RU2726729C1 - Wire insulation defectiveness monitoring device - Google Patents

Abstract

FIELD: test technology.SUBSTANCE: invention relates to electrical tests technique and can be used for quality control of wires insulation. Control device of insulation defects winding wire sensor comprises – an electrode, a high voltage source, defect pulses generator consisting of front and rear edges shaper reference and differential amplifier source, defect counter, speed sensor, speed pulse shaper, speed pulse counter, key device, defect length counter with adjustable conversion factor, flip-flop, light-emitting diode and photodiode, two metal yokes, two springs, two sliding contacts, two leads for connection of power supply, two guiding bushings, disk with uniformly made through radial slots. Sensor-electrode and the wire speed sensor are made in the form of a single functional unit made in the form of two stainless steel rollers having a U-shaped groove along the generatrix.EFFECT: reduction of control voltage and improvement of sensor resolution.1 cl, 6 dwg

Description

The invention relates to electrical testing techniques and can be used to control the quality of wire insulation.

Known device for monitoring the defectiveness of wire insulation, described in [1].

The device is designed to control point damage by high voltage, for wires with a conductor nominal diameter of over 0.050 to 1.600 mm inclusive. In this case, to monitor defects in the insulation of wires on the insulation of wires from 0.050 to 0.25 mm, the high-voltage electrode (sensor) used is made in the form of two. The rollers in the device must be made of stainless steel and ensure, each, contact with the wire over a length of (25 ± 2.5) mm.

When testing for point insulation of wires with a nominal wire core size of 0.250 to 1.600 mm, one high-voltage electrode in the form of a roller is used. The roller should be made of stainless steel and provide contact with the wire over a length of 25 ÷ 30 mm.

The disadvantage of the device is, firstly, the low versatility of the sensor, since for wires with a core diameter lying in the range from 0.050 to 0.25 mm, an electrode-sensor made in the form of two rollers is used, and the monitored wire is pulled through 4 rollers, two of which are guides and the other two are sensor electrodes. For wires with a diameter ranging from 0.25 to 1.600 mm, this sensor is no longer applicable, and instead of it, one high-voltage electrode of a larger diameter is used.

Secondly, both when inspecting wires with a core diameter ranging from 0.050 to 0.25 mm and when inspecting wires with a diameter ranging from 0.25 to 1.600 mm, the wire is repeatedly bent. This leads to high mechanical loads on the wire insulation from the side of the rollers, which leads not only to a weakening of the mechanical and electrical strength of the insulation of the tested wire, but also causes additional defects in the wire insulation. Therefore, using the prototype device, only selective control is carried out, at a constant and relatively low wire pulling speed equal to (275 ± 25) mm / s.

Closest to the claimed object is a device for monitoring the defectiveness of an insulated wire, described in [2]. The device is a prototype for monitoring the defectiveness of wire insulation, contains a sensor electrode, a high voltage source, the first output of which is connected to the first input of the defect pulse former, the output of the defect counter connected to the input, a speed pulse shaper and a speed sensor are introduced into it, and the second output a high voltage source is connected to the sensor electrode, the speed sensor is connected through the speed driver to the second input of the defect pulse former, the latter consisting of a reference voltage source, a shaper of the leading and trailing edges and a differential amplifier, the first, second inputs and output of which are connected respectively to to the first input of the defect pulse former, to the output of the reference voltage source and to the first input of the leading and trailing edge shaper, the second input and output of which are respectively the second input and output of the defect pulse former.

The disadvantage of the prototype device is the high control voltage, as well as the complexity of the design, due to the fact that the sensor electrode and the speed sensor are made in the form of two separate functional blocks.

The technical problem posed within the framework of this invention is to reduce the control voltage and simplify the design of the device.

