Electrical installation rules indicate the existence of several types of overhead power transmission towers. Their classification is necessary, because each of the pillars has its own function, accumulates a certain amount of electricity carriers. In addition, air poles are made of different materials, which gives them certain disadvantages, advantages, and also have a different method of fixing at the installation site.
Classification by product purpose
This subdivision of power transmission line supports is made based on the nature of the perceived loads, that is, there are poles that are able to hold the tension force of wires, cables, and there are also supports that are designed for a different load. Thus, electrically supporting structures are divided into intermediate and anchor installations. The first are mounted on straight sections. Capable of withstanding vertical loadscable weight and insulator weight, as well as horizontal wind resistance.
Anchor support is a structure that is placed in areas where the direction of the power line changes, at the beginning and end of the route, at the intersection of roads, railway lines, water bodies, ravines. It is stable, durable compared to intermediate posts. The installation perceives the tension (force) of wires, cables from spans adjacent to the support, so the installation of anchor supports is a huge necessity for creating powerful power line systems.
Types of supports
Depending on the design, destination on a particular section of the line, the anchor support can be made in several variations. Namely:
- terminal - mounted at the beginning and end of the route, capable of absorbing unilateral forces;
- Angle Anchor Support - installed in areas where the direction of the power line changes;
- branch - mounted for a branch from the main route;
- cross - suggests location in places where power lines intersect;
- transpositional - are installed in areas when the phases on the support itself change;
- transitional - the installation of anchor supports of this type is necessary in places where you need to cross railways or roads, rivers, reservoirs, ravines, etc.
Classification by material of manufacture
There is a wooden, metal, reinforced concrete anchor support. The photo makes it possible to clearly see a significant distinguishing feature. Each material has its advantages and disadvantages according to its characteristics. Depending on the load, the volume of the bearing mass of the wires, certain poles are mounted. Metal poles are used to guide the route with high power and for long sections. For garden, private purposes, wooden supports are suitable. In order to provide food in urban areas, reinforced concrete structures are most often used. Also, to solve the issue of installing supports, they appeal to the power for which the track is intended.
Purpose, advantages and disadvantages of types of supports
Wooden anchor support is used for power up to 110 kV. The advantages lie in the low price of the product, because wood, a production method, is less expensive than others. The disadvantage, like any wooden structure, is the susceptibility to rotting, the formation of harmful mold, the defeat of wood pests, birds. Timber construction requires periodic treatment to maintain its load-bearing capacity.
Metal poles are designed for voltages from 35 kV. They have several varieties, require periodic surface treatment, but are durable, relatively light in weight.
Reinforced concrete product is installed on the sections of the route with a power of up to 500 kV. The advantage is durability, no needservice during the entire period of operation. At present, the production of reinforced concrete poles has a large scale, demand among contractors serving the city's power supply networks, and also belongs to a number of low-cost reinforced concrete products.
Modern technologies for the production of concrete have made it possible to manufacture light weight supports, which reduces labor costs, material volume, 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 reinforced concrete support is its fragility. For example, in an accident, when a car crashes into a pole, it breaks, falls, breaking the wiring system, which can lead to a short circuit and fire.
Installation of supports
Each type of pole has its own technology of strengthening at the installation site. Wooden supports are installed either by direct immersion in the ground, or using a reinforced concrete stepson. When installing a post in the ground, it is better to use a type of wood such as larch to reduce the risk of rapid decay at the point of contact of the product with the soil. Metal structures are installed on reinforced concrete foundations. This is due to the fact that metal supports have a large height, mass, and therefore must be firmly connected to the ground. Reinforced concrete poles are attached to special anchors that are built into the base. Fastening is most often done by bolting.
