Restoring the winding wire. Winding wires

The most optimal technological scheme winding wire restoration is a method in which the old winding is transferred from the disassembly site to the restoration site, after passing all restoration operations and appropriate control, it is sent to the material warehouse of the enterprise, and from there to the workshop on a general basis along with other winding wires.
Due to the complexity of the work, aluminum winding wires and copper wires with a diameter of less than 0.8 mm and a length of less than 2 m with a surface so damaged that the wire cannot be used after calibration to a smaller diameter cannot be restored.
Old winding wires are restored with wires of the PBD and PVO brands, while on new machines they use wires of the brands PELBO, PEV, PETV, etc., which are thinner in diameter (including insulation) than PBD and PVO and cannot be restored due to the obvious economic inexpediency. Therefore, the main problem when rewinding stators and rotors with PBD and PVO wires is the correct placement in the machine slots of the same number of turns of wire that were in the new machine with PELBO and PEV wires, i.e. maintaining the same power of the machine.
The technological process of winding restoration contains the following operations; removing old winding wire from the grooves of the machine and old insulation, annealing and winding the wire onto coils.
Removing the old winding wire from the grooves of the machine and sorting the wires. The old burnt wire is cleaned of caked varnish by annealing in special electric ovens, where the stators or rotors are placed for 10 - 11 hours. The varnish softens and flows out at a temperature of 270 - 300 ° C, and part of the insulation burns out, after which the wire is easily removed from the grooves. Residues of varnish and yarn, when burned, protect the wire from excessive oxidation. Annealing is carried out in an electric furnace, in which the required temperature can be accurately maintained and uniform heating of the entire wire can be achieved. During a thorough external inspection, deviations in the size and shape of the wire from the original ones are determined, then the wire is sorted by diameter, cross-section and length.
In machines with micanite insulation (with open slots), to remove sections of the winding, the latter are heated to a temperature of 70 - 80 °C with current or in an oven. The wedges are then removed and the winding sections are lifted, driving a thin steel wedge between the lower and upper sections and between the section and the bottom of the groove. To remove loose winding, depending on the type of impregnating varnish, they resort to either heating to 70 - 80 ° C (if using bitumen varnishes), or to burning out the varnish at high temperatures (if resin cementing varnishes are used). To protect copper from oxidation, annealing is carried out without access to air. After annealing, the wire is removed through the hole slot.
Removing old insulation by annealing, straightening and welding wires. Wires with a diameter of more than 1.5 mm are annealed at a temperature of 550 - 600 °C, with a diameter of 1 - 1.5 mm - 300 °C and less than 1 mm - 250 °C. At temperatures below 250 °C, the insulation does not burn completely, and above 600 °C, burnout and significant oxidation (scale) of the wire can occur.
After annealing, to completely remove the remains of the old insulation, the wire is etched in an aqueous solution of sulfuric acid (4 - 5%) heated to 50 ° C for 5 - 10 minutes, then washed in a running water cold water. Residues of sulfuric acid are neutralized by immersion in a one percent soap solution heated to a temperature of 60 - 70 °C. Neutralization lasts 15 - 25 minutes, then the wire is dried.
When cleaning windings from insulation with increased heat resistance (glass and asbestos), the described method of removing insulation is not applicable. In order to melt glass insulation, it is necessary to bring its burnout temperature to a value much higher than the burnout and oxidation temperature of the conductor. Glass insulation does not lend itself to chemical exposure. Therefore, it is removed using sandpaper and a knife, pre-heating the wire in order to melt the varnish that covers the conductor.
The wires are straightened and welded on a melting machine. The ends of the straightened and sorted bare copper wire are butt welded together using special electric welding machines. The wire is then wound onto a reel and fed to a drawing machine. During the drawing process, the wire is pulled to a smaller diameter - this is one of the main operations when restoring wires with impaired dimensional parameters: local thickenings, dents and scratches on the outer surface and an oval cross-section. If the listed defects are absent, then drawing can be excluded and the wire is calibrated - passed through a gauge corresponding to the diameter and cross-section of the wire. This requirement is mandatory, since you cannot be sure that the wire does not have any defects along its entire length.
Annealing and winding wire onto coils. During drawing and calibration copper wire acquires hardening and becomes hard-drawn (under the influence of high temperatures, copper also loses its plastic properties). Such wire is unsuitable for winding electric motors and is annealed in a furnace without air access to prevent oxidation.
The annealing process, depending on the diameter of the conductor, is carried out at a temperature of 400-500 °C for 30 - 50 minutes. In the case of annealing in an oxidizing atmosphere, cuprous oxide and oxide are removed from the surface by etching in a bath with a 5% solution of sulfuric acid at a temperature of 30 - 40 ° C for 5 - 10 minutes, and then neutralized in a 1% soap solution at a temperature 60 -70 °C for 10 - 20 minutes.
After drying, the wire is wound onto spools. When performing winding work, it is necessary not only to apply insulation to the wires, but also to remove it at the joints. However, this is quite difficult for wires with high-strength enamel insulation. Usually, special machines are used for this purpose, in which the insulation is removed from the wires with rotating wire brushes. To remove dust, the machines are equipped with exhaust ventilation.

