When power cables are concealed in underground trenches, we need to prevent car pressure subsidence, rats nibbling and sharp stones scratches, etc., this time we need to use armored cables.
Armored cable, also known as PVC insulated PVC sheathed steel armored power cables, is a kind of cable that can be directly buried in the ground.
It is to add a layer of metal protection to the outermost part of the product so that the internal utility layer will not be damaged during transportation and installation.
In the armoring of cables, a layer of insulating sheath is usually added on the outside.
Cable armor materials include steel tape, steel wire, copper tape, tinned steel wire, and so on, their selection is mainly based on the customer's use of the environment and requirements to choose from.
An armored cable mechanical protection layer can be added to any structure of the cable to increase the mechanical strength of the cable to improve erosion resistance.
It is a telephone cable designed for areas that are susceptible to mechanical damage and extreme erosion.
It can be laid in any way and is more suitable for direct burial in rocky areas.
1 Armored cable is generally fixed laying power cables, commonly known as fixed in one place and do not move, power line transmission of electrical energy.
2 Cables plus the purpose of the armored layer in addition to the above, can also enhance the tensile strength, compressive strength, and other mechanical protection to extend the service life.
3 Armored with a certain degree of resistance to external forces, but also to prevent rats from biting, not to cause power transmission problems through the armor.
The bending radius of the armor should be large, the armor layer can be grounded to protect the cable.
Shielded cable has the word shielded, as the name implies is in the transmission cable plus a shielding layer formed in the way of resistance to external electromagnetic interference ability of the cable. The cable structure of the so-called "shielding" is also a measure to improve the distribution of electric fields. A cable conductor is stranded from multiple strands of wire, it is easy to form an air gap between the insulation layer, the conductor surface is not smooth, which will cause the electric field concentration. Then the following editor will give you detailed knowledge of shielded cable.
1 In the conductor surface plus a layer of semi-conducting material shielding layer, it is shielded with the conductor equipotential, and good contact with the insulation layer, thus avoiding the conductor and insulation layer occurring between the partial discharge. This layer of shielding is also known as the inner shield. In the insulation surface and sheath contact, there may also be gaps, cable bending, and oil paper cable insulation surface is easy to cause cracks, these are factors that cause partial discharge.
2 On the surface of the insulation layer plus a layer of semi-conducting material shielding layer, it is shielded with good contact with the insulation layer, and the metal sheath equipotential, thus avoiding partial discharge between the insulation layer and the sheath.
The shield layer of the cable evens out the conductive core and insulation electric field, 6kV and above, medium and high voltage power cables generally have a conductor shielding layer and insulation shielding layer, part of the low-voltage cables are not set shielding layer. The shield layer has semi-conductive shielding and metal shielding of two kinds.
The shielded cable shielding layer is mostly woven into a mesh metal wire or using a metal film, there are a variety of different ways of single shielding and multi shielding.
Single shielding refers to a single shielding network or shielding film, which can be wrapped in one or more wires.
The multi-shielded way is more than one shielding network, shielding film in a cable.
Some of them are used to isolate the electromagnetic interference between the wires, and some of them are double shielding to strengthen the shielding effect. The mechanism of shielding is to ground the shield so that it isolates the external conductor of the induced interference voltage.
The semi-conductive shielding layer is usually set in the conductive core of the outer surface and the outer surface of the insulation layer, respectively, known as the inner semi-conductive shielding layer and outer semi-conductive shielding layer.
The semi-conductive shielding layer is composed of very low resistivity and a thin thickness of semi-conductive material.
Inside the semi-conductive shielding layer is to even out the electric field on the outside surface of the core, to avoid the conductor surface is not smooth as well as the core stranding of the air gap caused by the conductor and the insulation occurs partial discharge.
The outer semi-conductive shielding layer and the outer surface of the insulation layer contact are very good, and with the metal sheath equipotential, to avoid the cable insulation surface cracks and other defects and the metal sheath partial discharge.
For low-voltage power cables without metal sheath, in addition to setting up a semi-conductive shielding layer, but also to increase the metal shielding layer.
The metal shielding layer is usually made of copper tape or copper wire winding and mainly plays the role of shielding the electric field.
Because the power cable through the current is relatively large, the current around the magnetic field will be generated.
In order not to affect other components, adding a shielding layer can shield this electromagnetic field in the cable.
And the cable shield can play a certain role in grounding protection.
If the cable core damage occurs, the leakage of the current can flow along the shielding layer such as the grounding network, which plays a role in safety protection.
It can be seen that the role of the cable shielding layer is still very big.
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