The solution to this technical problem is achieved by the fact that the device for monitoring the defectiveness of the insulation of the winding wires containing a sensor - an electrode, a high voltage source, a defect pulse shaper, consisting of a reference voltage source for a leading and trailing edge shaper and a differential amplifier, a defect counter, a speed sensor, a pulse shaper speed, while the first input of the high voltage source is connected to the first input of the defect pulse former, the output of which is connected to the input of the defect counter, the second output of the voltage source is connected to the sensor - electrode, the speed sensor through the speed former is connected to the second input of the defect pulse former, the first and the second inputs of the differential amplifier are connected, respectively, to the first input of the defect pulse former, to the output of the source of the shaper of the leading and trailing edges, the second input and output of which are respectively the second input and output In addition to the defect pulse generator, a speed pulse counter, a key device, a defect length counter with an adjustable conversion factor, a trigger, a LED and a photodiode were additionally introduced , while the electrode electrode and wire speed sensor are made as a single functional block made in the form of two rollers from stainless steel, having a U-shaped groove along the generatrix, and the rollers are placed in a housing, which is made in the form of a channel, between the parallel walls of which a dielectric base is fixed to accommodate sensor elements, also made in the form of a channel, the parallel walls of this base are fixed with fasteners to parallel the walls of the sensor body, and the base of the said base is perpendicular to the base of the sensor body, two metal rocker arms, two springs, two sliding contacts, two leads for connecting a power source, two guide bushings, a disk with equal with through radial slots, one plane of which is made in the form of a cylindrical glass, and the rocker arms are made in the form of metal plates, at one end of each of which cylindrical axes for bearings are rigidly fixed perpendicular to the plane of the plate, at the other end of each plate the rocker arms are made perpendicular to the plane rocker arm holes under the axle, which are rigidly fixed on a dielectric base to accommodate the sensor elements, rotating rollers pressed by springs to each other by forming surfaces at the point of contact lying on the vertical axis of symmetry of these rollers, a glass is coaxially attached to the side surface of one of the rotating rollers the said disk with radial slots, grooves are made along the forming surfaces of the rollers, which lie when the rollers touch each other and serve to fix and limit the movement of the wire in the transverse direction, to the central part of the rollers bearings are pressed into the cylindrical axes mentioned above, rigidly fixed to the movable end of the rocker arms, the fixed ends of the rocker arms, the holes on them are put on the axles, mechanically fixed on a dielectric base to accommodate the sensor elements, the rollers are pressed against each other by their forming surfaces using two springs , one end of which is mechanically fixed to one of the rocker arms, and the other two ends of the springs are mechanically fixed to the dielectric base to accommodate the sensor elements, the voltage is applied to the working surfaces of the rollers by sliding contacts made in the form of elastic leaf springs, one end of which is pressed against the axes of the rollers, the other end is electrically and mechanically connected to the end with leads for connecting a power source, guide bushings are fixed in the walls of the sensor housing, the longitudinal axes of symmetry of which coincide with the axis of the wire, the ultraviolet LED is located in the gap between the disk with a uniform made in it through radial slots, from the side of the plane made in the form of a cylindrical glass and the surface of the roller, to which the glass is mechanically attached, the ultraviolet photodiode is located on the opposite side of the said disk with radial slots, while the output of the photodiode is connected to the input of the speed pulse shaper, one from the outputs of which is connected to the key device, the output of the key device is connected to the input of the counter of the length of defects with an adjustable conversion factor.

In FIG. 1 shows a block diagram of the proposed device. In FIG. 2 shows an oscillogram of the sensor signal in the absence of ultraviolet illumination in it. In FIG. 3 shows the design of a single functional unit including a sensor-electrode and a speed sensor; FIG. 4 individual structural elements of the said unit. In FIG. 5 shows an example of a shaper of the leading and trailing edges of a defect pulse. In FIG. 6 shows an oscillogram of the sensor signal - an electrode with ultraviolet illumination.

In FIG. 1 introduced the following designations: 1 - high voltage source; 2 - electrode sensor; 3 - defect pulse former; 4 - speed pulse shaper; 5 - speed sensor; 6 - counter of the number of defects; 7 - wire vein; 8 - differential amplifier; 9 - reference voltage source; 10 - shaper of defect pulse fronts; 11 - key device; 12 - counter of the length of defects with an adjustable conversion factor; 13 - speed pulse counter; 14 - ultraviolet radiation. The position 15 denotes a single functional unit, which includes a sensor - electrode 2 and a speed sensor 5.

FIG. 2, the following designations are introduced: a - the first zone of the signal from the electrode - sensor, is observed when the defect approaches the sensor - electrode 2; b - the second zone of passage of the defect through the sensor-electrode 2; c, d - the third zone, the removal of the defect from the sensor, is similar to the first zone.

In FIG. 3 introduced the following designations: 16 - sensor body; 17 - dielectric base for fastening the working elements of the sensor; 18 and 19 - two freely rotating rollers; 20 and 21 - bearing axles; 22 and 23 - bearings, 24 and 25 - rocker arms; 26 and 27 - the axis of the rocker arms; 28 and 29 - sliding contacts; 30 and 31 - fastening elements to the terminals of the sensor power supply; 32 and 33 - terminals for connecting a power supply; 34 and 35 - guide bushings; 36, 37 - springs; 38, 39-elements for fastening the springs to the dielectric base; 40 - controlled wire; 41, 42, 43 and 44 - fasteners; 45, 46 - holes for attaching the springs to the rocker arms; 47 - disc with uniformly made through radial slots in it.

In FIG. 4 introduced the following designations: 48 - a fragment of the speed sensor, one side of which is made in the form of a cylindrical glass 49, 50 - ultraviolet light-emitting diode; 51 - ultraviolet photodiode.

