Purpose winding electrical wires consists in their use in the manufacture of windings of transformers, devices, electrical machines and appliances. In these windings of electrical devices, there are usually a huge number of turns of wire.

Winding wires, unlike installation and installation wires, are characterized by the diameter of the cores, and not by their cross-sectional area. Therefore, many brands winding wires have cores of very small diameter, while the thickness of the insulating layer is negligible.

There are about 100 brands of wires of very small diameter, and all this is due to the development of technology for the production of extra thin wire and the creation of advanced electrical insulating materials.

For a long time, winding wire strands were made only of copper. But today aluminum is used for these purposes, as well as alloys with a significant specific electrical resistance. The use of aluminum makes it possible to save copper - a scarce material, and the use of alloys with high resistivity makes it possible to increase the heat resistance of winding wires.

Winding wires are classified depending on the type of insulation , while taking into account the material from which the conductive conductors are made:

With enamel, fiberglass or fiber insulation;
- with enamel-fiber (combined) insulation;
- with film insulation.

In the manufacture of winding wires, varnishes are used (for insulating cores) and lavsan, cotton, silk threads (for insulating cores and in the production of braids and windings).

Winding wires are designated according to the same principle as mounting wires - with the help of letters they indicate the material from which the core or insulation is made.

Let's talk about the main letter designations, with the help of which indicate the brand of winding wires. The first step is to determine the material from which the strands of the winding wires are made. In the first place put the letter P in the stamps of all copper wires and at the same time designate: "wire", its cores are made of copper. In order to distinguish copper wires with enamel insulation from aluminum ones, the letter A is put at the end of the brand, for example: PEV - wire with copper conductors; PEVA - wire with aluminum conductors.
In the marking of wires made of alloys with high resistivity, the letters are indicated: HX - nichrome, K - constantan, M - manganin; if it is necessary to indicate that the wire is soft (annealed), then after the letter M or K put the letter M; to determine that the wire is solid, put the letter T. For example: PEMM - wire, its core is made of soft manganin wire; PEMT - wire, its core is made of solid manganin wire; there are no other differences in the arrangement of these wires.

Letters for marking the type of insulation of winding wires:

EV - high-strength enamel on a polyvinyl acetate basis;
EL - oil-based enamel;
EM - high-strength enamel based on polyvinylformal;
ELR - high-strength enamel based on polyamide resol;
Ш - natural silk;
L - lavsan;
C - fiberglass;
O - one winding layer;
B - cotton yarn;
D - two layers of winding;
ShK - capron.

In the existing designation, the second letter P, film insulation is marked, for example: PPF - wire insulated with a fluoroplast film.

When indicating that the wire grades are made of combined insulation, the letters are determined in the order of the insulation layers from the inner layer to the outer one, for example: PELSHO - copper wire, with oil-based enamel insulation and one layer of natural silk winding.

Examples (how the brands of winding wires are deciphered):

PELR - copper wire with high-strength enamel insulation on a polyamide-resol basis; PEVKM - wire made of soft constantan wire with high-strength enamel insulation on a polyvinyl acetate basis;

