The design and technology of manufacturing self-supporting insulated wires (SIP) was developed more than half a century ago by engineers of Finnish grid companies with the assistance of power equipment manufacturers as an alternative to bare aluminum wires and cable rope systems. The installation of such lines does not require the performer special skills. Significantly simplified various technological operations: laying on the supports, connecting SIP to SIP, to existing power lines, to consumers.
Types and technical characteristics
To date, the market for electrical materials presents various versions of self-supporting wires: from SIP-1 - a four-wire version with a zero-core carrier for 380 V networks - to complex systems including control conductors, and SIP-3, rated at 35 kV. Isolation, as a rule, is made of cross-linked stabilized polyethylene resistant to ultraviolet radiation, current-carrying veins with a cross section from 16 to 150 mm 2 - from an aluminum alloy. SIP of special purpose is produced: sealed (SIPg), not supporting combustion (SIPN) and others.
Materials for connecting CIP
Each brand of wires has its own characteristics and, accordingly, the fitting used for mounting has some differences. For functional purposes, all materials can be divided into several groups:
- Intermediate suspensions, hooks and brackets, anchor clamps, fastening elements intended for fixing wires to supports, structural elements, building facades, distribution and input devices.
- Puncture clamps. They are used for creating connections and branch lines, connecting CIPs to wires and consumers.
- Earthing kits, safety devices, insulating materials.
- Tools and accessories for installation.
For the production of materials, high-quality steel with an anti-corrosion coating and polymers resistant to weathering and UV radiation are used.
All by the rules!
Requirements and standards for the laying of isolated overhead lines (VLI) are set forth in the normative document "UWP up to 1kV", compiled on the basis of the Electrical Code of Ukraine (Rules for the installation of electrical installations), taking into account the norms of current SNiPs and GOSTs. At the PU, the minimum permissible distances of wires of the VLI to the surface of the earth, motor roads, navigable highways, walls and roofs of buildings, windows and balconies are prescribed. Clear instructions are given on how to install and secure the power supply line, the rules for connecting SIP, overvoltage protection devices and grounding elements.
The minimum lifetime of the self-supporting insulated wire, according to the manufacturers, is 25 years, and the claimed life is about 40. The main advantage of this air line is the minimization of labor costs during installation, operation and maintenance.
In the course of preparation for the main works, they clear the territory of large branches of trees and bushes, freeing up the space for installing supports, rolling and stretching the SIP. If possible, the brackets for the wires are mounted on the supports still on the ground. The installation of overhead lines should be carried out at an ambient temperature above -10 ° C. SIP is laid along the supports using a system of rollers and tension rope. Next, the winch is gradually stretching and fixing the wires on each span. The tension force is controlled by a dynamometer (the optimum tension values are indicated in the tables for each type and cross section of the SIP, in the accompanying technical documentation). At the same time, the sag value is visually checked. If the length of the highway exceeds 100 meters and the cross-section of the veins is 50 mm 2 , the above works are performed with the help of mechanization means.
On the extreme supports are left behind the wire release latches to connect the previous and subsequent sections of the power line.
Connections and branches
Conventional twisted strips, which are customary for many electricians, have been replaced by special tapping devices in self-supporting systems-hermetic piercing clamps. With their help, without removal of insulation it is possible quickly, reliably and, most importantly, it is safe to make SIP connections to the SIP trunk, to exposed aluminum wires or to outgoing cables. The mechanism providing good contact consists of plates with pyramidal teeth and a clamping screw with a stall head (most often a 13 or 17 mm key). In modern clamps, electrical contact between the plates and the head is excluded, therefore, the artist can perform the work with the appropriate qualification without relieving tension. On the body, reinforced with fiberglass, the sections of the main and branch lines for which the clamp is intended are indicated.
Installation of branches
A branch to consumers can be made by an air line or an underground cable. When electrifying private households, the first method is most often used. For connection, you can use SIP-4 (without a zero-core carrier). The anchor fastening with the clamp for the wire is mounted to the nearest main building. When connecting the SIP to the main line (only after the wires are wired into the shield!) Use the above described piercing devices. The second clamp is screwed onto the wall of the building (at a height of not less than 2.75 m) and pulls the wire. If the distance is more than 25 meters, it is necessary to install an additional support with supporting clamps (not more than 10 m from the structure). The height of the wire from the ground surface between the supports must be at least 6 meters. Regarding the rules for the further laying of the line from the anchorage point to the entry board at the electricians' forums, unflagging and lively disputes are being conducted. What is the essence of the problem?
Connecting the CIP to the house
Variants, when the electric board is located on the outer wall of the building, almost do not cause disputes - the SIP is recommended by running into the corrugated or cable channel fixed to the facade, put in a shield and connected to the input automaton. And if the electrical panel is inside the room? In this case, electricians, according to their convictions, are divided into two irreconcilable camps.
The first argue that SIP can be directly through a hole in the wall with a pre-installed metal or plastic sleeve to bring inside the building and then in a penalty - to the shield. Their opponents argue that the self-supporting wires are intended only for the laying of overhead lines and the insulation of the SIP will be adversely affected by constant contact with the wall surface and mechanical loads and it will not be able to provide proper electrical and fire safety indoors. Therefore, near the SIP fixing point, a sealed box with a terminal block or circuit breaker should be installed, and from there it must be connected to the building with a cable (for example, VVGG).
Who is right?
Both options are fairly common and do not raise objections from monitoring organizations when accepting a building. Many manufacturers of cable products have developed their own specifications and have mastered the production of CIP-5ng wire, according to their assurances, adapted for indoor installation. But if you really follow the letter of regulatory documents (PUE and GOST R 52373-205), then the second option with the installation of a connecting hermetically sealed box looks more preferable.
Now it remains only to connect the SIP to the SIP on the input support with the help of a leakproof piercing clamp. It remains to note that these devices are recommended to be used only once, although some modifications have dismounting bolts.
Maintenance and repair
The lifetime of the self-supporting wires and clamping devices declared by the manufacturers for connecting the self-supporting insulated wire to the self-supporting insulated wire is 40 years. In maintenance, as such, such systems do not need. It is enough to conduct a periodic visual inspection. If, at the same time, violations of the integrity of the insulation coating or the cores themselves are detected, it will be necessary to perform repair work.
A vein with damaged insulation is separated from the common bundle by means of special wedges or improvised devices made of dielectric material and a double layer of insulating tape is applied to the defective area.
In case of damage to the current-carrying conductor (up to 2 m in length), this section is replaced with a new wire, similar in cross-section and grade. The connections are made with leakproof piercing clamps. With a longer length, it is more advisable to replace completely the entire vein (or tourniquet).
Competent installation and timely repair - a guarantee of uninterrupted power supply of the site.