Measurement device, measurement method, and program

Abstract

The occurrence state of partial discharge in the object to be measured is measured while suppressing the application of excessive voltage according to the characteristics of the object to be measured. [Solution] The measuring device 1 includes a detection circuit 50 that detects partial discharges occurring in the object to be measured 2 based on a voltage signal generated in the object to be measured 2 by an application circuit 40 that repeatedly applies an impulse voltage to the object to be measured 2 multiple times. The measuring device 1 controls the operation of the application circuit 40 so that the impulse voltage increases stepwise each time the impulse voltage is repeatedly applied to the object to be measured 2 multiple times, and stops the increase control of the impulse voltage based on a status index that indicates the occurrence of partial discharge detected for each impulse voltage value. The measuring device 1 controls the operation of the application circuit 40 so that the impulse voltage decreases stepwise when the increase control is stopped.

Description

[Technical Field]

[0001] The present invention relates to a measuring device, a measuring method, and a program for measuring a voltage related to the occurrence of partial discharge. [Background technology]

[0002] Patent Document 1 discloses a measurement system that observes an applied voltage signal representing the impulse voltage applied to an object to be measured while gradually increasing the impulse voltage each time a predetermined number of impulse voltages are applied. This measurement system stops increasing the applied voltage when the impulse voltage applied to the object to be measured exceeds an upper limit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6134101 Summary of the Invention [Problem to be solved by the invention]

[0004] A measuring device having the above-described measurement system determines whether the impulse voltage applied to the object to be measured exceeds an upper limit value before stopping the boosting of the applied voltage.

[0005] In this way, the increase in the applied voltage is stopped based on the upper limit value of the impulse voltage. Therefore, depending on the setting of the upper limit value or individual differences in the object to be measured, the application of the impulse voltage may affect the performance of the object to be measured before the impulse voltage reaches the upper limit value.

[0006] The present invention has been made in response to such problems, and aims to measure the occurrence state of partial discharge in an object to be measured while suppressing the application of excessive voltage depending on the characteristics of the object to be measured. [Means for solving the problem]

[0007] According to one aspect of the present invention, a measurement device for measuring a voltage associated with the occurrence of partial discharges in a measurement object, which is composed of one or more coils, includes an application circuit that repeatedly applies an impulse voltage to the measurement object multiple times, and a detection circuit that detects partial discharges occurring in the measurement object based on a voltage signal generated in the measurement object by the application circuit. The measurement device also includes a boost control means that controls the operation of the application circuit so that the impulse voltage increases stepwise each time the impulse voltage is repeatedly applied to the measurement object, and a stop means that stops the increase control of the impulse voltage by the boost control means based on a status index that indicates the occurrence of the partial discharge detected for each value of the impulse voltage. The measurement device further includes a step-down control means that controls the operation of the application circuit so that the impulse voltage decreases stepwise when the increase control is stopped by the stop means, and a processing means that acquires the number of times partial discharges are detected in the measurement object among the multiple times for each value of the impulse voltage. The processing means calculates the ratio of the number of times for each value of the impulse voltage generated by the boost control means, and obtains a first voltage value indicating the magnitude of the impulse voltage when the ratio becomes equal to or greater than a first threshold value included in the status index, and the stopping means stops the increase control of the impulse voltage when a criterion different from the first threshold value is met. [Effects of the Invention]

[0008] According to this aspect, the increase control of the impulse voltage is stopped depending on the occurrence state of partial discharge in the object to be measured to which the impulse voltage is applied, so that it is possible to prevent excessive voltage from being applied to the object to be measured. As a result, even when the decrease control of the impulse voltage is performed, it is possible to measure the voltage related to partial discharge while suppressing the influence of excessive applied voltage on the object to be measured.

