Method for determination of impregnation coefficient for electrical machines coils. RU patent 2521439.

FIELD: electricity.

SUBSTANCE: invention is related to the field of electric engineering, and namely to non-destructive quality control procedures for electrical products, in particular, to impregnation of windings of electrical machines. According to the suggested method for determination of impregnation coefficient for electrical machine windings impregnated by cured polymer composition capacitance values C_cbi and C_cui in regard to the ground are measured for each electrical machine winding in the batch before and upon impregnation by the polymer composition and drying. Then, upon impregnation and drying of windings temperature of each winding T_1ui is measured and through the wire of each tested winding stabilised direct current I₀ is passed and its values is selected depending on section area S of the winding wire strand within the range of maximum current density permitted for the material of the winding wire from j_min up to j_max within the range of values j_minS ≤I₀≤j_maxS. At that the above selected current I₀ is passed through the winding during a certain period of time t₀ and voltage drop is measured at the winding U_1i at the moment of stabilised current delivery to it and voltage drop at the winding U_2i at the above period of time t₀. Upon the above operations according to measurement results the impregnation coefficient K_ic is determined for each tested winding in the near-body cavities and impregnation coefficient K_tt of turn-to-turn cavities in the windings as per the following formulas: $${К}_{ic}=\frac{1}{\ln {\epsilon }_{is}}\times \ln \frac{{С}_{cui}({С}_{eq}-{С}_{cbi})}{{С}_{cbi}({С}_{eq}-{С}_{cui})},(4)$$ (4), $${К}_{tt}=\frac{1}{m_{0tt}{с}_{с}}\{I_0\times t_{о}[\frac{U_{1i}(U_{1i}+U_{2i})\alpha }{2(U_{2i}-U_{1i})[1+\alpha ({Т}_1-20]}]-[1+\alpha ({Т}_1-20)]\frac{B_2}{U_{1i}}+B_1\},(5)$$ (5), where $${С}_{eq}=\frac{рS_a{\epsilon }_0{\epsilon }_{э}{\epsilon }_{fi}}{(d_e{\epsilon }_{fi}+d_{fi}{\epsilon }_e)}$$ is equivalent capacity of in-series capacitance of enamel and frame insulation of the winding; p is a number of slots in the magnet core to which the tested part of the winding is placed; S_a is an area of the slot surface; ε₀=8.854187·10^-12 is the electrical constant; ε_e is dielectric capacitivity of enamel film at the winding wire; ε_fi is dielectric capacitivity of frame insulation; d_ei is thickness of enamel insulation of the wire; d_fi is thickness of frame insulation at the wire; c_c is specific heat capacity of the dried impregnation composition; $$m_{0tt}=d_c{S}_c{l}_w(1-\frac{р}{4}{К}_f)\times \frac{р}{2}-рS_a^2{\epsilon }_0(\frac{{С}_{eq}-{С}_{dc}}{{С}_{dc}{С}_{eq}})$$ is a limit mass of dry impregnation composition which can be placed in turn-to-turn cavities of the winding at 100% of their filling; d_c is density of dried impregnation composition; S_cs is cross-sectional area of the slot; l_w is length of the winding turn; K_f is the slot filling coefficient; α is temperature coefficient of the winding wire resistance; B₁ = C_eehc + C_fiech is equivalent heat capacity of enamel $${С}_{eehc}={с}_e\frac{\pi (D_e^2-D_w^2)}{4}{1}_w{\rho }_e$$ and frame insulation C_ei = C_fi × P × d_fi × L × p × c_fi; c_e is specific heat capacity of enamel; D_e is the diameter of enamelled wire of the winding; D_w is the diameter of the winding wire strand; l_tw is rated length of the wire in the tested winding part; ρ_e is enamel density; c_fi is specific heat capacity of the frame insulation; P is the slot perimeter; d_fi is thickness of the frame insulation; L is the slot length; ρ_fi is density of the frame insulation; $${В}_2={с}_w\times {\rho }_{20}\times I_0^2{\rho }_w{l}_w^2$$ is the constant rate; c_tw is specific heat capacity of the material used for the winding wire strand; ρ₂₀ is specific resistivity of the material used for the winding wire at 20°C.