The operation of the proposed device is carried out as follows. In the initial state, in the absence of a defect on the wire insulation, the high voltage source 1 (see Fig. 1) generates a high constant voltage, which is fed to the sensor-electrode 2 through the current-limiting resistance in the high voltage source 1. The voltage at the sensor-electrode 2 , reduced on the voltage divider located in the high voltage source 1, is fed to the input of the shaper 3. When the wire 7 moves, the speed sensor 5 generates speed pulses, the frequency of which is proportional to the speed of the wire 7. These pulses are fed to the input of the speed pulse shaper 4, where their formation according to the voltage and steepness of the fronts. The generated velocity pulses are fed to the control input of the defect pulse shaper 3 from the corona discharge.

When the front boundary of the defect approaches the sensor-electrode 2, a corona discharge is ignited. The signal at the sensor electrode 2 during the ignition of the corona discharge has the form shown in FIG. 2.

This signal can be conditionally divided into three zones. The first zone a is observed when the defect approaches the sensor-electrode 2. It should be noted that the first pulses of this zone can appear at a considerable distance from the front boundary of the defect from the sensor-electrode 2, which is associated with the probability of the appearance of free electrons near the sensor-electrode 2, with the surface the conductivity of the insulation of the wire 7, the final vibrations of the wire relative to the sensor-electrode 2, the relief of the defect and other factors. This zone has great instability of corona discharge combustion.

In this zone, the corona discharge can extinguish for a while, after which, as the front boundary of the defect approaches the sensor-electrode 2, it lights up again.

The second zone b of the passage of the defect through the sensor-electrode 2. It is characterized by the constant burning of the corona discharge. This zone is much more stable than the first zone.

The third zone c, d - removal of the defect from the sensor, is similar to the first zone. Corona discharge combustion is also unstable in this zone.

, где t₃ - время задержки; $${\overline{l}}_{э}$$

- среднестатический отрезок провода, который проходит через датчик-электрод с момента погасания до момента зажигания коронного разряда в зонах его нестабильного горения при подходе к датчику-электроду и выходу из него дефектного участка изоляции; σ - среднеквадратичное отклонение 1_э от среднего значения; V - скорость провода.When generating a defect signal, which is recorded in the counter 6 of the number of defects, it is necessary to take into account the instability times of the corona discharge. The time of unstable burning of the corona discharge is inversely proportional to the speed of movement of the wire 7. At a high speed, the defect enters the zone of the sensor-electrode 2 faster, reducing the time of unstable burning of the discharge. To eliminate errors in counting the number of defects, it is necessary to form the leading edge of this defect pulse at the first pulse of the corona discharge. The trailing edge of this pulse is formed with a delay after the last pulse of the corona discharge for a time $$t_3\ge \frac{{\overline{l}}_{\mathrm{uh}}+3\sigma }{V}$$

, where t ₃ is the delay time; $${\overline{l}}_{\mathrm{uh}}$$

- the average static piece of wire that passes through the sensor-electrode from the moment of extinction to the moment of ignition of the corona discharge in the zones of its unstable combustion when approaching the sensor-electrode and leaving the defective section of insulation; σ is the standard deviation of 1 _e from the mean; V is the speed of the wire.

статистически меняется по нормальному закону распределения. Поэтому отрезок $${\overline{l}}_{э}$$

+ 3σ - это максимальное значение отрезка провода, проходящего через датчик-электрод 2 с момента зажигания до момента погасания коронного разряда при подходе к датчику и выходу из него дефектного участка изоляции. Оно зависит от конструкции электрода-датчика 2, уровня напряжения на нем и т.п., и определяется экспериментально в каждом конкретном случае.Value $${\overline{l}}_{\mathrm{uh}}$$

changes statistically according to the normal distribution law. Therefore, the segment $${\overline{l}}_{\mathrm{uh}}$$

+ 3σ is the maximum value of a piece of wire passing through the sensor-electrode 2 from the moment of ignition until the moment of extinction of the corona discharge when the defective section of insulation approaches and leaves the sensor. It depends on the design of the electrode-sensor 2, the voltage level on it, etc., and is determined experimentally in each specific case.

