JP2010164453A - Device and method for monitoring partial discharge generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for monitoring partial discharge generation, reducing a data quantity of partial discharge in a charge lifetime test by a charge sample for evaluating insulation performance, and reducing a storage capacity for storing partial discharge data. <P>SOLUTION: The device 2 for monitoring partial discharge generation to detect, measure and monitor partial discharge generated in the charge sample 3 by a partial discharge detection device 6 in the charge lifetime test performed by applying an AC test voltage to the charge sample 3 includes: an input means 8 for inputting a discharge signal S of the partial discharge from the charge sample 3 detected by the partial discharge detection device 6; a detection means 9 for detecting polarity inversion of a voltage waveform of a test voltage inputted through a potential divider 5; and a determination-output means 11 for determining at every half period of the test voltage whether a signal level of the inputted discharge signal S exceeds a prescribed threshold P or not, and outputting in one bit, a determination result on existence of discharge at every half period. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a partial discharge generation monitoring apparatus and method for measuring and monitoring a partial discharge of an applied sample in an applied life test for evaluating the insulation performance of an electric device or its insulating material.

  Electrical equipment uses electrical insulators, and electrical, mechanical, and thermal stresses are applied during operation, which can cause deterioration of the insulation and eventually cause failure of the electrical equipment. is there. In order to ensure the reliability of electrical equipment, it is necessary to grasp the insulation performance of electrical equipment.

  One of the evaluations of the insulation performance is an electric life test in which a predetermined voltage is continuously applied to an electrical device or its insulating material over a long period of time to measure and evaluate the time until dielectric breakdown. It is known that when a voltage is applied under certain conditions, a partial discharge occurs near the insulator, and this partial discharge contributes to the deterioration of the insulator. Therefore, it is important to grasp the state of occurrence of partial discharge in evaluating the performance of the insulator and examining the degradation mechanism in the electric charging life test.

  On the other hand, an oscilloscope is generally used for measuring the signal waveform. However, since the discharge signal of the partial discharge in the charging life test is in the frequency band of several kHz to GHz, in order to measure the partial discharge waveform It is necessary to raise the sampling frequency to about the discharge frequency or higher. For this reason, since the amount of data is enormous in order to store the partial discharge waveform, not only a large amount of storage capacity is required, but also a lot of time is required for data processing and transmission.

  In such a situation, when measuring a partial discharge waveform, there is a method of reducing the amount of data by holding the positive and negative peak values to suppress the number of sampling points (see, for example, Patent Document 1). This method is suitable for storing and analyzing partial discharge waveforms. However, it is necessary to continue to store data for a long time in order to grasp the state of occurrence of partial discharge in the electric charging life test.

JP 2008-39606 A

  The present invention has been made in view of the above situation, and its purpose is to measure a partial discharge generated in a charged sample in a charged life test for evaluating the insulation performance of electrical equipment and the like. It is an object of the present invention to provide a partial discharge occurrence monitoring apparatus and method capable of reducing the amount of partial discharge data obtained by the above method and reducing the storage capacity of a storage device for storing partial discharge data.

  The present invention achieves the above object, and in the partial discharge generation monitoring apparatus and monitoring method of the present invention, the partial discharge generation monitoring apparatus applies an AC test voltage to the applied sample and performs an applied life test. A partial discharge generation monitoring device that detects, measures, and monitors a partial discharge generated in the charged sample by a partial discharge detection device, the portion from the charged sample detected by the partial discharge detection device Input means for inputting a discharge signal of the discharge, detection means for detecting polarity reversal of the voltage waveform of the test voltage input through a voltage divider, and the signal level of the input discharge signal has exceeded a predetermined threshold value A determination / output means for performing determination of whether or not the discharge voltage is generated every half cycle of the test voltage and outputting a determination result as to whether or not there is a discharge for each half cycle in one bit. Is.

  The partial discharge occurrence monitoring method is a partial discharge occurrence monitoring method in an electric charge life test in which a partial discharge generated by applying an AC test voltage to a charged sample is detected, measured, and monitored. After detecting the signal level of the discharge signal accompanying the partial discharge of the sample and the polarity reversal of the voltage waveform of the test voltage, it is determined whether or not the signal level exceeds a predetermined threshold. It is a method characterized in that it is performed every cycle and monitoring is performed by counting the presence or absence of discharge every half cycle.

