Armored cable for laying in the ground: stamps, calculation

This article will look at how armored cables are routed underground. In addition, we will talk about their markings and directly about how the lines are calculated.

Grounding requirements for armored cable

The laying of armored cable lines, like any construction process, can be divided into stages. In this case, it is important to take into account a clear sequence and correct implementation of the plan, as well as the implementation of all installation conditions.

Before you start laying cables, you must consider the following requirements:

• The cable trunk should without any obstacles conduct the operating voltage of the network, so it should not interfere with pipes laid underground, tree roots and other objects. It is also not permissible to block cable lines.
• During cable wiring, it is planned to develop a drainage cushion made of sand or a special fiber, in this regard, the depth of the ditch should be from 75 centimeters to 1 meter.
• An armored cable for laying in the ground must be provided with grounding.
• The best layer for a cushion embankment is sandstone, gravel and substances that are difficult to burn.
• If during laying it becomes necessary to place two or more armored conductors in one pit, then the distance between the cable line should be at least 11 centimeters.
• When connecting an armored cable from the VLEP side, end couplings are used.

Laying armored cable in the ground

Cable ditch is an alternative to VLEP. The styling plan is quite simple, but it has a rather long and laborious work process.

1. When preparing the trunk for laying, the armored cable for laying in the ground is checked for its integrity over the entire surface. In the case when they find minor damage, they are corrected or isolated, and with more damage, they are replaced with a new one. It is also necessary to remember that work is carried out with hard material, therefore, in order not to damage it, it is mounted on a rolling machine and fixed on a gantry.
2. Armored cable for laying in the ground must not be laid without a plan. A special development of the site on which the work will be carried out should be made. Such a plan will help to understand the general information about the sites selected for laying. The pit, as already mentioned above, should be at least 65 centimeters in depth, and the width is calculated taking into account the length between the cables and the walls of the trench.
3. Posting a sand or fibrous cushion to the very bottom of the trench is made in an even layer. Then lay the wire without stretching - in waves.
4. Then the armored cable for laying in the ground is additionally covered with a layer of sand at least 10 centimeters. Then the top layer of the sand cushion is covered with brick or stone. This is necessary to protect conductive wires from unplanned deformation when excavation is carried out near the installation site.
5. After the trench, they fill up with an additional layer of earth 15-20 centimeters, after ramming it.

Armored Cable Features

Armored power cables for laying in the ground consist of one or more conductive cores. Cable cores can be made of different conductive materials, most often copper and aluminum.

Cables can also be made with a grounding conductor, as a rule, it has a cross section an order of magnitude lower than the main cores. Insulation is necessary to ensure the necessary electrical strength of conductive conductors between themselves and the armored shell. It is made from various polymeric materials.

Now consider the features of a copper armored cable. The armor of such a cable is able to protect from harmful and aggressive environmental conditions. An armored copper cable for laying in the ground is excellent for laying and installing conductive paths with a high probability of damage. A product of this type is surrounded by two armored tapes and covered with a layer of polyvinyl chloride.

What features does the aluminum armored cable have? Conductors of this type are used for large cross-sections of conductors; they are not subjected to strong bending or stretching, since aluminum is a rather fragile material. An armored aluminum cable for laying in the ground is formed by winding galvanized tapes around insulating material plastic or PVC.

Benefits of Armored Cables

As for the advantages of armored cables, they are as follows:

1. Huge strength and resistance to mechanical stress.
2. Minimum storage requirements.
3. Long special service (up to 60 years).
4. Resistance to temperature extremes, as well as the ability to work at temperatures from +55 to -60 Celsius.
5. Reliability and ease of maintenance.
6. Wide range of applications.
7. Large selection of products.
8. Corrosion and moisture protection

Types of armor on the outer protective layer

Long service life and high corrosion resistance guarantee the materials used for cable defense. Different types of armor are selected depending on the type of laying and soil features. One of the most famous markings is AABL, AVBBSHV, VBBSHV. The cross section of the conductors of such conductors is from 1.5 mm ² to 270 mm ² . Such lines can be with a different number of cores (from 1 to 5).

Types of external protection:

1. Steel metal tapes are very strong armor that protects the electric line from external physical influences, for example, when excavating an excavator with a bucket, hitting with a crowbar or shovel.
2. Stainless steel wire provides resistance to moisture and corrosion.
3. Steel tapes made in the form of corrugations. This type of armor is covered by telephone wire lines. This layer perfectly protects against moisture and mechanical shock.

Armored Cable Brands

Brands of armored cables for laying in the ground are necessary to select the appropriate characteristics, based on the calculation of conditions. And the purpose of marking is necessary to display the characteristics of the product:

• the material lived;
• appointment;
• type of insulation;
• design feature;
• section of a product;
• Rated voltage;
• rated current.

For example, a wire of the type VBBSHV, where:

• In - veins isolated from polyvinyl chloride.
• B - a protective layer of wires, armor made of sheets and wound with a spiral tape.
• B - bitumen layer between the conductor. It is used for conductors with a large cross section.
• SHV - an external layer from polyvinyl chloride.

Cable line calculation

As the name implies, it will now explain how to conduct the calculation. An armored cable for laying in the ground is calculated to select the type and optimal cross-section of the power conductors of the wire. First, it is necessary to determine the rated currents by the formula, which is presented below.

R _n - rated power of the consumer, watts.

To _with - the coefficient of consumer demand.

U _with - rated voltage of the network, V.

cos - consumer power factor.

n _with - the efficiency of the network.

Next, calculate the mechanical strength of the cable.

After calculation, select the cross section of the core greater than or equal to the calculated.