JP4094469B2 - Partial discharge measuring device and signal processing circuit used in the device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a partial discharge measuring instrument and a signal processing circuit used in the apparatus.
[0002]
[Prior art]
When a high-voltage rotating machine is operated for a long period of time, deterioration of the electrical insulator inside the device proceeds due to electrical, thermal, mechanical and environmental stresses. Since the deterioration of the insulator eventually leads to dielectric breakdown and equipment failure, it is extremely important to accurately detect the insulation deterioration of the equipment from the viewpoint of improving the reliability of the equipment and operation management.
[0003]
By the way, as a method of detecting the deterioration of the insulator, a pulsed partial discharge signal generated due to the deterioration of the insulation is detected by sensors installed inside and outside the device, and this detection signal is processed by hardware and software for quantification. Methods for converting and analyzing are known. When processing the waveform, the analog waveform of the detected partial discharge is converted from analog to digital and loaded into a computer for statistical analysis or waveform analysis. Such a technique is disclosed in, for example, Patent Document 1, Patent Document 2, Patent Document 3 and the like. The partial discharge pulse is directly passed through a filter, a peak hold circuit, and an analog / digital conversion circuit, and the partial discharge signal is sharpened. The initial price is recorded on a computer.
[0004]
[Patent Document 1]
JP-A-8-182257 [Patent Document 2]
JP 2001-264378 A [Patent Document 3]
Japanese Patent Laid-Open No. 2002-71742
However, in many cases, the pulse signal waveform of the partial deterioration partial discharge vibrates positively and negatively due to reflection or vibration in the propagation path. For this reason, when detecting the peak value and polarity of a pulse, the peak value and polarity may be erroneously detected due to vibrations and reflected waves generated after the pulse waveform, and the detection accuracy of the partial discharge signal is reduced. was there. In addition, if the number of samplings during signal digitization is increased to increase the detection accuracy of the signal waveform, the number of data per unit time increases, increasing the data capacity and taking too much time for transfer and analysis. there were.
[0006]
Furthermore, when detecting a partial discharge, not only a partial discharge signal but also a noise signal from the surrounding environment is often detected. When a noise signal is mixed, it is difficult to distinguish between the noise signal and the partial discharge signal. Therefore, in the insulation diagnosis, particularly in the online diagnosis, it is indispensable to remove and reduce the noise signal, which is a factor that lowers the diagnosis accuracy. For example, in Patent Document 1, countermeasures such as attaching noise filters to the switchboard side of the power cable and the power cable connection part of the device have been performed as noise countermeasures for noise removal of the measuring device. However, noise may not be attached in all cases, and noise may be mixed even if measures such as attaching a noise filter are taken. In that case, there is a problem that the partial discharge detection and the insulation diagnosis with high accuracy cannot be performed.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and its problem is that a signal processing circuit for detecting the peak value and polarity of a partial discharge signal generated by a high-voltage rotating machine and partial discharge measurement using the signal processing circuit. To provide an apparatus.
[0008]
[Means for Solving the Problems]
To achieve the above object, the invention of the signal processing circuit according to claim 1 is characterized in that a positive electrode connected in parallel detects a peak value of an electrical partial discharge signal waveform including a pulse characteristic or vibration after a pulse. A plurality of arithmetic circuits each consisting of a peak detection circuit for each of the positive and negative half-waves and an addition circuit for adding the outputs of the both peak detection circuits, and the first half of the partial discharge signal waveform Waveform shaping is performed only on a single half-wave having a wave peak value and polarity.
[0009]
According to the first aspect of the present invention, in the signal processing circuit, from the peak value detection circuit for each of the positive and negative half-waves connected in parallel, and the addition circuit for adding the outputs of the peak value detection circuit It is possible to reshape the first peak value and polarity of the partial discharge signal waveform with multiple peak values into a single half-wave by using a configuration in which multiple arithmetic circuits are connected. Is prevented, and signal detection with high accuracy is enabled.
[0010]
According to a second aspect of the present invention, in the signal processing circuit according to the first aspect, the peak value detection circuit is integrated before the signal processing circuit that digitizes the peak value and polarity of the partial discharge signal waveform. The peak value detection circuit is provided to lower the frequency of the detection signal.
