brackets that can be steel or aluminum are mounted directly on concrete, wooden or lattice steel poles. Depending on technical solution, they can be fixed to the pole with bolts or stainless steel straps. Tension clamps or Suspension clamps are installed on the brackets. As their name suggests, Tension clamps have the role to tension the network. Usually, two Tension clamps are installed on the main routes, each on one side of the pole. Apart from tensioning the network, they are also used in places where the angle of the route changes. On branch networks, Tension clamps have the role to form the direction of the line from the pole towards the object that is connected to power network. Suspension clamps have the role to suspend the network on the straight parts of the route, where its configuration allows it. In cases when the conductors of LV ABC should be jointed in the middle of the route, in the span between two poles, most often MJPB and MJPT joints are used. They are insulated, withstand applied mechanical load, are waterproof and, which is very important, the junction is made in such a way that it is very safe even when the conductor is under voltage. In cases when LV ABC should be jointed on the pole itself or LV ABC is connected to an underground cable which is routed to the top of the tension pole, junction can be done with insulated piercing connectors type CDRS or insulated joints with PA screws. It is recommended to put end caps at the ends of LV ABC in order to prevent the penetration of moisture into conductor’s wires, and to keep these points adequately electrically insulated, and thus safe when the conductor is under voltage. In cases of branching, insulated piercing coonectors are most often used, and you'll find more information about them on Insulated Piercing Connectors page.
