RU2745446C1 - Method for controlling and repairing wire insulation - Google Patents

Abstract

FIELD: electrical measuring technology.SUBSTANCE: invention relates to electrical measuring technology and can be used in the cable industry for monitoring and repairing the enamel insulation of wires. The invention is characterized in a method for monitoring and repairing the insulation of winding wires, consisting in detecting a defect in the insulation of a moving wire by means of control, in measuring the length thereof, the application of the identified defect of enamel varnish during the passage of the defective section under the enamel-making unit, the removal of the excess insulation applied to the defective section by passing the mentioned section through the size, the inside diameter of which corresponds to the diameter of the insulated wire, in the drying and baking of the liquid enamel film applied to the defective section thereof, a unit for applying enamel in the form of a hollow body which covers the surface of the moving winding wire, the internal surface of which, facing the wire, are provided with openings equidistant from each other equidistant about the circumference, furthermore, during the passage of the defective section of the enamel insulation under the metering device, a lacquer portion is fed under pressure into the internal cavity of the above-mentioned metering device, which, through the above-mentioned openings of the metering device under the action of excessive pressure in the metering unit, is pushed on a defective section of insulation, wherein the duration of the delivery of the enamel varnish into the metering unit is changed in proportion to the length of the defective section in such a way that it is equal to the time of passage of the defective section under the nozzle, after which the surplus applied to the defective section of the insulation is removed, the defective section of the liquid enamel film is dried and baked.EFFECT: technical result is a simplification by eliminating a high-voltage source for the electrostatic charge of the jet, a more uniform supply of enamel varnish to the defective section, and an efficiency of concealing defects in the claimed method is substantially higher.1 cl, 1 dwg

Description

The invention relates to electrical engineering and can be used in the cable industry for monitoring and repairing enamel insulation of wires.

A known method for monitoring the defectiveness of the insulation of wires, described in [1].

According to this method, the integrity of the insulation is expressed in terms of the number of point faults on a wire of a certain length, recorded with an electrical tester.

A wire sample with a length of (30 ± 1) m is pulled at a speed of (275 ± 25) mm / s between two felt plates immersed in an electrolytic solution of sodium sulfate Na ₂ SO ₄ in water (concentration 30 g / l). In this case, a test voltage of direct current (50 ± 3) V is applied between the core wire and the solution connected in an electric circuit with an open circuit. The force applied to the wire should be no more than 0.03 N. Point damage is recorded by a corresponding relay with a counter. The meter should be triggered when the wire insulation resistance is less than 10 kOhm for at least 0.04 s. The counter should not work with a resistance of 15 kOhm or more. The fault detection circuit shall operate at an actuation speed of (5 ± 1) ms, providing registration at a frequency of (500 ± 25) faults per minute when pulling the wire without insulation. The control according to the specified method is carried out on segments of wire 30 m long, cut off from the end of the wire of coils selected selectively from a batch of coils of the same type. One test is performed. The number of point faults on a wire length of 30 m is recorded. If the number of point faults exceeds a certain value permissible for a given type of wire, then the batch of coils from which the test sections of wires are selected are rejected.

The disadvantage of this method is that it is used selectively, for a piece of wires cut off from randomly selected wire coils from a batch. This leads to the fact that the main part of the wire in each controlled coil remains uncontrolled, and the rest of the batch coils that did not fall under selective control are also uncontrolled, which reduces the reliability of control. In addition, to implement the method, it is necessary that the controlled piece of wire is pulled under the point damage sensor with a constant relatively low (275 ± 25) mm / s wire speed. This reduces the accuracy and performance of the inspection. The selected point damage sensor has low sensitivity, therefore, this method is used only for wires with a nominal diameter of up to 0.050 mm, inclusive, with a thin thickness of enamel insulation. Meanwhile, as practice shows, there are defects on wires with a large wire diameter, where this method is not applicable. This limits the scope of the method. In addition, the method is very costly, since not only 30 meter lengths of wire are wasted, but all rejected coils of the batch, which do not fit into the range of permissible values of the number of point damage in the enamel insulation of wires.

There is a known method for monitoring defectiveness of wire insulation, through which the wire is pulled through a sensor-electrode, to which a high voltage is applied relative to the wire core [2]. At the moment of passage of a defect in enamel insulation through the sensor-electrode, a corona discharge is ignited and from it, by integrating the discharge pulses with an integration time constant, a defect pulse is formed, which is recorded in the counter. The insulation quality is assessed by the number of registered impulses in the meter, considering that their number is equal to the number of defective sections of the wire insulation.