[0011]
According to the second aspect of the present invention, in the signal processing circuit according to the first aspect, the peak value of the partial discharge signal waveform and the peak value of the partial discharge signal waveform are reduced by adopting an integral type peak value detection circuit. The detection accuracy can be improved by reducing the sampling error that occurs when digitizing the polarity, and the number of data can be reduced by reducing the number of sampling points per unit time by lowering the frequency, thereby improving the data transfer efficiency. Improves and shortens analysis time.
[0012]
According to a third aspect of the present invention, in the signal processing circuit according to the first or second aspect, a dead time zone is provided after the peak value of the partial discharge signal waveform is detected.
[0013]
According to the third aspect of the present invention, when the peak value of the first half wave is lower than the peak value of the second half wave in the partial discharge signal waveform having a plurality of peak values before waveform shaping. After waveform shaping, since the single half wave consisting of the first peak value and polarity of the partial discharge waveform and the single half wave consisting of the second peak value and polarity are output, after the signal detection of the first half wave By providing a dead time zone, the second half-wave is ignored to prevent erroneous detection of the peak value and polarity, thereby enabling highly accurate signal detection.
[0014]
According to a fourth aspect of the present invention, the signal processing circuit according to any one of the first to third aspects is used for processing a partial discharge signal generated in a high-voltage rotating machine. Features.
[0015]
According to the fourth aspect of the present invention, the partial discharge measuring device accurately determines the peak value and polarity of the signal waveform of the partial discharge composed of a plurality of peak values and half waves of polarity caused by vibration and reflection of the measurement circuit. By detecting it, a highly accurate insulation diagnosis is enabled.
[0016]
According to a fifth aspect of the present invention, in the signal processing circuit according to any one of the first to third aspects, when the partial discharge signal is generated, only the peak value is digitized and stored in the storage device. To do.
[0017]
According to the fifth aspect of the present invention, the partial discharge measuring device reduces the amount of data per unit time by transferring the peak value and the polarity and storing them in the storage device only when a signal is detected, thereby transferring data. The efficiency can be improved and the analysis time can be shortened, more signals can be stored in a storage device of the same capacity, and a highly accurate insulation diagnosis can be performed by analyzing a large number of data.
[0018]
The invention according to claim 6 is the partial discharge measuring device according to claim 4 or 5, wherein the partial discharge signal is detected and processed in a frequency band of 5 MHz or more.
[0019]
According to the invention described in claim 6, since the noise signal from the inverter, which is the main cause of noise, is mainly 2 MHz or less, the partial discharge signal contains high frequency components of more than 10 MHz, By detecting a signal of 5 MHz or higher using a high-pass filter in the partial discharge measuring device and performing waveform shaping processing, the inverter noise signal is removed / reduced to enable highly accurate partial discharge detection and insulation diagnosis.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of a signal processing circuit according to a first embodiment of the present invention.
As shown in the figure, the signal processing circuit 30 of the present embodiment includes two positive-polarity and negative-polarity half-wave peak value detection circuits 20A and 20B connected in parallel, and both the peak value detection circuits 20A, The first stage arithmetic circuit 27 includes an adder circuit 21 that adds the outputs of 20B, and the second stage arithmetic circuit 27 has the same configuration as the first stage arithmetic circuit 27. As shown in FIG. 5, this peak value detection circuit holds the peak value of the pulsed partial discharge waveform 1 and outputs a single pulse having a wave tail length determined by the time constant of the integration circuit in the detection circuit. . The adder circuit 21 adds the instantaneous values of the signal waveforms input to the two terminals 23 and 24. The signal processing has a configuration in which the combination of the peak value detection circuit and the addition circuit is repeated.
[0021]
2 and 3 show schematic diagrams of the input partial discharge waveform 1 and waveforms passing through the nodes of the block diagram of FIG. 1 in order to clarify the signal processing process of the first embodiment. That is, among the input vibration waveforms 1 shown in FIGS. 2 (a) and 3 (a), the first pulse waveform is the first wave, the waveform oscillated to the next reverse polarity is the second wave, and the next vibration. The half waves are named in order as the third wave. In an ideal case, the input signal has the largest peak value of the first wave of the vibration waveform, and the amplitude gradually attenuates and becomes so small that it can be ignored.