EFFECT: simplification of the method due to avoidance of measuring capacity in regard to the ground for one random winding and self-capacitance before impregnation, dipping of the above winding into impregnating liquid with the known dielectric capacitivity and measuring of this winding capacity in regard to the ground and self-capacitance again with the winding placed in the impregnating liquid as well as die to avoidance of double measurements of self-capacitance for each of the tested winding before and upon impregnation, improvement of accuracy because the value of impregnation coefficient does not depend on relative position of turns in the slot, as well as increase in information content of control because this method allows to determine distribution of the impregnation composition inside the winding and impregnation coefficients for near-body and turn-to-turn cavities of windings.

1 tbl, 2 dwg

The invention relates to the electrical engineering, namely to non-destructive methods of quality control of technological processes of manufacture of electrotechnical products, in particular impregnation of windings of electrical machines.

There is a method of quality control impregnation of windings of electrical machines, proposed in [2], which is to measure the capacity of winding relatively magnetic core to impregnation With PD and capacity relative to the magnetic cores after impregnation and drying of windings With PP and the quality impregnation asked to judge by the coefficient impregnation To PR defined from the expression

Disadvantage of this method is the counterpart is the low precision of control, as the magnitude of APS and PP depend on the location of turns in the coil, as well as on how they are distributed in the composition of the body cavities of the winding. When getting the same amount (mass) of impregnating composition in two similar types of winding of one party To the PR , which is determined by the formula (1)may give rise to significantly different from each other values. Therefore, the formula (1) does not allow to objectively judge the saturation of cavities winding impregnation composition.

There is a method of determining the coefficient of impregnation of windings, as described in [2], partially eliminate the above drawbacks analogue.

The method is similar in the way that each winding of the party are measured capacity relative to the body prior to treatment and after impregnation and drying, one of the windings, randomly selected from the party, after measuring capacity relative to the body prior to treatment immersed in impregnation liquid with known dielectric constant winding and measure the capacity of the relative to the housing without removing the winding of penetrating fluids, and the coefficient of impregnation for each of the remaining windings of this party is determined by the formula

where APS , With PP - capacity winding relative to the housing, respectively, prior to treatment and after impregnation and drying;

- capacity of an arbitrarily chosen winding relative to the body prior to treatment;

- capacity of an arbitrarily chosen winding relative to the body after exposure in penetrating fluids with known dielectric permeability to fill her cavity winding; ε 1 - dielectric permeability penetrating fluids; ε 2 - the dielectric constant of the cured impregnating composition.

The disadvantage of this method is the need for one randomly selected windings to measure the capacity relative to the body prior to treatment, then, after measuring capacity relative to the body prior to treatment, immerse the winding impregnation liquid with known dielectric permeability and measure the capacity of the winding relative to the housing without removing the winding of the impregnation liquid. The introduction of this operation and the need for dual measuring capacity prior to treatment and after it complicates the process.

In addition, the above method is only defined by an average coefficient impregnation prykordonnyk cavities of the windings To the CRC . Meanwhile, no less influence on the quality of the windings and has a coefficient of impregnation interturn cavities of the windings To the MPR , which at the specified method not determined.

Closest to the claimed is a method of determining the coefficient of impregnation curable polymer composition of windings of electrical machines, described in [3].

In the way-the prototype of each winding of the party are measured capacity relative to the body prior to treatment and after treatment polymer composition and drying and one randomly selected winding after measuring capacity relative to the body prior to treatment immersed in impregnation liquid with known dielectric permeability, stand to fill her cavity winding and measure the capacity relative to the housing without removing the winding of penetrating fluids and on the results of measurements determine the coefficient impregnation prykordonnyk cavities of the windings To the CRC , then all the windings of the party and randomly selected winding after each of the aforementioned dimensions change their own capacity, and the coefficient determined by impregnation expression

where e - dielectric constant of the cured (dry) impregnating composition;

With CDP , With cat - capacity winding relative to the housing respectively before and after the impregnation of polymer composition and drying; With the SDT With WFP - own capacity winding, respectively before and after the impregnation of polymer composition and drying; ε 1 - dielectric permeability penetrating fluids;

- constant coefficient;

- capacity of an arbitrarily chosen winding relative to the housing, respectively, prior to treatment and after soaking in penetrating fluids;

- constant coefficient,

- own capacity randomly selected winding respectively prior to treatment and after soaking in penetrating fluids.

