JPS58769A - Method of detecting dielectric resistance, insulation thereof is insufficient, of electrodynamic machine winding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Quality of insulation of high-voltage electric machine windings? The problem to be evaluated is known from Ibo. However, since there is more than one cause for the deterioration of the winding insulation, conventionally we had no choice but to focus on the Fi test, but if the evaluation using the M test does not go well, the winding of the electrical machine will be in perfect condition. This is a loss to the manufacturer due to the need for rewinding, and the method used for empirical evaluation does not allow predicting impending perforation of the electrical machine insulation, so it is not recommended to use it. It would also be a loss for Nagisa.

A recent study by WAH has shown that the insufficient dielectric strength of apparently perfect winding insulation is due to the formation of local partial discharges inside the insulation that appear after a threshold voltage of Ta. However, since local partial discharges inside the insulation cannot be directly measured, there is no way that this knowledge can simply be transferred.

According to the generally accepted view of the prior art.

A local fraction tFi within the insulation occurs, especially at more or less distributed gas absorption points during the high voltage gap. If a partial discharge occurs inside a considerably large number of pores as the voltage increases beyond the voltage value at which a partial discharge occurs, the capacity of the winding will change as the inside of the pores, which is the seat of the discharge, becomes a conductor. Varies as a function of applied voltage. With this enlightenment, TERAS
E(El@ctr.

En@, Jap, February 1973) it proposed a nine-point quality criterion based on the course of the curve of the winding capacitance as a function of the applied voltage. This characteristic can be determined with the help of a capacitance measuring bridge, for example a Schelling bridge. According to the TERASE method, beneficial knots can be drawn out only when this occurs.

However, in many other cases, there are not enough distinguished guests to define the critical features of the evaluation. I! In other cases, the effect of Ku is completely masked by other phenomena.

It is an object of the present invention to provide useful evaluation criteria from physical aspects based on harmful partial discharge and/or ion mobility, which is very sensitive and can be carried out with existing measurement equipment. We aim to provide a detection method to obtain the desired results.

In the measuring path of the capacitance measuring bridge, the conductor of the winding and the mass part of the electric machine arranged in the area of the winding are connected, and each measured alternating current contained within a predetermined voltage range is connected. For voltage, the measuring bridge is balanced, and the frequency of the alternating voltage is calculated from the frequencies occurring in the windings under the conditions of use of the machine. In the method of detecting, a high selectivity measuring device of current flow or current passing through one predetermined number of aphrodisiacs or each different predetermined frequency! l! l
A high-selectivity multiple measuring device f of the electric current tllllJ-4 pulse or current to be passed is placed after the phase, and the side? and placed in the balanced diagonal side of the bridge.

The detection method is characterized in that the value of the measured voltage is swept between a value lower than the working voltage and a value at least equal to or higher than the maximum permissible voltage of the electric machine. Preferably, as a function of the applied voltage, one or both of the repetition rate or frequency and the amplitude of the current or the Norms measured by the highly selective measuring element or Fi measuring device are recorded. , from the shapes of the curves of these quantities, it is evaluated whether the insulation of the windings of the electric machine is poor or not.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be further described with reference to the accompanying drawings.

The measuring bridge shown in FIG. 1 has four side edges and one balanced diagonal edge. The four sides are the capacitance to be measured 1 (in this example, the capacitance of the stator winding of the motor relative to the motor mass), the reference capacitor 2, the balance resistor 3, and the balance capacitor 4 (connected in parallel with the variable resistor 5). ). A changeover switch 6 is arranged on the measurement diagonal side, and is connected to the switch 6Fi balance indicator 7K or the ferrite core saturable high-wave transformer 8, and the secondary winding of the high-dark wave transformer 1ls8 is Power is supplied to the wave height voltmeter 9.

Instead of providing the switch 6, a transformer 8 may be permanently connected in the measuring diagonal, and the Ronso blue filter may be connected in series with the balance indicator 7. To,
All other devices that measure the maximum amplitude of current flow based on partial discharges can also be used. The electron pulse with the largest amplitude is clearly the deleterious p4 pulse.

The measurements are carried out as follows: for each measured voltage in the range of the nominal voltage of the motor, the bridge is first balanced with the aid of the balance indicator 7 at a wavenumber of 53 Hz. This measures the capacitance of the stator winding with respect to the mass of electric current #IJ1m. In the bridge power supply state shown in Figure 1, the stator mass of the motor must be insulated from the ground, and the Stator of @@
When measuring each i of , it is necessary to supply power to the Pritsuno from the measurement sides K or to use another type of bridge as illustrated in Figure 2. It becomes PK.

