The choice of a power cable for arranging a power line is a responsible event, on which the further operation of the electrical network largely depends. Insulation reliability, structural strength, the ability to use in various climatic conditions - these and other parameters determine the ability of cable and wire products to be successfully used for their intended purpose. Users are offered SIP - a practical, easy-to-use power wire with excellent characteristics that make it in demand in many household, construction and industrial fields. In the article we will talk about the SIP wire, give its detailed characteristics.
Purpose, marking, classification
SIP is an abbreviation (self-supporting insulated wire), which largely characterizes the features of the product, which is a set of insulated phase conductors twisted together and a neutral conductor. In some modifications (SIP-1, -2), the neutral core is equipped with a steel core and is a carrier. In SIP-2, it is covered with insulation, while the first model does not have such a coating. SIP-4 and -5 designs do not have a separate carrier core. They can consist of 2 or more cores. SIP-3 is a single insulated conductor with a steel core inside.
Unlike SIP-1, the zero core of SIP-2 has an insulating coating
Another difference between the first and second modifications is the insulation material. If in the first case it is thermoplastic polyethylene, then in the second case it is silanol-crosslinked polyethylene. In addition to the increased strength achieved through cross-linking, it has light-stabilized qualities, which increase its service life and improve heat resistance. The third, fourth and fifth modifications also have a sheath made of cross-linked light-stabilized polyethylene.
Additional letters may be present in the cable marking:
- A - means that the zero core is covered with an insulating layer (for example, SIP-1A);
- n - informs that aluminum alloy is used as a conductive material;
- t - notes that the product is resistant to temperature rises up to + 90 ° C.
The purpose of the SIP is the installation of air electrical mains, branches and inputs to the premises, outdoor laying along the walls and facades of buildings. Read also the article: → "".
Performance characteristics, installation features
The products in question are used to transmit electricity with voltages from 380 V to 1 kV, and SIP-3 - up to 35 kV. The main technical characteristics are:
| Options | SIP-1 | SIP-2 | SIP-3 | SIP-4 | SIP-5 |
| Cross-sectional area of cores | 16 to 120 mm² | 16 to 120 mm² | 35 to 240 mm² | 16 to 120 mm² | 16 to 120 mm² |
| Zero conductor | Yes | Yes | No | No | No |
| Line voltage, kV | 0,38 – 1,0 | 0,38 – 1,0 | Up to 35 | 0,38 – 1,0 | 0,38 – 1,0 |
| Insulation material | Thermoplastic. polyethylene | Cross-linked polyethylene | Cross-linked polyethylene | Cross-linked polyethylene | Cross-linked polyethylene |
| Temperature range | -60°C to +50°C | -60°C to +50°C | -60°C to +50°C | -60°C to +50°C | -60°C to +50°C |
| Permissible R bend | min 10 D external | min 10 D external | min 10 D external | min 10 D external | min 10 D external |
| Working resource | 40 years | 40 years | 40 years | 40 years | 40 years |
Cable installation is carried out at an ambient temperature of at least -20 ° C, since the insulating sheath becomes brittle and can be damaged when the product is bent. Other indicators characterizing the product are also summarized in the table:
| Section of the phase core,mm² | Number of wires in the conductor, pcs. | min— maxouter dimensionsDcores, mm | Conductor resistance, Ohm/km (no more) |
| 16 | 7 | 4,6 – 5,1 | 1,91 |
| 25 | // | 5,7 – 6,1 | 1,2 |
| 35 | // | 6,7 – 7,1 | 0,87 |
| 50 | // | 7,85 – 8,35 | 0,64 |
| 70 | // | 9,45 – 9,95 | 0,44 |
| 95 | // | 11,1 – 11,7 | 0,32 |
| 120 | 19 | 12,5 – 13,1 | 0,25 |
| 150 | // | 14,0 – 14,5 | 0,21 |
| 185 | // | 15,45 – 16,15 | 0,17 |
| 240 | // | 17,75 – 18,45 | 0,13 |
The use of SIP allows you to replace a whole system of four or more wires with one cable, while eliminating the risk of overlap and subsequent short circuit.
Advantages of SIP when equipping overhead power lines
Unlike traditional bare aluminum wires used to transmit electricity up to 1 kV, self-supporting insulated wires have a number of advantages:
- high reliability, long working life;
- admissibility of joint laying with other electrical lines;
- ease and speed of installation, safety for service personnel and for possible accidental contacts;
- no need to use insulators and complex suspension structures when installing;
- the presence of isolation reduces the impact of external factors (extraneous electromagnetic radiation) and reduces the reactance of the line;
- resistance of polyethylene to snow and icing, reduces the likelihood of breakage.
Some modifications provide, in addition to the main power cores, in their design, the presence of additional conductors of a smaller cross section for use as a lighting line, which makes the product more functional.
Disadvantages of insulated products
The main weaknesses of the described cables compared to non-insulated counterparts are:
- less efficient cooling;
- lower values of permissible current loads with the same cross section;
- higher cost.
The solution of the first two issues is achieved by using products with a large cross-section of conductors. This may seem economically unprofitable, but the advantages listed above more than cover these problems, and the duration of operation completely nullifies them.
Application of self-supporting cables
The peculiarity of the cable and wire products under consideration lies in the possibility of its use only in those areas that are regulated by its purpose. This means that SIP wires cannot be used:
- for laying underground;
- as house wiring;
- for laying in concrete screeds;
- when arranging wiring in baths or outbuildings.