When a corona discharge is ignited, pulses from a voltage divider located in a high voltage source 1 (see Fig. 1) are fed to the input of a defect pulse shaper 3 from a corona discharge. In it, the pulses are fed to the inverting input of the differential amplifier 8. A reference voltage is supplied to the non-inverting input from the reference voltage source 9. The reference voltage is set to the order of 0.7-0.9 voltage, supplied in the absence of a defect in the area of the sensor-electrode 2 to the inverting input of the differential amplifier 8 from the high voltage source 1. The upper value of this range is selected taking into account the device's noise immunity, the lower value - taking into account the accuracy characteristics. Differential amplifier 8 amplifies these pulses relative to the reference voltage and inverts them. From the output of the differential amplifier 8, positive pulses are fed to the shaper 10 of the leading and trailing edges of the defect pulse, to the control input of which the velocity pulses are received from the shaper 4 of the velocity pulses. The repetition period of these pulses is equal to the passage through the sensor - electrode 2 of a piece of wire l . According to the first positive pulse from the input of the differential amplifier, the leading edge of the defect pulse is formed in the shaper 10 of the leading and trailing edges of the defect pulse. The trailing edge of the defect pulse is formed only in time t ₃ after the last pulse of the corona discharge.

Time t ₃ is set by the arrival time m - the number of speed pulses

. $$t_3\ge \frac{{\overline{l}}_{\mathrm{uh}}+3\sigma }{V}\ge \frac{ml}{V}$$

.

Thus, the trailing edge of the defect pulse is formed if, after the end of the last pulse at the output of the differential amplifier 8 (corona discharge), a certain number of velocity pulses arrived at the control input of the shaper 10 of the trailing and leading edges of the defect pulse, the number of which m determines the delay time. The generated impulse of defects enters the input of the counter of the number of defects 6, where it is registered. The circuit of the shaper 10 of the leading and trailing edges of the defect pulse is shown in FIG. five.

Let's consider how this scheme works. The counting input C (the fourteenth output of DD1) receives speed pulses from the shaper of 4 speed pulses with a repetition period equal to the passage of 0.5 mm of wire under the speed sensor. At the output K (the seventh pin DD1) there is a potential of a logical unit, which at the M input (thirteenth pin DD1) prohibits the counter. At the output K (DD2.1) there is a logic zero level. The first pulse of the corona discharge coming from the output of the differential amplifier 8, the counter is reset. The inhibiting counting signal is removed from input M. At the output K (DD2.1), the leading edge of the defect pulse is formed. Subsequent corona discharge pulses, upon arrival, reset the counter. Between these pulses, the counter counts the speed pulses. After the last impulse of corona discharge upon arrival of the third impulse of velocity, the counter is prohibited from counting at the input M and at the output K (ДД2.1) the trailing edge of the defect pulse is formed. Jumper L sets the number of pulses, upon arrival of which the trailing edge of the defect pulse is formed.

Formation occurs after the arrival of the third speed pulse. The delay time is

$$t_3=\frac{3÷0.5}{V(mm/\mathrm{from})}$$

In this method and device, the error at the average static size of defects, which is 300-400% in the calculation of the number of defects, is eliminated, since only one pulse is always generated from one defect.

In addition, in this device, the end of the pulse from the defect is formed through a precisely defined number of speed pulses following the trailing edge of the last corona discharge pulse. Since the duration of one speed pulse corresponds to the passage through the sensor of defects of a strictly fixed elementary wire length l , the value of which remains unchanged when the speed changes, then the uncontrolled section of the wire following each defect is equal to l _pr-3 = l × m, where m is a given the number of speed pulses, after which the trailing edge of the pulse from the defect is formed. This improves the accuracy of the control.

Let us consider how the control of the length of defects is carried out.

, то за время одного периода сигнальных импульсов провод пройдет расстояние, принятое за протяженность эквивалентного точечного повреждения, равное по величине When pulling the monitored wire through the speed sensor 5, the latter outputs a signal whose frequency is proportional to the speed of pulling the wire under the sensor. This signal enters the shaper 4 (Fig. 1) of the pulses, which is a frequency multiplier. Let us denote the repetition period of pulses from the frequency multiplier through T ₁ . If, at the speed of the wire V , pass pulses into the counter 13, with a frequency f ₁ = $$\frac{�}{{�}_{�}}$$

, then during one period of signal impulses the wire will travel the distance taken as the length of the equivalent point damage, equal in magnitude

l _eh = V ₁ ×T ₁ (1)

When measuring the wire pulling speeds by a factor of g, the frequency of pulses of equivalent point damages changes in proportion to it by a factor of g, which leads to the invariability of the value determined by expression (1).

Indeed, the frequency of the speed pulses changes in proportion to the speed of the wire V _pr

f = K ₁ × V _pr (2),

where K ₁ is the proportionality coefficient depending on the design of the speed sensor.

During one period of the voltage induced in the speed sensor, a wire section of length l _e , equal to

$$\frac{V_{пр}}{f}=\frac{V_{пр}}{K_1{V}_{пр}}=\frac{1}{K_1}$$

, (3)l _e = V _pr × T _e $$\cong$$

$$\frac{V_{PR}}{f}=\frac{V_{PR}}{K_1{V}_{PR}}=\frac{1}{K_1}$$

, (3)

where T _e = l / f is the period of the pulses in the speed sensor.