Insulation technology for restoring the insulation of winding wires

The windings of electrical machines and transformers are mainly made of copper winding wires, which are very scarce materials. Therefore, when repairing the windings of electrical machines, the copper winding wires of damaged windings are reused. To do this, the winding is disassembled, removing it from the grooves of the stator core, wound rotor or the armature of a collector machine.
Disassembly of windings placed in open slots consists of knocking out the slot wedges, unsoldering the connections between the coils and lifting the coils from the slots. If the coils sit tightly in the grooves, they are lifted by driving textolite wedges first between the upper and lower coils, and then between the lower coil and the bottom of the groove.
Disassembling the windings of stators, rotors and armatures with half-open and half-closed slots is made difficult by the fact that the coils are firmly glued to the walls of the slot and to each other impregnating varnish. To facilitate unwinding of the stator, rotor or armature, they are heated to a temperature of 350 °C, burning off the insulation. It is also allowed to pass a low voltage electric current (40 - 60 V) through the winding when heating it until the insulation burns out and the adhesion between the turns is broken. In addition, the windings are removed by immersing the stator, rotor or armature for 8 - 12 hours in a 3% aqueous solution soda ash, heated to 80 - 100 °C. In this case, the varnish is destroyed and the winding easily comes out of the grooves.
The winding placed in an electrical machine with a stator, rotor or armature, having closed slots, is dismantled by unwinding it.
To remove old insulation, the dismantled winding is most often fired in an oven at a temperature of 450 - 500 °C. Temperature firing should be strictly controlled, since at a lower temperature it becomes more difficult to further remove unfired insulation, and with an unacceptable increase in temperature, the wire burns out, which leads to a change in the structure of the metal and a sharp deterioration in its electrical and mechanical properties.
The burned hot winding is washed in water at a temperature of 60 - 70 ° C, completely cleaning it from the insulation that has decayed in the oven. Then the wire is straightened, pulled between two compressed wooden dies, and insulated on a special machine.
In repair practice, restoration of the winding wire insulation of damaged windings is carried out mainly using devices attached to a conventional lathe.
As insulating materials for winding wires of transformers, paper tape, cable or telephone paper with a thickness of 0.05 - 0.12, a width of 15 - 25 mm is often used, spirally wound onto the wire with an overlap of 1/3 or 1/2 (semi-overlapping) of the tape width . Thin paper (0.05 - 0.07 mm) is applied to the wire in two or three layers, with the bottom layer wound end-to-end, and the top layer overlapped by 1/2 the width of the tape. Strips of insulating paper tape are glued to each other and to the ends of the braided wire with bakelite varnish.
If necessary, obtain insulated wire of a large length, for example, when making a continuous winding, individual pieces of baked wire are first butt-welded, and then the joint section is processed (filed), eliminating the thickening formed at the joint.
19.3. Winding insulation onto wires
After removing the insulation and cleaning the old winding wires, insulation is wound on them. Missing wires are usually replaced with PBD brand wires.
The PBD wire has double cotton insulation. Preparing the yarn and applying it to the wire are very important operations. The thickness of the wire insulation depends on its diameter. The easiest way to restore the following windings is:

1. PBO brand wires are a copper core insulated with one layer of cotton yarn winding. Wires of this brand are used only when repairing excitation coils;
2. PBD grade wires are a copper core insulated with two layers of cotton yarn winding. Wires of this brand are used as the main winding wire, especially for windings with sharp bends. The insulation on such wires is less likely to open when bent due to the fact that its two layers are wound in different directions. In addition, PBD brand wire is used when there is a significant potential difference between the turns of the coils.

Choice of yarn number and wire braiding technology. Cotton yarn for winding wires is selected according to the table. 1.
Yarn numbers given in table. 1, determine the thickness of the winding thread: the number is equal to the number of meters of thread in one gram of yarn. Yarn, starting from No. 100 and above, is made from long-staple cotton. To improve the electrical properties, the yarn is washed. Typical yarn numbers for textile production (40, 50, 60) produce thick insulation, the use of which can cause a decrease in engine power due to a deterioration in the fill factor of the grooves.
Table 1
Cotton yarn numbers for wire windings

Spinning mills produce yarn in the form of cobs or shanks wound into a single thread. To obtain a dense layer of windings (without gaps), you need to lay from 1200 to 20 thousand turns of yarn per linear meter of wire. To speed up the winding, it is carried out with several (6 - 24) threads at once. For this purpose, the yarn is pre-wound onto bobbins, the size of which is determined by the design of the winding machine. Then the yarn is wound onto wires made of cotton or asbestos and glass yarn.
When cleaning windings from insulation with increased heat resistance (glass and asbestos), the methods used to remove other types of insulation are not applicable.
One of the features of braided wires with glass insulation is its sliding properties. Therefore, in factories that produce glass-insulated wires, the latter is applied to a varnish base (gluing the varnish insulation onto the conductor). Since this technology requires complex special equipment, repair shops at enterprises use a simplified technology for braiding wires with glass yarn. In this case, it is applied to the conductor, adding cotton yarn, which prevents the glass from sliding.
Wire testing. Acceptance and testing of restored windings is carried out in accordance with the requirements of GOST.
During restoration, the quality of the braid is checked: it is removed from the grooves of the machine, inspected and the diameter is measured. After removing the old insulation, welding, drawing and annealing, the mechanical and electrical properties of the wire are checked. A sample 1 m long is cut from the coil and its ohmic resistance is measured with a bridge. The tensile strength is determined using a tensile testing machine. After braiding, impregnation and drying, the applied insulation is inspected and checked for electrical strength, bending and sliding (final tests). The wire is stored wound on wooden spools in a closed, dry and heated room without sudden temperature fluctuations. The sizes of the coils are standardized depending on the diameters of the wound wires. Wires with a diameter of more than 1.68 mm are left in coils.

Winding wires are intended for the manufacture of windings of various electrical machines, devices and measuring instruments.

Winding wires with polyimide insulation have the highest heat resistance among enameled wires, fairly good electrical characteristics, which practically do not change when heated to a temperature of 230 C. However, the production of these wires is associated with the use of expensive, scarce and toxic materials, which complicates their production and significantly limits areas of their application.

Winding wires are intended for the manufacture of windings of electrical machines, instruments and apparatus.

Winding wires are produced with conductive cores made of copper, aluminum and high-resistance alloys. Wires with copper and aluminum conductors are used for the manufacture of windings of electrical machines and devices, and wires with conductors made of high-resistance alloys are used for the manufacture of electrical heating elements, rheostats and reference resistances.

Winding wires with fiber and film insulation can have copper and aluminum conductors round and rectangular shape, as well as conductors made of nichrome, constantan and manganin wires.

Winding wires with paper insulation belong to TI 105 and are produced mainly for the manufacture of windings of oil transformers. Round copper and aluminum wires PB and APB brands with insulation from telephone or cable paper tapes with a thickness of no more than 0-12 mm are produced in the range of diameters T 18 - b and 1 32 - 8 00 mm, respectively.