When the balance of the bridge is obtained, the position of the movable contact of the switch 6 is changed so that all the circuits of the balance indicator 7 are quickly disconnected and the transformer vs8 is inserted on the diagonal side for measurement. Transformation 5SFi,
The reciprocal of the duration O of the trailing edge of the average pulse 1 of the local partial discharge is t! It is a high selectivity transformer with a corresponding frequency tK high selectivity. In FIG. 5, t4 is decomposed into a component 1p representing the arrow part and a component 9 representing the trailing edge.

Component 1. The vibration part is small but the duration is very long, so the duration is very short.1. contributes more to the dielectric breakdown effect. The trailing edge duration is component 1.・fsis of half the height of the wave height of 1. is the duration of The passband of the transformer 8-voltmeter 9 unit is preferably a very narrow range around the frequency f=''-.

0 This passband is component 1. as well as all kinds of parasitic pulses? : Selected so that it can be removed.

Depending on the selection of the transformer 8, a predetermined frequency f, l! In the case of option I, the detection device is sensitive to an average pulse whose duration 0 corresponds to the reciprocal of the frequency 1.

That is, the shape of the average pulse of a local partial discharge can vary as a number of applied voltages, and can vary from one insulation to another, and the variation as a function of voltage is among the variations encountered. To easily measure the discharge of S minutes, which is the largest in There must be. This makes it possible to eliminate the influence of the steep wave crest of the Norse from the measurement. This steep wave front or element represents the energy necessary to generate a charge within the tL insulation, which is not harmful in itself. What is detrimental is the kinetics of removal of these charges represented by component 1°. Due to the 141i selectivity of the transformer 8, it is possible to determine the measured voltage value at which the average discharge voltage has a duration of zero. The reason is that the curve representing the value measured by the peak voltmeter 9 as a function of the #lJ constant voltage reaches a maximum at the above voltage value. On the contrary, if the measured curve does not show significant local maxima, then the phenomenon of ponding, which is related to local partial discharges and does not degrade the insulation, is likely to occur in the pores.
It must be assumed that it appears in the location.

Therefore, in this case, the insulation can be considered normal. Transformer 8F
It is an unsaturated compressor, and saturation begins to occur when the amount of charge between both ends of the primary wire of the transformer IS8 exceeds a value that is greater than the value that is commensurate with the local partial discharge phenomenon. Therefore, the phenomenon recorded when this @ value is exceeded has nothing in common with a local partial discharge, such as a surface discharge.

In place of the wave height voltmeter 9, a counter for harmful pulses may be used. Naru no! The harmfulness of a virus is evaluated by its size and repetition frequency. If a pulse consisting of the following occurs for each alternation of the frequency of the measured alternating current voltage, there is a permanent phenomenon that should break down the insulation within a more or less short period of time. On the contrary, the degree of repetition of harmful 9 russ is measured at 5! : If it is 0.5 or less for each alternation of current voltage, the pulse can be considered as a regular pulse or an irregular pulse that does not lead to breakdown of the insulation within a short period of time. .

For the purpose of this counting, the counter of harmful pulses preferably has a manual stage with gm possible -1 shift and adjustment 0Tjfl! Only Heirusu whose strength is below the threshold will pass through this human power stage. On the other hand, the sampling period of this counter is 50 to 10,005 times the frequency of the measured voltage! It is preferably selected within the range of IF.

To avoid unnecessarily prolonging the measurement time, set the above period to 1.
It is advisable to keep the value smaller than 000 alternations.Also, in order to reduce the influence of noise due to parasitic pulses that occur in the circuit when switching on and off the switch, it is recommended to observe the minimum value of the first half cycle of 50 alternations. Should.

The measurement dimensions may be selected such as the selection of a single threshold value for the entire measurement range, the selection of a series of different adjustments of the threshold value for each measurement voltage, or as a function of the measurement voltage, e.g. proportional to the #-1' measurement voltage. may consist in selecting a single threshold value for each measured voltage.