  According to the present invention, it is possible to reduce the amount of data of partial discharge in an electric charging life test designed to detect partial discharge generated in an electric charge sample, and to store data even in a long-term test. Thus, the storage capacity of the storage device can be reduced, and the device has a simple configuration, so that the storage device can be inexpensive.

1 is a configuration diagram of a partial discharge generation monitoring system according to a first embodiment of the present invention. It is a circuit diagram for demonstrating the partial discharge generation | occurrence | production monitoring system which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the control flow in the 1st Embodiment of this invention. It is a figure which shows the output data of the input signal waveform and discharge determination in the 1st Embodiment of this invention. It is a figure which shows the number of the discharge determination data output in the 1st Embodiment of this invention. It is a block diagram of the partial discharge generation | occurrence | production monitoring system which concerns on the 2nd Embodiment of this invention. It is a circuit diagram for demonstrating the partial discharge generation | occurrence | production monitoring system which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the control flow in the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a first embodiment will be described with reference to FIGS. FIG. 1 is a configuration diagram of a partial discharge generation monitoring system including a partial discharge generation monitoring device, FIG. 2 is a circuit diagram of the partial discharge generation monitoring system including a partial discharge generation monitoring device, and FIG. 3 is a partial discharge generation. 4 is a flowchart showing a control flow in the monitoring device, FIG. 4 is a diagram showing an input signal waveform of the partial discharge generation monitoring device and output data of discharge determination, and FIG. 5 is a discharge determination data output from the partial discharge generation monitoring device. FIG.

  1 to 5, reference numeral 1 denotes a partial discharge generation monitoring system, which includes a partial discharge generation monitoring device 2 and is configured to perform an electrical charging life test for evaluating the insulation performance of an electrical device or its insulating material. ing. As the applied sample 3 to be applied to the applied life test, for example, a twisted pair sample simulating partial discharge generated between windings in a stator winding of a rotating electric machine is used. Twisted pair specimens are two twisted conductors covered with enamel coating used for stator windings. They are easy to manufacture, and multiple specimens can be prepared, so they are often used for insulation performance evaluation tests. Is done.

  The partial discharge generation monitoring system 1 divides and outputs a power supply 4 for applying a predetermined AC test voltage to the applied voltage sample 3 and a test voltage applied to the applied voltage sample 3 in addition to the partial discharge generation monitoring device 2. A partial discharge detector 6 that outputs a discharge signal S by detecting a discharge current that flows through the voltage divider (VT) 5, a partial discharge generated in the voltage applied sample 3, and a partial discharge occurrence monitoring device 2 is provided with an external storage device (PC) 7 for storing and storing partial discharge data output and transmitted at predetermined intervals.

  For the partial discharge generation monitoring device 2, the input means 8 for inputting the discharge signal S of the applied voltage sample 3 detected by the partial discharge detecting device 6 and the AC test voltage applied to the applied sample 3 from the power source 4 are divided. And detecting means 9 for detecting the polarity reversal of the voltage waveform of the test voltage by obtaining the output of the voltage divider 5 that is stepped down for measurement, and the signal of the input discharge signal S based on the outputs of the input means 8 and the detecting means 9 It is determined whether or not the level exceeds a predetermined signal level threshold P set in advance in the setting means 10 every half cycle of the test voltage. And a determination / output unit 11 for outputting the result in 1 bit.

  In addition, the partial discharge occurrence monitoring device 2 displays the determination result of the presence or absence of discharge on a display unit (not shown), for example, the cumulative number of discharge determination signals with respect to a predetermined elapsed time, and can monitor the occurrence of partial discharge. ing. Furthermore, the partial discharge occurrence monitoring device 2 is provided with an in-device memory 12 so that data on the determination result of the presence / absence of discharge can be temporarily stored in the in-device memory 12. It is possible to confirm the measurement result by transmitting to the external storage device 7 via serial communication at a predetermined interval set in advance via serial communication, storing, saving, and displaying on the display unit. It can be done.