Winding wires are wires used for the manufacture of windings of electrical machines, apparatus and devices. A significant amount of winding wires is also used in the manufacture of devices, in various radio engineering devices, in televisions, in aviation and space technology etc.
Winding wires can be classified:
according to the applied conductor materials: copper, aluminum and resistance alloys. An insignificant part of the wires is produced with conductors made of bimetals, precious metals and special alloys, in particular superconducting ones;
by type of insulation: winding wires with enamel insulation, or enameled wires; winding wires with fibrous or combined enamel-fibrous insulation, including those with fiberglass and paper; winding wires with plastic insulation, including film. In addition, winding wires with solid glass and glass-enamel insulation are produced in limited quantities;
according to the operating temperature (heat resistance class). The most common group of winding wires are enameled wires, which have significant advantages: thinner insulation allows you to increase the fill factor of the groove in electrical machines and devices, increase their power or reduce the overall dimensions of electrical devices while maintaining existing options. Also, from the point of view of production conditions, enameled wires are less labor-intensive compared to wires whose insulation is applied to the wire, for example, by winding. Therefore, when switching to the production of enameled wires, labor productivity at cable plants increases. An important trend in the production of enameled wires is the predominant growth in the production of the thinnest wires, due to the desire for microminiaturization of electronic equipment and computer technology. At the same time, the production of enameled wires for special purposes is expanding, in particular, wires with an additional adhesive layer used for winding coils of TV deflection systems, as well as in the production of solvent-free electric motor windings. An important point is also the transition to the use of enamel lacquers with less toxic solvents and the introduction of solvent-free resin melt enameling technology. The modern production of winding wires requires specialists from cable factories to have sufficiently deep knowledge in the field of equipment and technology, test methods, applied conductors and electrical insulating materials. The operability of winding wires as part of products is largely determined by the correct choice of them in terms of operating conditions and modes, product design, and also depends on the manufacturing technology of the product itself. The service life of the same wire as part of different products can vary several times, even if the operating temperatures are close. The main conductor material used for the production of winding wires is copper. In terms of electrical conductivity, copper surpasses all other materials, with the exception of silver, which makes it possible to ensure the minimum overall dimensions of the windings of electrical machines, apparatus and devices. In accordance with GOST 859–78, copper according to chemical composition divided into several brands. In the cable industry, only high-purity copper of grades not lower than Ml, M00k, M0k, M0ku, M0ob, M0b, M1k, M1b, M1u is used. Copper grade M1f with a high content of phosphorus (0.012 ... 0.06%), which reduces electrical conductivity, is not used. In addition, in the production of winding wires, M1p grade copper deoxidized with phosphorus and containing it in an amount of 0.002 ... 0.012% cannot be used, although such copper can be used for some other types of cable products, such as tapes. The content of copper together with silver in these grades of copper is 99.9 ... 99.99%. The grade indices have the following meanings: k, ku—cathode copper, b—oxygen free, y—remelted cathode, p and f—deoxidized. The numbers 00.0 and 1 determine the copper content, with the highest copper content being grades M00k and M006. Impurities have an adverse effect on the mechanical and
electrical properties of copper; therefore, copper with an impurity content of more than 0.1% is not used at all in cable production. The best parameters from the point of view of application in the production of winding wires, and first of all enameled ones, are oxygen-free copper, almost free of oxygen content. It surpasses the usual one in terms of plasticity and ensures the production of wire with best quality surfaces.
Appointment and classification of varnishes.
Electrical insulating varnishes used for wire enameling are solutions of high molecular weight film-forming compounds or low molecular weight reactive oligomers in volatile organic liquids. When the enamel lacquer is heated in an enamel oven, the molecular weight of the film-forming agents increases even more, and the solvent evaporates, as a result of which a hard enamel film is formed on the wire. Various synthetic resins are used as film-forming agents, as well as some vegetable oils. Solutions of film-forming agents in a particular solvent may have different concentrations depending on the solubility of the lacquer base. Enamel varnishes can have a synthetic or oil-resin base. Synthetic lacquers form stronger and more heat-resistant enamel films on the wire; therefore, they have practically replaced oil-resin-based lacquers, which also use extremely scarce vegetable oils, from the production of wires. So, at present, more than 95% of all enameled wires are made using synthetic varnishes.
General requirements to enamel varnishes
Another representative of polyvinyl acetal varnishes used in domestic practice, is varnish VL 941, or metalvin. Metalvin varnish is a solution of polyvinylformal and phenol-formaldehyde resins in a mass ratio of 2: 1 with the addition of a stabilizer - triethanolamine. The resulting film does not differ in its electrical and mechanical properties from the vinyl lacquer film, but surpasses the latter in resistance to organic solvents and water. Abroad, varnishes for enameling wire based on polyvinylformal resins are known as formex, formvar, formadur, etc. These varnishes differ from domestic ones in the composition of modifying agents, as well as in part in the methods of obtaining and the composition of the base resin.
Varnishes for wires with a temperature index of 105 ºС