Winding wires are made with enamel, enamel-fiber or fiber insulation. The heat resistance class of wire insulation is determined by the chemical composition of the enamel varnish and the nature of the fibrous material. Wires with fiber and enamel-fiber insulation containing cellulose and synthetic fibers, when impregnated, belong to heat resistance class A: they are moisture-resistant, chemically unstable and cannot be used for machines operating in conditions high humidity, tropical climates and in aggressive environments. PBD and one (O) cotton and the second (located closer to the core) lavsan, PLBD brand wires; wires with enamel-fiber insulation of the brands PEBO, PELSHO, PELSHO, PEVLO, PEPLO, insulated with a layer of enamel and on top of it with a braid of cotton (B), silk (Sh), nylon (K) or lavsan (L) yarn.

Winding wires with plastic insulation belong to TI 105 and are mainly used for the manufacture of windings of submersible electric motors that operate in a pumped liquid environment at elevated temperatures and pressures. They are produced, as a rule, with one-, seven- and nineteen-wire cores, the nominal diameter of which is in the range of 2 24 - 7 8 mm. Wires of the PVDP-1 and PVDP-2 brands have a two-layer insulation made of low- and high density, which allows them to be operated at voltages of 380 and 660 V, respectively. For operating voltages up to 3 kV, PPVL brand wire with two-layer polyethylene insulation is produced. The PPVM brand wire has a composition based on modified polypropylene as the outer layer.

Film insulated winding wires are also very widely used for submersible electric motors. Wires of the PETVPDL-3 and PETVPDL-4 brands are produced with copper wires in the diameter range 1 74 - 2 83 mm.

Winding wires with continuous glass insulation are obtained by pulling a thin metal thread from a metal rod heated by high-frequency currents and located in a glass tube, and belong to the class of microwires. Wires with a manganin core (diameter 3 - 100 microns) are brand PSSM and are mainly used for the preparation of resistors. PMS grade copper wires have a diameter of 5 - 200 microns, and the insulation thickness is 1 - 35 microns. Wires with continuous glass insulation are assessed by linear electrical resistance and temperature coefficient of resistance. In accordance with these parameters, they are divided into eight groups and three classes.

Copper and aluminum winding wires are used for the manufacture of windings of electrical machines, devices and devices. Winding wires are produced with enamel, fiber and film, as well as with enamel-fiber insulation.

Enamel insulation has the smallest thickness (0.0074-0.065 mm) compared to fiber and film insulation of winding wires. This allows you to place a larger number of wires in the same coil volume and thereby increase the power of an electrical machine or device. Therefore, enameled wires are the most promising among winding wires. The enamel insulation on a wire is a flexible varnish coating obtained by hardening a layer of varnish applied to the wire. A layer of varnish is applied to the wire using enameling machines. One of the common methods of applying liquid varnish to a wire is to immerse the wire in a bath of varnish. . In this case, the wire moves along the rollers at a speed of 6-32 m/min. The varnish film on the wire dries and hardens in enamel ovens (with electrically heated), through a tubular hole through which the wire passes after dipping it into a bath of varnish. Before being immersed in a bath of varnish, the bare wire unwinds from the spool , cleaned by passing through a felt wipe . Application enamel coating on the wire is done by repeatedly immersing the wire in varnish (from 2 to 8 times). After each immersion of the wire in a bath of varnish, it passes through a metal gauge, with the help of which the thickness of the varnish layer applied to the wire is adjusted through the interior of the enamel oven, where the temperature is maintained at 300-450 ° C.

The residence time of the wire in the oven is 2-50 seconds. The effect of high temperature on the layer of applied varnish is necessary for the processes of hardening the varnish film on the wire.

In table 6 and 7 show the main assortment of copper and aluminum wires with enamel insulation. It should be noted that the heat resistance of enamel insulation on aluminum wires is on average 6-10°C higher compared to the corresponding enamels on copper wires. This is explained by the lesser catalytic effect of aluminum on the organic enamel coating. Due to the need to save conductor copper, the range of aluminum winding wires will increase. Of greatest practical interest are winding wires with high-strength enamel coatings based on polyvinyl acetal and polyester resins (PEV and PETV wires), as well as wires with a high-strength enamel coating based on polyurethane resin (PEVTL wire). The latter are characterized by high electrical resistance and dielectric strength of their insulation. Due to the removal of the film of polyurethane varnish when heated to 300-360°C, PEVTL wires are quickly tinned without preliminary cleaning of the enamel layer and without the use of special etching compounds.

Copper winding wires with enamel insulation. Table 6.

Aluminum winding wires with enamel insulation. Table 7.

Windings made of wires with enamel insulation require impregnation with electrical insulating varnishes, just like windings made of wires with fiber insulation. The fact is that in a thin layer of enamel insulating coating there is always a small amount through holes(spot damage) caused by imperfect wire enameling technology (Table 8) and the presence of burrs on the wire.

Permissible number of point damage on wires with enamel insulation. Table 8.

The most important characteristics of enameled wires are: elasticity, heat resistance and electrical strength of enamel coatings. Other characteristics worth noting are the electrical resistance of enamel insulation, its thermoplasticity and mechanical strength during abrasion. Here we will look at the first three characteristics.

Elasticity of enamel coating for wires with a diameter of up to 0.38 mm is determined by smooth stretching of the wire until it elongates by 10% or until it breaks. In this case, the enamel film should not crack. For wires of larger diameter, the elasticity of the enamel coating is determined by winding the wire onto a steel rod, the diameter of which is three times the diameter of the bare wire (without enamel). For example, a wire with a diameter of 0.96 mm wound onto a steel rod with a diameter of 3x0.96=2.88 mm. In this case, no enamel cracks should be found on the turns of the wire.

Heat resistance of enamel insulation determined as a result of thermal aging of sample pieces of enameled wire.

To do this, pieces of wire are placed in a heated chamber (thermostat), where they are kept for 24 hours. at a temperature of 105, 125, 155 or 200°C, depending on the composition of the enamel coating. After being kept in a thermostat (thermal aging), a piece of enameled wire, cooled to room temperature, is stretched to a certain elongation value. Wires with a diameter of more than 0.38 mm after thermal aging, they are wound onto a round steel rod of a certain diameter. During these tests, no cracking of the enamel on the wire should be observed. Otherwise, the wire is considered to not meet the heat resistance requirements.

Electric strength enamel insulation is determined on two wires twisted (twisted) together with a length of 200 mm. Number of twists per length 200 mm is set depending on the diameter of the wire (Table 9). As the wire diameter increases, the number of twists decreases accordingly.

Breakdown voltage of wires with enamel insulation. Table 9.