  The partial discharge detection device 6 that detects partial discharge includes a high frequency transformer (CT) 13 that detects a discharge current due to partial discharge, and a filter that removes a noise signal from the output of the high frequency transformer 13 and outputs a discharge signal S. 14. As the partial discharge detection device 6 for detecting partial discharge, in addition to the above-described one, a photomultiplier tube for detecting discharge light due to partial discharge, an electromagnetic antenna for detecting electromagnetic waves accompanying partial discharge, a discharge charge, etc. It is also possible to use a coupling capacitor or the like for detecting.

  And the control flow of the measurement and monitoring of partial discharge of the partial discharge generation | occurrence | production monitoring apparatus 2 comprised as mentioned above is as showing below, and it demonstrates with reference to FIG.

  In the first step S1, the count value of the counter C provided to count and store the number of discharge determination signals in the memory 12 in the apparatus is set to “0”. In the subsequent second step S2, a discharge determination flag F is provided, and “L” (Low) is first written and initialized. The discharge determination flag F is a flag that stores whether the magnitude of the read discharge signal is “H” (High), which is larger than the threshold P of the signal level, or “L” below the threshold P. It is.

  In the next third step S3, the discharge signal S input from the partial discharge detector 6 is read, and the process proceeds to the fourth step S4. The reading interval of the discharge signal S is set to a time shorter than ½ of the pulse width of the discharge waveform when the partial discharge is generated in order to prevent a partial discharge detection failure.

  In the fourth step S4, it is determined whether or not the level of the read discharge signal S exceeds a preset signal level threshold value P. The threshold value P is set slightly larger than the noise level of the discharge signal S. Further, since the noise level changes depending on the test environment, the test apparatus, and the measurement sample (electrically charged sample 3), the discharge determination threshold value P is changed to the setting means 10 configured so that the threshold value can be variably set according to the noise level. By setting, the accuracy of discharge determination can be increased.

  When the level of the discharge signal S exceeds the preset threshold value P (fourth step S4: YES), the process proceeds to the fifth step S5. In the fifth step S5, since the level of the discharge signal S exceeds the threshold value P, the determination result “H” is written in the discharge determination flag F, and the process proceeds to the sixth step S6. When the level of the discharge signal S is equal to or lower than the threshold value P (fourth step S4: NO), the process proceeds to the sixth step S6.

  In the sixth step S6, the voltage level obtained by stepping down the test voltage input from the voltage divider 5 is read, and then the process proceeds to the seventh step S7. The interval at which the voltage is read here is, for example, the same as the interval at which the discharge voltage is read. However, the discharge signal S of the partial discharge is in the frequency band from several kHz to GHz, and the interval at which this discharge signal S is read is extremely short with respect to the voltage waveform. Therefore, since an interval of the order of several hundreds μs is sufficient for the determination of polarity reversal, the reading interval of the discharge signal S is determined until the reading interval of the voltage is increased and the reading interval of the voltage is increased. Control may be performed so as to repeat the fifth step S5.

  In the seventh step S7, it is determined whether or not the polarity of the read voltage is inverted. Here, for example, the discharge determination result is stored for each voltage half cycle. Therefore, the discharge determination result is stored once each when the positive and negative portions of the voltage waveform, that is, when the polarity of the voltage is reversed. The half cycle may be set appropriately by shifting the phase. However, since the frequency of partial discharge is low near the voltage of 0 [V], the polarity reversal point at which the voltage becomes 0 [V] is set. It is desirable to be a boundary for discharge determination. If the polarity of the voltage is reversed (seventh step S7: YES), the process proceeds to the eighth step S8. If the polarity of the voltage is not reversed (seventh step S7: NO), the third step Returning to S3, the next discharge signal S is read, and the discharge determination is repeated.

  In the eighth step S8, it is determined whether or not the content stored in the discharge determination flag F is “H”. When the discharge determination flag F is “H” (eighth step S8: YES), the process proceeds to the ninth a step S9a, “1” is written and stored in the memory 12 as the discharge result, and the process proceeds to the tenth step S10. . When the discharge determination flag F is “L” (eighth step S8: NO), the process proceeds to the ninth b step S9b, “0” is written and stored in the memory 12 as the discharge result, and the process proceeds to the tenth step S10. .

  In the tenth step S10, "1" is added to the count value of the counter C which counts and stores the number of discharge determination signals in the memory 12, and the process proceeds to the eleventh step S11. In the eleventh step S11, it is determined whether or not the count value of the counter C is equal to or greater than a preset count value threshold value N. If it is determined that the count value of the counter C is equal to or greater than the threshold value N (first step). 11 step S11: YES), it progresses to 12th step S12.

