In the process of repairing and rewinding electric motors, you cannot do without a winding wire with a round or rectangular cross-section. The brand of wire depends on the material of the current-carrying core and the type of insulation used. The most commonly used products are from copper wire.

Any brand has the letter P (wire) in its name. Next comes the insulation marking code. There is fiber, enamel and combined insulation.
Fiber insulation made from natural and artificial silk, cotton fiber, nylon, fiberglass and lavsan. Such wires are used mainly for the manufacture of windings of oil transformers.
Enamel insulation is a mixture of synthetic varnishes that, when heated, forms a durable thin layer. Used for winding electric machines and devices that do not have strict restrictions on the thickness of the wire insulation.
Fiber insulation

• Natural silk - Ш
• Cotton yarn - B
• Kapron - K
• Artificial silk - IS
• Asbestos fiber - A
• Fiberglass - C

The letter code O or D indicates the number of layers of insulation used, one or two, respectively.
Enamel insulation

• Viniflex (high-strength enamel) - EV
• Heat-resistant polyester enamel - ET
• Varnish-resistant enamel - EL
• Polyamide resole enamel - ELR
• Polyurethane enamel - EVTL

Combined insulation consists of several layers, inner covering It is made of enamel, and the outer is a fibrous material. For example, the PELSHO marking stands for copper winding wire insulated with a layer of natural silk and varnish-resistant enamel.
If the winding wire is impregnated with heat-resistant varnish and insulated with fiberglass, the marking will contain the letter K. This wire is quite common due to its high reliability indicators; it is used for winding electric motors for cranes, including shipbuilding ones.
Aluminum wires have an additional letter A in the marking.
Marking examples winding wires:

• PETV - Enameled winding wire, heat-resistant with enamel insulation, is a copper core wire;
• PETV2 - where “2” is the number of layers of varnish on the wire;
• PELSHO - copper winding wire insulated with varnish-resistant enamel and a layer of natural silk;
• PB - copper winding wire, insulated with paper in several layers;
• PBO - winding wire made of copper, insulator - one layer of cotton yarn;
• APB - aluminum wire round or rectangular cross-section, insulated with cable paper in several layers;
• APSD - aluminum winding wire, insulated with two layers of fiberglass winding impregnated with heat-resistant glyphthalic varnish;
• PETSO - wire insulated with viniflex enamel increased strength, and one layer of glass yarn winding.

PETV

Types of wire sections

The cross-sectional size of a rectangular wire has standard values. For the square wire used in most transformers, the thickness is 1.35 - 5.9 mm, width 3.8 - 14.5 mm.



The ratio of thickness and width may be different, but this value must comply with GOST 6324 - 52. There are inconveniences in using wires square section, since when winding it on coils there is a high probability of damage to the coil insulation. In addition, it is almost impossible to distinguish by eye the smaller side of such a wire from the larger one.
An important part of the winding is the turn of the winding wire around the magnetic core. Depending on the rated power of the load current, select and required section turn. Round wire is suitable for low current, for high current, rectangular wire should be selected. When making windings, it is possible to use several parallel wires to increase the wire cross-section.
The number of turns of the winding depends on the voltage. The turns of the winding are collected into coils, electrical device may consist of several windings or coils (transformers, motors), less often of one (chokes, electromagnets). In the process of winding a coil, the turns are placed next to each other (serial winding) or one on top of the other (layers). The winding method determines the type of winding that results.

Subtleties of choosing a winding wire

When choosing a product brand, the following criteria should be taken into account:

1. Required heat resistance class. For windings with high speed Wires with enamel insulation are not suitable for rotation, since temperatures above 160 - 170 degrees Celsius can melt the protective layer.
2. Permitted thickness of the insulating layer. Combined and fiber insulation have the greatest thickness of wire insulation. However, their use in conditions high humidity undesirable.
3. Requirements for the required level of mechanical strength, moisture resistance, frost resistance and protection from chemicals.

Quality criteria for winding wires

Depending on the size and brand, wires are produced in coils, drums and coils. The winding of the wire must be even, twisting of the turns is unacceptable. The insulation layer must be uniform; thickening of the layer is not allowed. The winding rows should be uniform and dense, without gaps or ribbing. Permissible enamel sagging at specific points on the wire is strictly regulated in the accompanying documentation.
Drums and reels of wire are wrapped in paper. Matting or burlap is used to pack the bays. The coils are additionally placed in boxes, the permissible weight of which should not exceed 80 kg.