Copper winding wires with fiber and film insulation . Table 10

Twisting of two pieces of enameled wires is carried out in a special machine, in which the twisted wires are subjected to a tension of 1 kg by 1 mm cross-sectional area of ​​the wire. In table 9 are given smallest values breakdown voltage for two layers of enamel on twisted sections of wires.

Winding wires with fiber and film insulation have a large insulation thickness (0.05-0.22 mm) compared to enameled wires. The main range of copper and aluminum wires with fiber and film insulation is given in (Tables 10, 11).

Aluminum winding wires with fiber insulation. Table 11

The following yarns are used as fibrous insulation: cotton, silk, nylon fibers, asbestos and glass fibers.

The greatest heat resistance of winding wires is achieved by using glass and asbestos yarn, glued to the surface of the wire using glypthal and organosilicon varnishes, which are characterized by increased resistance to heat.

Film insulation of winding wires consists of tapes made of triacetate film (cellulose triacetate), applied to the surface of the wire using adhesive varnishes (glyphthalic, etc.)

For the manufacture of oil-insulated transformer windings, wires with insulation made from paper tapes, which are well impregnated with mineral oil, are widely used. This ensures high electrical strength of the insulation of transformer windings.

To increase the mechanical strength of windings made of paper or triacetate tapes, a winding of cotton (wires of brands PBBO, PPBO-1, etc.) or nylon (wires of brands PPKO-1, PPKO-2, etc.) is placed on top of it. Wires with film insulation have increased electrical strength.

In addition to those listed, winding wires with enamel-fiber insulation are also produced. For these wires, a winding of cotton, silk, nylon or glass yarn is applied over a layer of enamel. This kind of winding wires is used for more severe working conditions in traction, mine electric motors and in other electrical machines and devices where enamel insulation is required protective covering from fibrous materials. Winding made of nylon fibers has the greatest mechanical strength. Winding made of glass yarn has increased heat resistance.

In table 12 shows the main assortment of winding wires with enamel-fiber insulation.

The requirements for winding wires with fiber insulation are as follows. For wires with fiber insulation there should be no gaps between the threads of the winding applied to the wire. There should be no breaks in the threads when winding the wire onto a steel rod with a diameter equal to five times the diameter (but not less than 3 mm) wires with fiber insulation in two layers (wires of the PBD, GIL brands, etc.), or when winding a wire with a single layer of insulation (wires of the PBO brands, etc.) onto a rod with a diameter equal to ten times the diameter of the wire (but not less than 6 mm).

Table 12

The electrical insulating properties of winding wires with fiber insulation are relatively low, since all types of fiber insulation are hygroscopic, i.e. absorb moisture from the air. The hygroscopicity of glass and nylon fibers is somewhat less than the hygroscopicity of cotton and silk fibers.

Windings made of wires with fiber insulation require careful drying and impregnation with insulating varnishes or compounding (impregnation with insulating compounds without solvents).

The electrical strength of wires with fibrous insulation is determined by the electrical strength of the air enclosed between the fibers, as well as the electrical strength of the enamel insulation of PELPYU wires. PELSHKO, PELBO, etc.

The electrical strength of fiber insulation is determined by testing sections (samples) of wires wound around a metal rod. In this case, voltage is applied to the rod and metal core of the wire under test. Breakdown voltage of the fiber insulation layer of PBD wires. PShD, PShDK is in the range of 450-600 IN, and the wires are PELBO. PELPYU and 11EL1PKO - 700-1000 IN. Approximately the same breakdown voltage is observed in wires with glass insulation impregnated with heat-resistant varnishes (wires PSD. GCLR). For wires with asbestos insulation, the breakdown voltage is 450-500 IN.

Wires with film insulation (cellulose triacetate and other films) have the best electrical characteristics. The water resistance and electrical strength of film insulation is significantly higher than fiber insulation, even in combination with enamel. The electrical strength of film insulation is in the range of 40-50 kV/mm, therefore, wires with a diameter of 2 to 4 mm with an insulation layer thickness of 0.1 mm breakdown voltage is 4-5 kV, and for wires with a diameter of 0.5-2.0 mm with a film insulation thickness of 0.0075 mm breakdown voltage is 3.0-3.75 kV.

For rectangular winding wires with film insulation (PPBO-1. IIIIKO-1. PPBO-2. PPKO-2) the average breakdown voltage is 1.3-6.0 kV. The given values ​​are much higher than the breakdown voltages of fiber-insulated wires.

In addition to copper and aluminum wires with enamel, fiber and enamel-fiber insulation, winding wires are also produced from high-resistance alloys (manganin, constantan and nichrome with the same types of insulation). Manganin wires with high-strength enamel insulation (Viniflex, Metalvin) are produced with a diameter of 0.02 to 0.8 mm. They are made from soft manganin (grades PEVMM-1, PEVMM-2). from solid unfired (grades: PEVM G-1. PEVMT-2) wire. Wires from nichrome wire produced in diameters from 0.02 to 0.4 mm(brands PEVNHL, PEVNH-2). and constantan wires made of soft and hard wire are produced with a diameter of 0.03 to 0.8 mm (brands PEVKM-1, PEVKM-2. IEVKT-1. PEVKT-2). In all wire brands, the number 2 indicates a thicker layer of enamel insulation.

Number of point damage at length 15 m for these wires should not exceed 20 - for wires with an insulation layer of normal thickness and 10 - for wires with a thicker insulation layer.

Enameled wires must withstand test voltages from 200 V (wires with a diameter of 0.02-0.05 mm) to 450 V (wires with a diameter of 0.55-0.8 mm). Otherwise, enameled wires made of high-resistance alloys are subject to the same requirements as copper wires with enamel insulation. In addition to wires with high-strength enamel, wires with conventional oil-drying enamels are also produced. Wires made of manganin (PEMM and PEMT brands) and constantan (PEK brand) have such insulation.

In addition, manganin, constantan and nichrome wires with heat-resistant (organosilicon) enamels are produced. Such wires can operate for a long time at temperatures up to 180°C.

Only manganin and constantan wires are produced with enamel-fiber insulation. For them, enamels with drying oils are used, on top of which one layer of winding made of silk (PESHOMM, PESHOMT, PESHOK brand) or cotton (YUBOK brand) yarn is applied.