  In the following twelfth step S12, all data stored in the in-device memory 12 is transmitted to the external storage device 7 by serial communication. And after transmitting, it progresses to 13th step S13. On the other hand, when it is determined that the count value of the counter C is less than the threshold value N (11th step S11: NO), the process returns to the second step S2 to determine the partial discharge in the next voltage half cycle. Repeat steps.

  As described above, when the predetermined amount of data is accumulated in the memory 12 in the twelfth step S12, that is, when the count value exceeds the threshold value N, the data is periodically transferred, so that the capacity of the in-device memory 12 is increased. Can be reduced. In the electric charging life test, the discharge is constantly monitored for a long period of time, and the discharge determination signal is continuously stored in the memory 12. Therefore, by transferring the data in the memory 12 to the outside, the storage capacity of the in-device memory 12 is increased. It is possible to save, and even during the test, it is possible to confirm the state of occurrence of the discharge so far even outside. The threshold value N of the count value is set in advance to an appropriate value in accordance with the storage capacity of the in-device memory 12 and the confirmation interval.

  In this embodiment, since 1 bit is output in a half cycle of the test voltage, the amount of data output in the discharge monitoring with respect to the measurement time is as shown in FIG. That is, when the frequency of the test voltage is 60 Hz, the data amount is 54 kbytes in one hour and 473 Mbytes in one year. Therefore, in the partial discharge occurrence monitoring for a long time, discharge data can be obtained over the entire period while suppressing the data amount. In this embodiment, data is transmitted at regular intervals using the counter C. However, the data may be transmitted only when there is a transmission instruction without using the counter C.

  In the thirteenth step S13, when an instruction to end the measurement is input (13th step S13: YES), the measurement ends. At the end of this measurement, since all data stored in the internal memory 12 in the previous twelfth step S12 has been transmitted to the external storage device 7, no data is stored in the internal memory 12 become. If no measurement end instruction is input (13th step S13: NO), the process returns to the first step S1, the count value of the counter C is returned to "0", and the subsequent steps are executed again. Continue measuring.

  With the configuration as described above, the presence or absence of partial discharge is stored in one bit every half voltage period, so that partial discharge generation can be monitored while suppressing the amount of data even in a long-term charging life test. It can be carried out. Further, by reducing the amount of data, the memory capacity of the in-device memory 12 and the external storage device 7 can be reduced, and the device configuration can be simplified by limiting the function to outputting the presence or absence of discharge. Therefore, the apparatus can be made inexpensive. Furthermore, when detecting or measuring a partial discharge, since the discharge signal S from the partial discharge detection device 6 may contain noise, a threshold of a signal level when performing discharge determination according to the noise level. By setting P appropriately, partial discharge can be measured and monitored with accuracy suitable for the measurement environment.

  Next, a second embodiment will be described with reference to FIGS. FIG. 6 is a configuration diagram of a partial discharge generation monitoring system including a partial discharge generation monitoring device, FIG. 7 is a circuit diagram of the partial discharge generation monitoring system including a partial discharge generation monitoring device, and FIG. 8 is a partial discharge generation. It is a flowchart which shows the control flow in a monitoring apparatus. In addition, the same code | symbol is attached | subjected to the same part as 1st Embodiment, description is abbreviate | omitted, and the structure of this embodiment different from 1st Embodiment is demonstrated.

  6 to 8, reference numeral 21 denotes a partial discharge generation monitoring system, which includes a partial discharge generation monitoring device 22, and performs an electric charging life test for evaluating the insulation performance of an electric device or its insulating material, for example, a rotating electric machine. This is performed by using a charged sample 3 of a twisted pair sample that simulates a partial discharge generated between windings of the stator winding. Further, the partial discharge generation monitoring system 21 includes a power source 4, a voltage divider (VT) 5 that divides and outputs an AC test voltage, in addition to the partial discharge generation monitoring device 22, and a partial discharge generated in the applied sample 3. And a partial discharge detector 6 that outputs a discharge signal S, and an external storage device (PC) 7 that stores and stores partial discharge data output and transmitted from the partial discharge generation monitoring device 22 at predetermined intervals. It is configured.

