The basis for laying cable lines is, of course, the selection of the right cable, because individual types may differ in the material material, the rated voltage, which of course cannot be lower than the planned rated voltage of the network or insulation. So let's take a closer look at the parameters of various types of cables.

Cross -section of cable veins in cable lines

One of the very important parameters is the cross -section of the cable vein, because it must be selected to the conditions in which the cable will be operated. The value of the cable load current may not exceed the long -term load capacity. The short circuit current is also taken into account to avoid the situation when its value is too high and the cable will heat up to a higher temperature than the permissible declared by the manufacturer. When performing the project, you need to take into account the most adverse cooling conditions that may appear on the route of a specific cable line. The omission of temperature when choosing a cable is possible only for the power supply lines of one receiver and not in every case. This is allowed if the line is so arranged that its possible failure will not move to other cable lines, and its route does not run through the areas at risk of explosion or fire. This solution is only used if it is technically and economically justified. The permissible temperature should always be taken into account if the cable line runs through channels, tunnels or ladders with other cables.

Additional parameters must be taken into account at low voltage cables (below 1 kV), because they must be selected in the event of a voltage drop. The regulations of anti -tire protection must also be taken into account. They are already important at the stacking stage, when equipment such as cable press is used, but it all starts at the stage of choosing the right cables.

Insulation, coatings, armor, covers

Some solutions are resigned to ensure more and more safety and performance. Cables with paper insulation, especially saturated with dripping synovas, are already less and less commonly used. An important protection of the cable are coatings, armor and covers, because it is thanks to them that the insulation will not be damaged by dangerous factors located on the cable line route. Plastic covers are often used because they protect against damage due to moving soil or wandering currents. The armor made of wires protects against excessive stresses. Significant cables require special security - they must be secured in the event of the impact of the electromagnetic field. After repairs or replacements, you should always restore tight protection of the cable, which is why tools such as cable clamps are used during the joints.

Cables designed for special applications

When designing cable lines, some kind of obstacles cannot be avoided, so you need to adapt to them. It happens that cables must run in water or under the bottom of rivers, canals and other water reservoirs. Moisture is very harmful to cables and can quickly lead to their damage, so in such places should be used armored cables with an anti -corrosive cover made of plastic.

Particular caution is also necessary in tunnels, channels and other types of rooms. There is an increased risk of fire here, which is why cables with increased resistance to flame spread are used. There are deviations from this principle, but then you need to take care of fire protection.

Cable protection against damage

Even the best selected cable is not completely resistant to damage, but due to the fairly high repair costs at cable lines, a number of security are used that reduce the risk of failure to a minimum. The first types of damage to which you should protect are, of course, mechanical damage. In places where the risk is particularly high, the cables should be laid in covers. It is primarily about cables laid on:

• Bridges, viaducts, abutments.
• At a height above 250 cm (if bystanders can access the cable).
• Under roads, tracks, trails, water reservoirs, etc.

In exceptional situations, you can give up the use of covers. However, this only applies to cables with a rated voltage of a maximum of 30 kV. Other conditions regarding the ground must also be met: cables without shields can be laid under roads with undressing surface and under roads (collective, local, access) with non -stey surface, if in parallel to the cable line route, free surrounding cover runs.

Of course, mechanical damage is not the only risk to protect the cables against. Therefore, external coatings resistant to corrosion, coatings or protecting covers are also used and UV -resistant cables are used.

The cable lines are durable and safe, but for them to work optimally, it is necessary to choose the right cables and security. That is why factors such as the material of the cover, armor or insulation are of great importance.