In addition, our industry produces manganin and constantan wires only with fibrous insulation, consisting of two layers of silk yarn winding (brands PShMM, PShDMT, PShDK). Windings made of fiber-insulated wires, when impregnated with varnishes, can operate at temperatures up to 105°C.

Wires made from high-resistance alloys are used for the manufacture of potentiometers, additional and reference resistances, as well as in electrical measuring instruments.

End of work -

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ELECTROMATERIALS SCIENCE

ELECTROMATERIALS SCIENCE Ust-Kamenogorsk Compiled by Nina Fedorovna Karakatova, teacher of Ust-Kamenogorsk...

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Ust-Kamenogorsk 2011
Compiled by: Nina Fedorovna Karakatova, teacher at Ust-Kamenogorsk Polytechnic College. Tutorial intended

The values ​​accepted in the book.
α - temperature coefficient of linear expansion ω - angular frequency γ - specific conductivity

Fundamentals of metallurgy.
Metallurgy is a science that studies the composition, internal structure and properties of metals and alloys in their interrelation, as well as the patterns of their changes under thermal, chemical and mechanical influences

Structure and properties of metals.
Crystal structure of metals. The diverse properties of metals, due to which they are widely used in technology, are determined by their structure. Metals

Iron and its alloys.
State diagram of iron-carbon alloys. Iron-carbon alloys are divided into steels, containing up to 2.14% carbon, and cast irons, containing from 2.14 to 6.67%

The influence of alloying elements on the properties of steel.
Chromium (Cr) increases hardness, strength and ductility, maintains toughness, increases the corrosion resistance of steel, increases hardenability, allows hardening in

M - molybdenum
Marking of alloy steel. To designate alloy steel, a certain combination of numbers and letters is used, showing the approximate composition of the steel. For structural steel

Structural alloy steels
This group of steels is used mainly for the manufacture of critical machine parts and metal structures(GOST 4543 – 71). Chrome steels. Widest

Tool alloy steels
Tool alloy steels have advantages over tool carbon steels. With the introduction of certain alloying elements, steel acquires red resistance,

Steels with special properties.
The development of technology, the needs of aviation, energy, chemical and other industries place special demands on steels: for example, the ability to resist corrosion and

Thermal and chemical-thermal treatment of metals.
Heat treatment of metals and alloys is the process of changing internal structure(structures) of metals and alloys by heating, holding and subsequent cooling in order to

Annealing and normalization.
Depending on the heating temperature and cooling conditions, there are the following types heat treatment: annealing, normalization, hardening and tempering. They have various purposes and different from each other

Hardening, heating rate, quenching media, hardening methods.
Hardening is a heat treatment operation in which steel is heated to a temperature slightly above the critical temperature, maintained at the temperature and then quickly cooled in water, oil, or

Surface hardening.
It is often required that a machine part have a very hard wear-resistant surface, but that its core remains tough, strong, and can withstand impacts and alternating loads well. TO

Cold treatment.
Cold treatment (with negative temperatures) is a new method of heat treatment developed by Soviet scientists A.P. Gulyaev, S.S. Steinberg, N.A. Minkevich. Holo processing

Tempering and aging of hardened steel.
Tempering is a heat treatment process used after hardening steel in order to eliminate internal stresses, reduce brittleness, reduce hardness, increase toughness and improve

Cementation.
Cementation is the process of saturating the surface layer of low-carbon steel with carbon. The purpose of cementation is to obtain high hardness surface layer of parts while maintaining viscous and soft

Nitriding, cyanidation.
Nitriding is the process of saturating the surface layer of steel parts with nitrogen. The purpose of nitriding is to obtain high hardness and wear resistance, good resistance to alternating

Diffusion metallization.
Diffusion metallization is the process of saturating the surface layer of steel products with aluminum, chromium, silicon, boron and other elements in order to give it scale.

Corrosion of metals and alloys. The concept of corrosion, its types.
Corrosion (Latin - “corrosion”) of metals and alloys is their destruction under the influence of the external environment. Almost all metals (with the exception of the so-called noble metals)

Protection of metals from corrosion.
The essence of measures to protect metals or corrosion is to prevent direct contact of the metal with the destructive environment. This is achieved, first of all, by applying

Copper and its alloys.
Many non-ferrous metals and their alloys have a number of valuable qualities: good ductility, toughness, high electrical and thermal conductivity, corrosion resistance, etc. Thanks to these qualities

Aluminum and its alloys.
Aluminum- light metal silver-white color, density 2.7 g/cm3, melting point 660 °C. Mechanical properties aluminum is low, therefore, as a structural material

Magnesium and titanium alloys.
Magnesium is a light metal with a silvery color, density 1.74 g/cm3, melting point 651 °C. At temperatures slightly above the melting point, it is easy

Conducting copper and its properties.
Copper is one of the main conductor materials due to its high electrical conductivity, mechanical strength and resistance to atmospheric corrosion. By electrical conductivity

Copper-based conductor alloys (bronze and brass).
From copper-based alloys greatest application in electrical engineering they received bronze and brass. Bronzes are alloys of copper with tin, aluminum and other metals, specially

Conducting aluminum and its properties.
Aluminum belongs to the group of light metals. The density of aluminum is 2.7 g/cm3, i.e. aluminum is 3.3 times lighter than copper. Availability, relatively high conductivity

Conducting iron and steel.
In nature, iron is found in various compounds with oxygen (FeO; Fe203; Fe304, etc.). It is extremely difficult to isolate chemically pure iron from these compounds. Electrical and Magnetic

Lead and its properties.
Lead is a very soft metal, light gray, possessing high ductility and corrosion resistance to many reagents (sulfur, salt and acetic acid, sea ​​water And

Noble metals used in electrical engineering.
Noble metals are those that oxidize in air when room temperature. The group of noble metals includes: platinum, gold and silver. Of these metals in electrical engineering

Refractory metals used in electrical engineering.
Of the refractory metals, tungsten and molybdenum are most widely used in electrical engineering. Tungsten is a gray metal with a very high temperature melting point 3370°C and

Conductor materials with high resistivity.
In some cases, conductor materials require high resistivity p, low temperature coefficient of resistance and resistance to oxidation at elevated temperatures.