[0022]
Next, the signal processing process will be described by taking as an example the case where the first wave of the input wave 1 as shown in FIG. When the first wave having a positive peak value enters the peak value detection circuit from the node 22, the first wave is detected by the first-stage positive peak value detection circuit 20A as shown in FIG. The pulse is shaped into a positive single pulse waveform 5 having a peak value proportional to the peak value and having a longer wave tail than the vibration wave, and is output to the node 23. Subsequently, when the negative half wave of the second wave enters the circuit from the node 22, the peak value of the second wave is detected by the negative peak value detection circuit 20B of the first stage as shown in FIG. Is shaped into a negative single pulse waveform 6 having a peak value proportional to the frequency and is outputted to the node 24. Next, the positive and negative single waveforms are added by the first stage addition circuit 21. If the wave tail length of each single shaped wave is sufficiently longer than the oscillation period of the input wave, the positive first waveform wave tail is added to the negative second waveform as shown in FIG. As a result, the single pulse waveform 7 of only the first wave is output to the node 25. Next, as shown in FIGS. 2E and 2F, the output 9 of the negative peak value detection circuit is zero and positive by the positive and negative peak value detection circuits in the second stage. The peak value detection circuit has a peak value proportional to the peak value of the input waveform, and a single pulse 8 whose wave tail is longer than the vibration waveform of the input pulse in FIG. Subsequently, a positive single pulse 10 as shown in FIG. 2G is output from the node 26 by the second stage addition circuit.
[0023]
In this way, the vibration waveform in which the first wave is positive has a peak value proportional to the peak value of the first wave by the signal processing circuit shown in FIG. 1, and the wave tail does not vibrate and is a long waveform. To be shaped.
[0024]
3A to 3G show an outline of waveform shaping when the first wave is negative. In this case, since the first wave is negative in FIG. 2 when the first wave is positive, the subsequent waveform processing can be performed by processing the positive wave of FIG. 2 as a negative wave, and as a result, FIG. Although (a)-(g) are obtained, since the description overlaps, it abbreviate | omits.
However, depending on the measurement target device and measurement conditions, unlike the case of FIG. 2A, the peak value of the second wave of the input wave may be larger than the peak value of the first wave.
[0025]
FIG. 4 shows a waveform processing process when the peak value of the second wave is large. When a waveform 1 with a large peak value of the second wave is input as shown in FIG. 4A, the output waveform of the first stage adder circuit is two positive and negative as shown in FIG. The waveform 7 has a peak value. However, it can be formed into a single pulse 10 as shown in FIG. 4G by the peak value detection circuit and the addition circuit in the second stage.
[0026]
As described above, the first stage includes two positive and negative half-wave peak value detection circuits connected in parallel and an addition circuit (waveform calculation circuit) for adding the outputs of the both peak value detection circuits. By connecting a plurality of eye arithmetic circuits and their arithmetic circuits, the first half-wave peak value and polarity of a single discharge waveform having a large vibration of either the first wave or the second wave peak value are obtained. It is possible to provide a signal processing circuit that can shape the waveform to only one half wave and accurately detect the magnitude and polarity of the partial discharge pulse.
[0027]
FIG. 5 is a flowchart for explaining signal processing according to the second embodiment of the present invention.
In this embodiment of FIG. 5, in the peak value detection circuit in the signal processing circuit 30 of FIG. 1, the partial discharge signal 1 input by adopting the integration type detection circuit is reduced in frequency 2 in this way, 3 is a flowchart of signal processing in which a peak value is detected by a digital conversion circuit 31 and stored in a storage circuit 32. FIG. That is, in FIG. 5, a single pulse waveform 2 having a wave tail length determined by the time constant of the integration circuit is output by integrating the pulse characteristic input to the peak value detection circuit and the partial discharge waveform 1 oscillating after the pulse. To do.
[0028]
FIG. 6 is a diagram showing digitization (sampling) of a vibration wave and a single pulse wave having a long wave tail length.
As shown in FIG. 6, by shaping the input wave 1 into a waveform 3 having a long wave tail length and sampling, the peak value error due to sampling is reduced. In addition, since the number of samplings required for a waveform with a long wave tail length is small, the amount of data stored can be reduced, and efficient data transfer can be achieved. Here, 2 is the peak value of the first wave of the input wave, 4 is the peak value of the waveform after shaping, 5 is the sampling time, 6 is the waveform sampling value, 7 is the sampling value error, and 8 is the voltage 0 level. It is.