Coatings based on polyvinyl acetal varnishes are most widely used as insulating coatings for enameled wires. Polyvinyl acetals are products of the interaction of polyvinyl alcohol with various aldehydes (formaldehyde, acetaldehyde, butyric aldehyde, etc.). Depending on the type of aldehyde used, polyvinyl acetals are called polyvinyl formals, polyvinyl ethyls, polyvinyl butyrals, etc. Polyvinyl acetals are used as film-forming enamel varnishes. The most common polyvinyl acetate left varnish in domestic practice is VL 931 varnish, or vinyl flex. It is a solution of polyvinyl formal ethylal and resole phenol formaldehyde resins in a mixture of technical chlorobenzene and ethyl cellosolve in a ratio of 1: 1. abrasion resistance.
Varnishes for wires with a temperature index of 120 ºС
Polyurethane varnishes are used for enameling wires with a temperature index of 120 ºС. Polyurethanes are the product of the interaction of diisocyanates with compounds containing two or more hydroxide groups. Domestic varnish UR 973 is produced by the interaction of monophenylurethane, phenolic and polyester resins with the addition of polyvinyl acetal resin. Small additions of polyvinyl formal ethital improve the flow of the varnish and increase the surface quality of the wire. Recently developed for enameling wires of small diameters, polyurethane varnish of the brand UP 9119 has a number of advantages over varnish UR 973. The additional introduction of 0.3% zinc naphthenate into the varnish accelerates the curing process during the heat treatment of the coating on the wire. Coatings based on UR 9119 lacquer have increased blocking resistance.
Varnishes for wires with temperature index 130...180 ºС
For the production of enameled wires with TI 130, 155 and 180, varnishes based on polyester, polyesterimide, polyethercyanouratimide and polyesteramidimide are used. This group of varnishes is currently the main one both in our country and abroad. In domestic practice, two polyester varnishes are used, which differ in the method of preparation, PE 943A and PE 939. Despite the relatively high heat resistance, insulation based on polyester varnishes has a specific drawback - reduced resistance to thermal shock, which lies in the fact that when stretched or bending wires to a certain extent, a sharp short-term exposure to elevated temperatures can lead to cracking of the insulation. Modified polyester varnishes are used to improve the thermal shock resistance of enameled wires with polyester insulation while increasing heat resistance. Modified polyester varnishes have been developed to improve the heat resistance of enameled wire insulation, its mechanical abrasion resistance, resistance to thermal shock and some solvents. Isocyanuric acid derivatives are used to modify polyester resins. The heat resistance of insulation based on polyester cyanurate varnishes is 155...180 ºС. The main types of modified polyester varnishes are polyesterimide and polyestercyanouratimide. Polyetherimides are heat-resistant polymers containing imide, ether groups and aromatic rings. In domestic practice, polyesterimide varnish has a brand of PE 955 and is a product obtained from dimethyl terephthalate, ethylene glycol, glycerin, trimellitic anhydride and diaminodiphenylmethane. PE 999 polyether cyanurathimide varnish is a solution of polyether cyanuratimide resin based on dimethyl terephthalate, ethylene glycol, TGEIC, trimellitic anhydride and 4,4 diaminodiphenylmethane in a mixture of tricresol and xylene. The domestic lacquer ID 9142 differs from the lacquer PE 999 by a higher content of the imide part. Coating based on ID 9142 lacquer has increased abrasion resistance, adhesion, insulation penetration temperature, and thermal shock resistance. For the production of wire enamel brand PEVTL 155, polyurethane varnish UR 155K is proposed, containing up to 28 ... 32% of the non-volatile part, in the composition of cresol, solvent, xylene, with a viscosity of 25 ... PI 180FB, the chemical basis of which is an alicyclic polyimide. The breakdown voltage is 8000/10000 V. Cresol, solvent, xylene are used as solvents for these varnishes. Their viscosity according to VZ 246 at 20 ºС: 120...106 s (for PI 180FA) and 35...45 s (for PI 180FB). Wire PET 180 belongs to freon-resistant wires. The intensification of the manufacturing process of enameled wires using high-speed enamel aggregates required the development of new enamel varnishes with specific properties: good spreadability, low content of low-molecular fragments of film-forming resin that burn out at elevated enameling temperatures, etc. ZAO Elektroizolit was developed for high-speed enameling varnishes Elizvan 155 (155T) and PI 180 FM for enameling wires on enamel aggregates with VD > 50. The usual way to obtain alicyclic polyimides is polycondensation, when, as a result of the interaction of dianhydrides and diamines, polyamic acid is first formed, from which a film is formed, which is then thermally reversed into polyimide, and temperature regime heat treatment of prepolymers is quite hard - from 80...100 to 300...350 ºС. It is known that polyimide film occupies a special place among polymer film materials due to its high thermal, physical and mechanical properties, dielectric characteristics, and chemical resistance.
Varnishes for wires with a temperature index of 200...240 ºС
For wires operated for a long time at a temperature of 200 ... 220 ºС, polyamideimide-based varnishes are used. Polyamidimides are polymers which, in addition to amide groups, contain imide aromatic rings. Domestic polyamideimide varnish AD 9113 is a solution of polyamidimide in a mixture of N methyl 2 pyrrolidone with coal solvent in a ratio of 9: 1; in the varnishes PAI 200A, PAI 200B, the composition of solvents N methylpyrrolidone, xylene is used. In addition to high heat resistance, polyamideimide varnishes provide coatings with mechanical strength exceeding even the strength of coatings based on polyvinyl acetal resin. Polyimide varnishes are used for insulation of wires operated for a long time at 220...240 ºС. During storage at room temperature, the viscosity of polyimide varnishes decreases. At elevated temperatures, on the contrary, gelatinization is possible due to cyclization and a strong increase in viscosity. The production of polyimide varnishes is associated with the use of expensive and scarce materials. Labor productivity decreases when enameling with polyimide varnishes, which also leads to an increase in the cost of the wire. Therefore, the use of wires with polyimide insulation is limited. In addition, it should be taken into account that the enamel film based on polyimides has a lower mechanical abrasion resistance than, in particular, the film based on polyesters.

