SU1339462A1 - Device for checking the windings - Google Patents

Abstract

The invention relates to electrical engineering, namely, devices for controlling the winding, and can be used to detect defects in the windings of electrical machines during their manufacture or repair. The aim of the invention is to increase the sensitivity of the device. The inductor winding of two parts 4, 5, the monitoring device is connected to the output terminals of the modulator 8, consisting of a transformer 9 with windings 10, 11, connected by terminals 12, 13 to a sinusoidal voltage source 14. The modulator 8 contains fully controlled semiconductor switches 15, 16 of alternating current, each connected to both its own output terminal of the modulator, and to its common one its input terminal. The device can be used to control the multi-turn windings of machines with increased sensitivity of the device. 6 Il. С /) from 00 CD 4.

Description

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The invention relates to electrical engineering and can be used to detect defects in windings of: electrical machines during their manufacture or repair.

The purpose of the invention is to increase the sensitivity of the device.

Figure 1 shows the conventional circuit of the proposed device; Figures 2-6 are time diagrams of voltages on various elements of the device and a diagram of the corresponding switching function.

The device (Fig. 1) contains an W-shaped magnetic circuit 1, on the middle core of which the indicator winding 2 is located with a measuring device 3 at its clamps, and on the extreme rods there is an inductor winding consisting of two parts connected in series and two parts which is connected to the output terminals 6 and 7 of the modulator 8, consisting of a transformer 9 with windings 10 and 11, connected by the input terminals 12 and 13 to the source 14 of sinusoidal voltage. The winding 11 of the transformer 9 is connected in parallel with the fully controllable semiconductor key 15, while using another fully controllable semiconductor key 16, the winding 10 of the transformer 9 can be directly connected to the source 14 of sinusoidal voltage. The W-shaped magnetic core 1 of the proposed device is superimposed on the magnetic system 17 of the rotor (or stator) with controlled winding in its grooves 18 so that the distance between the middle and one of the extreme rods of the H-shaped magnetic core 1 corresponds to one tooth division magnetic system 17 of the rotor (or stator) with a controlled winding in its grooves, and the distance between the outermost rod w of the magnetic circuit 1 - double-toothed division of the magnetic system 17.

Controlled semiconductor switches 15 and 16 of alternating current (Fig. 1) can be realized, for example, in the form of diode bridges shunted by each chain of inductance and thyristor, while the same electrodes of these thyristors are connected to each other by switching capacitors, as a result of which

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the locked thyristor on the DC side of its diode bridge simultaneously leads to the locking of a previously open thyristor on the side

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DC current of another diode bridge. In other words, in such an implementation of fully controlled AC keys 15 and 16, in the proposed device, their alternate unlocking and locking take place.

A curve of the sinusoidal voltage of the energy source 14 is shown in FIG. 2. The switch plots for keys 15 and 16 (Fig. 3) correspond to one option for selecting the switching frequency of these keys. The voltage on the series-connected parts 4 and 5 (Fig. 4) of the inductor winding of the device proposed is obtained by multiplying the sinusoid (Fig. 2) by the switching diagram (Fig. 3). The diagram of the switching function (Fig. 3) corresponds to another selected value of the switching cycle period of the keys 15 and 16, the positive half of which corresponds to the open state of one of these 1 keys and the negative half of the other; accordingly, the switching diagram (Fig. 3) shows the sinusoidal voltage curve on the inductor winding (Fig. 6) of the proposed device. It can be seen from the curves of FIG. 4 or 6 that the frequency of the main component of the output non-sinusoidal voltage of the modulator 8 is expressed by the difference between the frequencies of the network and the switching cycles of the keys 13 and. sixteen; the amplitude of this basic component of the modulator output voltage is 2/11 times different from the amplitude of the sinusoidal voltage of the modulator. An analysis of these non-, sinusoidal curves of FIGS. 4 and 6 also shows that the same amplitude has a component of frequency as a sum of network frequencies and switching cycles.

