Armored cable for laying in the ground: stamps, calculation

In this article, let's look at how armored cables are carried underground. In addition, let's talk about their marking and directly about how the lines are calculated.

Requirements for laying an armored cable in the ground

The laying of armored cable lines, like any construction process, can be divided into stages. It is important to take into account the precise sequence and correctness of the plan, as well as the implementation of all installation conditions.

Before you start laying the cables, you need to consider the following requirements:

• The cable mains must be able to conduct the working voltage of the network without any obstacles, therefore, pipes, tree roots and other objects laid down under the ground must not interfere with it. It is also impermissible to block the cable lines.
• During the cable wiring, the development of a drainage cushion from sand or a special fiber is provided, so the depth of the ditch should be from 75 centimeters to 1 meter.
• Armored cable for laying in the ground must be grounded.
• The best layer for a cushion mound is sandstone, gravel and substances that are not easily combustible.
• If, during the laying, it becomes necessary to place two or more armored conductors in one well, the distance between the cable line must be at least 11 centimeters.
• When connecting the armored cable from the side of the VLEP, end couplings are used.

Armored cable laying in the ground

Ditch for cables is an alternative to VLEP. The laying plan is quite simple, but it has a rather long and time-consuming 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 damages, they are corrected or isolated, and with a greater number of damages they are changed to a new one. Also it is necessary to remember that the work is conducted with a rigid material, therefore, in order not to damage it, it is installed on the rolling and fixed on the goats.
2. Armored cable for laying in the ground can 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 chosen for laying. The pit, as already mentioned above, should be at least 65 centimeters deep, and the width is calculated, given the length between the cables and the walls of the trench.
3. Wiring a sandy or fibrous pillow to the very bottom of the trench is made evenly. Next lay the wire without stretching - waves.
4. Then the armored cable for laying in the ground is additionally covered with a layer of sand not less than 10 centimeters. Then the top layer of the sand cushion is covered with a brick or stone. This is necessary to protect current-carrying veins from unplanned deformation, when excavations are carried out near the place of laying.
5. After the trench fall asleep an additional layer of land 15-20 centimeters, pre-rammed it.

Special features of armored cables

Power armored cables for laying in the ground consist of one or more conductors. The cores of cables can be made of different conductive materials, most often copper and aluminum.

Also, the cables can be made with a grounding core, as a rule, it has a cross section of an order lower than the main veins. Isolation is necessary to ensure the necessary electrical strength of the conductive wires between themselves and the armored shell. It is made of various polymer 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. Copper armored cable for laying in the ground is great for laying and installation of conductive paths with a high probability of damage. The product of this type is updated with two armored strips and covered with a layer of PVC.

What features does the aluminum armored cable have? Conductors of this type are used for large cross-sections of cores, it is not subjected to strong bends or stretches, since aluminum is a brittle enough material. The armored aluminum cable for laying in the ground is formed by winding zinced bands around the insulating material plastic or PVC.

Advantages of armored cables

As for the advantages of armored cables, they are the following:

1. Huge strength and resistance to mechanical stress.
2. Minimum requirements for storage.
3. A long special service (up to 60 years).
4. Resistance to temperature changes, 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. Protection against corrosion and moisture

Types of armor on the outer protective layer

Long service life and high corrosion resistance are guaranteed by the materials used to protect the cable. Depending on the type of piling and the characteristics of the soil, different types of armor are selected. One of the most famous markings is AABL, AVBBSHV, VBBSHV. The cross-section of cores of such conductors is from 1.5 mm ² to 270 mm ² . Such lines can be with different number of cores (from 1 to 5).

Types of external protection:

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

Armored cable brands

Marks 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:

• Material of veins;
• Purpose;
• Type of insulation;
• Feature of the design;
• Cross-section of the product;
• Rated voltage;
• rated current.

For example, wire type VBBSHV, where:

• B - veins insulated from polyvinyl chloride.
• B - protective layer of wires, armor made of sheets and wound with a spiral tape.
• B - bituminous layer between the conductor. It is used for conductors with a large cross-section of cores.
• ШВ - an outer layer from polyvinylchloride.

Calculation of cable lines

As you can understand from the title, now it will be told how to calculate. The armored cable for laying in the ground is calculated to select the type and optimum cross-section of the power wires of the wire. First it is necessary to determine the calculated currents by the formula, which is presented below.

Р _н - rated power of the consumer, Wt.

К _с - consumer demand coefficient.

U _s - rated line voltage, V.

Cos Φ is the power factor of the consumer.

N _с - efficiency of the network.

Then calculate the mechanical strength of the cable.

After the calculation, the cross-section of the core is chosen to be greater than or equal to the calculated section.