PVA wire is successfully used not only in household, but also in industrial extension cords, as well as for laying lighting. If the power consumption and wire cross-section match, it can be used to connect an electric tool to the network. Decoding PVS will help you understand how this electrical cable works.
Content
- Varieties of conductors
- Decoding and application
- Construction and connection
- Specifications
Varieties of conductors
Various electrical wires are used in apartments and private houses. Depending on the technical and operational features, they are divided into types. Among the power ones, the most common cable is VVG, which has from 1 to 5 single or stranded cores, PVC insulation, but lacks external protection.
It has a cross-section of about 1.5-240 mm², suitable for the transmission of electricity with an operating voltage of 660-1000 V and a frequency of 50 Hz. Withstands large temperature differences (from -50 to +50) and humidity up to 98%. There are different categories of VVG:
- AVVG. The copper core in it is replaced with an aluminum one.
- VVGng. Has a shell with increased incombustibility.
- VVGp. It has a flat shape.
Another power copper cable with - NYM has from 2 to 5 stranded conductors with a cross section of 1.5-16 mm². Between the insulating layers there is a layer of coated rubber, which provides additional heat resistance and strength. Designed for power and lighting networks with a voltage of 660 V. Due to its high temperature range, it is suitable for outdoor installation, but needs protection from direct sunlight.
Flexible cable (KG) consists of cores (from 1 to 6), characterized by increased flexibility. Designed for AC voltage up to 660 V, DC - 1000 V. KG has proven itself as an element for connecting various portable devices used in the open air (welding machines, heat guns, generators, and the like).
Flat wire (PUNP) consists of 2 or 3 copper conductors covered with PVC insulation and outer sheath. It is used for the equipment of fixed-type lighting systems. Withstands a maximum voltage of 250 V, has a bending radius of at least 10.
PUGNP in its characteristics is similar to PUNP with the difference that its conductors are multiwire and the minimum bending radius is 6. Its good flexibility allows it to be laid in places with a lot of bends.
The PVS conductor belongs to the household category. With a single gasket, it does not spread combustion, withstands temperature differences. Used for the production of extension cords and cords. For the repair of electrical networks, PVA wire is also chosen.
Decoding and application
Most experts working with electricity know what PVA wire means. The decoding of this abbreviation is interpreted as follows:
- P - belonging to the category of wires.
- B - the presence of an outer vinyl shell (in this case, made of polyvinyl chloride).
- C - belonging to the power class.
In the marking of conductors of this type, additional letter and number combinations are used, reflecting the design features and functional properties of individual products. The following designations are most often encountered:
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a - the presence of aluminum in the composition; - b - the presence of armor;
- d - lack of isolation;
- l - tinned copper conductor;
- t - increased resistance to moisture, called "tropical" performance.
- ps - sheath made of polyethylene with polyvinyl chloride;
- pv - sheath made of rubber and PVC.
The marking is always applied to the outer surface of the conductor. In addition to letters, it can contain numbers 2, 3, 4 or 5. They indicate how many cores were used in its production. After the number of cores, an x sign is put and then another number follows (this can be 0.75, 1.00, 1.50, 2.50), indicating the cross-section of the wire.
For example, if the cable has an inscription PVS 3 x 1 5, it means that it consists of three cores, the cross-section of each of them is 1.5 mm². However, according to GOST 22483 - 77, the actual and nominal cross-sectional dimensions may differ. It is important that the electrical resistance meets the established standards.
The category of electrical conductors of the PVA type has found wide application in various fields. Most often, they are used to:
- connecting household electrical appliances (such as refrigerators, microwaves, irons, etc.);
- connection of electrical network elements designed for a rated voltage of 380 V;
- installation of wiring in residential and domestic premises;
- connection of small agricultural equipment.
Despite the great possibilities of using PVA cable, it has some disadvantages. The main one is the inconvenience of laying hidden wiring. The round shape prevents its dense installation under plaster.
Another disadvantage is the presence of a multi-wire core, which, unlike a monolithic one, is subject to corrosion. For this reason, the service life of the PVS in street conditions will be minimal and will not exceed two years.
Construction and connection
Conductor type PVA consists of insulated copper conductors enclosed in a sheath of polyvinyl chloride. The dielectric insulation contains additives that prevent fire and protect the conductors.
The wire can include from two to five metallic conductive elements. Each contains several thin wires, twisted together and covered with colored insulating material. Different colors simplify the connection process and minimize the risk of making mistakes. The phase conductors are usually blue, black or brown, and the ground is yellow-green. The outer shell can be in different shades.
Depending on the place of installation, such a cable can be external and internal. The first type is three-phase, consists of zero, phase and ground. Serves to supply voltage from an external supply transformer to the distribution board in the room. The inner wire on the device is similar to the outer one, but has less reliable protection against environmental influences. Suitable for indoor use only.
The peculiarity of PVA installation is that the cores, consisting of several wires, tend to flatten when connected under a screw, creating the impression of an unreliable contact. To improve it, the conductors are crimped with special tips such as NVI and NKI, or washers are used. It is forbidden to connect wires by twisting. It is also not recommended to resort to soldering and tinning.to connect the PVA cable.
Specifications
Indicators of a technical and electromechanical nature are regulated by GOST. The temperature regime at which the product retains its operational properties is in the range from -25 to +40 degrees. For models marked with the letter Y, the lower temperature limit is reduced to -40 degrees, provided that during operation the conductive elements do not heat up to more than 70 degrees.
The flame-resistant wire can be used at a relative humidity of 98%. Its working resource reaches 5 thousand hours, and in the case of application in stationary devices - at least 12 thousand hours.
PVA manufacturers declare that products with a radius of 40 mm with a cross section of up to 1 mm² and products with a radius of 60 mm and a cross section of more than 1.5 mm² can withstand 30 thousand bends at a nominal voltage of up to 380 V. The warranty period of the wire service, calculated from the moment of the start of operation, is equal to 24 months. The total service life can be up to 10 years, depending on the connection used (mobile or fixed).
A standard cable product withstands an alternating current with a voltage of 2 kW for 5 minutes. After immersion in water for an hour, this time increases to 15 minutes. Typically, the wire has a length of 30 to 200 meters and is sold in cable drums and coils.
There are several advantages due to which PVA wire is appreciated. Technical characteristics guarantee it the following properties:
- high elasticity and mechanical strength;
- good indicator of thermal expansion;
- large coefficient of resistance;
- corrosion resistance.
The cable shows high reliability of work with insulators and ballasts. Preliminary oxide treatment makes it possible to use it for connecting high-power devices and electrifying enterprises of the chemical and metallurgical industries, gas stations and others.
