XLPE cable: technical characteristics, main advantages

XLPE cable appeared on the world market in the last century, in the first half of the 1970s. Companies using this technology have gained a lot of experience. This applies to the installation, testing of this product and to all operational points. In the post-Soviet space, a cable made using this technology appeared relatively recently.

Advantages of polyethylene cable

XLPE insulated cable has several advantages over others. That is why it has proved itself to be excellent in the CIS countries.

Advantages of XLPE cable:

1. XLPE tolerates high temperatures much better. This allows the wire to stay cool, which increases the throughput. Also, when high voltage is applied, the insulation does not melt (the core can get quite hot).
2. It perfectly tolerates power surges and does not deteriorate in case of short circuits. The insulation withstands this.
3. The cost of the finished product has been reduced, since there is no need to use a steel wire binding. This opportunity is provided by a high rate of moisture resistance.
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4. It tolerates strong bending, which can significantly reduce the turning radius when installing the power grid.
5. It does not need to be warmed up when laying in extremely low temperatures, because polyethylene is very elastic and flexible. Insulation has the same characteristics.
6. Due to its flexibility and elasticity, it can be laid in one electrical network on several levels at once.
7. It is easy to install in all conditions, because the XLPE cable is very light and its size is relatively small.
8. The comparative cost is low. This is possible due to the ease of manufacture.

At the moment, such a cable is used everywhere. When laying new power lines, they use it.

Production technology

People have known for a long time that XLPE is an excellent insulating material. But the full potential of this insulator was revealed only recently, since the technology for using in the production of wire was grossly underdeveloped.

Conventional thermoplastic polyethylene has many drawbacks and disadvantages when used in cable production. The critical temperature is +85 degrees. At the threshold of +85, it begins to melt and change its shape. The insulating properties are drastically reduced.

XLPE does not begin to deform even at +135 degrees. The term "crosslinking" in this industry actually means vulcanization, that is, heating to the maximum temperature for a material. In the structure, connections occur at the molecular level. A mesh is formed, due to which the material has thermal stability, increased strength, and also an increased electrical insulation characteristic.

Types of vulcanization

At the moment, all the world's manufacturers of XLPE cables use two types of vulcanization. Each uses a different polymer for the heat treatment process.

Stitching types:

1. Peroxide crosslinking is very often used in manufacturing. Peroxides are the main component used in the vulcanization process of conventional polyethylene. This procedure is performed at very high temperatures from +300 to +400 degrees Celsius. The used pressure is up to 12 atmospheres. This is a dry stitching method. The peroxide cured cable is used in the construction of medium and high power transmission lines. The limiting voltage is 35 kV.
2. The second method uses a mixture called silane. This technology is called strong. In this version, the temperatures are low - from 80 to 90 degrees. Water and steam are also used. The technical characteristics of such a cable are below. Used for networks with voltages up to 1 kV.

This cable has a complex structure and uses multi-layer insulation. When connecting and connecting, the wire must be cut. This will require special devices and tools.

Cable stripping

There are a large number of tools on the market from different manufacturers. But experts give priority to special pullers. The stripper is a special device for quick and easy removal of insulating layers. This does not damage the cores of the power cable.

Cutting the power cable must be treated very responsibly and scrupulously (so that there are no deformations of the cores), since this structure consists of many layers. Otherwise, it may start to overheat greatly. In this process two pullers are used. Each of them is designed for its own task. The first one removes the outer insulation. The second is used to clean the core itself. You can change the blades for each tool. It is also possible to choose the depth of the slot.

You can purchase XLPE cable stripping kits in stores. They include two pullers, an edge cutter (used to chamfer the wire), and a knife that is used when processing the edges of the core.

Test technology

Regardless of the type of cable, tests must be carried out without fail. In the process, the compliance of all characteristics and properties is checked for compliance with standards. Previously, such tests involved the passage of current, the strength of which was several times greater than the nominal (about 6 times).

This method was discarded, because during the verification process, the characteristics of the power lines decreased due to too high a voltage. Especially those that have been used for a long time and have poor insulation.

Currently for testing use a different technology. She is also called "sparing". This method uses a voltage that is only 3 times higher than the nominal voltage. But at the same time the current frequency is equal to 0.1 Hz. Volumetric charges are not generated during such tests. Thanks to this, there is no negative impact on the insulating layers.