As follows from expression (3), the value of l _e does not depend on the speed of the wire. Taking l _e as a unit of measurement, it is possible to determine what length of the wire passed through the damage sensor if we count the number of speed pulses n counted in counter 13 (Fig. 2) during the time T of the passage of the specified wire segment through the sensor-electrode 2.

l = n × l _e , (4)

where l_i - the length of the piece of wire passed through the sensor; n is the number of speed pulses in time T passing through the sensor wire section of the wire length l.

Since the speed of the wire V₁ , taken as an example 2 times the speed V₂, then the frequency of the speed pulses at these speeds also differs by a factor of 2. However, the pulse duration T_1i and T_2iformed from a defect of the same length l_i at different speeds of movement of the wire will also differ twice, but the number of elementary sections of the wire l_eh, remains the same in both cases and equal to n.

When the front border of the defective section of the wire insulation approaches the sensor-electrode 2, it generates a signal that turns on the key device 11, and pulses from the speed pulse shaper 4 are fed to the input of the counter of the length of defects 12 with an adjustable conversion factor. The conversion factor in the counter 12 is set based on the size (resolution zone) of the defect sensor 3.

The resolution zone of the electrode-sensor 2 depends, in particular, on the voltage across it and the presence or absence of ionizing ultraviolet radiation in the area of the gas-discharge gap. Therefore, to determine the resolution zone (sensor resolution), it is first necessary to calibrate the defect sensor and determine at what voltage the control will be carried out. The optimum control voltage U _r will be a voltage at which a point defect in the form of insulation piercing guaranteed, with 100% probability is registered sensor defects. To determine the value of the mentioned voltage, a defect-free section of the wire is selected and a point defect is applied in its insulation, in the form of a puncture of the insulation with a needle to the conductive core of the wire. A voltage is applied to the sensor - electrode 2 from the power source 1 of such a value, at which the corona discharge is guaranteed not to ignite when the said defective section of the wire insulation passes. In the process of sensor calibration, the said defective section of the wire insulation is repeatedly pulled through the defect sensor, the gas-discharge gap of the defect sensor is continuously irradiated with ultraviolet light 15, and with each subsequent pulling the voltage on the sensor 2 is increased. This procedure is repeated until the specified point defect is guaranteed to be registered electrode - defect sensor 2. The voltage at which this happens and will be the operating voltage U _p of the defect sensor. Since the point defect is made in the form of an insulation puncture, then, in the first approximation, we can assume that this defect has a negligible length. However, when the mentioned defect, which is negligibly small in length, passes through the sensor of defects, a pulse of duration t _s will appear on the latter _{, the} number of speed pulses k recorded during this time arriving at the counter 13, and will determine the systematic error of the sensor L _p , the value of which will be equal to L _p = k × l _e .

The conversion factor k in the counter 12 is set equal to the difference between the number n of speed pulses arriving at the counter 13 and the number of pulses n _i that should have passed to it with a known defect length. Determination of the conversion factor k and maintaining the counter 12 with an adjustable conversion factor makes it possible to exclude a systematic error in determining the length of defects due to the finite dimensions of the sensor 3 of defects and its resolution.

The trailing edge of the signal from the counter 12 sets the trigger located in the key device 11 to a single state, and the trailing edge of the sensor signal - the electrode of defects 2 - to zero. At the output of the key device 11, a pulse occurs, the duration of which T _i is determined by the true length of the defective area. In this case, the counter of the length of defects 12 with an adjustable conversion factor counts the speed pulses, the number of which is proportional to the length of the damaged insulation.

At 15 in FIG. 1, a single functional unit is designated, which includes a sensor-electrode 2 and a speed sensor 5.

Let us consider the principle of operation of the mentioned functional unit, including the sensor-electrode 2 and the speed sensor 5, using FIG. 4. Since the test object is a round extended body covered with an insulating film, moving relative to the primary converter (defect sensor), and a defect in the insulation can be located at any point on the surface of this body, then to ensure the same conditions for detecting any of the defects, so that all points of the test object are equidistant from the surface of the primary converter. This condition could be satisfied by any sensor symmetrically covering the wire. However, when choosing a sensor design, one should take into account the fact that the wire in real technological processes, where it is used, moves at high speeds, while making transverse vibration vibrations. If the sensor is made in the form of a stationary body, inside which the controlled wire is passed, then when the insulation comes into contact with the sensor surface, it can be destroyed. Therefore, in order to avoid destruction of the wire insulation, it is necessary to reduce the friction of the insulation against the sensor. The above requirements are satisfied by the sensor, the design of which is shown in Fig. 3.