High resistance conductor alloys based on copper and nickel.
Conducting alloys used for the manufacture of precise (example) resistances are manganins. They are composed of copper (Cu), manganese (Mn) and nickel (Ni). The most common

Heat-resistant conductor alloys.
For heating elements used in electric heating devices and resistance furnaces, wire and tapes are required that can operate for a long time at temperatures from 800 to 1200°C. Described

Properties of superconductors.
The phenomenon of superconductivity was discovered by the Dutch physicist H. Kamerlingh-Onness in 1911. According to modern theory, the main provisions of which were developed in the works of D. Lardin, L. Cooper,

Electrocarbon materials and products.
Electrocarbon products include brushes for electrical machines, electrodes for electric ovens, contact parts, high-resistance carbon resistors and some other products

Basic properties of electric carbon products.
Of the electrocarbon products, the most widely used are electric brushes, which are most often simply called brushes. We will look at them in more detail. Currently used

Screen materials.
Shielding efficiency is the ratio of current voltages, electric and magnetic field strength in the shielded space in the absence and presence of a screen. E=U/U"=1/1"

Installation wires.
Installation wires are used to connect various devices and parts in electrical devices and machines. The conductive cores of installation wires are made from conductor metals

INSTALLATION WIRES
b) Fig. 19 . Installation wires with rubber insulation: a - PR brand, b - PRG brand; 1 - single-wire core. 2 - vulcanized rubber insulation

Control cables.
Control cables are designed for permanent connection to electrical appliances, devices, electrical terminal assemblies distribution devices with nominal variable

Power cables with rubber insulation.
Power cables with rubber insulation are used for transmission and distribution electrical energy in installations with voltages of 500, 3000 and 6000 V alternating current. Cables with re

Paper insulated cables.
Power cables with impregnated paper insulation produce voltages of 1,3,6,10,20,35 kV and higher. Here we consider widely used cables for voltages up to 35 kV.

Electrical insulating materials.
Rice. 36. Paths of volumetric and surface leakage currents through a dielectric: 1- dielectric, 2- electrodes It is known that each of the materials

Polarization of dielectrics.
(p Polarization of dielectrics is the process of ordering connected electric charges inside the dielectric under the influence of voltage. The process of polarization can be clarified by representing

Energy losses in dielectrics.
When polarization processes occur in a dielectric, an electric current caused by these processes flows through it, since electric charges move during polarization.

Breakdown of dielectrics.
Dielectrics are used as electrical insulating materials in electrical installations, machines and apparatus, where they are exposed to high voltage and can be destroyed

Methods for measuring the electrical characteristics of dielectrics.
Resistivity is the main electrical characteristics any electrical material (conductor, electrical insulating and semiconductor). It is calculated by

Thermal characteristics and methods for measuring them.
The flash point of vapors of liquid dielectrics (oils) is determined using a PVNO type device (Fig. 68). The basis of the device is a brass vessel with a lid 8, consisting of two parts: the lower

Physico-chemical characteristics of electrical insulating materials.
Acid number is the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize the free acids contained in 1 g of liquid dielectric. Acid number defined

Humidity properties of dielectrics.
When choosing insulating material for a specific application, you have to pay attention not only to its electrical properties in normal conditions, but also consider their stability at

Hygroscopicity of electrical insulating materials.
Electrical insulating materials are more or less hygroscopic, i.e. have the ability to absorb moisture from environment, and are moisture permeable, i.e., capable of passing through

Gaseous dielectrics. Importance of gaseous dielectrics.
Gaseous dielectrics include all gases, including air, which is a mixture of a number of gases and water vapor. Many gases (air, nitrogen, etc.) are used as dielectrics

Electrical conductivity of gases.
In all gases even before exposure to them electrical voltage there is always a certain amount of electrically charged particles - electrons and ions, which are in a disorderly thermal

Gas breakdown.
The development of the process of impact ionization in a gas leads to a breakdown of a given volume of gas (point n on the current-voltage characteristic). At the moment of breakdown of the gas, the current in it increases sharply, and the voltage tends to

Gas breakdowns at the interface with solid dielectrics.
Above, we considered the phenomena of gas breakdown in the absence of solid dielectrics in it. In practice, cases of gas breakdown at the boundary with a solid dielectric often occur. An example of this is by

Mineral electrical insulating oils.
Mineral oils obtained by fractional distillation of oil. Their chemical composition is determined by the composition of the oil. All petroleum oils are a mixture of various paraffinic (methane) hydrocarbons, n

The influence of impurities and physicochemical factors on the properties of electrical insulating oils.
The properties of oils change depending on the impurities that can get into them under operating conditions, as well as on temperature and other factors. Rice. 94. Depends

Cleaning and drying of electrical insulating oils.
Despite measures to protect the oil from oxidation, it still oxidizes and, over time, solid and liquid oxidation products and water appear in it. Therefore, the oil in use is necessary

Regeneration of electrical insulating oils.
As the degree of oil aging increases, its acid number increases. If the acid number in the oil reaches 0.25-0.50 mg KOH/g, then the oil is regenerated, i.e. restore it chemically

Vegetable oils.
Great importance in electrical insulating technology they have vegetable oils - viscous liquids obtained from seeds various plants. Among vegetable oils, drying ones should be especially noted

Synthetic liquid dielectrics.
Of the synthetic liquid dielectrics, Sovol and “calorie-2” are the most widely used. Sovol is a liquid synthetic dielectric. The starting material for manufacturing is crystalline

Polymerization organic dielectrics.
Polymerization dielectrics widely used in electrical engineering include polystyrene, polyethylene, polyvinyl chloride, etc. Polystyrene is a solid, transparent

Polycondensation organic dielectrics.
Of this group of high-polymer materials, the most widely used in electrical engineering are resol, novolac polyester, polyvinyl acetal and epoxy resins. Resol resins

Natural electrical insulating resins.
Of the natural resins, rosin, shellac and bitumen are most widely used in electrical engineering. Rosin is a brittle glassy substance in the form of pieces of irregular

Heat-resistant high-polymer dielectrics.
One of the most important tasks of electrical materials science is the development of electrical insulating materials with increased heat resistance. The use of such materials in the insulation of electrical machines and applications

Electrical insulating plastics.
Plastics, or plastics, are materials that are capable of acquiring plasticity when heated, that is, easily taking the given shape of a product and maintaining it. Plast

Properties and applications of plastics.
Plastic products used in electrical engineering are diverse, since there are many possibilities for their use and the requirements for them are different. In addition to electrical properties,

Film electrical insulating materials.
Film electrical insulating materials are flexible films and tapes made from synthetic high-polymer dielectrics: polystyrene, polyethylene, fluoroplastic-4, etc.