The disadvantages of the prototype method are:

- the need for one randomly selected windings to measure the capacity relative to the body and its own capacity to impregnation, then immerse the winding impregnation liquid with known dielectric permeability and again measure the capacity of this winding relative to the housing and own capacity without taking the winding of the penetrating fluids, which complicates the way;

- the necessity of each of the controlled winding twice to measure its own capacities: prior to treatment and after it, which leads to additional complexity of the method;

- low precision control, due to the large variation in own containers from one coil to another, which is associated with a random location of turns in the coil, and the dependence of the value of the capacitance of the windings from how distributed impregnating composition, between what turns winding;

- low information control, due to the fact that according to the formula (3) determine average coefficient impregnation only interturn cavities winding, and how he distributed inside winding and what is the ratio of impregnation prykordonnyk cavities, the method of the prototype does not define.

Technical challenge, which is aimed invention is to simplify the way, improvement of its informational content and accuracy.

The goal of the project is solved by the fact that the method of determining the coefficient of impregnation curable polymer composition of windings of electrical machines, in which each winding of the party prior to treatment and after treatment polymer composition and drying measure capacity the KDP and the cat on the hull additionally after measuring capacity relative to the body, each controlled winding With the PPC after impregnation and drying, measure the temperature of the winding T 1ppt , then through the wire each controlled winding miss constant stabilized current I 0 , the value of which is selected depending on the sectional area of S veins wire winding in the range of permissible for material wire winding current densities from j min to j max , range of values j min S≤I 0 < j S max, and referred to the current I 0 is passed through a coil within a certain time t 0 and measure the voltage drop across the coil U 1P at the moment the supply to it a constant current and voltage drop across the coil U 2s at the time mentioned time t 0 , then each controlled winding for measurement results determine the coefficient impregnation prykordonnyk cavities To Ki and winding ratio impregnation To mV interturn cavities winding by formulas

- equivalent capacity consistently United tanks enamel and Cabinet winding insulation; p - the number of slots in the magnetic core, in which poured controlled part of the winding; S p a surface area of ESD; ε 0 =8,854187·10 -12 - electric constant; e e - dielectric constant of the enamel film wire winding; e to - the dielectric constant of Cabinet-type isolation d e is the thickness of the enamel wire insulation; d - thickness of Cabinet insulation of the wire, c is the specific heat of dry impregnating composition,

- limit the dry weight impregnating composition, which can be used in turn-to-turn cavities winding at 100% filling; d is the density of the dry impregnating composition; S - sectional area of ESD; l w - length coil winding; C - coefficient of filling groove; α temperature coefficient of resistance of a wire winding; 1 =AEM +ek - equivalent to the heat capacity of layers of thermal capacities enamel

and Cabinet insulation With EC =Ki x P x d Ki x L x R x CI ; c uh - specific heat enamel; D'oex - diameter enamelled wire winding; D PR - diameter wire winding; l PR - nominal length of the wire is controlled portions of winding; with GM - density enamel; Ki - specific heat of Cabinet isolation, N - perimeter groove; d Ki - thickness of Cabinet insulation; L - length of a groove; Ki - density Cabinet insulation,

- constant coefficient; with PR - specific heat capacity of a material of conductor wires winding; p 20 - specific resistance of the material veins wire coil at 20 degrees C.

Figure 1 presents a cross-section of winding in one of the slots, representing a layered system.

It consists of winding wires 1, coated with a layer of enamel 2, Cabinet insulation 3, the surface of the groove 4, air cavities between the surface winding and Cabinet insulation of 5 and air pockets between the Cabinet insulation and surface groove 6, magnetic core (building) 7, interturn 8 cavities.

Figure 2 shows the capacity of winding on the hull, which is a magnetic core stator electric machines, presented in the form of a layered flat condenser prior to treatment (Figo) and after it (FIVB). On figa and figb entered the same labels, only to figb instead positions 5 and 6 introduced the position 9 and 10, as the air cavity winding 5 and 6 after impregnation and drying partially filled impregnating composition. In this regard, items 9 and 10 marked the same layers 5 and 6, but filled statistically distributed through these layers of particles impregnating composition. Figure 1, figure 2 serve to clarify the essence of the invention.

The method consists in the following.