Thus, the proposed device differs from the known one by the presence of an additionally introduced modulator of the 8, whose task is to obtain on the inductor winding instead of a sinusoidal voltage

with a nasi-periodic non-sinusoidal stress, characterized by n; 1, the difference of periodically repeated jumps of this voltage with an almost rectangular front, this is due to

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The occurrence of similar periodically repeated voltage surges on the sections of its controlled winding embedded in the slots of the machine is observed.

The modulator 8 performs the conversion of the sinusoidal voltage of the source 14 to a non-sinusoidal voltage with periodically repeating opposite polarity pulses, the shape of which can be judged by the curves of FIGS. 2-6.

When the key 15 is closed, the winding 11 of the transformer 9 is short-circuited, which in the subsequent time interval operates in the short circuit mode. If we neglect the active resistance and dissipation inductance of the transformer 9, during this time interval it is possible to consider zero the voltage drop on the winding 10 and therefore the voltage on the output terminals 6 and 7 of the modulator 8 is almost the same as its input voltage. During the subsequent opening and closing of the key I 5 and the closing of the key 16 winding

The 11 transformer 9 is directly connected to the source 14 of sinusoidal voltage, and the voltage induced in the winding 11 is transformed into the winding 10 of this transformer, during this time interval the voltage at the output terminals

12 and 13 of the modulator 8 is equal to the voltage on the winding 10. From the marking of the terminals of the windings 10 and 11 of the transformer 9 it follows that the initial phase of the voltage on the output terminals I2 and 13 in this interval will change by one hundred and eighty degrees in comparison with the initial phase of this voltage in the previous time interval. If the numbers of turns of the windings 10 and And are chosen to be the same, the amplitudes of the pieces of the sinusoid voltage at the output terminals of the modulator are kept unchanged in accordance with the curves (Fig. 2). Next, the key 16 is opened, the key 15 is locked, and the electromagnetic processes are repeated.

The output voltage of the modulator 8 can be represented as a result of multiplying the sinusoidal voltage (Fig. 2) by the diagram of the switching function (Fig. 3) and obtaining a curve (Fig. 4) or multiplying the sinusoid (Fig. 2) by the switching function

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(Fig. 5) and get the curve OUT1 O

voltage (Fig.6).

The resulting non-sinusoidal, almost periodic voltage with opposite polarity pulses is applied to the inductor winding, divided into two series-connected parts 4

10 and 5 with equal numbers of turns and located on the extreme rods of the magnetic circuit 1 of the device. On the middle rod of the magnetoresis), water 1 is located indicator winding 2,

15 which is not penetrated by the flow of the inductor winding and therefore the flow of this winding does not directly affect the indicator winding 2. To enhance this effect, there is an air gap underneath the middle rod of the magnetic conductor 1 separating this rod from the steel package of the machine part (stator or rotor), in the slots of which are placed

25 conductors controlled winding.

The flow of the inductor winding induces an emf in the conductors of a part of the winding placed in the adjacent two slots of the machine, covered by the extreme rods of the H-shaped magnetic circuit 1, of the device. Under the influence of the high-frequency components of the EMF, which replicate the voltage on the inductor winding of the device with intermittently different polarized pulses in accordance with the curves (Figures 2-6), the currents in the conductors of this pair of slots of the machine flow as in with distributed parameters

4Q even in the absence of damage iso-. ltsii these conductors. If in one of these two grooves of the machine there are conductors with damaged insulation that do not form a circuit with a metal short circuit, under the action of periodically repeated opposite-polarity voltage pulses induced in these machine conductors by similar impulses of inductor winding of the device, currents flow in different or in phase from the currents in the conductors of the adjacent groove. Under this condition, this difference of currents or magnetized

The gg of the loosening forces in the indicator winding 2 is induced by the voltage indicated by the measuring device 3.

