The rules for the installation of electrical installations indicatethe existence of several types of supports of overhead power lines. Their classification is necessary, because each of the pillars carries a function, accumulates a certain number of carriers of electricity. In addition, the air supports are made of different materials, which gives them some disadvantages, advantages, and also have a different method of mounting on site.
Classification by purpose of the product
This division of the power transmission line supportsis made based on the nature of the perceived loads, i.e. there are poles that are capable of retaining the tension force of wires, cables, and also supports that are designed for a different load. Thus, the electrical carrying structures are divided into intermediate and anchor installations. The first are mounted on straight sections. Capable of withstanding vertical loads from cable saturation and insulator weight, as well as horizontal resistance to wind impact.
Anchor support is a construction,which is located in the areas of change in the direction of power lines, at the beginning and end of the route, when crossing roads, railway lines, water objects, ravines. It is stable, solid in comparison with the intermediate pillars. The installation perceives the tension (force) of wires and cables from adjacent spans, so the installation of anchor supports is an enormous necessity for the creation of powerful power line systems.
Types of supports
Depending on the design, purpose on a particular section of the line, the anchor support can be made in several variations. Namely:
- end - mounted at the beginning and end of the track, is capable of perceiving unilateral efforts;
- angular anchor support - is installed on the sections where the direction of the power transmission line changes;
- branch - is mounted for a branch from the main route;
- cross - assumes an arrangement in places where power lines intersect;
- transposition - are installed on the sections with a change in the arrangement of the phases on the support itself;
- transitional - the installation of anchor supports of this type is necessary at the places where it is necessary to cross railroads or highways, rivers, ponds, ravines, etc.
Classification by material of manufacture
There is a wooden, metal,reinforced concrete anchorage. The photo provides an opportunity to visually see a significant distinctive feature. Each material has its own disadvantages and advantages. Depending on the load, the volume of the carrier weight of the wires are mounted those or other poles. For the direction of the route with high power and for long sections, metal poles are used. For garden, private purposes wooden supports will do. In order to ensure food in urban conditions, reinforced concrete structures are most often used. Also for the decision of a question of installation of supports appeal with capacity for which the route is intended.
Purpose, advantages and disadvantages of types of supports
Wooden anchor support is used forpower up to 110 kV. The advantages are the low price of the product, because wood, the way of production is less expensive compared to other. A disadvantage, like any wooden structure, is susceptibility to putrefaction, the formation of harmful mold, damage to wood pests, birds. The wooden structure requires periodic processing to preserve its bearing capacity.
Metal supports are designed for a voltage of 35 kV. They have several varieties, require periodic treatment of the surface, but differ in strength, relatively light weight.
The reinforced concrete product is installed onsections of the route with a capacity of up to 500 kV. The advantage is durability, no need for maintenance during the entire period of operation. At present, the production of reinforced concrete poles is of a large scale, the demand among contractors serving the city's electricity supply networks, and also belongs to a number of inexpensive reinforced concrete products.
Modern technologies for the production of concreteallowed to produce supports of light weight, which reduces labor costs, material volume, prime cost, transportation costs, reduces the use of large-sized (specific) equipment for their installation, but at the same time does not reduce the strength of the product. The disadvantage of the reinforced concrete support is its fragility. For example, in an accident, when a car crashes into a pillar, it breaks, falls, breaking the wire system, which can lead to a short circuit and a fire.
Installation of supports
For each type of pillar inherent technologyreinforcement on site. Wooden supports are installed either by direct immersion in the ground, or using a reinforced concrete stepson. When you install the post into the ground is better to use this type of timber as larch, to reduce the risk of rapid decay at the point of contact with the ground product. Metal structures are installed on reinforced concrete foundations. This is due to the fact that the metal supports have a large height, weight, and therefore must be firmly connected with the ground. Reinforced concrete poles are attached to special anchors, which are mounted in the base. Fasteners are most often made by means of a bolted joint.