The basic part of the winding of electric machines are placed into the grooves of magnetic core, is a layered system (see figure 1). Since the thickness d e enamel insulation 2 wires 1, thickness d to Cabinet insulation 3 and total thickness d in air pockets between the surface winding and Cabinet insulation of 5 and air pockets between the Cabinet insulation and surface groove 6 are infinitely small and amount to several microns, then the capacity of the winding relative to the housing can be dismissive low measurement uncertainty present in the form of a layered flat capacitor (see figure 2). Capacity not impregnated windings relative to the magnetic core (body) prior to treatment With PD in accordance with figa can be represented as the following ratio:

where e , K , With in - capacity of a layer-time abilityasia, capacity of a layer of Cabinet of isolation, the total capacity of air layers 5 and 6 (2), respectively.

It should be noted that the range of thickness of the enamel and Cabinet insulation of the same type windings negligible, so the equivalent capacity of these layers in the same type windings can, with a scornful little error, be considered equal and constant from one coil to the other coil. The spread of the vessels covered With KDP windings mainly due to the spread equivalent containers in from one coil to the other and connected with difference from coil to coil air cavities 5 and 6 (figure 1 and figa).

Equivalent capacity With EQ consecutive layers of enamel and Cabinet insulation can be written in the form

Taking into account that capacity enamel layers in accordance with figa can be represented in the form of a series of plane condensers and taking into account a thickness of enamel d e and Cabinet-type isolation d and dielectric permittivities e e, e C , the expression 7 can burn

where e 0 =8,854187817·10 -12 - electric constant.

Equivalent to the capacity of air layers 5 and 6 (Figo) record

where d is the total thickness of the air layers 5 and 6.

Taking into account expression (6), (7) and (9), and the fact that the dielectric constant of air ε in =1, we can write a formula to determine the total thickness of the air gap in d

V Ki-V p - air volume in the layers 9 and 10, ε* - the dielectric constant of a statistical mixture in layers 9 and 10.

Given that the dielectric permittivity of air ε in =1, a ln ε =0, equation (11) can be written in the form

In expression (12) ratio

there is nothing more than a factor of impregnation To PR prykordonnyk cavities 9 and 10, which characterizes the degree of filling of cavities V Ki impregnating composition.

If to consider, that after impregnation and drying impregnating composition, dielectric permeability which e p statistically distributed by volume layers 9 and 10, the equivalent capacity of these layers can be presented by the expression

Substituting into equation (6) instead of in value To item from the expression (13), we can write the expression for the capacity of the CPR

From (14) we Express the total thickness of d layers, 9 and 10

Because after impregnation and drying of thickness d in layers 9 and 10 in each controlled winding remained equal to the total thickness of air gap d in not impregnated windings, one can equate the right-hand part of the expression (10) to the right side of the expression (15) and get

From the relation (16) Express e* and by converting the received the expression, record

Express from the relation (12) ratio impregnation prykordonnyk cavities winding To the key , get

Substituting into equation (18) the value e* from (17), we obtain

Thus, to determine the degree of saturation prykordonnyk cavities windings impregnation composition enough of each of the controlled winding up impregnation and after impregnation and drying to measure capacity relative to the housing With the KDP and the CPR and to determine the coefficients impregnation prykordonnyk cavities windings on the above formula (19).

Consider the principle of measurement of the degree of saturation of an impregnating composition of the inter-track 8 (1) of cavities winding. First, we will show how, using thermal method, to determine the total mass of impregnating composition, which is in turn-to-turn and prykordonnyk cavities winding.

Prior to treatment equivalent to the heat capacity of the winding With the EAF is equal to the amount of heat capacities

where the EPR =CR x m PR - equivalent to the heat capacity of the wire controlled winding; With EEM =s e x m a is equivalent to the heat capacity of enamel wire insulation; With EKI =Ki x m Ki - equivalent to the heat capacity of the wire enamel; with the PR , with em , with Ki - specific heat capacity of the material wires, enamel, Cabinet isolation, respectively; m PR , m e , m CI weight of conductor wires, enamel and Cabinet and isolation, respectively.