[0009] Therefore, it is possible to measure the occurrence state of partial discharge in the object to be measured while suppressing the application of excessive voltage depending on the characteristics of the object to be measured. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the functional configuration of a measurement device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of the functional configuration of a processing unit in the measurement device. [Figure 3] FIG. 3 is a conceptual diagram showing an example of a measurement result when voltage control of an impulse voltage is switched from increasing control to decreasing control based on the frequency of occurrence of partial discharge in the object to be measured. [Figure 4] FIG. 4 is a conceptual diagram showing an example of a measurement result when voltage control of an impulse voltage is switched from increasing control to decreasing control based on the intensity of partial discharge occurring in the object to be measured. [Figure 5] FIG. 5 is a conceptual diagram showing an example of measurement results of reference RPDEV and reference PDEV for grasping the validity of RPDEV and PDEV. [Figure 6] FIG. 6 is a diagram showing an example of an image displaying the measurement results obtained by the measurement device. [Figure 7] FIG. 7 is a flowchart showing the measurement method in this embodiment. [Figure 8] FIG. 8 is a flowchart illustrating an example of a processing procedure for the PDIV measurement process included in the measurement method. [Figure 9] FIG. 9 is a flowchart illustrating an example of a procedure for a repeated measurement process included in the PDIV measurement process. [Figure 10] FIG. 10 is a flowchart showing an example of a processing procedure of the RPDIV measurement process included in the measurement method. [Figure 11] FIG. 11 is a flowchart showing an example of a procedure for a return measurement process included in the measurement method. [Figure 12] FIG. 12 is a flowchart showing an example of a processing procedure of the RPDEV measurement process included in the measurement method. [Figure 13] FIG. 13 is a flowchart illustrating an example of a processing procedure for PDEV measurement processing included in the measurement method. [Figure 14]FIG. 14 is a flowchart illustrating an example of the processing procedure of the reference voltage update processing included in the PDEV measurement processing. [Figure 15] FIG. 15 is a flowchart showing an example of a processing procedure for a result output process included in the measurement method. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] FIG. 1 is a block diagram showing the functional configuration of a measurement device according to this embodiment.

[0013] The measuring device 1 is a partial discharge measuring device that measures a voltage related to a partial discharge (PD) of a measuring object 2 configured by one or more coils. Examples of the measuring object 2 include an electric motor, a converter, an inverter, a solenoid valve, and a rectifier circuit.

[0014] In this embodiment, the object to be measured 2 is a three-phase electric motor consisting of three coils L1 to L3, and the measuring device 1 measures an index specified in IEC61934TS as a voltage related to two-phase partial discharge in the three-phase electric motor.

[0015] Hereinafter, the indexes defined in IEC61934TS will be referred to as PD indexes. Examples of PD indexes include partial discharge inception voltage, repetitive partial discharge inception voltage, partial discharge extinction voltage, and repetitive partial discharge extinction voltage, which will be referred to as PDIV, RPDIV, PDEV, and RPDEV, respectively.

[0016] The measuring device 1 measures at least one of the voltage step-up indicators PDIV and RPDIV and at least one of the voltage step-down indicators PDEV and RPDEV. The measuring device 1 in this embodiment measures at least four PD voltage indicators: PDIV, RPDIV, PDEV, and RPDEV.

[0017] The measuring device 1 is a computer, and is configured with a processor, a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and a bus that interconnects these elements.

[0018] The measurement device 1 includes a display unit 10, an operation unit 20, a processing unit 30, an application circuit 40, a detection circuit 50, and a storage unit 60.

[0019] The display unit 10 is configured with an LED (Light Emitting Diode) display, a liquid crystal panel, a touch panel, or the like for displaying images. The display unit 10 displays the measurement conditions and measurement results for the voltage related to partial discharge in the measurement object. In other words, the display unit 10 functions as an output means for outputting the results obtained by the processing unit 30.

[0020] The operation unit 20 is composed of a plurality of push buttons provided around the display screen that constitutes the display unit 10, a touch sensor arranged within the display screen, a keyboard, a mouse, etc. The operation unit 20 accepts input operations from a user who uses the measuring device 1, and generates an operation signal that indicates the content of the accepted input operation.

[0021] Examples of input operations include an operation of pressing the power button, an operation of setting measurement conditions, an operation of instructing the execution of measurement processing, an operation of instructing the stop of measurement processing, and the like.

[0022] When the operation unit 20 receives an input operation by the user to set measurement conditions, it outputs an operation signal indicating the measurement conditions to the processing unit 30 to record the operation signal in the storage unit 60. Furthermore, when the operation unit 20 receives an input operation by the user to instruct the execution of a measurement process, it outputs an operation signal indicating the content of the input operation to the processing unit 30.

[0023] The processing unit 30 is configured by a processor, such as a CPU (Central Processing Unit) or an MPU (Micro Processor Unit).

[0024] The processing unit 30 executes a measurement process for measuring a voltage related to partial discharge in the measurement object 2. The processing unit 30 in this embodiment controls the operations of the application circuit 40 and the detection circuit 50 to acquire the PD index of the measurement object 2.