The sensor consists of two cylindrical roller-electrodes 18 and 19 adjoining along the generatrix. The electrodes through bearings 22 and 23 are placed on axes 20 and 21, which are fixed on movable levers (rocker arms) 24 and 25, allowing the roller electrodes 18 and 19 to make vertical movements synchronously with the vibrations of the wire. The electrodes 18 and 19 are pressed together by means of springs 36 and 37, the two ends of which 38 and 39 are attached to the protruding pins of the dielectric base 17 for attaching the working elements of the sensor, and the other two ends to the holes 45 and 46 drilled in the rocker arms 24 and 25 respectively. Voltage is applied to electrodes 18 and 19 through sliding contacts 33 and 34. In this case, one end of each of sliding contacts 28 and 29 is mechanically and electrically connected to terminals 32 and 33 for connecting a power source. The power supply is connected to pins 32 and 33. When testing, the wire is pulled through bushings 34 and 35, fixed coaxially in the housing 16, and in the grooves pressed by the springs 36 and 37 to each other by the forming surfaces of the rollers - electrodes 18 and 19. Under the action of friction of the wire surface with the surfaces of the grooves in the electrodes 18 and 19, the latter begin to rotate on bearings 22 and 23 around axes 20 and 21, mechanically fixed to the levers - rocker arms 24 and 25. When the roller 18 rotates, the disc 47 attached to it by the glass 49 coaxially comes into rotation (see Fig. 3) with it through radial slots 48. The ultraviolet light-emitting diode 50 emits ultraviolet light, which is transmitted through the slots 48 to the ultraviolet photodiode 51. Since the radial through-slots 48 are evenly spaced over the surface of the disc, the ultraviolet light passing through the said slots initiates the photodiode, which acts as a receiver, is converted into a pulse current. The number of pulses of the current induced in the photodiode per one revolution of the roller 18 will be equal to the number of n - slots, and the length of the wire l passing through the sensor in one revolution will be equal to

l = 2π × (D-d) (5),

where D is the diameter of the roller 18, in mm; d is the diameter of the groove for the wire along the generatrix of the roller 18, in mm.

For a time equal to the duration of one pulse of the photocurrent at the output of the photodiode 51, an elementary piece of wire will pass through the sensor equal to

(5).l _e = $$\frac{�\times ��-��}{�}$$

(five).

In this case, regardless of the speed at which the wire will be pulled through the sensor, the value of an elementary wire segment l _e , determined by formula 5, will always remain unchanged, since all values included in formula 5 are constant.

In this case, the larger the number of slots n, the smaller the value of l _e , taken as a unit of measure of length, and the higher the accuracy of determining the specified length. By the number N of photocurrent pulses from the output of the photodiode 51 that have passed into the electronic circuit of the defectiveness meter, the length L of the monitored wire can be determined by the formula

N (6)L = l _e $$\times$$

N (6)

In addition to the length of the tested wire L, you can also determine the resolution of the sensor and the length of each defective section of the wire, which will be shown below.

In addition, the introduction of an ultraviolet light-emitting diode 50 into the sensor leads to a decrease in the control voltage at the sensor, and to a significant increase in the stability of the signal from the output of the defect sensor when a defective section of insulation passes through it. This is due to the fact that ultraviolet light ionizes the gas near the electrodes (rollers) of the sensor, which reduces the discharge delay time and facilitates the transition of a non-self-sustaining discharge into a self-sustained one. This is clearly confirmed by the oscillograms from the defect sensor shown in Fig. 2 and FIG. 6.

The signal shown in FIG. 6 is similar to the signal from the sensor of defects in the electrode-sensor in the prototype, since there is no ultraviolet illumination in it. Since the number of defects in the insulation of the monitored wire is counted by the number of pulses arriving at the counter of the number of defects from the output of the defect sensor, the use of the signal shown in FIG. 2 will result in significant errors. For example, with the signal shown in FIG. 2, the counter of the number of defects will count not one defect, but at least 4. In addition, due to the high instability of the time t _p , which changes from defect to defect, it is very problematic to control the length of defects with such a sensor.

Ultraviolet illumination significantly changes the structure of the defect signal (see Fig. 6).

An example of a specific implementation. A meter for the defectiveness of the winding wires was manufactured, the block diagram of which is shown in Fig. 1. The claimed device monitored the defectiveness of the insulation of the PETV winding wire with a diameter of 0.8 mm. As a speed sensor 1 and an electrode - sensor 5, a functional unit 15 was used, which includes these elements. Said block 15 is shown in FIG. and FIG. 4 included a photoelectric displacement transducer.