[0029]
As described above, by adopting the integral type peak value detection circuit in the multistage peak value detection circuit of FIG. 1, the detection error of the peak value and polarity of the partial discharge waveform having vibration is reduced, and the data storage amount is reduced. In addition, a signal processing circuit capable of improving data transfer efficiency can be provided.
[0030]
FIG. 7 is a flowchart showing a partial discharge detection method according to the third embodiment of the present invention.
As shown in FIG. 7A, the detection dead time zone 34 is adopted from the multi-stage peak value detection circuit 30 shown in FIG. 1 and the analog / digital conversion circuit 31 shown in FIG. 4 to the sampling value peak value detection circuit 33. And the partial discharge detection method memorize | stored in the memory | storage device 32 is shown.
[0031]
Further, as shown in FIG. 7B, the sampling value peak detection circuit 33 stores the peak value of the first half wave (point 3) as a dead zone for a certain period of time after it is stored in the storage device 32. Stop importing to. Here, 2 is a signal waveform, 3 is a sampling value, 4 is a detection dead time, and 5 is a voltage 0 level.
[0032]
As an application example, as shown in the waveform of FIG. 8A, the peak value of the second wave is the first wave in the partial discharge waveform having the pulse property and the vibration after the pulse depending on the measurement target machine and the measurement conditions. A waveform that is larger than twice the peak value of may occur. At this time, the signal processing process is the same as in FIG. 2, but the output waveform of the signal processing circuit shown in FIG. 1 is a pulse having the same polarity as the first wave of the input vibration waveform 10 as shown in FIG. In addition, pulse waveforms having different polarities for the second wave are also output. Further, when detecting the peak value of the waveform shown in FIG. 8 (g), by providing the detection dead time 11 after detecting the peak value of the first wave, the first wave, the polarity and the peak value are determined. It is possible to prevent erroneous detection of different second waves and third waves.
[0033]
In this way, by adopting the detection dead time zone in the analog / digital conversion circuit attached to the subsequent stage of the multi-stage peak value detection circuit, it is possible to prevent erroneous detection of peak values and to accurately detect partial discharge pulses. A circuit for detecting the size and polarity of the signal can be provided. In addition, by capturing only the peak value of partial discharge pulses into the storage device, the number of data per unit time is reduced, the data transfer efficiency is improved, and the analysis time is shortened. Since data can be accumulated, a large number of pulse data can be acquired by a single data transfer from a storage device, and a signal processing circuit capable of acquiring partial discharge data with high accuracy and efficiency can be provided. The duration of the vibration of the waveform varies depending on the device, but 5 to 15 μs is preferable as the dead time zone.
[0034]
FIG. 9 is a block diagram of a partial discharge detection device according to a fourth embodiment of the present invention.
As shown in the figure, the present embodiment uses the signal processing circuit of the first to third embodiments. That is, the configuration of this embodiment includes a high-pass filter circuit 35 having a cutoff frequency of 5 MHz in the previous stage, as shown in a fifth embodiment to be described later, and the multistage peak value detection circuit of the first to third embodiments and It comprises an arithmetic circuit 27, an analog / digital conversion circuit 31, a peak value detection circuit 33 provided with a dead time zone 34, and a storage device 32. A personal computer 37 can be connected to control the partial discharge measuring instrument and acquire data. Reference numeral 36 denotes an amplifier.
[0035]
FIG. 10 is a diagram showing a partial discharge measuring method in which the signal processing, analog / digital conversion circuit, and detection dead time zone of the first to third embodiments are adopted in the partial discharge measuring instrument of FIG.
[0036]
Electrical, optical, and acoustic signals of pulsed partial discharge generated inside the high-voltage electrical equipment are detected by a sensor 39 attached inside or outside the equipment 38, and the electrical signal is taken out or converted into an electrical signal. The partial discharge measuring device 40 performs signal processing. 41 is a power supply wire, and 42 is a ground point.
[0037]
FIG. 11A shows a positive partial discharge pulse waveform 1 detected by a high-frequency current transformer attached to a high voltage line terminal of the electric motor, and FIG. 11B shows a portion of FIG. It is the waveform 2 after the discharge pulse is waveform-shaped by the peak value detection and addition circuit in the partial discharge measuring device.