As m PR >>m e and m PR >>m Ki , and is equivalent to the heat capacity not impregnated windings from the expression (20) is determined mainly by the size of the EPR , it is this value, you must define (measure) with a minimum error, and the assumption that value With EEM and EKI constant for all of the same type windings and equal nominal value, not bring noticeable errors in quality control impregnation. On this basis, we can assume that

where D e , D PR - nominal diameters enamelled and bare wires; l PR - nominal length of the wire is controlled portions of winding; p em - density enamel; d Ki - nominal thickness of Cabinet insulation; P - perimeter groove, L is the length of the groove; p - the number of grooves in which sapana winding; p Ki - density Cabinet isolation.

We denote the sum EEM and EKI letter B 1 =AEM +With EKI =const. With the entered symbol B 1 expression (22) can be rewritten in the form

The largest error in the size of the EAF , as noted above, may apply jitter (range) from coil to coil size m PR due to differences from coil to coil wire cross-section that is why the value of m PR in each of the controlled windings must be controlled. Show how this can be done. Let the control is carried out at temperature T=20 Degrees C. Then the coil resistance at the moment of admission to it of electrical energy equal to R 20 . Usually, however, especially after impregnation and drying of windings their temperature (denote it by T. 1 ) differs from 20 degrees C. If the winding temperature at the moment of connection of heating of current I 0 , equal T 1 and differs from T=20 C, the resistance R 20 can be defined by the formula

& alpha - temperature coefficient of resistance.

Heat soaked winding most rationally constant stabilized current I 0 . The constant constant current I 0 , chosen on the basis of a valid current density j. Which, for example, copper wire ranges from j min =6 mm 2 to j max =10 a/mm 2 [5] and square wire cross-section S.

So the bottom border of the current density, equal to, for example, copper wire, j min =6 mm 2 is considered normal density, taken with reserve, and the current density of the top border, equal, for example, for copper wire j max =10 a/mm 2 is the maximum density that is suitable only for short-term operation. In our case, at short-term influence of constant constant current I 0 for the testing object (winding), it is advisable to choose the current density, close to the maximum current density, equal to j max =10 a/mm 2 . This is because, first, the effect of current on a wire winding process control impregnation short, and secondly the fact that the higher current density, the faster the change of the temperature of the wire, which reduces the time control. Therefore, to develop ways of controlling the quality of impregnation of windings of electrical products should obesity interval current density up values from j min =6 mm 2 to j max =10 a/mm 2 . The specified selected interval current for control impregnation of windings of electrical products made of copper wire, due to the following reasons. The current density for copper wires over j max =10 a/mm 2 is not valid. The value of the current density is less than j min =6 mm 2 increases control time and accuracy of measurement of factors of impregnation.

For aluminium wires permissible current densities are in the range 4-6 ampere per square millimeter [5]. So if controlled winding wire made of aluminum wire, then you can choose a value stabilized direct current I 0 should be based on the mentioned permissible current densities for aluminum.

If energy is supplied to the coil in the form of a constant current I 0 , the value of which is constant and known, the amount of R 20 can be determined by measuring on a winding, at the moment t=0 the supply to it current, voltage U 1n from expressions

Substituting into the expression (24) the formula (25), we obtain

on the other hand

where p 20 - specific resistance of the wire at 20 C; S - sectional area of the wire.

Multiplying the numerator and denominator of the expression (27) the density of the material wires p PR and the length of the wire l PR , get

From expressions (28) and (26) it follows that

Based on the expression (29) is equivalent to the heat capacity of the wire winding equal

a constant characteristic controlled type windings, and used to control constant stabilized DC residual current I 0 . We substitute the expression (30) in (23), we obtain

Thus, in accordance with expression (31) to determine the equivalent of heat capacity of any controlled not impregnated windings there is no need to make any measurements have not impregnated windings, and it is sufficient to measure only the winding temperature T 1 and the voltage U 1P at the time of filing in impregnated winding (t=0) constant current I 0 .

On the other hand, With equal Epps

- the energy that went on heating impregnated windings; U 2P - voltage on the coil after a time t o its heat; Delta t=T 2-T 1 - increment winding temperature when heating it with the energy of Q; T 2 - winding temperature at time t o .