[0025] As a specific example, the processing unit 30 repeatedly applies the same impulse voltage from the application circuit 40 to the object to be measured 2, and detects the occurrence of partial discharge in the object to be measured 2 based on the output signal of the detection circuit 50. Then, each time the impulse voltage output from the application circuit 40 to the object to be measured 2 is repeatedly applied, the processing unit 30 gradually increases the value of the impulse voltage, and then gradually decreases the value of the impulse voltage.

[0026] The processing unit 30 in this embodiment controls the operation of the application circuit 40 in accordance with the method specified in IEC61934TS. The processing unit 30 measures the occurrence frequency and occurrence intensity of partial discharges in the measurement object 2 for each impulse voltage value based on the voltage signal output from the detection circuit 50, thereby obtaining a PD index of the measurement object 2. The processing unit 30 records the obtained PD voltage index in the storage unit 60 as a measurement result.

[0027] The application circuit 40 is a pulse supply circuit that repeatedly applies a pulsed impulse voltage multiple times to the object to be measured 2. In this embodiment, the output terminals of the application circuit 40 are connected to two terminals of any two phases of a three-phase motor, which is the object to be measured 2. The output terminals of the application circuit 40 may also be connected to two terminals of the terminals of each phase and the neutral terminal.

[0028] The application circuit 40 repeatedly applies the same impulse voltage ten times at predetermined time intervals to two terminals of any two phases of the three-phase motor. The application circuit 40 also changes the value of the impulse voltage repeatedly applied to the measurement object 2 in stages in accordance with a control signal from the processing unit 30. The number of times that the application circuit 40 applies the impulse voltage may be less than ten times or more than ten times.

[0029] The detection circuit 50 is a discharge detection circuit that detects partial discharges occurring in the object to be measured 2 based on a voltage signal generated in the object to be measured 2 by the application circuit 40. In this embodiment, both terminals of any two phases of a three-phase motor, which is the object to be measured 2, are connected between a pair of terminals of the detection circuit 50.

[0030] The detection circuit 50 detects the voltage generated between both terminals of the three-phase motor each time an impulse voltage is applied from the application circuit 40. The detection circuit 50 outputs a voltage signal indicating the magnitude of the detected voltage to the processing unit 30.

[0031] When a partial discharge occurs in the object to be measured 2 to which an impulse voltage is applied, a pulse-shaped voltage is superimposed on the voltage signal output from the detection circuit 50. Therefore, it is possible to detect a partial discharge in the object to be measured 2 by extracting the pulse component of the output signal of the detection circuit 50 and measuring the peak value of the extracted pulse component. For example, in order to extract the pulse component of the output signal of the detection circuit 50, a filter circuit is provided between the detection circuit 50 and the processing unit 30. Instead of the filter circuit, digital filtering may be performed in the processing unit 30.

[0032] The storage unit 60 is composed of RAM and ROM. The storage unit 60 stores information related to the measurement process executed by the processing unit 30. The storage unit 60 records measurement conditions and measurement results as information related to the measurement process.

[0033] The measurement conditions include the sweep range of the impulse voltage applied to the measurement object 2, thresholds for the frequency and intensity of partial discharges occurring in the measurement object 2, and the like.

[0034] The storage unit 60 also stores a program for the processing unit 30 to execute the measurement process in this embodiment. That is, the storage unit 60 is a computer-readable storage medium on which programs for controlling each part of the measurement device 1 are recorded.

[0035] The communication unit 70 is configured by a communication circuit that communicates with an external device of the measurement device 1. For example, the communication unit 70 can receive measurement conditions and transmit measurement results to an external device wirelessly or via a wired connection through a network such as the Internet or a telephone network. In other words, the communication unit 70 functions as an output means that outputs the results obtained by the processing unit 30.

[0036] Next, an example of the configuration of the processing unit 30 in the measurement device 1 will be described with reference to FIG.

[0037] 2 is a block diagram showing the functional configuration of the processing unit 30 in this embodiment. The processing unit 30 includes a control unit 30A and a calculation unit 30B.

[0038] The control unit 30A controls the operation of the application circuit 40 so that the same impulse voltage is repeatedly applied multiple times to the measurement object 2. The control unit 30A then increases the peak value of the impulse voltage output from the application circuit 40 in a stepwise manner from the start voltage value of the sweep range, and then decreases the peak value of the impulse voltage in a stepwise manner to the end voltage value of the sweep range.