An advantageous measuring method for % is the combination of measurement with a pulse height voltmeter and measurement with a nodalus counter. The pulse counter of the threshold input stage is then shunted in parallel to the pulse height voltmeter 9. The threshold value of the Noyals counter is adjusted manually or automatically so that the voltage has an amplitude slightly smaller than the maximum amplitude of the pulse applied to the pulse height voltmeter, for example, a voltage with an amplitude of 98 to 80 cm of the maximum amplitude. Ru. Comparison of the respective measurement values recorded by the pulse height voltmeter and the Noyals counter allows the most reliable evaluation of the phenomena that can lead to failure of the windings of the machine under test.

The advantages of the measurement method described above are not lost even in the case of the detection of internal discharges, which, due to the selectivity of the measurement method for internal discharges according to the invention, can be used for detecting one surface discharge or another, such as a notch discharge. This becomes easier if there is a discharge of this nature. However, below the measurement voltage level, the measurement of internal discharges is masked by surface discharges and/or notch discharges. However, this is not indispensable in practical cases where it is only important to determine the quality of the insulation. cannot be shown.

It is also possible to determine which of internal discharge, surface discharge, and notch discharge causes an increase in the voltage value measured by the wave height voltmeter 9. In fact, the rate of increase in the voltage value measured by the wave height voltmeter 9 as a function of the measured voltage is the highest.In the case of a 1ml discharge, the KF-1 operator was impressed by the characteristic ozone odor, and due to the surface discharge. I can hear the noises that occur. If the operator takes a little time in each measurement, the cyclic steel weight of surface discharges at high voltages in % may vary from e.g. 1 discharge per alternation to 1 discharge per 50 alternations*VCW less than do.

When notch discharge appears, there are subtle but incidental manifestations such as audible noise and the smell of ozone. *Evaluation of the dielectric strength of mechanical insulation. FIG. 4 is a superimposed diagram of various measurement curves analyzed by the detection device of the present invention, which can reveal a series of characteristic phenomena that can be useful for The measured voltage H is plotted on the horizontal axis, and the measured values of various quantities are plotted on the vertical axis Kf. As indicated by the confession @,
10th track 1110H1 Relative increase in the capacitance of the coil to the mass of the electrical machine, curve @ tgJ of 11-insulation, curve 12Fi wave Voltage value measured by high voltage needle, curve 1
:lj The 0 curve, which is the number of discharges per alternating cycle counted by the counting amount of harmful nodalus, does not show insulation defects by 10.11, but the same is true for 1 song @12.13.
At voltages considerably lower than the nominal voltage LJn of the electrical machine, which is fixed at 1ull, a large number of internal discharges with small amplitudes are measured by a pulse-height voltmeter, appearing approximately at the alternation of each R, but the measured voltage As the voltage increases, a discharge of larger amplitude occurs, which is measured by the crest voltage needle and recorded by the counter. This is the reason for the decreasing shape of songs 1!13. However, the maximum width of the discharge measured by the wave height voltmeter 9 passes through the tube at a maximum value at the nominal voltage. Curve 1112d shows a knee at a voltage slightly higher than the nominal voltage, from which an increasing curve portion due to surface discharge extends. Since the operator senses the odor peculiar to ozone at the measured voltage corresponding to this knee, surface discharge occurs. The repetition frequency of the discharges, measured by a counter of harmful pulses, shows two maxima, which are burnt out after the high voltage, which consists of several small spots that give rise to surface discharges. It shows. Since the most harmful internal discharges are still only of an episodic nature and specific surface discharges occur only at measured voltages considerably higher than the nominal voltage of the machine, an insulation with a curve according to Figure 4 is considered relatively good. be able to. However, the fact that the thickest point of curve 12 is at the nominal voltage indicates that this insulation must be checked at relatively short intervals.

The measuring bridge shown in the tIXs diagram is similar to the one shown in Figure 1, but with a number of grains on its equilibrium side for measuring the ego, % cap, or current with high selectivity. Measurement II
P votes (each passing a different predetermined #i11 wave number) are included. These oil constant elements may be the same as the elements already explained with respect to Figure 1.2, but in addition, they may also be connected to the filter 15 and connected to the filter 15 for the frequency of the measurement voltage (commercial frequency), for example 5QHz. Vessel 14 and
Oscillograph indication useful as an equilibrium indicator! It may be 1g.

an input stage 1 connected to the peak voltage needle 9 and with an adjustable threshold;
A highly selective transformer SFi, connected in parallel to the counter 10, is sensitive to frequencies, for example in the range from 100 to 500 Hz, corresponding to the duration of the trailing edge of the harmful partial discharge.