The principle of operation of most electrical machines is based on the interaction of magnetic fields that are created using coil windings. Coils are an indispensable part of generators and transformers, almost all electronic devices.

To create them, use a winding wire. Let's talk about its types and brands, features and applications different types.

Why do you need to know the features of wires for winding

Many make repairs with their own hands, or assemble home-made structures. Often a burned-out electric motor is rewound independently, electromagnets (solenoids), transformers, magnetic antennas and inductors for electronic devices are wound. In this case, only the diameter of the wire and the number of turns are taken into account (these characteristics can be found in reference books, repair manuals or calculated).

• But often not only they are important, but also the type of wire - and it may not be indicated. For example, the required number of turns due to the choice of a brand with a thicker layer of insulation may simply not fit into the dimensions of the coil.
• The type of wire is also important for the reliability of the device, and even its safety, if you choose it with insufficient insulation resistance or not intended for operation at such a temperature, an interturn short circuit or breakdown may occur.
• If the first will only lead to the failure of the device, then the second, if safety measures are not observed (grounding, grounding, etc.), can be life-threatening.

In addition to the above, the price of wires with the same electrical characteristics, but different types, can vary significantly. Knowing this, you can save on material.

Why overpay for a wire designed to operate at elevated temperatures and humidity for a transformer in which a widely used PEV brand can also work perfectly.

Wire classification

Wires are classified according to several criteria.

Conductor material

It:

1. Copper- the most widespread.
2. Aluminum- because of the greater resistivity than that of copper, they are used less often. But, recently, their use is expanding, as aluminum is cheaper.
3. From resistance alloys (nichrome and the like)- used for some devices.

Section geometry

Wire cross-sections are round and rectangular. The second is used if necessary, passing through the conductor high current, for conductors with a large cross-sectional area. For cooled coils, hollow wire is used.

Insulation material

Various materials are used - from paper and natural fibers to glass. Often several layers are used, for example: paper and enamel.

For insulation, not only dielectric properties are important, but also mechanical strength, as well as thickness. The smaller it is, the more turns can be placed in the coil for a given wire diameter.

Wire marking

They are marked with several letters and numbers, after the brand they usually indicate the diameter of the section.

Attention. The diameter of the wire section is determined by copper, so if you want to know it by measuring, for example, with a micrometer, first remove the insulation.

Copper wires have the letter P (wire) first, aluminum wires are designated AP, resistance alloys have their own designations. Then comes the designation of the insulation, usually by the initial letters of the materials of its constituents and the number of layers. For rectangular wires, the letter P (rectangular) is placed at the end, then a number that distinguishes the types can follow through a hyphen.

For example PELSHKO - Wire Enamel Lacquer Silk Nylon Single, copper wire covered with lacquer enamel and additionally insulated with one layer of nylon silk. If there were two layers, then the letter D (double) would stand.

Attention. We give the markings generally accepted in our country. For imported wire, it may differ, to the extent that each company has its own designation system. Therefore, when buying material from foreign manufacturers, it is necessary to study the passport characteristics and select analogues according to operating conditions.

paper insulation

Such wires, due to low dielectric properties, are usually used in low voltage devices combined with other materials. Paper for their production is used special: cable or telephone.

widely used winding wire in paper insulation for oil-filled transformers. In them, the oil not only cools the windings, but increases the breakdown resistance. An example of APB marking is aluminum winding wires in paper insulation.

Attention. The letter B can denote not only paper but also cotton yarn, very similar to it in characteristics.

Fiber and film insulation

Various fibers and films are used for it: both natural (cotton, silk) and synthetic. They withstand greater mechanical loads than winding wires with paper insulation, but lose to them in thickness.

They are most often made by multilayer winding of fibers on a conductor. A variant is also possible when the threads are intertwined - this method is used for large diameters. The film is applied by passing through a bath of liquid insulating material. To improve properties, such insulation is combined with enamel, or the same paper.

The designations of the winding materials are as follows:

• asbestos - A;
• arimid - Ar;
• cotton - B;
• lavsan - L;
• capron - K;
• trilobal - Kp;
• plastic - P;
• glass - C;
• glass with polyester - Sl;
• fluoroplast (teflon) - F;
• natural silk - Sh.