[0039] The control unit 30A in this embodiment sets a predetermined initial value as the starting voltage value in the application circuit 40, and applies an impulse voltage indicating that value to the measurement object 2 repeatedly 10 times.

[0040] The control unit 30A includes a step-up control unit 31, a step-down control unit 32, and a circuit control unit 33.

[0041] The boost control unit 31 functions as a boost control means that controls the operation of the application circuit 40 so that the impulse voltage increases stepwise each time the impulse voltage is repeatedly applied to the measurement object 2 multiple times.

[0042] In this embodiment, the boost control unit 31 increases the peak value of the impulse voltage output from the application circuit 40 by a predetermined increment every time the same impulse voltage is applied 10 times. The predetermined increment is a predetermined value, and is set to, for example, 10 V.

[0043] The step-down control unit 32 functions as a step-down control means that controls the operation of the application circuit 40 so that the impulse voltage decreases stepwise from the peak value of the impulse voltage when the increase control by the step-up control unit 31 is stopped.

[0044] In this embodiment, the step-down control unit 32 reduces the peak value of the impulse voltage output from the application circuit 40 by a predetermined amount every time the same impulse voltage is applied 10 times. The predetermined amount of reduction is a predetermined value and may be the same as or different from the predetermined amount of increase. The predetermined amount of reduction is set to, for example, 10 [V].

[0045] The circuit control unit 33 functions as a stopping means for stopping the boost control unit 31 from increasing the impulse voltage based on a state index indicating the occurrence state of partial discharge detected for each value of the impulse voltage by the boost control unit 31.

[0046] Examples of partial discharge status indicators include a discharge ratio, which indicates the ratio of the number of times partial discharge was detected in the object to be measured 2 out of 10 times, and a discharge peak value, which indicates the peak value of the pulse component caused by partial discharge in the output signal of the detection circuit 50.

[0047] In this embodiment, the circuit control unit 33 determines whether the discharge ratio is smaller than a switching threshold value. The switching threshold value is a threshold value for switching the impulse voltage increase / decrease control from increasing control to decreasing control. The switching threshold value is acquired from the operation unit 20 or the communication unit 70 and is stored in advance in the storage unit 60.

[0048] In this embodiment, the switching threshold is set to a value greater than the boost threshold of the discharge ratio required to obtain RPDIV, for example, 100% (percent). This makes it possible to obtain a discharge ratio at an impulse voltage higher than RPDIV, and by understanding this discharge ratio, it becomes possible to determine the validity of RPDIV.

[0049] When the circuit control unit 33 determines that the discharge ratio of the partial discharge is smaller than the switching threshold, it continues the increase control of the impulse voltage by the boost control unit 31, and when it determines that the discharge ratio has reached the switching threshold, it stops the increase control of the impulse voltage, thereby switching the voltage control of the impulse voltage from the increase control to the decrease control.

[0050] Furthermore, the circuit control unit 33 determines whether the size of the range of impulse voltage in which the discharge ratio is continuously 0% is greater than a predetermined value when the impulse voltage is being reduced in a stepwise manner by the step-down control unit 32. If the size of the range of impulse voltage is equal to or less than the predetermined value, the circuit control unit 33 continues to reduce the impulse voltage.

[0051] On the other hand, if the magnitude of the range of the impulse voltage is larger than a predetermined value, the circuit control unit 33 stops the step-down control of the impulse voltage, which makes it possible to end the measurement before the impulse voltage drops to the end voltage value, thereby shortening the measurement time.

[0052] The calculation unit 30B calculates a PD index and a reference PD index for determining the validity of the PD index based on the voltage signal output from the detection circuit 50. The calculation unit 30B includes a state index calculation unit 30C including a PD intensity detection unit 34 and a PD frequency acquisition unit 35, a PD index acquisition unit 36, and a reference PD index acquisition unit 37.

[0053] The state index calculation unit 30C calculates a state index that indicates the occurrence state of partial discharges that occur in the measurement object 2 due to the application of an impulse voltage to the measurement object 2. The state index calculation unit 30C in this embodiment detects the occurrence intensity and occurrence frequency of partial discharges that occur in the measurement object 2 as state indexes of partial discharges in the measurement object 2.

