Interestingly, with the help of a cable gland, they not only connect the cables, but also provide sealing and additional insulation of the connector (docking points). a modern cable line can reach tens of kilometers, and manufacturers of cable products cannot produce products of this length, they use cable couplings.
What can be the sleeve for the cable?
At the moment, the electrical market offers 3 types of cable sleeves:
- Connecting (they are used to connect cable segments).
- Branch off.
- Terminal (used to lead the cable to the busbars of switchboard inputs of electrical installations).
Couplings
They are installed in trenches under a layer of soil, and can be used to join cables with plastic or paper insulation. But there is a special type of couplings that can be used for both types of insulation.
Depending on the complexity of the installation, the cable joint can be stop and stop-transition. Such devices are used on vertical or steep tracks. With their help, it is possible to prevent the drainage of the cable masses.
End couplings
Such devices are installed in special metal cases near electrical installations and are protected from access by unauthorized persons with a lock. That is, their main purpose is to ensure the connection of the cable with the electrical apparatus.
Branch couplings
This is a specialized electrical fittings used to connect a branch cable to a main power line.
Heat shrinkable sleeves
Regardless of the type of cable insulation, cold-shrinkable or heat-shrinkable couplings can be used to connect its segments.
In terms of materials, cast iron, lead, epoxy, plastic, or other materials can be used to make electrical couplings. But at the moment, it is heat-shrinkable products that are becoming more and more popular. They are easy to install and reliable to use. The material of the sleeve is a high-tech polymer that shrinks during heating. It has high elasticity, durability and safety.
Requirements for cable glands
The cable sleeve must have the following properties:
- tightness;
- resistance to external influences, including mechanical;
- moisture resistance;
- electrical strength.
Since the coupling is, in fact, a series element of an electrical line, connecting sections of cables, it must also conduct electricity. In this case, voltage losses should be as small as possible. It is also worth knowing that the insulating layer of the coupling must reliably protect against breakdown to the body, and be resistant to aggressive soil.
Choice of cable sleeves
When choosing this device, first of all, pay attention to the scope, rated voltage, number of cores, as well as the size of the cross section.
In terms of size, cable glands are small-sized and normal. They may also differ in shape.
Based on the magnitude of the operating voltage, couplings are divided into 2 main types: for work in installations up to 1 kV, and also used in high-voltage lines.
Coupling installation
To connect two sections of a cable line using a coupler, you must first cut the ends of the cable by removing the insulating layers in them. To connect the conductors, a whole set of parts is used, depending on what process needs to be performed: termination, branching or connection of conductors. The composition of the kit is influenced by the type of conductor insulation, frequency, voltage, and other electrical parameters.
During the installation of heat-shrinkable couplings, it is not necessary to perform harmful operations on bitumen filling or brazing. No hazardous gases will be released during the installation of this electrical product.
As for cold shrinkage couplings, their installation does not require heating at all, so the installation time is much less. Such a coupling consists of EPDM rubber stretched over a spiral. During installation, the spiral is retracted, and the coupling easily shrinks, thereby providing the necessary tightness indicators.
Such a cable sleeve is not afraid of mechanical stress, since it has thick walls. In addition, rubber perfectly resists the aggressive effects of ultraviolet radiation, moisture, alkalis and acids.
Thanks to heat-shrinkable sleeves and cold shrink sleeves, it is possible to ensure the safety of such an indicator of the cable as flexibility. In addition, they will not collapse with soil displacement or cyclical temperature fluctuations when seasons change.