The value of Delta t can be determined by varying the voltage on the wire winding in the process of its heating expressions

Subtract U 1n from U 2n using expression (36) and (35), we get

From the expression (37) should

Substituting in expression (33) the expression (34) and (38), we obtain

Substituting into the expression (32) With the EAF and Epps from expressions (31) and (39) and converting the resulting expression with respect to m , get

Volume prykordonnyk cavities winding V Ki can be found from the expression (10)

The total volume of cavities in the winding 0 V by the formula [4]

where S is the cross-sectional area of the groove.

The volume of interturn cavities in the winding V 0mV equal

Mass impregnating composition, penetrated into Prikarpatye cavity winding equal to

The coefficient impregnation interturn cavities in the coil can be calculated by the formula

where m 0 - ultimate weight impregnating composition, which can be placed in the cavity of wrapping with their 100% of fullness dry impregnating composition

where m 0K - ultimate weight impregnating composition, which can be placed in prykordonnyk cavities winding, when 100% of fullness dry impregnating composition

The expression (33) holds for perfectly insulated winding from the magnetic core and the environment, when all summed up the energy to the wire winding Q expended only on heating of windings, as heat losses in the magnetic core and the environment are missing. It can be shown that at heating time of winding t 0 ≤0,02 t, where t=races (beta x So) -1 - time constant heating winding; With RAS total design capacity impregnated windings and magnetic core;? - coefficient of heat transfer; S o - surface cooling magnetic core and winding; with the loss of heat from the windings can be neglected and read it with disparaging low measurement uncertainty, perfectly insulated.

On the other hand, the increment of the resistance of the windings during her heat should be large enough to ensure that it was possible to measure with a small margin of error, the time of heating the windings should be large enough. It can be shown that at t 0 >0,01 t, measurement error increment temperature by the method of resistance dismissive small.

In reality, the time t 0 is selected for each type of controlled winding experimentally, this criterion correctly selected control time t 0 is the minimal error of determination of the coefficient of interturn cavities winding:

p 20 =0,0178 Ohms x 2 mm /m

U 1n =20,268 Century

Example. Produced determination of the coefficients of impregnation five winding of stators of the asynchronous electric motor type AM on the method prototype and claimed method.

In controlled winding determined by expression (6) the size of EQ based on the following wrapping data.

The total number of slots in the magnetic core p =36. Stator winding has been linked star with insulated neutral. When control is consistently the coefficients of the impregnation of every two phases winding. Therefore, the number of slots R, in which vzyalas controlled part of the winding, was equal to

S n =5,375 x 10 -3 m 2 ; d uh =0,04 x 10 -3 m; d =0,1 x 10 -3 m; ε e =of 5.92; ε to =3,85;

ε e =2,5; ε K =2.7; d uh =0,04 x 10 -3 m; d =0,49 x 10 -3 m

Proceeding from the above wrapping data was calculated From EQ in the formula (19)

8,854187817

Before impregnation was measured capacity controlled winding With EAF relatively magnetic core stator frequency of the electric field f=1000 Hz bridge E2-12.

The results of measurements of vessels With EAF controlled winding prior to treatment and after it is shown in table 1.

After measuring tanks of windings on the magnetic core (body) they varnish impregnated KP-34 inkjet-drop method. After drying of windings were measured again capacity relative to the magnetic coils of the stator core With EPP . The results of measurements With Epps listed in table 1.

In the course of measurements With EPP each controlled winding, before submitting it stabilized direct current I 0 , measured input temperature T 1 , which also was entered in the table 1.

As can be seen from table 1, the values of their temperature T 1 ranged from 25 to 35 C, which was due to the fact that after winding impregnation and drying did not have time to cool to room temperature.

Expected coefficient B 1 in the formula (5), using the following wrapping data:

with e =984 j/kg x hail To; D PR =1,32 x 10 -3 m D uh =1,4 x 10 -3 m; p em =1230 kg/m 3 ; p CI =810 kg/m 3

1 CR =160 m; CI =840 j/kg x deg K; L=0.125 m; N=4,3 x 10 -2 m

Equivalent to the heat capacity of enamel is equal to:

J/hail To

,0 j/hail To

Equivalent to the heat capacity of Cabinet isolation equal to:

With EKI =p x L p x P x p Ki x d Ki x c Ki=24×0,125×4,3×10 -2 ×810×0,49×10 -3 ×840=430 J/hail To;

B 1 =AEM +With EKI =33+430=463 j/grad K.