Each coil, reel or drum must have a label with information about the brand of wire, manufacturer, weight and diameter of the winding wire. The wire must be stored in indoors with low humidity levels.

and many other mechanisms.

A winding wire, unlike other types of conductors, has as its main parameter the diameter of the current-carrying core, and not its cross-section. There is very thin wire for windings, and having a negligible layer of insulation. The thinnest winding conductors are made according to special technology production for especially thin conductors and electrical insulation materials.

For a long time, winding wires were made exclusively of copper. Today, aluminum and other alloys with significant resistance are often used for them. Aluminum allows you to save expensive and scarce copper.

Classification

Winding wires are classified according to insulation material, cross-sectional shape and core material.

Insulation material

The winding wire is manufactured with the following types of insulation:

1. Fibrous.
2. Enamel.
3. Combined.

Fibrous

Wires with fiber insulation have increased mechanical strength. The thickness of the fibrous insulation is quite large, and can reach up to 0.4 mm per side. Chemical resistance and the moisture resistance of such wires is low.

Fiber insulation of wires used for rewinding electric motors and production of oil spools, may include paper, cotton fabric, glass, asbestos fibers, lavsan, silk. These fibers and fabrics are layered like a woven stocking.

Enamel insulation

The materials used for enamel insulation are viniflex, metalvin, silicone base, polyether terephthalic acid, polyurethane.

The winding wire, coated with special enamel, has electrical strength, moisture resistance, and aggressive chemicals. A feature of enamel winding wires is the very small thickness of the insulated layer (the largest thickness is 0.09 mm). The enamel strength of PEL wire is low; such wire is used only for windings of coils operating in a stationary state.

High-strength enamel wire PETV, as well as PET-155, is used for windings of electric motors with a power of up to 100 kilowatts. Enameled wire, grade PET-155, is used for the production of a new series of electric motors; the strength of its insulation allows the wire to be wound on automatic machines. Enamel wires They also have high heat resistance and can withstand temperatures up to 155 degrees.

Combined

The winding wire with combined insulation in its parameters is in an intermediate position between the two types of wires considered. The combined type of insulation includes several layers. The outer covering usually consists of fibrous material, and the inner coating is enamel. For example, PELSHO wire means: copper winding wire with insulation made of silk and varnish enamel.

If the conductor is impregnated with heat-resistant varnish and covered with fiberglass, then its marking contains the letter “K”. This type of wire has become popular due to its high reliability, and is used for electric motors of hoisting and transport mechanisms, including shipbuilding cranes.

Section shape

Winding wires come in two cross-sectional shapes:

1. Round.
2. Rectangular.

Round wire cross-section is used in various fields. This wire has high strength and electrical characteristics.

The dimensions of rectangular wire sections are standardized. This wire is often used for transformer windings. The thickness of the rectangular reins reaches up to 5.9 mm and the width up to 14.5 mm.

The ratio of these sizes may vary. There are some disadvantages expressed in the use of flat winding wires. When it is wound onto a coil, there is a high probability of damaging the insulation, and also, with very small cross-sections of the wire, it is visually difficult to distinguish the smaller side of the section from the larger one.

In any winding important element is a turn of conductor around the core. The required wire cross-section is selected based on the current power. Round wire is generally used for light loads, while rectangular wire is used for higher loads.

Conductor material

Most winding wires are made from the following materials:

1. Copper.
2. Aluminum.

Copper wires for windings are most of all produced wires. They have low resistivity and significant weight. Price copper wires high.

IN Lately instead of copper wires for windings, they began to use aluminum wire, which is much lighter in weight, has a lower cost, but has a higher resistivity compared to a copper conductor.

Marking

To designate a wire, it is marked, which indicates the material of the core and insulation.

• At the beginning of the designation is the letter “P” for copper wire, and means “wire”.
• To distinguish aluminum and copper wires, there is a letter “A” at the end of the marking, for example, PEVA.
• If the core is made of an alloy having a large resistivity, then the designation contains additional letters, for example, NH - nichrome, M - manganin, K - constantan.
• The symbol “M” is used to designate a soft conductor, and “T” is used for a hard conductor. For example, PEMT wire is copper wire made of hard wire, and PEMM wire is made of soft wire.