The manufactured functional unit 15 is shown in FIG. The body 16 was milled in the form of a stainless steel channel. The distance between the parallel walls of the housing 16, which was 8 mm thick, was 100 mm. A base 17 made of caprolactam was fixed to the walls of the housing 16 to accommodate the block elements. The base 17 was also made in the form of a channel. The parallel walls of said base 17 with a thickness of 10 mm were fixed with fasteners 41, 42, 43 and 44 to the parallel walls of the block body 16, and the base of the said base 17 was located perpendicular to the base of the block body 16. In addition, two metal rocker arms 24 and 25 were introduced into the block, made of stainless steel plates, 3 mm thick. Rollers 18 and 19, made of stainless steel, served as the working element of the block. The roll diameters were 12 mm. On the generatrix of the surface of the rollers, grooves with a radius of 1 mm were cut. The forming surfaces of the rollers 18 and 19 pressed against each other springs made of steel elastic wire 1 mm in diameter. To the side surface of the roller 18 was mechanically (by welding) attached a glass 49 of a disc with uniformly made through radial slots 48 in it. With a diameter of 19.1 mm of a disc 47, we were able to make a raster with 240 slots by photolithography.

The two sliding contacts 28 and 29 were made of 2 mm thick stainless steel plates. Two pins 32 and 33 for connection to the sensor power supply were made in the form of pins from copper rods with a diameter of 20 mm. Leads (pins) 32 and 33 were screwed in along the thread cut in the through holes of the dielectric base 17. In addition to the external thread at the leads 32 and 33, in them, from both ends along the axes, internal holes were made, the M5 thread was cut, with the help of which screws 30 and 31 connected the sensor power supply through terminals 32 and 33 to sliding contacts 28 and 29. The power supply was connected to terminals 32 and 33 from the outside of the dielectric base (not shown in Fig. 3) through the contacts of the limit switch. The two guide sleeves 34 and 35 have been machined from stainless steel. The inner diameter of the sleeves was 2 mm, which made it possible to pass through them any monitored wire having an insulation diameter of less than 2 mm. Bushings 34 and 35 served to make the wire straight without bending movement, and limited the lateral vibrations of the wire during its movement. A vfhrb UV-Inspector 2000 lamp was used as an ultraviolet lamp 50 [3]. The battery life on a single charge is about 4 hours. UV intensity at 400 mm: 2000 μW / cm ² . Wavelength: 365 nm.

As the photodiode 51, an ultraviolet photodiode from SGLUX made on the basis of silicon carbide (SiC) was taken.

A frequency multiplier with a multiplication factor equal to 10 was used as a speed pulse shaper 4 (FIG. 1). Using the functional block shown in FIG. 3 and introducing a frequency multiplier into the device, it was possible to provide the value $$l_{\mathrm{uh}}=0.025\begin{array}{cc}mm.& \end{array}$$

Before testing, the electrode - sensor 5 (Fig. 1) located in the functional unit 15 (Fig. 3) was pre-calibrated. For this, an artificial point defect in the form of a puncture was applied to the defect-free section of the insulation 10 of the wire segment to the conductive core 7 of the wire, which was grounded. Initially, a constant voltage of 100 V was applied to the defect sensor 3 from an adjustable source 1, and this defective area was pulled through the defect sensor electrode 5, while irradiating the gas discharge gap with ultraviolet irradiation 14. At a voltage of 100 V, a corona discharge when passing through the defect sensor electrode 5 did not ignite. The voltage from the source 1 at the sensor 5 was increased, and the defective section of the insulation under continuous ultraviolet irradiation 14 of the gas-discharge gap was again pulled through the defect sensor 5. This procedure was carried out until, when the defective section of the wire passed in the zone of the defect sensor 5, a stable corona discharge. This happened when the voltage on the electrode-sensor of defects 5 was equal to 0.45 kV. When a corona discharge was ignited between the core wire 7 at the site of the defect and the electrode-sensor of defects 5, a defect pulse was formed with a durationt _from , and counted in counter 13 the number of speed pulsesk generated over timet _from . This number turned out to be equal to k = 80. This value was fixed and entered, as a conversion factor in the counter 12. After this operation, the voltageU _R =0.45 kV, at which the above-mentioned corona discharge is ignited, was taken as the operating voltage, and the wire insulation was monitored at the above-mentioned voltage across the sensor. In accordance with the claimed method, when each defective section of insulation passes through the sensor of defects, a defect pulse of durationt _i and the number ofn _i generated speed pulses for the mentioned timet _i . Lengthl _i each defect should be determined by the formulal _i = l _eh (n _i - k),Wherel _eh - the length of an elementary piece of wire passed through the sensor of defects during one generated speed pulse.

To determine the characteristics of the control of the length of the defect on the defect-free section of the insulation of a piece of wire, a defect with a length of 0.5 mm was applied. The section of the wire with this defect was pulled through the electrode - the sensor of defects 5, continuously irradiating the gas-discharge gap with ultraviolet light 14 and the number n _{i of the} velocity pulses passed into it during the time t _n (see Fig. 1) of the signal pulse from the sensor of defects 5 was recorded in the counter 12. The value n _i turned out to be equal to n _i = 100. The length l _{i of the} defect was determined by the formula l _i = l _e (n _i - k) = 0.025 × (100-80) = 0.5 mm.