[0054] The PD intensity detection unit 34 detects the magnitude, i.e., the intensity, of a partial discharge that has occurred in the measurement object 2. Specifically, the PD intensity detection unit 34 detects the peak-to-peak value of the voltage signal output from the detection circuit 50 every time a single impulse voltage is applied from the application circuit 40 to the measurement object 2.

[0055] The PD intensity detection unit 34 in this embodiment has, for example, a high-pass filter (HPF), and extracts a pulse component of the voltage signal output from the detection circuit 50 and measures the peak value of the pulse component every time a single impulse voltage is applied to the measurement object 2. If the measured peak value exceeds a detection threshold for detecting partial discharge, the PD intensity detection unit 34 outputs the measured peak value to the PD frequency acquisition unit 35 as the peak value of partial discharge.

[0056] The PD frequency acquisition unit 35 detects the frequency of partial discharges occurring in the measurement object 2. Specifically, the PD frequency acquisition unit 35 acquires the number of times or the ratio of the number of times partial discharges are detected among the number of times repeated application is performed.

[0057] The PD frequency acquiring unit 35 in this embodiment acquires a discharge ratio indicating the ratio of the number of times partial discharge is detected out of 10 for each impulse voltage value. Then, the PD frequency acquiring unit 35 outputs the discharge ratio acquired for each impulse voltage value to the PD index acquiring unit 36.

[0058] The PD index acquisition unit 36 ​​acquires a PD index related to the measurement object 2 based on the discharge ratio acquired for each value of the impulse voltage by the step-up control unit 31 and the step-down control unit 32.

[0059] The PD index acquisition unit 36 ​​functions as a processing means that calculates a discharge ratio for each value of the impulse voltage generated by the boost control unit 31 and acquires a first voltage value that indicates the magnitude of the impulse voltage when the discharge ratio becomes equal to or greater than a first threshold value.

[0060] In the present embodiment, the PD index acquisition unit 36 ​​acquires a PDIV indicating the magnitude of the impulse voltage when the discharge ratio becomes equal to or greater than the start threshold value, among the impulse voltage values ​​set by the boost control unit 31. This PDIV corresponds to the first voltage value.

[0061] The above-mentioned initiation threshold is the ratio when the partial discharge is detected once, and corresponds to the first threshold. In this embodiment, this initiation threshold is set to 10%, which is 1 / 10 when the impulse voltage is repeatedly applied 10 times, and is stored in advance in the storage unit 60. The initiation threshold may be set by an input operation on the operation unit 20, or may be obtained from an external device via the communication unit 70.

[0062] The PD index acquisition unit 36 ​​then acquires RPDIV, which indicates the magnitude of the impulse voltage when the discharge ratio becomes equal to or greater than the boost threshold, from among the impulse voltage values ​​set by the boost control unit 31. RPDIV also corresponds to the first voltage value.

[0063] The boost threshold is a discharge ratio indicating a state in which a partial discharge is occurring to a moderate degree, and corresponds to a first threshold. In this embodiment, the boost threshold is set to 50% and is stored in advance in the storage unit 60. The boost threshold may be set by an input operation on the operation unit 20, or may be obtained from an external device via the communication unit 70.

[0064] The PD index acquisition unit 36 ​​also functions as a processing means for acquiring a third voltage value indicating the magnitude of the impulse voltage when the increase control is stopped by the circuit control unit 33. This third voltage value is the maximum value of the impulse voltage to be boosted, and is hereinafter referred to as a folded voltage.

[0065] In addition, the PD index acquisition unit 36 ​​functions as a processing means that calculates a discharge ratio for each value of the impulse voltage generated by the step-down control unit 32 and acquires a second voltage value that indicates the magnitude of the impulse voltage when the discharge ratio becomes less than a second threshold value.

[0066] In the present embodiment, the PD index acquisition unit 36 ​​acquires RPDEV, which indicates the magnitude of the impulse voltage when the discharge ratio first becomes less than the step-down threshold, among the impulse voltages set by the step-down control unit 32. This RPDEV corresponds to the second voltage value.

[0067] The voltage drop threshold is a discharge ratio that indicates a state in which partial discharge is occurring to a moderate degree, and corresponds to the second threshold. In this embodiment, the voltage drop threshold is set to 50% and is stored in advance in the storage unit 60.