The disadvantage of this method is the low accuracy of defectiveness control, due to the peculiarities of the corona discharge in the sensor-electrode. These features are that the corona discharge current has a pulsed form, and under the influence of various factors (transverse vibrations of the wire, changes in the environment, the presence of contamination on the wire, etc.) at the moments when the defect approaches the sensor-electrode and leaves it the discharge can go out for a while.

In the mentioned method, corona discharge pulses with an integration time constant are integrated to normalize the defect pulse. This leads to the fact that at low speeds of the wire movement, when a defect approaches and leaves the sensor-electrode, the extinction times of the corona discharge can exceed the integration time, as a result of which one defect can be registered as two, three or more defects.

At high wire speeds, a significant length of wire will pass through the sensor-electrode during the integration time. If there are defects on this section of the wire, they will not be registered. In addition, if there are N defects on the wire and the time it takes for the wire sections to pass between adjacent defects is less than the integration time, then these N defects will be registered as one defect.

There is a method for monitoring defectiveness of wire insulation, according to which a controlled wire is pulled through a sensor-electrode, a high voltage is applied to it until a corona discharge occurs, the frequency of corona discharge current pulses is measured [3].

However, the known technical solution has disadvantages: the influence of the corona discharge instability zone is not taken into account, which leads to the fact that from two identical defects on the surface of the controlled wire a different number of corona discharge pulses will be recorded, as well as the fact that when the speed of the wire changes, the number corona discharge pulses from two identical defects in the enamel insulation varies in an even wider range.

These reasons do not allow for a quantitative assessment of the presence of microcracks (defects) on the wire, but give only some approximate qualitative assessment of the state of the wire, which significantly reduces the accuracy and reliability of control is known. In addition, all the above analogs are aimed only at improving the accuracy of monitoring defects in wire enamel insulation, but not one of them provides for the possibility of eliminating the identified defects. This leads to the fact that wires with high defectiveness are recycled, or, even worse, are used in the electrical industry, for example, for the manufacture of electric motor windings, which, due to the poor quality of enamel insulation, can at any time lead to failure of electric motors and to possible accidents. The rejection of defective wires or their use in products leads to significant economic losses, since expensive materials (enamel, wire, etc.) are wasted, and the costs of processing these wires occur.

Closest to the claimed is a method of monitoring and repairing the insulation of winding wires [4].

, где t_з - время задержки; 1_к - среднеквадратическое значение длины контролируемого участка провода с момента погасания до момента зажигания коронного разряда в зонах его нестабильности горения при подходе к датчику-электроду и выходу из него дефектного участка изоляции;

-среднеквадратичное отклонение 1_к от среднего значения; v - скорость движения контролируемого провода, затем после формирования переднего импульса дефекта через время t₂ = (D- v Т_д)/v, где Т_д- время от открытия электромагнитного клапана узла нанесения эмали до попадания струи эмали из узла нанесения эмали на поверхность дефекта, расширяют импульс дефекта до величины Т_р= Т_i+Т_д, по переднему фронту этого импульса открывают в момент времени t₂ в узле нанесения эмали электромагнитный затвор и формируют электростатически заряженную струю эмали, путем пропускания ее вдоль поверхности высоковольтного электрода, на который в момент времени t₂ открытия электромагнитного затвора одновременно подают постоянный высоковольтный потенциал относительно заземленной жилы провода, величина которого лежит в диапазоне 2-5 кВ, сформированную струю электростатически заряженной жидкой эмали подают на дефектный участок в течение времени Т_i, затем по заднему фронту расширенного импульса, отключают высоковольтный потенциал с высоковольтного электрода, и закрывают электромагнитный затвор в узле нанесения эмали, снимают излишки эмали, нанесенной на дефектный участок эмальизоляции, путем пропускания упомянутого участка с нанесенной на него жидкой эмалью через калибр, внутренний диаметр которого соответствует диаметру изолированного провода, после чего дефектный участок с нанесенной на него жидкой эмалью подвергают запечке и сушке.The prototype method consists in pulling the monitored wire through the sensor electrode, in supplying it with a high voltage relative to the wire core, in the ignition of a corona discharge when defective sections of the wire insulation pass through the sensor electrode, and in the formation of impulses of defects from the corona discharge, while, To repair defective sections of the insulation, wires are installed at a strictly fixed distance D from the corona sensor-electrode, the enamel application unit, and in the presence of a defect, a pulse of the length of the defect is generated, the duration of which T _i is equal to the transit time of the defect in the zone of action of the corona sensor-electrode, the leading edge of the said pulse is formed at time t ₁ by the first pulse of corona discharge from the defect, and the trailing edge of the pulse is formed with a delay after the last pulse of corona discharge from the defect for time t _h

, where t _s is the delay time; 1 _k - the root-mean-square value of the length of the controlled section of the wire from the moment of extinction to the moment of ignition of the corona discharge in the zones of its combustion instability when approaching the sensor-electrode and exiting the defective section of insulation;