Transformer 18. A tensimeter 19 with an expensable gain, e.g. commercially available with Kt in the range 200-800 Hz - a filter 20 with high selectivity for a given m wavenumber and a capacitive input stage amplifier 1) Another measuring element consisting of 21 is connected to a peak voltmeter 22. This ion ll11: Or used to detect phenomena related to moving guests. The wave height voltmeter 22Fi may be the same as the wave height voltmeter 9, as long as the fi high voltmeter 9 is preferably equipped with an automatic selector for an appropriate measurement range. In order to insert these detection circuits one after another into the circuit, 6 switches are connected as shown in Figure 1, and 2 switches are connected as shown in Figure 85.
By means of a switch 6.6' with a separate movable contact, this is carried out as explained in connection with FIG.

In this case, the primary side of the voltage transformer flag 14.18 may be permanently connected in series to the balanced side (number II), and one measurement selection line may be performed using only the movable switch 6'.

! Pressure gauge 18, I tensimeter 19. filter 20
The measuring element consisting of the amplifier 21 and the amplifier 21 will be explained in detail below. The transformer 18 is permanently shunted to the balanced side (so that the selectivity of the measuring element at the selected frequency is not thereby lost; in fact at commercial frequencies the resistance is 4 tensiometers). 19, whose tip is small compared to the impedance of the capacitor in the input stage of the amplifier, whereas at the selected frequency this resistor R#'i Therefore, in the case of the filter 20 for a frequency significantly higher than the commercial frequency, the response of the amplifier 21 is not proportional to the terminal voltage on the balanced side, but proportional to the current flowing through the balanced side t. In the W flow, caused by ions moving in the isolated part of the electric machine due to the alternating current measuring voltage applied to the electric machine,
The measured voltage p detected by the wave height voltmeter 22? Generate.

An example of the curve @230 of the voltage V detected by the peak voltage needle 22 as a function of the measured voltage U in the commercial wavenumber is shown in FIG. Un is the nominal voltage of the electrical machine.

The shape of the curve, on the low voltage side, is mainly determined by the density of mobile ions between two adjacent barriers and the mobility of these ions and hence the transit time of these ions from one barrier to the other. Determined. The product of these two quantities determines the shape of the curve 23, starting from the increasing curve section, passing through the maximum value and asymptotically reaching the WL level. After that, the second level is
In the case of the new ea part, it is explained by the dissociation of the complexes of the species under the influence of high voltage and the increase in the ion concentration due to the formation of local electrolysis due to the charge. For all insulation parts, after the threshold voltage Us, a delicate current is generated due to the local electric field, which precedes the breakdown of the insulation 11, and this current generation causes an exponential increase in the voltage measured by the wave height voltmeter 22. This is explained by the beginning of . The test shall be discontinued after this voltage increase begins.

The same wave number selected for measurement by the wave height voltmeter 22 should be different from the commercial frequency to avoid direct influence of the applied voltage on the measurement. On the other hand, the mobile ions are each moved by a constant alternating voltage in the space between the barriers in the space corresponding to each mobile ion, so that the current induced during the Britno equilibrium path is such that the measured voltage is derived from it. Alternating current (number) with a frequency that is an integral multiple of the line frequency (commercial frequency)
Consists of a superposition of . But ω=-(KT here,
is the average transit time of a mobile ion between two adjacent barriers)
[The S width of wtlt becomes zero with respect to the wave number.

Therefore, the filter 201 is used to pass the wave number #I, which is an integer multiple of the commercial 8 wave number which is higher than the commercial frequency by an amount of light, and the frequency considerably lower than the wR wave number, in fact KTF 200 to 800 H2. debt.

By curve 23, new? In the case of three edges, we can find two thresholds due to the onset of the delicate current and the ion concentration, which makes it possible to determine the permissible limit voltage for the operation of the Klt-air machine, so that it is possible to find an auxiliary explanation about the normality of the absolute part. You can get a good plan. In the case of old insulating parts, the ion connection time becomes longer due to the mold removal table of the plastic paulownia material used.

Therefore, the voltage Us ij decreases and the second level cannot occur.