[0068] This step-down threshold may be set by an input operation on the operation unit 20, or may be acquired from an external device via the communication unit 70. The step-down threshold may be the same value as the step-up threshold, or may be a different value.

[0069] Furthermore, the PD index acquisition unit 36 ​​acquires PDEV, which indicates the magnitude of the impulse voltage when the discharge ratio first becomes less than the extinction threshold, from among the impulse voltage values ​​set by the step-down control unit 32. This RPDEV corresponds to the second voltage value.

[0070] The above-mentioned extinction threshold is the discharge ratio when the number of partial discharge occurrences is one, and corresponds to the second threshold. In this embodiment, this extinction threshold is set to 10%, which is 1 / 10 when the impulse voltage is repeatedly applied 10 times, and is stored in advance in the storage unit 60. The extinction threshold may be set by an input operation on the operation unit 20, or may be obtained from an external device via the communication unit 70.

[0071] In this way, the PD index acquiring unit 36 ​​acquires PDIV, RPDIV, the folded voltage value indicating the maximum value of the impulse voltage, PDEV, and RPDEV as PD indexes related to the measurement object 2. Then, the PD index acquiring unit 36 ​​outputs the acquired PD indexes to the storage unit 60 as measurement results.

[0072] Furthermore, the PD index acquiring unit 36 ​​outputs to the reference PD index acquiring unit 37 the discharge ratio corresponding to each value of the impulse voltage in the increase control and the discharge ratio corresponding to each value of the impulse voltage in the decrease control.

[0073] The reference PD index acquisition unit 37 functions as a processing means for acquiring a reference PD index for grasping the validity of the PD index based on the discharge ratio acquired for each value of the impulse voltage by the step-down control unit 32.

[0074] The reference PD indicators include a reference RPDEV for determining the validity of RPDEV and a reference PDEV for determining the validity of PDEV. The reference RPDEV and the reference PDEV correspond to related voltage values.

[0075] The reference PD index acquisition unit 37 acquires, as a reference RPDEV related to RPDEV, the lowest voltage value among multiple impulse voltages whose discharge ratio becomes less than the step-down threshold when the step-down control unit 32 lowers an impulse voltage whose discharge ratio is equal to or greater than the step-down threshold by one step.

[0076] In this embodiment, the reference PD index acquisition unit 37 acquires, as a candidate value for the reference RPDEV, the impulse voltage value at which the discharge ratio becomes less than the step-down threshold when the impulse voltage whose discharge ratio is equal to or greater than the step-down threshold is reduced by one step during the step-down process of the impulse voltage.The reference PD index acquisition unit 37 then selects the lowest voltage value from the acquired candidate values ​​and sets the selected voltage value as the reference RPDEV.

[0077] In addition, the reference PD index acquisition unit 37 acquires, as a reference PDEV related to the PDEV, the lowest voltage value among multiple impulse voltages whose discharge ratio becomes less than the extinction threshold when the step-down control unit 32 lowers the impulse voltage whose discharge ratio is equal to or greater than the extinction threshold by one step.

[0078] In this embodiment, the reference PD index acquisition unit 37 acquires, as a candidate value for the reference PDEV, an impulse voltage value at which the discharge ratio becomes less than the step-down threshold when the impulse voltage whose discharge ratio is equal to or greater than the extinction threshold is decreased by one step.The reference PD index acquisition unit 37 then selects the lowest voltage value from the acquired candidate values ​​and sets the selected voltage value as the reference PDEV.

[0079] In this way, the reference PD index acquiring unit 37 acquires the reference RPDEV and the reference PDEV as the reference PD indexes. Then, the reference PD index acquiring unit 37 outputs the acquired reference PD indexes to the storage unit 60 as measurement results.

[0080] Similarly, the reference PD index acquisition unit 37 outputs the discharge ratio corresponding to each value of the impulse voltage in the increase control and the discharge ratio corresponding to each value of the impulse voltage in the decrease control to the memory unit 60 as measurement results.

[0081] The above-mentioned measurement results and measurement conditions are stored in the storage unit 60. The measurement conditions include an opening start threshold, a boost threshold, a switching threshold or tolerance value, a drop threshold, a disappearance threshold, a start voltage value, and an end voltage value.

[0082] In this embodiment, the reference PD index acquiring unit 37 is provided in the calculation unit 30B, but the reference PD index acquiring unit 37 may be omitted.

