The subject of our conversation today is the SIP wire. What is it, you can understand from the name. It is a bundle of isolated phase conductors twisted by a zero carrier. As an insulating material, polyethylene, resistant to ultraviolet radiation and weathering, is used. The conductor is made of aluminum or its alloy. In the central part of the cross section of the zero core, a steel core passes, and round it rounds of aluminum wire are twisted .
The self-supporting insulated SIP wire is used in overhead power lines, in power networks and is used for lighting at voltages up to 1000 V.
Benefits
Varieties of SIP designs have appeared as an alternative to bare wires fixed to insulators. Their advantages are as follows:
- maintenance is cheaper;
- more stable parameters during electric power transmission;
- resistance to atmospheric influences: snow and ice sticks much less, high chemical resistance of isolation to hostile environment;
- installation is simpler and faster, no heavy equipment is required;
- reactive losses are reduced by 3 times compared with traditional wires on insulators;
- the percentage of theft of electricity due to illegal connections is reduced;
- lack of short circuits when overlapping wires under the influence of wind;
- For actual operating conditions, you can select the optimal type of wire.
Wire brands
SIP wire - what is it? The answer will be more clear if you evaluate all types of the mentioned product. Different brands differ structurally and in materials.
- SIP-1 has the same phase conductors, but zero carriers are different. In this embodiment, the zero core is exposed, and in the brand with the index "n" - insulated.
- SIP-2 is made in the same way, but the insulation is cross-linked polyethylene, which retains high mechanical and electrical properties at a temperature of 130 0 (ordinary material loses its shape even at 85 0 ). Products of this brand are used in conditions of active atmospheric influences.
- SIP-3 consists of only one core with a steel core and can be used in overhead power lines with a capacity of up to 35 kV.
- SIP-4 and 5 - products contain conductive wires in the absence of a zero carrier. If there is a designation "n", then this indicates that the material is an aluminum alloy. Marks of wires are used to create branches from power lines to residential buildings and for lighting networks. In addition to them, another brand can also be used, for example, SIP-2x16 wire. The last number here means the minimum cross-sectional size in square mm.
Here it is so different - SIP wire. What is it, you already have an idea. In simple words, the products we are considering can be defined as cable products, divided into three systems:
- with bare neutrality;
- with isolated neutral;
- self-supporting system.
Let us dwell on each form in more detail.
Bare neutral system
SIP first appeared in France and Finland in the 50s, and after 30 years it was widely used in Russia. This system contains:
- one neutral carrier without insulation from aluminum or its alloy with a steel core;
- insulated phase conductors made of aluminum (1 to 4), twisted around the neutral.
The system includes domestic brands SIP-1,2 and the Finnish analogue AMKA.
The neutral is used to suspend the tow and carries the entire load from the tension and mechanical stress of external factors. It is grounded on each support to prevent the occurrence of a life-threatening potential that is possible during phase imbalance.
Insulated Neutral System
The difference is that the neutral carrier wire is insulated. The system includes wires SIP-1a, 2a and AMKA-T.
The use of insulated neutral is caused by the need to prevent corrosion in coastal marine areas or in chemically active environments. A significant drawback of the system is the high load on the insulation of the neutral conductor. With its use, anchor spans are reduced so that the protective layer is not destroyed. In all other cases, naked neutral is used.
SIP wire: characteristics of a self-supporting system
The self-supporting system does not contain a neutral wire on which the entire harness is held. It includes from 1 to 4 identical insulated conductors. It includes a single SIP-3 wire and twisted into a SIP-4 and 5 bundle. All of them are equally loaded under tension, which creates an obvious advantage over other brands.
It is recommended to use wires with bearing neutrals in the mains and outlets to consumers. SIP-4, 5 are better suited for creating branches to residential buildings and when laying wires on facades and walls.
Common SIP parameters
- Operating Temperature - Range -60 ... +50 0 .
- Execution for a temperate and frigid climate.
- Possibility of installation at temperatures up to -10 0 .
- The warranty period is 5 years, and the declared one is up to 40 years.
The cross-section of the SIP wires is in the range of 16-150 mm 2 . In most cases, it is not required to enter calculations of permissible power to enter the house, since the minimum size is enough with a margin. On the marking, the first digit determines the type of wire, and then the number of cores and cross-section, for example, SIP-2x16 wire, is indicated.
Wires are subject to mechanical stress. To calculate the strength, it is necessary to know the weight of the SIP wire, from the action of which a vertical load occurs. In addition, he is still affected by icing and wind force acting in the horizontal direction. The weight of any wire brand can be determined from the tables.
Mounting
Wiring does not require heavy equipment and special skills, although it must be done carefully to avoid damage to the insulation.
Anchor mounts and roll rollers are installed on the poles, after which the leader rope is started. A wire is attached to it and stretched, reeling from a coil. The rollers are usually coated with a protective layer of plastic. The wire must not come in contact with soil and foreign objects. Create tension by controlling its value with the help of devices. Then the wire is removed from the rollers, fixed in the span, and the line is mated or tapped by connecting and branching airtight clamps, respectively.
A feature of insulated wires is the creation of reliable electrical contact using piercing spikes. They are made on clamps. Live connection possible: this design allows for safe work.
On the supports, the wire is fixed by anchor fastening, and when installing the branch at the other end, a wall bracket is used. If the distance to the house is large, an intermediate support is installed with a supporting clamp.
Where are SIP wires used
Laying such wires does not require large expenses. Existence of isolation creates protection against short circuit at contact between wires. They can be attached to the walls of structures without insulators. Installation requires fewer supports.
For the most part, the wire is intended for power networks or for lighting at voltages up to 1 kV. The wire is used in the construction of overhead power lines and branches in residential buildings and domestic buildings.
Conclusion
Not so long ago, few people knew about such a product as an SIP wire. What is it, they realized when they saw its many advantages in many respects over the outdated air line at the insulators. Laying is done in a short time, without complex and heavy equipment, but the tools are needed in a complete set, and the qualifications of electricians must be high. Polyethylene insulation requires careful handling.