The rules for the installation of electrical installations indicate the existence of several types of supports of overhead power lines. Their classification is necessary, because each of the pillars has its own function, accumulates a certain amount of energy carriers on itself. In addition, the air supports are made of different materials, which gives them certain disadvantages, advantages, and also have a different mounting method at the installation site.
Product Classification
This subdivision of power transmission line supports is based on the nature of the perceived loads, i.e. there are poles that can hold the tension of wires, cables, and there are supports that are designed for a different load. Thus, the electrical supporting structures are divided into intermediate and anchor installations. The first are mounted on straight sections. Able to withstand the vertical load from cable saturation and the weight of the insulators, as well as horizontal resistance to wind.
An anchor support is a structure that is located 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 steady, strong in comparison with intermediate columns. The installation perceives the tension (force) of wires, cables from spans adjacent to the support, therefore the installation of anchor supports is a huge need to create powerful systems of power lines.
Types of supports
Depending on the design, the purpose of 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 route, capable of perceiving one-sided efforts;
- angular anchor support - is installed in areas where the direction of the power line changes;
- branch - mounted for branching from the main route;
- cross - involves the location in places where power lines intersect;
- transpositional - are installed in areas when the phase arrangement on the support itself changes;
- transitional - the installation of anchor supports of this type is necessary at the places where you need to cross railway or motor roads, rivers, ponds, ravines, etc.
Material classification
There is a wooden, metal, reinforced concrete anchor support. The photo gives you the opportunity to visually see a significant distinguishing feature. Each material in its characteristics has disadvantages and advantages. Depending on the load, the volume of the bearing mass of the wires, certain poles are mounted. To direct the route with high power and to long sections, metal poles are used. For garden, private appointments, wooden poles are suitable . In order to provide food in urban conditions, reinforced concrete structures are most often used. Also, to resolve the issue of installation of supports, they appeal with the power for which the route is intended.
Purpose, advantages and disadvantages of types of supports
Wooden anchor support is used with power up to 110 kV. The advantages are the low price of the product, because wood, the production method, is less expensive than others. The disadvantage, like any wooden structure, is its susceptibility to decay, the formation of harmful mold, and the defeat of wood pests and birds. The wooden structure requires periodic processing to maintain its load-bearing abilities.
Metal poles are designed for voltages from 35 kV. They have several varieties, require periodic surface treatment, but differ in strength, relatively light weight.
Reinforced concrete product is installed on sections 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. Currently, the production of reinforced concrete poles is large-scale, the demand among contracting organizations serving urban electricity supply networks, and also belongs to a number of inexpensive reinforced concrete products.
Modern technologies for the production of concrete made it possible to manufacture lightweight supports, which reduces labor costs, material volume, cost, transportation costs, reduces the use of large (specific) equipment for their installation, but at the same time does not reduce the strength of the product. The disadvantage of a reinforced concrete support is its fragility. For example, in an accident, when a car crashes into a pole, it breaks, falls, violating the system of wires, which can lead to a short circuit and fire.
Installation of supports
Each type of column 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 column in the ground, it is better to use a type of wood such as larch to reduce the risk of rapid decay at the place where the product comes into contact 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 pillars are attached to special anchors, which are mounted in the base. Fastenings are most often made by bolting.