Example: PBBO wires are winding wires with paper insulation, the layer of which is reinforced with a layer of wound cotton yarn.

Enamel

These wires are the most commonly used. Almost all windings of transformers and inductors in electronic devices are wound with them. The photo at the beginning of the article shows the coils of these wires in the factory packaging.

They are used in widely used electromechanical devices. Nearly every standard motor, generator, or contactor we encounter that is not designed to operate in special conditions, will most likely have coils that use enamel-insulated winding wires.

The advantage of this type of insulation is the small thickness of the protective layer and ease of application. It is enough to dip the wire into the enamel. Designate the insulating material with the letter E, followed by the next one shows the type of enamel.

1. Polyamide - An.
2. Winiflex - V.
3. Polyamidofluoroplastic - I.
4. L - varnish-resistant oil-based enamel. The most common type. This is not a reservation, it means resistance to the effects of electrical varnish, or rather the solvents included in its composition. The fact is that the coils for additional protection and mechanical fixation conductors after winding are impregnated with varnish. Enamel should not lose properties after this operation.
5. Polyethercyanouratimide resistant to freons - F. Winding wires with enamel insulation of this type are used for windings cooled by freons.
6. polyester - E.
7. Polyetherimide - EI.

The wires are also distinguished by maximum temperatures that their coating can withstand without losing their properties. They are divided into groups (index) - 105, 120, 130, 155, 180, 200, 220 and above °C, respectively.

What other insulation features can be indicated in the marking

In addition to the type of insulation material and the number of its layers, the marking may additionally indicate:

1. The fact that it is reinforced - W.
2. Refined - I.
3. Covered with a layer of additional varnish on the surface - L.

Winding wire for high frequencies

• In addition to standard solid wires for coils operating at high frequencies, use special wires - litz wires.
• The fact is that high-frequency currents pass only along the surface of the conductor. The resistance in this case does not depend on the cross-sectional area of ​​\u200b\u200bthe conductor, but on the length of its perimeter.
• In order to maximize it, the winding wire is made stranded - from a bundle of thin, fractions of a millimeter in diameter, conductors. Transplantation is also carried out in a special way. Designate such wires with the letter L.

We list the most common brands of such wires:

1. Power lines and lines- the bundle of conductors does not have additional general insulation.
2. LESHOE and LESHD- wrapped with silk in one and two layers, respectively.
3. LEPKO- with fibrous nylon coating.

Attention. It is difficult to remove the insulation from such wires mechanically, because of the thin wires, therefore, before tinning them, special pickling compounds are used for desoldering. Only power lines and LEPKO can be soldered immediately - their insulation is removed when heated with a soldering iron tip.

How to choose a wire for winding or coil

By the way, manual winding is of special quality (with the appropriate qualifications of workers).

The cross section and brand of the wire in the windings is usually indicated in the product passport, often the data is written on the device itself. If the document is lost, then there are several ways to find out the data.

1. For electric motors, contactors, inductors and chokes, it is easy to find the characteristics in the reference books - only if you don’t come across a foreign-made copy, or with an erased marking.
2. If the voltages on the windings of the transformer and its power are known, then there are simple calculation methods. The instruction on how to do this is simple - you need to measure the cross section of the core, and calculate just a few formulas. Even simpler, electromagnets and inductors and inductors are calculated.
3. If it is impossible to apply the previous two methods, then simply, when disassembling a burnt or broken winding, we measure the diameter and count the number of turns. Of course, it will take a long time for a large number of turns, but a winding device with a counter can be used.

Knowing the cross section and the number of turns, we select the wire, with the right insulation considering all factors. The required marking can be approximately determined by visually recognizing the insulation.

But other factors must also be taken into account. So, for fast-rotating windings, wires with enamel insulation are not used - its dielectric properties are lost at temperatures above 180 degrees Celsius, and it simply melts.

If the device operates in conditions of high humidity, then do not use a fibrous winding due to its hygroscopicity. The operating conditions of the wires are detailed in the passports.

Advice. If there is a problem with purchasing a wire of the required diameter, then you can wind a winding of two three connected in parallel, the main thing is that the sum of their cross-sectional areas (can be found in reference books) is equal to the required value. Well, of course, to fit into the dimensions of the coil.

We will be glad if our article helped you in the repair of various devices or in their independent design and assembly. Not bad even if we just deepened our knowledge of electrical engineering and now you know how winding wires with paper insulation differ from the PEV type.