[0038]
FIGS. 11A and 11B are observed at the same time. One scale on the time axis in FIG. 11A is 0.05 μs, and one scale on the time axis in FIG. 11B is 0.2 μs. The time for the single pulse in FIG. 11 (b) to rise is slower than the partial discharge pulse in FIG. 11 (a), but this is due to a time delay due to signal processing.
[0039]
As shown in FIGS. 11A and 11B, the pulsed vibration waveform of the partial discharge signal is converted into a single pulse having the same polarity as the first wave of the vibration waveform and a long wave tail by the partial discharge measurement device. Can be shaped. As shown in the second embodiment, by digitizing the shaped waveform, it is possible to reduce the error in capturing the polarity and peak value of the partial discharge signal. Further, as shown in the third embodiment, after detecting the peak value, a dead time is set and only the peak value is taken into the storage device, thereby reducing the data amount per unit time and improving the data transfer efficiency and analyzing time. Can be shortened, and a large number of partial discharge data can be acquired and analyzed in a single measurement, enabling accurate diagnosis.
[0040]
As described above, by providing the partial discharge measuring device with the signal processing, the analog / digital conversion circuit, and the signal processing circuit having the detection dead time zone, it is possible to provide a partial discharge measuring device capable of accurate detection and diagnosis.
[0041]
FIG. 12 is a diagram showing a detection frequency band of the partial discharge measuring apparatus according to the fifth embodiment of the present invention. That is, the detection frequency band of the partial discharge measuring device is shown so as to remove the noise signal by detecting and processing the electric pulse in the frequency band of 5 MHz or more.
[0042]
FIG. 13 is a diagram showing a measurement waveform example (negative polarity) of inverter noise which is a main factor of external noise.
Although different depending on the device, the inverter noise waveform 1 is determined by the peak value 2 and the rise time 4 of the waveform as defined in FIG. 3 is the 0 level. Usually, the rise time of the first wave is about 0.4 μs, and the frequency component is mainly several MHz or less.
On the other hand, as shown in FIG. 11A, the rise time of the first wave of the partial discharge signal is about 0.01 μs or less (several ns) and includes a frequency component of several tens of MHz.
[0043]
Therefore, if the detection frequency band of the detector is set to 5 MHz or more, the peak value of low-frequency inverter noise can be reduced to ½ or less (when a high-pass filter of −6 dB / oct is employed). For this reason, as shown in FIG. 9, a high-pass filter 35 having a cutoff frequency of 5 MHz is provided in the signal processing circuit in the partial discharge measuring apparatus shown in the fourth embodiment.
[0044]
FIG. 15 is a diagram illustrating an inverter noise and partial discharge signal detection test method of a partial discharge measuring device as an example of partial discharge detection.
In the figure, 43 is an AC power source, 44 is a transformer, 45 is a model motor bar coil, 46 is a partial discharge measuring device, 47 is a coupling capacitor, 48 is a detection resistor, 49 is an inverter, and 50 is a grounding point. Here, a partial discharge is generated by applying a voltage of 5 kV to a model coil 45 simulating a stator coil of an electric motor. At the same time, the inverter 49 is driven to generate noise. The inverter noise is considered to enter the partial discharge measuring device 46 through the power line and the ground line.
[0045]
FIG. 16 is a diagram showing a response of the measuring device when partial discharge or inverter noise is input. FIG. 16A shows a case where a partial discharge signal is input to the partial discharge measuring device. FIG. It shows the response of the measuring device when inverter noise is input to the measuring device. Here, 1 is an input partial discharge signal to the partial discharge measurement device, 2 is an output response signal of the partial discharge measurement device, 3 is an input noise signal to the partial discharge measurement device, 4 is an output response signal of the partial discharge measurement device, 5 is a time axis and 6 is a voltage axis.
[0046]
As shown in FIG. 16, it can be seen that the partial discharge measuring device does not respond to the inverter noise but responds to the partial discharge signal. Thereby, only the partial discharge signal can be detected.
[0047]
Thus, in the partial discharge measuring apparatus having the signal detection circuit of the first to third embodiments, the noise signal is removed and reduced by detecting and processing the partial discharge signal having a cutoff frequency of 5 MHz or more. It is possible to provide a partial discharge measuring device with high detection accuracy and diagnostic accuracy.