Then winding subjected to electro thermal control.

In each controlled-soaked winding mentioned selected stator filed constant stabilized current I 0 value of 12.4 A. the constant constant current, selected on the basis of a valid current density j, for copper wire ranging from j min =6 mm 2 until i max =10 a/mm 2 [5], and the sectional area of the wire.

However, the current density j min =6 mm 2 is considered normal density, taken with reserve, and the current density of 10 a/mm 2 is the maximum density that is suitable only for short-term operation. In our case, at short-term influence of constant constant current I 0 for the testing object (winding), it is advisable to choose the current density, close to the maximum current density, equal to (i max =10 a/mm 2 . This is because, first, the effect of current on a wire winding process control impregnation short, and, second, the fact that the higher current density, the faster the change of the temperature of the wire, which reduces the time control. Therefore, to develop ways of controlling the quality of impregnation of windings of electrical products should obesity interval current density up values from j min =6 mm 2 until i max =10 a/mm 2 . The specified selected interval current for control impregnation of windings of electrical products made of copper wire, due to the following reasons. The current density for copper wires for more than 10 a/mm 2 is not valid. The value of the current density is less than j min =6 mm 2 leads to the increase in time control and reduce the accuracy of the coefficients of impregnation. In this particular case the cross section of copper wire controlled winding was equal 1,7424 2 mm . Based on a selected range of current density in the range from j min =6 mm 2 until i max =10 a/mm 2 , the value of a constant constant current I 0 must be between 10,45 And to 17,424 A. We have chosen the current lying in the specified range, equal to 12.4 A.

Expected coefficient B 1 in the formula (5), using the following data wrapping

with e =984 j/kg x hail To; D PR =1,32 x 10 -3 m; D e =1,4 x 10 -3 m; p em =1230 kg/m 3 ; p CI =810 kg/m 3 ;

1 CR =160 m; CI =840 j/kg x deg K; L=0.125 m; N=4,3 x 10 -2 m

Equivalent to the heat capacity of enamel is equal to:

J/hail To

,0 j/hail To

Equivalent to the heat capacity of Cabinet isolation equal to:

Based on the selected constant constant current I 0 =12,4 And, wrapping data with PR =0,38309 x 10 3 j/kg deg K, p 20 =0,0178 Ohms x 2 mm /m=0,0178 x 10 -6 Ohms x 2 mm /m, p PR =8,89 x 10 3 kg/m 3 , l PR =160 m, determined the coefficient 2

19243,51

Through each controlled winding missed mentioned constant stabilized current I 0 =12,4A during the time t 0 =20 C. Time t 0 =20 was determined experimentally, based on the criterion of minimal error of determining the equivalent of heat capacity impregnated windings by the formula (33).

Measured voltage U 1P on the coil in the supply moment to her current I 0 =12,4A and voltage U 2s at time t 0 =20 C.

According to the formula (40), given that the specific heat of impregnating composition, with =1,652 x 10 3 j/kg x C and density impregnating composition, with =1,23 x 10 3 kg/m 3 , m identified with .

The total volume of cavities in the winding V 0 found by the formula (42) [4], it was equal to

0,000283

where S c =8,8 x 10 -5 m 2 ; 1 w =0,572; C =0,678.

Estimates show that the volume prykordonnyk cavities winding V Ki according to the expression (10) is of the order V CI =(3% to 3,2)x 10 -6 m 3 . The total volume of cavities in the winding V 0 is 0,283 x 10 -3 m 3 .

Since V 0 >>V Ki , from expression (44) and (45)it follows that the mass of an impregnating composition, caught in turn-to-turn cavity m , a lot more mass penetrated in Prikarpatye cavity winding m , i.e. m >>m K , and formula (45) to determine impregnation interturn cavities winding To mV can be written in the form

According to formulas (19) and (48) determined the coefficients impregnation prykordonnyk To the key and turn-to-turn To mV cavities windings which are also included in table 1.

For comparison with the method of the prototype of the values defined by the method prototype coefficients impregnation To the PR also listed in table 1.

The experimental values required to define the factors impregnation, and the results of inspection by the present method and the method prototype listed in table 1.

With CDP , pF

With PPC , pF

With EAF

With EPP

From table 1 it is possible to draw the following conclusions.

