when to use armored cable ?

Views: 0     Author: Site Editor     Publish Time: 2022-03-29      Origin: Site

Armored Cables are generally used in underground situations, and armored cables are required for cable trench laying or direct burial.

1. Armored cables are made of conductors of different materials in metal sleeves with insulating materials, and are processed into a bendable solid assembly.

Armored cables include armored thermocouples, armored thermal resistances, armored heaters and armored leads, which are mainly used for temperature measurement, signal transmission and special heating in chemical industry, metallurgy, machinery manufacturing, power generation and scientific experiments. The ones are armored thermocouples.

2. The purpose of adding armor layer to the cable is to enhance the mechanical protection such as tensile strength and compressive strength and prolong the service life.

The armored has a certain resistance to external force, and can also prevent mice from biting, so as not to cause power transmission problems through the armored, the bending radius of the armored should be large, and the armored layer can be grounded to protect the cable.

《 GB 50217-2007 Code for Design of Electric Power Engineering Cables 》 Stipulates:

3.5 Cable outer sheath type
3.5.1 The selection of cable sheath shall meet the following requirements:

1. For single-core power cables of AC systems, when it is necessary to enhance the resistance of the cables to external forces, non-magnetic metal armoring shall be used, and steel armoring without effective non-magnetic treatment shall not be used.

2. For cables that are in a humid, chemically corrosive environment or easily immersed in water, the metal layer, reinforcement layer and armor should have a polyethylene outer sheath, and the thick steel wire armor of the cable in the water should have an extruded outer sheath.

3.5.3 The selection of the outer sheath of the cable for direct burial laying shall meet the following requirements:
direct burial cable

1. When the cable is under greater pressure or there is a danger of mechanical damage, it should have a reinforcement layer or steel tape armor.

2. In the soil where displacement may occur, such as quicksand layer, backfill belt, etc., steel wire armored cable should be used.

3. For extruded cables used in areas seriously endangered by termites, a higher hardness outer sheath should be selected, or a thin outer sheath with higher hardness can be extruded on the ordinary outer sheath, and its material can be copolymerized with nylon or special polyolefin. It can also be armored with metal sleeves or steel tapes.

3.5.4 The selection of cable sheath for fixed laying in air shall meet the following requirements:

1. When the small-section extruded insulated cable is laid directly on the arm support, it should steel tape armored cable.

2. In places with high safety requirements and serious rodent infestation, such as underground passenger transport and commercial facilities, the plastic insulated cable should be armored with metal tape or steel tape.

3. When the cable is under the stress condition of high drop, the multi-core cable shall have steel wire armor, and the AC single-core cable shall comply with the provisions of paragraph 1 of Article 3.5.1 of this code.

3.5.8 The selection of the cable sheath for underwater laying shall meet the following requirements:

1. For cables that do not need armour to withstand tension in ditches, non-navigable rivers, etc., steel tape armour cable can be used.

2. For cables in rivers, lakes and seas, the steel wire armor type selected should meet the stress conditions. When the laying conditions require prevention requirements such as mechanical damage, an outer sheath that meets the requirements for enhanced protection and corrosion resistance can be selected.

《 GB 50057-2010 Design Code for Lightning Protection of Buildings 》  also stipulates:

Article 3.2.3 The measures to prevent lightning waves from invading people in the first category of lightning protection buildings shall meet the following requirements:

1. The low-voltage line should be laid directly with cables buried in the ground. The metal sheath and steel pipe of the cable should be connected to the grounding device for lightning protection at the household end. When it is difficult to use cables for the entire line, the overhead lines of reinforced concrete poles and iron cross arms can be used, and a piece of metal armored cable or sheathed cable should be directly buried through the steel pipe...

Therefore, the use of armor can not only improve the mechanical properties of the cable's tensile strength and radial protection, but also improve the cable's lightning protection and anti-low frequency interference performance.

2. Frequency converters, power cables, transformers, high-power motors, etc. are often accompanied by low-frequency interference, which cannot be solved by cables with high-conductivity materials as shielding layers, including original imported cables. Only the shielding layer made of high-permeability materials (such as steel tape, steel wire) can effectively suppress low-frequency interference. The most common method is to cover the cables with steel pipes or directly use armored cables made of high-permeability materials. Armoured bus cable for digital communication (model specification ASTP-120Ω (for RS485 & CAN) one pair 18 AWG).

Underground Armored Cable

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