Laminated electrical insulating plastics.
Laminated plastics (laminated plastics) are materials in which the filler is paper or fabric, creating a layered structure of the material. The binder in them is thermosetting compounds.

Waxy dielectrics
Characteristic Features waxy dielectrics are their softness, low mechanical strength and the presence of a greasy surface that is poorly wetted by water, as a result of which they are water-absorbing

Electrical insulating rubbers.
Rubbers are widely used in the production of electrical wires and cables, where they act as electrical insulating materials (electrical insulating rubber) or as protective covers

Enamels, compounds.
Varnishes are colloidal solutions of various film-forming substances in specially selected organic solvents. They are also called film-forming

Electrical insulating enamels.
Enamels are varnishes with finely crushed (finely dispersed) substances introduced into them - pigments. Used as pigments inorganic substances, mainly metal oxides

Thermoplastic compounds.
Compounds are electrical insulating compositions made from several starting substances. At the time of application, compounds are liquids that gradually harden. Unlike varnishes and

Thermosetting compounds.
Of great practical interest are thermosetting compounds that do not soften upon subsequent heating. Such electrical insulating compounds include MBC compounds; CGMS, which are

Electrical insulating materials.
Fibrous materials consist of fibers. According to their origin, fibers can be natural, artificial and synthetic. Natural materials include asbestos, cotton, linen, natural silk

Wood and its properties.
Wood has very high hygroscopicity, so its electrical insulating properties are very low. Freshly cut deciduous trees(oak, beech, hornbeam) contain from 35 to 45%

Fiber dielectrics.
From the tree by way of it chemical treatment They teach cellulose, or fiber, which is the raw material for the manufacture of various electrical insulating papers and cardboards. In the composition of the tree,

Textile electrical insulating materials.
Textile materials are widely used as electrical insulating materials: yarn, fabrics, tapes and other types of textile products. Such materials use natural

Wound electrical insulating products.
Layered wound electrical insulating products are produced in the form of cylinders, tubes, pressed rods and various shaped parts. For these products, paper coated with bakelite is used.

Electrical insulating mica and materials based on it.
Mica is natural mineral with a characteristic layered structure that allows mica crystals to be split into thin sheets up to 0.005 mm thick. Crystal splitting

Mikanites.
Mikanites are hard or flexible sheet materials obtained by gluing sheets of plucked mica using adhesive resins (shellac, glyphthalic, etc.) or varnishes based on these resins. Rice

Mikafoliy, micalenta.
Micafolia - rolled or sheet material, consisting of two or three layers of plucked mica (muscovite or phlogopite), glued onto thick telephone paper 0.05 mm thick. In quality

Mica electrical insulating materials.
When developing natural mica and manufacturing electrical insulating materials from it, about 90% of various waste is generated. Among them, a large percentage consists of small mica waste

Electroceramic materials.
Electroceramic materials are hard, stone-like substances that can only be processed with abrasives (carborundum, diamond). To electroceramic materials from

Insulating ceramics.
One of the widely used ceramic materials is electrical porcelain. Numerous designs of high and low voltage insulators are made from it. Isho

Porcelain insulators.
Electrical porcelain is used to make insulators for low voltage installations and for communication lines, as well as various electrical installation products (bases for plug fuses

Glass and glass insulators.
Inorganic glass is a cheap material because it is made from very accessible substances: quartz sand(SiO2), soda (Na2CO3), dolomite (CaC

Main characteristics of insulators.
Fig. 136. Testing a pin insulator to determine macro-discharge voltage: 1- wire, 2- insulator, 3- steel pin: A, B, C, D, D, E - path electrical discharge

Capacitor ceramic materials.
Capacitor ceramic materials differ from conventional ceramic materials in having a higher dielectric constant (e). In addition, most capacitor cores

Ferroelectric ceramics.
Among the ceramic capacitor materials considered, a special place is occupied by barium titanate (BaTiO3), which is very different great value dielectric constant (e = 1500&div

Mineral dielectrics.
Of the mineral dielectrics, the most widely used are quartz, marble, asbestos and asbestos cement. Quartz is a natural dielectric mineral,

Electrical conductivity of semiconductors
Semiconductor materials have electrical resistivities of 10-2-1010 Ohm * cm. Electricity in semiconductors is due to the movement of a relatively small

Semiconductor materials.
Each semiconductor material, as explained above, has electronic and hole electrical conductivity. Under the influence of an applied electrical voltage, free electrons move from

Basic characteristics of magnetic materials.
Magnetic materials include iron, cobalt and nickel in technically pure form and numerous alloys based on them. The most widely used materials are technically pure iron, steel and alloy.

Properties of magnetic materials.
The properties of magnetic materials are significantly influenced by their chemical composition, manufacturing method and types of heat treatment after manufacturing. Not all, however, properties are the same

Magnetically soft materials.
The most widely used magnetically soft materials are commercially pure iron, sheet electrical steel, alloys of iron and nickel with various nickel contents

Soft magnetic alloys
A ternary iron-based alloy containing 5.4% aluminum, 9.6% silicon, and 85% iron has good magnetic properties. This alloy is called alsifer. Its magnetic

Ferrites.
Behind last years New magnetic materials, called ferrites, were developed and became widely used in electrical engineering. These materials are non-metallic, and

Magnetic characteristics of some ferrites
Name of ferrites μn, A/cm r wsp:rsidR="000000

Basic properties of magnetically hard materials.
Hard magnetic materials are used to manufacture permanent magnets used in various electrical devices that require a permanent magnetic field.