The characteristics of the output voltage of the modulator 8 consists of:

com sinusoidal character of all its spectral components, i.e. in almost periodic nature and all non-sinusoidal voltage, which allows to transfer such voltage in the section of the tested winding of the electric machine by transformer through the inductor winding of the device; depending on the shape and spectral composition of this voltage on the selected frequency of alternate switching cycles of its keys 15 and 16 (Figures 2-6), which in each case allows you to select the desired shape and spectral composition of the voltage, ensuring the greatest efficiency of detection of defects in a controlled winding; in varying the shape and duration of the pulses of this voltage as the time changes even at a fixed value of the frequency of switching cycles of the keys 15 and 16, which also contributes to the increase in the efficiency of detection of defects in sections of the controlled winding.

The non-sinusoidal, almost periodic, voltage obtained by phase modulation of a single-phase sinusoidal source voltage can be represented as the product of the sinusoidal voltage of the source and the modulating function in the form of a rectangular sinusoid of unit amplitude with a repetition period different from the sinusoidal period of the source. In this case, the main component of the decomposition into a series of such a non-sinusoidal curve has a frequency in the form of the frequency difference between the supply source and the switching cycles; the frequency equal to it in amplitude of the other component of this voltage is expressed as the sum of the source frequencies and switching cycles. The following components follow: with a three-fold smaller amplitude, the frequencies of which are expressed by the sum and, accordingly, the difference between the source frequency and the tripled frequency of the switching cycles; with a magnitude lower by five times, whose frequencies are expressed by the sum and difference between, the source frequency and the five frequency of switching cycles, etc.

Thus, the frequency of the source of sinusoidal voltage is chosen sufficiently large: close to 5

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a circuit corresponding to the need to present the replacement circuit of the controlled winding in the form of a chain with distributed parameters; the frequency of the device key switching cycles is slightly higher than the frequency of a single-phase sinusoidal voltage source; spectral frequency

Q is the component, expressed as the sum of the source frequency and three times the frequency of switching cycles, ensures the achievement of the voltage resonance mode in the controlled winding, as

Ig in a circuit with distributed parameters and, similarly to the known device, ensures the transition of an clearly expressed defect of the tested winding into a clear breakdown. Under the conditions of the modulated voltage being considered, the informative component of the signal has many times less frequency expressed by the difference 25 sine wave voltage and frequency of the module. The ability to control the frequency of switching cycles to get a very low frequency of the informative component allows you to dramatically increase the signal

30 at the fundamental frequency as compared with the interference signals, even if the application E is not taken into account by the proposed differential device based on the use of a W-shaped electromagnet.

The proposed device allows to expand the field of application of the known device - to the multi-turn windings of machines located in their grooves, while maintaining the relative simplicity

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Claims (1)

and increased sensitivity. Invention Formula A device for controlling the winding in the grooves of an electric machine, the contents; its W-type magnetic core with indicator winding on the middle rod and inductor series-connected windings on the extreme rods, while the inductor windings are connected to a voltage source,. the indicator is connected to a measuring instrument, and the magnetic circuit is designed to be installed on a magnetic system of an electric machine under test, characterized in that with a sensitivity increase point of the device, it is abbreviated by a modulator containing a single-phase transformer and two fully controlled AC semiconductor switches, the primary winding of the transformer is connected by one input to the first terminal of the alternating voltage source, and the second to the inductor winding, the second output of which is connected to the secondary winding of the transformer connected by dl1339462 A first fully controlled semiconductor switch is connected to the second terminal of the voltage source, parallel to the secondary winding of the transformer, and a second fully controlled semiconductor switch is connected to the second voltage source terminal and the primary terminal of the transformer connected to the inductor winding. x Fi. h Fi.6 X / Compiled by V.Nikanorov Editor N.Rogulich Tekhred L.Oliynyk Proofreader A.Zimokosov Order 4215/34 Circulation 730 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4