- root-mean-square deviation of 1 _k from the mean value; v is the speed of the controlled wire, then after the formation of the front impulse of the defect after a time t ₂ = (D- v T _d ) / v, where T _d is the time from the opening of the electromagnetic valve of the enamel application unit until the enamel jet from the enamel application unit hits the surface defect, expand the defect pulse to the value T _p = T _i + T _d , along the leading edge of this pulse, open at time t ₂ in the enamel application unit the electromagnetic shutter and form an electrostatically charged stream of enamel, by passing it along the surface of the high-voltage electrode, to which at the moment of time t _{2 the} opening of the electromagnetic gate simultaneously serves a constant high-voltage potential relative to the grounded core of the wire, the value of which lies in the range of 2-5 kV, the formed jet of electrostatically charged liquid enamel is fed to the defective area for time T _i , then along the trailing edge of the expanded pulse , turn off the high-voltage potential from the high-voltage electrode, and close the electromagnetic shutter in the enamel application unit, remove the excess enamel applied to the defective area of enamel insulation by passing the said area with liquid enamel applied to it through a caliber, the inner diameter of which corresponds to the diameter of the insulated wire, after which the defective area with liquid enamel applied to it baked and dried.

10⁶Н/см, и относительно высокое удельное омическое сопротивление, превышающее 10^-6 Ом^-1 м^-1, что приводит невозможности электростатической зарядки частиц лака. Это исключает возможность эффективно «залечивать» дефектные участки эмалевой изоляции обмоточных проводов. Еще одним недостатком способ-прототипа является неравномерность нанесения эмалевой пленки на всю поверхность дефекта, что связано с тем, что струя эмалевой изоляции подается только на обращенную к струе часть дефекта. Между тем дефект изоляции провода или его часть, может находится на боковой или даже нижней части цилиндрической поверхности движущегося провода, куда эмаль от падающей струи может не поступить, и эта часть дефекта остается не «залеченной».The disadvantage of the prototype method is that the application of enamel insulation to the defective area requires a relatively high positive voltage of the order of 2-5 kV. In addition, for most enamel varnishes, for example, for PE-939 varnish, the surface tension coefficient exceeds the critical value of 5

10 ⁶ N / cm, and a relatively high specific ohmic resistance exceeding 10 ^-6 Ohm ^-1 m ^-1 , which leads to the impossibility of electrostatic charging of the lacquer particles. This eliminates the possibility of effectively "healing" defective areas of enamel insulation of winding wires. Another disadvantage of the prototype method is the uneven application of the enamel film on the entire surface of the defect, which is due to the fact that the jet of enamel insulation is supplied only to the part of the defect facing the jet. Meanwhile, a wire insulation defect, or a part of it, may be located on the lateral or even lower part of the cylindrical surface of a moving wire, where the enamel from the falling jet may not enter, and this part of the defect remains not "healed".

The technical problem posed within the framework of this invention is to exclude the use of a high voltage jet for electrostatic charging, to ensure uniform distribution of enamel insulation over the entire surface of the defective area, wherever this defect is located: from above, from the side or from the bottom of the generatrix of the cylindrical surface of the moving wire, which provides more effective elimination of defective areas in the enamel insulation of winding wires.

The solution to the technical problem posed is achieved by the fact that in the method of monitoring and repairing the insulation of winding wires, which consists in detecting a defect in the insulation of a moving wire by means of monitoring, in measuring its length, in applying enamel varnish to the detected defect during the time of passage of the defective area under the enamel application unit, in removing the surplus of the enamel insulation applied to the defective area, by passing the said area through a caliber, the inner diameter of which corresponds to the diameter of the insulated wire, in drying and baking the liquid enamel film applied to the defective area, an enamel application unit is performed in the form of a hollow body covering the surface of a moving winding wire , on the inner surface of which, facing the wire, holes are evenly spaced around the circumference, equidistant from each other, while at the time of passage of the defective section of enamel insulation under the dispenser, they are fed under pressure into the inner the cavity of the said dispenser, a portion of varnish, which is pushed through the said holes of the dispenser under the action of excess pressure in the dispenser onto the defective section of the insulation, while the duration of the flow of enamel varnish into the dispenser is changed in proportion to the length of the defective section, so that it is equal to the transit time of the defective section nozzle, after which the excess applied to the defective area of enamel insulation is removed, the film of liquid enamel applied to the defective area is dried and baked.

Figure 1 schematically shows a block diagram of a device that implements the inventive method. Figure 1 introduced the following designations: 1 - dispenser; 2 - dispenser cavity; 3 - electromagnetic shutter; 4 - enamel supply pipe; 5 - vein of the wire; 6 - holes in the wall of the dispenser; 7 - enamel wire insulation; 8 - insulation defect, length l _{d .}

The essence of the method and device is as follows.

