Power lines are one of the foundations of the energy complex. The main advantage of electric energy is the minimum time during which the receiving device will receive power. Power transmission lines have many devices and structures in their composition. Let’s list the main ones:
• supports;
• fittings and insulators;
• grounding devices;
• wires and cables;
• discharge devices;
• markers for marking wires;
• substations;
The different types of structure (poles or towers) used for supporting the overhead lines or wires, such types of structures are called line supports. The line support plays a major role in power transmission. It kept the proper spacing between the conductors and maintained the conductor at the prescribed distance from its ground parts. It also maintained the specified ground clearance. These clearances are decided by the electrical and mechanical considerations.
A transmission tower supports an overhead power line. The other names of transmission towers are power transmission towers, power towers, and electricity pylons. The transmission towers carry high-voltage transmission line to transport power from the generating station to electrical substations. The electrical substations transport power to the end users through distribution lines. The distribution line uses utility poles to carry the low-voltage conductor.
An EHT transmission tower consists of the following parts:
Classification by purpose:
The construction is divided into main types depending on the purpose:
1. intermediate supports (poles) — the most common type of supports, installed on straight sections of the overhead line route, designed only to support wires and cables, and not designed for one-way traction. Usually, the number of intermediate supports is 80-90% of all power transmission support lines. Intermediate supports are calculated mainly on vertical loads from the mass of wires, cables, insulators, fittings, so they have a sufficiently simple and light design;
2. anchor supports — are also installed on straight sections of the track, but the wires are anchored to them. Thus, the supports are designed for the last loads from the pull of the wires;
3. corner supports — installed at the corners of the track. The attachment of wires to them is also lacking in anchoring, but they appear in the form of intermediate corner supports;
4. end supports — are mounted in front of substations by traditional means;
5. transposition — intended for transposition of overhead lines;
6. branching — installed in places where the line branches off to an adjacent direction; transitory – to provide clearance over an engineering structure or a natural obstacle;
7. transitional — to provide clearance over an engineering structure or natural obstacle;
The choice of electrical poles depends on the cost, atmosphere, and line voltage of the line.The electrical poles are mainly classified into following types.
a. Wood Poles
It is one of the cheapest types of line supports and used for lines where spans are short, and tension is low. The wood poles have the limitations of height and diameter. The double pole structure of the A or H types is used where greater strength is required.
The strength of these types of constructions varies from two to four times the strength of the single pole. H-type of construction is usually employed for four terminal poles or those carrying switchgear and transformers.
Wood pole has a natural insulating property, and lesser flashovers are likely to take place due to lightning. One of the drawbacks of wood poles is that their strength and durability cannot be predicted with certainty.
b. Concrete Poles
Concrete pole gave greater strength and used in place of a wood pole. It has a longer life than that of a wood pole because of little degradation. Their maintenance cost is low. Concrete poles are very heavy and are liable to damage during loading, unloading, transportation and erection due to their brittle nature.
Handlings and transportation difficulties are overcome by the use of pre-stressed concrete supports which can be manufactured in pieces and then assembled at the job sites. The weight of pre-stressed concrete poles is more durable than any other type of pole. The material used is less, and it is more durable than any other types of poles.
c. Steel Poles
For low and medium voltage tubular steel poles or Grider steel supports are used. Longer spans are possible with steel poles. The poles need to be galvanised or painted periodically to prevent them from corrosion. Their maintenance expense is high.
Classification of transmission lines by construction: • with braces • free standing • increased • underestimated • single rack.
The catalog of power line supports includes many types of supports, as well as numbers of typical projects, series codes with conventional designations and markings according to draftings and assembly diagrams, pole weight and markings.
All products have quality Certificates also an international certificate of the quality management system for compliance with the requirements ISO 9001: 2015, as well as an international certificate of compliance with the requirements for controlling the properties of the coating applied by the hot-dip galvanizing method on finished steel and iron products in accordance with ISO 1461: 2009.
Our company works in accordance with all specified technical conditions and regulations rules, with an individual approach to each of your requests. Installation of power line supports is performed on the latest equipment under the supervision of professionally competent employees of our Company. We have the warehouses in central and western Ukraine.
If you have any questions on overhead line fittings. We will give the professional answers to your questions.