[0048]
【The invention's effect】
As described above, the signal processing circuit according to the present invention includes a multi-stage signal processing circuit including a peak value detection circuit and an addition circuit, a peak value detection circuit using an integration circuit, and a dead time zone after the peak value is detected. By providing this, the detection accuracy of the partial discharge signal can be improved.
[0049]
In addition, the partial discharge measuring apparatus according to the present invention employs the above signal processing circuit and a detection frequency band of 5 MHz or more, thereby performing noise removal / reduction and accurately detecting a large number of partial discharge signals for insulation diagnosis. be able to. Furthermore, by using a signal processing circuit for this device, it becomes possible to detect partial discharge with high accuracy and insulation diagnosis, which greatly improves the formulation of an appropriate repair plan for high-voltage rotating machines and the improvement of reliability. Can contribute.
[Brief description of the drawings]
FIG. 1 is a block diagram of a signal processing circuit according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a signal processing process of FIG. 1;
3 is a diagram showing another signal processing process of FIG. 1. FIG.
FIG. 4 is a diagram showing still another signal processing process of FIG. 1;
FIG. 5 is a flowchart of signal processing according to the second embodiment of the present invention.
6 is a diagram showing digitization of the input wave of FIG. 5;
FIG. 7 is a flowchart of signal processing according to the third embodiment of the present invention.
FIG. 8 is a diagram showing a signal processing process of FIG. 7;
FIG. 9 is a block diagram of a partial discharge detection device according to a fourth embodiment of the present invention.
10 is a diagram showing a measurement example using the partial discharge detection device of FIG. 9;
FIG. 11 is a diagram showing a signal-processed waveform according to the fourth embodiment.
FIG. 12 is a conceptual diagram showing a detection frequency band according to a fifth embodiment of the present invention.
FIG. 13 is a measurement waveform diagram of inverter noise used in FIG. 12;
FIG. 14 is a diagram defining an inverter noise waveform used in FIG.
15 is a circuit diagram showing a partial discharge signal detection test method in FIG. 12. FIG.
16 is a diagram showing a response of the measuring device in FIG.
[Explanation of symbols]
20A, 20B ... Peak value detection circuit, 21 ... Adder circuit, 22, 23, 24, 25, 26 ... Node, 27 ... Arithmetic circuit, 30 ... Signal processing circuit, 31 ... Analog / digital conversion circuit, 32 ... Memory circuit 33 ... Sampling value peak value detection circuit 34 ... Detection dead time zone 35 ... High pass filter circuit 36 ... Amplifier 37 ... Personal computer 38 ... Device 39 ... Sensor 40 ... Partial discharge measuring device 41 ... Power Power supply wire, 42 ... grounding point, 43 ... AC power supply, 44 ... transformer, 45 ... model electric motor bar coil, 46 ... partial discharge measuring device, 47 ... coupling capacitor, 48 ... detection resistor, 49 ... inverter, 50 ... grounding point .

Claims (6)

A peak value detection circuit for positive and negative half-waves connected in parallel to detect the peak value of an electric partial discharge signal waveform including vibration after pulse or pulse, and the peak value detection circuit A plurality of arithmetic circuits each including an adder circuit for adding circuit outputs are connected, and only a single half-wave having the first half-wave peak value and polarity of the partial discharge signal waveform is shaped. Signal processing circuit. The signal processing circuit according to claim 1, wherein the peak value detection circuit is provided with an integration type peak value detection circuit before the signal processing circuit that digitizes the peak value and polarity of the partial discharge signal waveform, A signal processing circuit characterized by lowering the frequency of a detection signal. 3. The signal processing circuit according to claim 1, wherein a dead time zone is provided after the peak value of the partial discharge signal waveform is detected. 4. A partial discharge measuring apparatus using the signal processing circuit according to claim 1 for processing a partial discharge signal generated in a high-voltage rotating machine. 4. A partial discharge measuring apparatus using the signal processing circuit according to claim 1, wherein only a peak value is digitized and taken into a storage device when a partial discharge signal is generated. Discharge measuring device. 6. The partial discharge measuring apparatus according to claim 4, wherein the partial discharge signal is detected and processed in a frequency band of 5 MHz or more.

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