In all these cases, wires and cables specially designed for this purpose with a rubber, plastic or polyvinyl chloride insulating sheath are used, which have the necessary class of fire and mechanical protection. Read also the article: → "".
Selection of the section of phase conductors
When choosing a self-supporting insulated wire, special attention is paid to the rated current. To establish its value, a scheme is drawn up taking into account the length of all sections of the network and the main load on each of them. Having established the estimated value of I calculated, you need to compare it with the data of I permissible from the table below and make a decision regarding the brand of cable and wire products.
Indicators for SIP-1, -2, -4:
| The cross section of phase conductors with their number from 2 to 4,mm² | Permissible continuous current for cores with thermoplastic polyethylene insulation,I add., A | Permissible continuous current for conductors with XLPE insulation,Iadd., A |
| 16 | 70 | 100 |
| 25 | 95 | 130 |
| 35 | 115 | 160 |
| 50 | 140 | 195 |
| 70 | 180 | 240 |
| 95 | 220 | 290 |
| 120 | 250 | 340 |
You can analyze: with a rated current of 110 A, you must choose SIP-1 with a cross section of 35 mm², or SIP-2 with a cross section of 25 mm². The second option is preferable because the wire will be lighter, stronger, and most importantly less susceptible to precipitation and wind.
Packing, storage and transportation of SIP products
Short-term storage of SIP wire on drums in open areas is allowed
According to the requirements of GOST 18690, self-supporting insulated wires are supplied on reels. Transportation is also carried out on drums. In some cases, transportation and storage in bays is allowed. At the same time, the cross-sectional area of the main core of the product should be 16-25 mm², and the mass of the coil should be no more than 25 kg. Storage is carried out under sheds or indoors. Placement in open areas for a short period of time is also allowed.
According to the norms of the standard, the outer part of the drums can be sewn up with mats. The product must have an accompanying document (label or passport), which is securely attached to the bay or cheek of the drum. For safety, the document is placed in a waterproof package.
Manufacturers of self-supporting insulated wires
On the territory of the Russian Federation there are several dozen enterprises manufacturing cable and wire products. Among them, there are several manufacturers of SIP cables of various modifications:
- Nexans Rus LLC, a representative of Nexans in Russia. In 2007, the company was recognized as the best supplier of electrical products. Produces wires SIP-1, -2, -3, -4, including modifications "A"
- CJSC "Tomskkabel" is one of the ten leading enterprises in the Russian Federation and the CIS countries in the production of cables and wires. One of the types of manufactured goods is a self-supporting insulated wire of various brands and sizes.
- Cable plant "Lyudinovokabel", located in the city of Lyudinovo, Kaluga region. It produces products SIP-1, -2, -3, -4, which it supplies to many enterprises in Russia and the CIS countries
- LLC "Plant Moskabel", Moscow, st. 2nd Cable. Successfully competes with other manufacturers due to the high quality of products. Manufactures all brands of self-supporting wires
- The Kolchuginsky plant of JSC Elektrokabel produces most of the nomenclature names of cables, including self-supporting insulated wire. A wide range and quality of goods has won the company a well-deserved reputation in the consumer market.
Plants for the production of cables and wires are equipped with precise modern equipment
In addition to the listed enterprises, there are other manufacturers of products for overhead power lines in Russia. The user can choose the most suitable manufacturer for himself.
Selecting and checking a product (step by step instructions)
The arrangement of power lines requires a responsible approach to the choice of current-carrying conductors. The main questions that arise when choosing a wire:
- type and brand of product;
- section of the current-carrying core;
- line length.
Practical advice: despite the difference in price between SIP-1 and SIP-2, that is, wires with thermoplastic and cross-linked polyethylene insulation (the latter are 1.5-2 times more expensive), in some cases the second option should be chosen. With a smaller cross section of the cores, they will be able to provide the same throughput, and at a cost approach the analogue due to the smaller diameter.
Before installing the wire for operation, it is necessary to check the integrity of the cores. This can be done with a "multimeter" tester:
- Set the device switch to the "continuity" position in the resistance sector, and then connect the red and black probes to each other. If the device is working, a signal should sound - a dial tone. Read also the article: → "".
- On a wire coiled or wound on a drum, touch the two ends of one of the cable cores with different probes. A conductor that is not damaged will “beep” through a continuity
- Repeat the above steps with all strands of the SIP wire.
A simple circuit for checking the circuit through the closure of the probes of different ends of the conductor
The same test can be carried out with the switch position on the tester in the resistance measurement sector from 200 ohms to 200 kOhm. The display of "0" indicates the integrity of the conductor, "1" - the presence of a break.
The most common mistakes in the installation of overhead power lines using SIP
- One of the most common mistakes is the use of any connections other than connecting clamps (sleeves) during the installation of electrical mains from self-supporting products.
- Another mistake can be considered switching wires on poles. The production of SIP connections should be carried out in the span, between two supports. The strength of the product does not decrease from this.
- A gross violation is the twisting of several products into one bundle for joint fastening on a power pole. Each wire must be routed and secured separately.
- The rolling of the wire must be carried out on special polymer-coated rollers. The implementation of rolling on the ground will lead to a violation of the insulating coating.
Proper installation work will extend the life of the product, as well as eliminate the need for revisions and repairs.