Letters for insulation

• EM – high-strength polyvinyl enamel.
• EL – oil base.
• EV – high-strength polyvinyl acetate enamel.
• L – lavsan.
• Ш – natural silk.
• B – cotton yarn.
• O – one layer.
• C – fiberglass.
• ShK - nylon.
• D – two layers.

If the marking contains the 2nd letter “P”, this means that the insulation is in the form of a film. The PPF wire is equipped with insulation in the form of a fluoroplastic film.

To mark combined insulation, the symbols are in the order of the layers, starting from the inner one. PELSHO - copper wire, oil-based enamel and single-layer silk braid.

Requirements

1. The winding wire is covered with uniform insulation. Allowed at some points of thickening according to the brand and size of the wire.
2. Wire is transported in coils, drums and reels, depending on the size and brand. The conductor in such packages must be wound evenly and tightly, without tangling of turns. The number of pieces of wire in a coil or coil must correspond to the size and brand of wire.
3. Packages must be packed with paper that can protect the wire insulation from damage during transportation. The maximum weight of a box with a wire should not be heavier than 80 kg.
4. A label is attached to the drum and reel indicating the manufacturer, weight, standard size and brand of wire, as well as other parameters.

How to choose winding wires for a motor

The selection of the required wire for rewinding electric motors is carried out taking into account the heat resistance class, the permissible insulation layer and other requirements.

Enamel conductors have a minimum thickness of the insulation layer. They are used with an increased percentage of groove filling during winding. Smooth surface insulation makes it easier to fit them into grooves, and its small thickness with increased heat transfer provides protection from overheating.

The use of enameled wires must correspond to certain types of varnishes and solvents used at a particular enterprise, or to those brands of varnishes that the enterprise is able to provide. There are solvents and varnishes that can destroy enamel. And also, when heated to 170 degrees, this insulation becomes plastic, which does not allow it to be used for windings of rotors rotating at high angular speed.

The maximum thickness of the insulated layer is for winding wire with a combined and fiber layer. Its use is prohibited for windings located in an aggressive or damp environment. For such purposes, it is advisable to use winding wires equipped with glass insulation, but the low insulation strength imposes certain restrictions on the use of such wires. Although, in terms of heat resistance, glass-insulated wires are suitable for similar classes of windings. When purchasing winding wire, it is necessary to take into account that the cost of a wire of one standard size depends on the brand. When repairing low-voltage electrical machines, the price of the wire will account for the majority of the financial costs of the total cost of the repair. In this regard, it is necessary to take into account technical and economic factors of choice, that is, price and technical parameters.

Page 1 of 2

WINDING WIRES WITH ENAMEL INSULATION

Winding copper wires with enamel insulation with TI 105 "C are produced with insulation based on oil varnishes(wires of the PEL brand) and based on synthetic varnishes - polyvinyl acetal resins PEV-1 and PEV-2, enameled with Viniflex varnish. The breakdown voltage of PEL brand wires depends on the diameter and varies from 200 V (00.02 mm) to 1600 V (02.5 mm), PEV-1 from 100 to 1700 V, PEV-2 from 400 to 2300 V at those same diameters.

In addition, electrical wires are also used in toilet cabins. Mostly, of course, aluminum wires.

TI 120 "C corresponds to enameled wires of the PEVL, PEVTL-1, PEVTL-2, PEVTL brands with insulation based on polyurethane varnish. The wires are soldered without stripping the insulation. Non-magnetic wires of the PEVTL-1, PEVTL-2 brands have the same insulation. Breakdown voltage of the wires depends on the diameter and varies from 350 V (00.05 mm) to 1700 V (02.5 mm) for PEVTL-1 and up to 2300 V for PEVTL-2.

For operating temperatures of 130 °C, wires of the PETV-1, PETV-2 brands with insulation based on polyester varnishes. PTVM brand wires are intended for mechanical winding of electric motor coils. The breakdown voltage of these types of wires depends on the diameter and varies from 650 V (00.06 mm) to 2800 V (02.5 mm).

PET-155 wires are insulated with polyetherimide-based varnish, have a TI of 155 °C (or heat resistance class F) and are intended for mass use in electrical engineering. Breakdown voltage from 700 to 3000 V.

For operating temperatures of 200 °C, PET-200 type wires with insulation based on polyamide imide resins are used. For temperatures up to 240 °C, PNET-imide wires with a bimetallic core (nickel-plated copper) insulated with polyamide varnish are recommended. Breakdown voltage from 2800 to 4400 V.

The technical data of some types of round copper wires are given in the following table.