[Brief explanation of the drawing]

1 is an electrical circuit diagram of a measuring bridge according to an embodiment of the invention, FIG. 2 is an electrical schematic diagram of a measuring bridge according to another embodiment of the invention, and FIG. Figure 4F
i11 pressure waveform diagram, FIG. 5 is an electric circuit diagram of a measurement circuit according to another embodiment of the present invention, and FIG. 6 is a heavy pressure ffI shadow diagram corresponding to FIG. Explanation of symbols 7... Balance indicator, 8... High S wave pressure booster (measuring device), 9.22... Wave height voltmeter (measured value W7t), 14
゜18...Transformer (measured value fi), 15...Filter (+III) constant M#), 16...Oscillograph indicator (measured value! 11), 20...High selectivity filter ( control; electric equipment fi11). 21...Amplifier (measuring device) Representative Patent Attorney Nakamura Nerui Yama
Honbu Dokushi
Oka Hachi Immediate Question Aya Otsuka Opening Shishi To Yoshi −
Procedure Tei IF document (method) 1984 patent +1J1 No. 70159 No. 3, Relationship with the case of the person making the amendment Yamato 4, Agent

Claims (1)

[Claims] α) During the measurement path of the capacitance measuring bridge, the winding 0 conductor and
The measuring bridge is placed around the winding and connected to a good electrical machine, and the frequency of the alternating voltage is In a method for detecting insufficient dielectric strength of the insulation of the windings of an electrical machine by selecting from among the frequencies occurring in the conditions of use of the machine, a current dulse or voltage passing one predetermined frequency consisting of High selection 4
& Measuring device 8.9 or a plurality of highly selective oils of current pulses or currents each passing a different predetermined frequency.
j! Price tag 14, 15, 16: 8.9: 17.18.20
．． 21 and 22 one after the other, K to replace the balance indicator 7, and a holder arranged in the balance diagonal side of the measuring bridge;
A detection method characterized by sweeping the value of a constant voltage between a value lower than the working voltage and a value equal to or higher than the maximum permissible voltage of the electric machine. (2) One of the highly selective measurement devices can measure the amplitude corresponding to the amplitude due to the zero partial discharge in the insulation of the OS as well as the winding IIO and the winding II
After the average current of local partial discharges occurring inside O III, 0
Claim 111(
Detection method described in section 1). (3) One of the highly selective measuring devices is selected so that the frequency of the measured voltage is equal to 0** times the frequency of the measured voltage, and the frequency of the measured voltage is also quite high and the frequency - (■ Here T is two times 2. The detection method according to claim 1, wherein the average transit time of ions between the barriers is passed. (4) A capacitance measuring bridge 0III containing a plurality of resistors and capacitors is disposed in the constant diagonal side, and nine balance indicators 7 are connected in series with one selection device 6 4111L, and a plurality of current pulses or current frequency 11 [Implementing the detection method according to any one of claims (1) to (3), which can be connected in parallel with one or more highly selective measurement elements. Rounding detection device. (5) characterized in that the measuring device is highly selective with respect to the frequency of the current pulses or currents and is sensitive to the amplitude and frequency corresponding to the eclipses caused by local partial discharges within the insulation of the winding; Claim No. (4)
Detection device described in section. 16) Detection device according to claim 5, characterized in that it comprises a transformer 8 with high selectivity for the frequency of which the device for measuring the predetermined amplitude of the current pulse is comprised. ()) #Il of the patent claim in which the highly selective transformer II8 is a saturable transformer! 1. The detection device according to item (6). (8) The device for measuring the predetermined amplitude of the electric flA pulse or current is formed by a wave-high voltage needle, and the wave-high voltage needle measures the amplitude of the maximum wave height of the current pulse or current applied thereto. Detection device according to scope item (6). (9) The device for measuring the predetermined amplitude of the electric RΔrus includes a predetermined sampling period and is a nine counter preceded by a manual stage that passes the RΔrus with a threshold amplitude or more. A detection device according to any one of paragraphs (5) to ()). a@ The sampling period is 50 to 1 of the frequency of the measuring voltage.
The detection device according to claim (9), characterized in that the detection device can be set within a range of 000 police boxes. A patent claim O characterized in that the alpha force predetermined amplitude O measuring device is formed by a parallel circuit of a pulse voltage needle and a counter, which is preceded by an input stage through which pulses having an amplitude equal to or greater than a threshold value are passed.
The detection device according to any one of SS paragraphs (8) to g. (b) The detection device according to item (a) of the claims, characterized in that a threshold value adjustment device is disposed in the manual section of the counter that operates as a function of the voltage value measured by the wave height voltmeter. (b) The high selectivity 0III constant device has a cough measurement frequency that is considerably higher than the measurement frequency and considerably lower than the frequency -=- (where KT is the average transit time of the movable ion between two adjacent barriers). Claim i! is sensitive to an integer multiple of ! ! Detection device according to paragraph (4).