Thus, the claimed method has the following advantages over the way- prototype:

- in the present method there is no need one randomly selected windings to measure the capacity relative to the body and its own capacity to impregnation, then immerse the winding impregnation liquid with known dielectric permeability and again measure the capacity of this winding relative to the housing and own capacity winding, without taking the winding of penetrating fluids, which simplifies the proposed method in comparison with the method of the prototype;

- in the present method there is no need each controlled winding twice to measure its own capacities: prior to treatment and after it, which leads to additional simplification of the proposed method;

- prototype method has low accuracy of control, due to the large variation in own containers from one coil to another, which is associated with a random location of turns in the coil, and the dependence of the value of the capacitance of the windings from how distributed impregnating composition, between what turns winding, claimed in the same way the values of the coefficient of impregnation does not depend on mutual arrangement of coils in the groove that makes the proposed method is more accurate;

- the claimed method in comparison with the method ofthe prototype has a higher information content control, due to the fact that according to the formula (3) in the way prototype determine the average coefficient impregnation only interturn cavities winding, and the proposed method allows to determine, impregnation of distributed inside winding and what are the odds impregnation prykordonnyk and interturn cavities of the windings.

The list of the used literature

1. Kondratiev N. and other Assessment, the possibility of using the electric capacity of the winding of stators for quality control impregnation of stators of electric motors low voltage. - Electrotechnical industry. Series "Electric machines", vol. 5/75, 1977.

2. A.S. №1241361. The method of determining the coefficient of impregnation of windings of electrical machines / Gvero, Inv. - Publ. 30.06.86. Bul. №24.

3. A.S. №1709470. The method of determining the coefficient of impregnation curable polymer composition of windings of electrical machines / Gview. - Publ. 30.06.86. Bul. no 24 - prototype.

4. Gvero. Reliability of isolation of windings of electrical products. - Tomsk: Izd. University, 1990, p.96 formula 3.3

5. http://www.ura-remontu.ru/raschet-secheniya-provoda-po-toku.html

The method of determining the coefficient of impregnation curable polymer composition of windings of electrical machines, in which each winding of the party prior to treatment and after treatment polymer composition and drying measure capacitance From the KDP, and With the CPT in relation to the body, wherein later after measuring the capacity relative to the body, each controlled winding With the PPC after impregnation and drying measure the temperature of the winding T 1ppt , then through the wire each controlled winding miss constant stabilized current I 0 , the value of which is chosen according to from section area S veins wire winding in the range of permissible for material wire winding current densities from j min to j max , range of values j min S≤I 0 < j S max, and referred to the current I 0 is passed through a coil within a certain time t 0 and measure the voltage drop across the coil U 1P at the moment the supply to it a constant current and voltage drop across the coil U 2s at the time mentioned time t 0 , then each controlled winding for measurement results determine the coefficient impregnation prykordonnyk cavities To Ki and winding ratio impregnation To mV interturn cavities winding by formulas

- equivalent capacity consistently United tanks enamel and Cabinet winding insulation; p - the number of grooves in magnetic core, in which poured controlled part of the winding; S the p - a area of ESD; e 0 =8,854187·10 -12 - electric constant; e e - dielectric constant of the enamel film wire winding; e to - the dielectric constant of Cabinet insulation; d e is the thickness of the enamel wire insulation; d - thickness of Cabinet insulation of the wire; c is the specific heat of dry impregnating composition;

- limit the dry weight impregnating composition, which can be used in turn-to-turn cavities winding at 100% filling; d is the density of the dry impregnating composition; l w - length coil winding; C - coefficient of filling groove; P - perimeter groove; α temperature coefficient of resistance of a wire winding; 1 =AEM +ek - equivalent to the heat capacity of layers of thermal capacities enamel

and Cabinet insulation With EC =Ki x P x d Ki x L x p x p CI ; with e - specific heat enamel; d'oex - diameter enamelled wire winding; d PR - diameter wire winding; l PR - nominal length of the wire is controlled portions of winding; p em - density enamel; Ki - specific heat of Cabinet insulation; d Ki - thickness of Cabinet insulation; L - length of a groove; p Ki - density Cabinet insulation;

- constant coefficient; with PR - specific heat capacity of a material of conductor wires winding; p 20 - specific resistance of the material veins wire coil at 20 degrees C.