For comparison, similar procedures were performed with the defect sensor, without ultraviolet irradiation of the gas discharge gap of the defect sensor 5 electrode, as it was in the prototype device. In this case, it was revealed that the sensitivity to defects U _rprot was equal to U _rprot = 1.2 kV, and the conversion factor determining the sensor resolution zone was equal to k = 200. With an operating voltage U _rprot = 1.2 kV and determining the length of the defect, 0.5 mm in length according to the prototype method, n _{i prot.} == 222 pulses.

The value l _i = l _e (n _i - k) = 0.025 × (222-200) = 0.55 mm.

Thus, in comparison with the prototype, the control voltage in the claimed method was reduced by 2.7 times, and the resolution of the sensor was improved by 2.5 times.

Sources used

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

2. USSR author's certificate No. 1786414, class. G01N27 / 00, Publ. 07.01.93. Bul. No. 1 (prototype).

3.http: //www.geo-ndt.ru/catalog-506-yltrafioletovie-lampi.htm

Claims (1)

A device for monitoring the defectiveness of the insulation of winding wires, containing a sensor - an electrode, a high voltage source, a defect pulse shaper consisting of a reference voltage source for a shaper of the leading and trailing edges and a differential amplifier, a defect counter, a speed sensor, a speed pulse shaper, with the first input of the source high voltage is connected to the first input of the defect pulse shaper, the output of which is connected to the defect counter input, the second output of the voltage source is connected to the sensor - electrode, the speed sensor is connected to the second input of the defect pulse former through the speed pulse shaper, the first and second inputs of the differential amplifier are connected respectively to the first input of the defect pulse shaper, to the output of the source of the shaper of the leading and trailing edges, the second input and output of which are respectively the second input and output of the defect pulse shaper, which is characterized by The fact that it additionally includes a speed pulse counter, a key device, a defect length counter with an adjustable conversion factor, a trigger, an LED and a photodiode , while the electrode electrode and wire speed sensor are made as a single functional block made in the form of two rollers made of stainless steel, having a U-shaped groove along the generatrix, and the rollers are placed in a housing that is made in the form of a channel, between the parallel walls of which a dielectric base is fixed to accommodate the sensor elements, also made in the form of a channel, the parallel walls of this base are fixed with fasteners to parallel to the walls of the sensor body, and the base of the said base is located perpendicular to the base of the sensor body, two metal rocker arms, two springs, two sliding contacts, two leads for connecting a power source, two guide bushings, a disk with uniformly made in it through radial slots, one plane of which is made in the form of a cylindrical glass, and the rocker arms are made in the form of metal plates, at one end of each of which cylindrical axes for bearings are rigidly fixed perpendicular to the plane of the plate, at the other end of each plate the rocker arms are made perpendicular to the plane of the rocker arms of the hole under the axes, which are rigidly fixed on a dielectric base to accommodate the sensor elements, rotating rollers pressed by the springs to each other by forming surfaces at the point of contact lying on the vertical axis of symmetry of these rollers, a glass of the said disk is coaxially attached to the side surface of one of the rotating rollers with radial slots, grooves are made along the forming surfaces of the rollers, which lie when the rollers touch each other and serve to fix and limit the movement of the wire in the transverse direction, a bearing is pressed into the central part of the rollers nicks mounted on the aforementioned cylindrical axes, rigidly fixed on the movable end of the rocker arms, fixed ends of the rocker arms, with the holes on them put on the axles, mechanically fixed on a dielectric base to accommodate the sensor elements, the rollers are pressed against each other by their forming surfaces using two springs, one end of which is mechanically fixed to one of the rocker arms, and the other two ends of the springs are mechanically fixed to the dielectric base to accommodate the sensor elements, the voltage is applied to the working surfaces of the rollers by sliding contacts made in the form of elastic plate springs, one end of which is pressed against the roller axes, the other the end is electrically and mechanically connected to the end with terminals for connecting a power source, guide bushings are fixed in the walls of the sensor housing, the longitudinal axes of symmetry of which coincide with the axis of the wire, the ultraviolet LED is located in the gap between the disk with uniformly made in it through radial slots, from the side of the plane made in the form of a cylindrical glass and the surface of the roller, to which the glass is mechanically attached, the ultraviolet photodiode is located on the opposite side of the said disk with radial slots, while the output of the photodiode is connected to the input of the speed pulse shaper, one of the outputs of which connected to the key device, the output of the key device is connected to the input of the counter of the length of defects with an adjustable conversion factor.

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