In the presence of a defective area of enamel insulation, the defectiveness meter generates a voltage pulse, the duration of which is equal to the transit time of the defective area of enamel insulation under the sensor. This time depends on the length of the defect and on the speed V of the wire movement under the defect sensor. The features of the pulse shaping in the defect meter are detailed in the prototype, as well as in the article [5].

Elimination of defects in wire insulation is as follows.

In the initial state, the electromagnetic shutter 3 (see Fig. 1) of the dispenser 1 blocks the access of the enamel varnish from the nozzle 4. When the defective area 8 in the enamel insulation 7 approaches, the electromagnetic shutter 3 opens and the enamel varnish begins to pump under pressure through the nozzle 4 in the cavity 2 dispenser, and through the holes 6 in the wall of the dispenser is fed into the defective area 8 of the enamel insulation 7. Since the holes 6 are evenly located on the inner circular surface of the dispenser, the enamel varnish is evenly applied to all parts of the defective area, regardless of where and how the indicated defective area is located on the wire insulation, which makes it possible to uniformly cover the entire defective area with a film of varnish 8. After the defective area 7 passes through the dispenser 1, the electromagnetic shutter 3 is triggered and the access of the enamel varnish to the dispenser 1 through the nozzle 4 stops. This also stops the supply of varnish through the holes 6 to the surface of the insulation of the moving wire.

Excess varnish is removed from the surface of the insulation and the captivity applied to the defective area is dried and baked.

An example of a specific implementation.

According to the prototype method and according to the claimed method, control and repair of the insulation of the PETV wire with a diameter of 0.8 mm was carried out. To implement both methods, 30 meter defect-free pieces of insulated PETV wire with a diameter of 0.8 mm were selected. 15 defects were applied to the insulation of each of the wire segments. Defects 8 were circular sections of the enamel film 7 to the core of the wire 5, length l _{d ;} = 5 mm. To eliminate defects in both cases, we used PE-939 enamel varnish. To implement the proposed method, a dispenser in the form of a hollow torus was made from a copper tube with a diameter of 5 mm. The inner diameter of the torus was 5 mm. Six holes with a diameter of 0.8 mm were drilled in the generatrix of the torus surface, enclosing the tested wire. After applying and baking to defective areas of enamel insulation, both wire sections were checked for defects. The control showed that according to the claimed method, all 15 defects were eliminated, while only 12 defects were eliminated according to the prototype method.

Thus, in comparison with the prototype method, the inventive method is significantly simplified, since it does not require the use of a high voltage source for electrostatic charging of the jet, the supply of enamel varnish to the defective area in the inventive method is realized more evenly than in the prototype, and the efficiency of hiding defects in the claimed method is significantly higher.

Sources used:

1.GOST R IEC 60851-5-2008. Winding wires. Test methods. Part 5. Electrical properties.

2. Smirnov G.V. Quality control device for enamel insulation of winding wires. J. Reliability and quality control, 1987, No. 10, p. 51.

3. USSR author's certificate No. 364885, class. G01N 27/00, 1971.

4. RF patent No. 2506601. // Method of control and repair of wire insulation // G.V. Smirnov, D.G. Smirnov. Published on 02/10/2014 Bul. No. 4. (Prototype).

5. Smirnov GV, Smirnov DG Non-destructive control of defectiveness of insulation of winding wires // Defectoscopy. - 2016. - No. 8, p. 63-74.

Claims (1)

A method for monitoring and repairing the insulation of winding wires, which consists in detecting a defect in the insulation of a moving wire by means of control, in measuring its length, in applying enamel varnish to the detected defect during the passage of the defective area under the enamel application unit, in removing the excess applied to the defective area of enamel by passing the said section through a gauge, the inner diameter of which corresponds to the diameter of the insulated wire, in drying and baking a film of liquid enamel applied to the defective area, characterized in that the enamel application unit is made in the form of a hollow body covering the surface of a moving winding wire, on the inner surface of which, facing the wire, holes are evenly spaced around the circumference, equidistant from each other, while at the moment of passage of the defective section of enamel insulation under the dispenser, a portion of varnish is supplied under pressure into the inner cavity of the said dispenser , which is pushed through the aforementioned holes of the dispenser under the action of excess pressure in the dispenser onto the defective section of the insulation, while the duration of the flow of enamel varnish into the dispenser is changed in proportion to the length of the defective section, so that it is equal to the time of passage of the defective section under the nozzle, after which the excess applied to the defective area of enamel insulation, applied to the defective area, a film of liquid enamel is subjected to drying and baking.

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