Composition and magnetic characteristics of cobalt steels
Name of steel Composition, % Magnetic characteristics Cr C W Co Fe

Magnetic hard alloys.
Magnetic hard alloys from which permanent magnets are made are called alni, alnisi, alnico and magnico. Alni is a ternary alloy consisting of aluminum,

Magnetically hard ferrites.
Permanent magnets They are also made from hard magnetic ferrites. Currently, hard magnetic materials based on barium ferrite are produced. Source materials for this f

Magnetic characteristics of barium magnets
Magnet brand Density, g/cm³ Ns, e, Gs

Electric welding.
Electric welding of metals is a Russian invention. The Russian scientist Vasily Vladimirovich Petrov in 1802 discovered the phenomenon of electric welding and showed the possibility of melting metals in a

Gas welding and cutting.
Gas welding refers to fusion welding methods. With this welding method, the edges of the parts being welded are connected by a seam in exactly the same way as in arc welding, but the heat source is not

Pressure treatment.
Metal forming (MDT) is called technological process manufacturing blanks or parts by targeted plastic deformation of the original metal after the application of external forces.

Casting and foundry production.
Foundry is the process of manufacturing foundry products, as well as the corresponding branch of industry. In factory practice, the term “casting” is widely used, under which

Types of casting.
The process of obtaining a casting consists of the following operations: 1) Making a casting mold. 2) Metal melting. 3) Pouring metal into the mold. 4) Hardened

Special types of casting.
Used to eliminate the disadvantages of casting in sand-clay molds - low dimensional accuracy and surface cleanliness, leading to large allowances on machining and metal losses in

Soldering.
Soldering is the process of producing a permanent connection between different metals using a molten intermediate metal that melts at a lower temperature than the metals being joined.

Blowtorches.
The parts to be soldered are heated with blowtorches and the solder is melted. They are used most often when soldering with low-melting solders, but sometimes they are used when soldering with refractory solders

Soldering tools. Types of soldered joints.
The main tool for soldering is a soldering iron. According to the heating method, soldering irons are divided into three groups: periodic heating, continuous heating with gas or liquid fuel, and

Soldering with soft solders.
Soft soldering is divided into acid and acid-free. For acid soldering, zinc chloride or technical hydrochloric acid is used as a flux; for acid-free soldering,

Tinning.
Surface coating metal products thin layer an alloy (tin, tin-lead alloy, etc.) corresponding to the purpose of the products is called tinning, and the applied layer is called

Hard soldering.
Soldering hard solders used to obtain durable and heat-resistant seams. Brazing is carried out observing the following basic rules: as well as

Features of soldering of some metals and alloys.
Low-carbon steels are easily soldered with both soft and hard solders. Tin-lead solders are used as soft solders, and chloris is used as flux.

Soldering defects and safety precautions.
Defects during soldering, their causes and preventive measures are as follows: the solder does not wet the surface of the metal being soldered due to insufficient flux activity, the presence of an oxide film, fat and

Page 2

Winding wires are wires used for winding electrical machines, devices and devices. The reason for this is the rapid progress in the field of electrical engineering and instrument making, which are the main consumers of enameled wires.

Winding wires are used for the manufacture of various windings of electrical machines, devices and devices. In connection with the rapid development of the domestic electric machine and apparatus manufacturing, the range and volume of production of winding wires has simultaneously increased sharply.

Winding wires with fiber insulation are used in electrical machines and devices where such insulation is necessary due to the conditions of manufacture and operation of the windings and where the increased thickness of the wire insulation is not of paramount importance. Winding wires with fiber insulation have increased operational reliability compared to enameled wires. Usually preference is given to the latter due to their lower cost, small thickness and better thermal conductivity of enamel insulation. Wires with fiberglass and delta-asbestos insulation are used for the manufacture of electrical machines with increased heat resistance classes. Until recently, paper-insulated wires have found the widest use in the manufacture of windings for oil transformers. Electrical insulating films have very high electrical strength. Wires with such insulation are used for electrical machines and high-voltage devices.

Winding wires with enamel and fiber insulation are also made with conductive cores from high-resistance alloys, mainly from constantan and manganin and in limited quantities from nichrome.

Winding wires required in the manufacture of storage devices for computers, as well as for transformers with ferrite cores and other devices and machines in which the ends of wire strands must be tinned without stripping of fibrous insulation, are manufactured using special technical specifications with polyurethane enamel insulation (PEVTL-1 wires) with lavsan fiber winding and subsequent heat treatment. As a result of heat treatment, the insulation becomes monolithic, but without melting the lavsan fibers. Such wires (PEPLOT brand) are manufactured with a diameter of 0 08 - 0 51 mm. They have insulation of a relatively small thickness (D - d Q 1 - bO 16 mm) and their core can be serviced without stripping the insulation.

Winding wires with fiberglass insulation are manufactured using gluing and impregnation of this insulation with heat-resistant varnishes. Impregnation increases the electrical strength of fiberglass insulation, since, on the one hand, when filling the air gaps with varnish, the degree of uniformity increases electric field(since 8L1), and on the other hand, the electrical strength of places filled with this varnish is significantly higher than in the case of air gaps.

Winding wires for transformer manufacturing are manufactured mainly with paper insulation.

Winding wires with film insulation are used for the manufacture of windings for high-voltage electrical machines. In the near future, triacetate film, which has low mechanical strength, should be replaced by a more durable Mylar film. In this case, there is no need to use telephone paper and cotton yarn, the quality (electric strength) of the wires will significantly increase and the insulation thickness will decrease.

Winding wires, as well as power installation wires of the PSU brand with a cross-section of over 16 mm2, are tested under voltage in a vessel filled with metal balls. It is allowed to use special metal sheaths made in the form of braiding on samples of the wires being tested.

Winding wires are insulated copper wires used for the manufacture of windings of electrical machines, devices and devices. They have extremely wide application in electrical engineering and belong to the group the most important species cable products.

Winding wires vary in shape and cross-sectional dimensions and type of insulation. The cross-sectional size is always determined by the copper core, without taking into account the thickness of the insulation; in this case, for round wires the diameter of the core is given, and for rectangular wires the dimensions of the wide and narrow sides of the rectangular section are usually indicated.

Winding wires are made of round and rectangular sections and, depending on the material of the wire (current-carrying core), the type and method of applying insulation, are divided into grades.

Winding wires are made with fiber, enamel and combined insulation.

The winding wire must be covered with a uniform layer of insulation. The braid should be applied to the wire in dense rows, without ribbing, gaps or thickening. At individual points, sagging of enamel or thickening of the braid is allowed within the tolerances established for each grade of wire size. Depending on the brand and size, winding wires are supplied in coils, drums and coils.