  Then, the partial discharge generation monitoring device 22 receives the AC test voltage applied to the applied sample 3 from the power supply 4 and the input means 8 for inputting the discharge signal S of the applied sample 3 detected by the partial discharge detecting device 6. The detection means 23 for dividing the voltage and obtaining the output of the voltage divider 5 that drops the voltage for measurement to detect the voltage waveform of the test voltage and the polarity inversion of the voltage waveform, and the input discharge based on the outputs of the input means 8 and the detection means 23 It is determined whether or not the signal level of the signal S exceeds a predetermined signal level threshold P preset in the setting means 10 every half cycle of the test voltage. A determination / output means 24 is provided for determining whether or not there is a discharge, outputting the result in one bit, and outputting the peak value of the voltage waveform in a half cycle when it is determined that there is a discharge.

  Further, the partial discharge occurrence monitoring device 22 has a determination result of whether or not there is a discharge on a display unit (not shown), for example, the cumulative number of discharge determination signals for a predetermined elapsed time or a half cycle of the test voltage when it is determined that partial discharge has occurred. The status of the peak value of each voltage waveform is displayed, and the occurrence of partial discharge can be monitored. Further, the partial discharge occurrence monitoring device 22 is provided with an in-device memory 12, and the determination result of the presence / absence of discharge, the peak value of the voltage waveform in the half cycle when it is determined that there is discharge, etc. are temporarily stored in the in-device memory 12. The stored determination result is transmitted by serial communication to the external storage device 7 via the transmission path of the determination / output means 24 at a predetermined interval set in advance, stored and saved, The measurement result can be confirmed by displaying on the display unit.

  And the control flow of the measurement and monitoring of partial discharge of the partial discharge generation | occurrence | production monitoring apparatus 22 comprised as mentioned above is as showing below, and it demonstrates with reference to FIG.

  In the first step S21, the count value of the counter C provided to count and store the number of discharge determination signals in the memory 12 in the apparatus is set to “0”. In the subsequent second step S22, a discharge determination flag F is provided, and first, “L” (Low) is written and initialized. In the third step S23, the voltage peak V is provided as the maximum value of the voltage amplitude, and the value is written as “0”.

  In the next fourth step S24, the discharge signal S input from the partial discharge detector 6 is read, and the process proceeds to the fifth step S25. The reading interval of the discharge signal S is set to a time shorter than ½ of the pulse width of the discharge waveform when the partial discharge is generated in order to prevent a partial discharge detection failure.

  In the fifth step S25, it is determined whether or not the level of the read discharge signal S exceeds a preset threshold P of the signal level. When the level of the discharge signal S exceeds the preset threshold value P (fifth step S25: YES), the process proceeds to the sixth step S26. In the sixth step S26, since the level of the discharge signal S exceeds the threshold value P, the determination result “H” is written in the discharge determination flag F, and the process proceeds to the seventh step S27. If the level of the discharge signal S is equal to or lower than the threshold value P (fifth step S25: NO), the process proceeds to the seventh step S27.

  In the seventh step S27, the voltage level obtained by stepping down the test voltage input from the voltage divider 5 is read, and the process proceeds to the eighth step S28. In the following eighth step S28, it is determined whether or not the absolute value of the read voltage exceeds the voltage peak V. If the absolute value of the read voltage exceeds the written voltage peak V (eighth step S28: YES), the process proceeds to the ninth step S29, the absolute value of the read voltage is written to the voltage peak V, Proceed to step S30. When the absolute value of the read voltage does not exceed the written voltage peak V (eighth step S28: NO), the process proceeds to the tenth step S30.

  In the tenth step S30, it is determined whether or not the polarity of the read voltage is inverted. If the polarity of the voltage is reversed (10th step S30: YES), the process proceeds to the 11th step S31. If the polarity of the voltage is not reversed (10th step S30: NO), the fourth step is performed. Returning to S24, the next discharge signal S is read, and the discharge determination is repeated.

  In an eleventh step S31, it is determined whether or not the content stored in the discharge determination flag F is “H”. If the discharge determination flag F is “H” (11th step S31: YES), the process proceeds to the 12th a step S32a, and “1” is written and stored in the memory 12 as the discharge result, and further the 13th step S33. Then, the voltage peak V in which the absolute value of the voltage read into the memory 12 is written is written and stored in the memory 12, and the process proceeds to the 14th step S34. On the other hand, when the discharge determination flag F is “L” (11th step S31: NO), the process proceeds to the 12b step S32b, “0” is written and stored in the memory 12 as the discharge result, and the process proceeds to the 14th step S34.

  In the fourteenth step S34, "1" is added to the count value of the counter C which counts and stores the number of discharge determination signals in the memory 12, and the process proceeds to the fifteenth step S35. In the present embodiment, since the voltage value is also stored simultaneously only when there is a discharge, the counter C and the amount of data stored in the memory 12 do not correspond. That is, instead of the amount of data, the data is transmitted to the outside with a constant time interval. For this reason, when setting a threshold value by the data amount, it is good also as control which adds the number of bits memorize | stored to the count value of the counter C, and integrates data amount. For example, when a 2-byte integer is used, the amount of data necessary to store the voltage value once is 16 bits.

  In the fifteenth step S35, it is determined whether or not the count value of the counter C is equal to or greater than a preset count value threshold value N. If it is determined that the count value of the counter C is equal to or greater than the threshold value N (first step). 15 step S35: YES), the process proceeds to the 16th step S36.

  In the following 16th step S36, all the data stored in the in-device memory 12 are transmitted to the external storage device 7 by serial communication. And after transmitting, it progresses to 17th step S37. On the other hand, when it is determined that the count value of the counter C is less than the threshold value N (15th step S35: NO), the process returns to the second step S22 to determine partial discharge in the next half voltage cycle. Repeat steps.

  In the 17th step S37, when an instruction to end the measurement is input (17th step S37: YES), the measurement is ended. If no measurement end instruction is input (17th step S37: NO), the process returns to the first step S21, the count value of the counter C is returned to "0", and the subsequent steps are executed again. Continue measuring.

  With the above configuration, the presence or absence of partial discharge is stored in one bit for each half voltage period, and the voltage peak value of the half period is stored simultaneously only when there is a discharge, so that it is possible to apply power for a long period of time. In the life test, the occurrence of partial discharge can be monitored while suppressing the amount of data, and the voltage at the time of discharge can be confirmed. The history of changes due to voltage fluctuations in the power supply system is clarified, and the reliability of the electrical charging life test can be improved. Further, the required memory capacity can be reduced by reducing the amount of data, and the apparatus configuration can be simplified, so that the apparatus can be made inexpensive.

DESCRIPTION OF SYMBOLS 1,21 ... Partial discharge generation | occurrence | production monitoring system 2,22 ... Partial discharge generation | occurrence | production monitoring apparatus 3 ... Electric charge sample 4 ... Power supply 5 ... Voltage divider 6 ... Partial discharge detection apparatus 7 ... External storage device 8 ... Input means 9, 23 ... Detection Means 10 ... Setting means 11, 24 ... Determination / output means 12 ... Memory

Claims (3)

A partial discharge generation monitoring device for detecting and measuring a partial discharge generated in the charged sample by a partial discharge detection device when applying an alternating test voltage to the charged sample and performing a charged life test. ,
Input means for inputting a partial discharge discharge signal from the applied sample detected by the partial discharge detection device; and detection means for detecting polarity reversal of the voltage waveform of the test voltage input via a voltage divider. The determination whether or not the signal level of the input discharge signal exceeds a predetermined threshold is performed every half cycle of the test voltage, and the determination result about the presence or absence of discharge every half cycle is 1 bit. A partial discharge generation monitoring device, characterized by comprising determination / output means for outputting in the above.   2. The partial discharge generation according to claim 1, further comprising a peak value output stage for outputting a peak value of a voltage waveform in a half cycle in which it is determined that there is a discharge when it is determined that there is a discharge in the determination of the presence or absence of discharge. Monitoring device. A partial discharge occurrence monitoring method in an electric charge life test for detecting, measuring and monitoring a partial discharge generated by applying an AC test voltage to a charged sample,
After detecting the signal level of the discharge signal associated with the partial discharge of the applied sample and the polarity reversal of the voltage waveform of the test voltage, it is determined whether or not the signal level exceeds a predetermined threshold value. A partial discharge occurrence monitoring method characterized by performing monitoring every half cycle of voltage and counting the presence / absence of discharge in each half cycle.

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