[0083] Next, the measurement results of the PD index obtained by the measurement device 1 will be described with reference to FIGS.

[0084] FIG. 3 is a conceptual diagram showing an example of the measurement results in this embodiment.

[0085] Fig. 3(a) shows the measurement results when the voltage control of the impulse voltage is switched from increasing control to decreasing control based on the discharge ratio of the measurement object 2. Fig. 3(b) shows, as a comparative example, the measurement results when the voltage control of the impulse voltage is switched from increasing control to decreasing control when the impulse voltage reaches a predetermined upper limit value.

[0086] In this example, an impulse voltage with a start voltage value Vs is repeatedly applied 10 times to the measurement object 2. After each application of the impulse voltage 10 times, the impulse voltage is increased by 10 [V], and then decreased by 10 [V] until the impulse voltage reaches an end voltage value Ve.

[0087] In addition, the start threshold T1 for obtaining the PDIV and the extinction threshold T2 for obtaining the PDEV are both the same value, and are set to 10%, which is the rate at which a partial discharge occurs once out of 10 applications of the impulse voltage.

[0088] The voltage increase threshold T1r for obtaining RPDIV and the voltage decrease threshold T2r for obtaining RPDEV are both set to the same value of 50%, and the start voltage value Vs and end voltage value Ve of the impulse voltage are both set to the same value.

[0089] In the example shown in Fig. 3(a), the switching threshold Tsw for switching the voltage control of the impulse voltage from increasing control to decreasing control is set to 100%, while in the example shown in Fig. 3(b), the upper limit for switching the voltage control of the impulse voltage from increasing control to decreasing control is set to 920 [V].

[0090] As shown in Figure 3(b), in the method of switching the voltage control of the impulse voltage to decreasing control when the impulse voltage reaches the upper limit voltage Vt, which indicates the upper limit value, the impulse voltage continues to increase even when the discharge ratio reaches 100%, depending on how the upper limit value is set or individual differences in the object of measurement 2. As a result, excessive voltage continues to be applied to the object of measurement 2, which may damage the object of measurement 2.

[0091] In contrast to this, in this embodiment, as shown in FIG. 3(a), the increase control of the impulse voltage is stopped depending on the magnitude of the discharge ratio, so that the influence of the applied voltage on the measurement object 2 can be suppressed.

[0092] In addition, in this embodiment, the switching threshold Tsw is set to a value greater than the boost threshold T1r. This allows the folding voltage to be set to a voltage value greater than RPDIV. By setting the folding voltage greater than RPDIV, the user can understand the appropriateness of RPDIV.

[0093] For example, the voltage value of RPDIV may be estimated based on the relationship between the discharge rate of PDIV and the discharge rate of the turn-back voltage, and the estimated value of RPDIV may be compared with the measured value to determine the validity of the measurement result.

[0094] Fig. 4 is a conceptual diagram showing an example of measurement results when voltage control of the impulse voltage is switched based on the discharge peak value instead of the discharge ratio. In Fig. 4, the start threshold T1, extinction threshold T2, boost threshold T1r, drop threshold T2r, start voltage value Vs, and end voltage value Ve are the same as those shown in Fig. 3.

[0095] Fig. 4(a) shows the measurement results when the voltage control of the impulse voltage is switched from increasing control to decreasing control based on the discharge peak of the measurement object 2. Fig. 4(b) shows, as a comparative example, the measurement results when the voltage control of the impulse voltage is switched from increasing control to decreasing control based on the upper limit value of the impulse voltage, similar to Fig. 3(b).

[0096] In FIGS. 4(a) and 4(b), the discharge ratio is indicated by a thick line and the discharge peak value is indicated by a thin line for each impulse voltage value.

[0097] In the example shown in Fig. 4(a), a tolerance value To is set for switching the voltage control of the impulse voltage from increasing control to decreasing control, while in the example shown in Fig. 4(b), the upper limit is set to 920 [V], similar to Fig. 3(b).

[0098] As shown in Figure 4(b), in the method of switching the voltage control of the impulse voltage to decreasing control when the impulse voltage reaches the upper limit, the impulse voltage continues to increase even if the discharge peak value becomes extremely large due to the way the upper limit is set or individual differences in the object of measurement 2. As a result, excessive voltage continues to be applied to the object of measurement 2, which may damage the object of measurement 2.

[0099] In contrast to this, in the method shown in FIG. 4(a), the increase control of the impulse voltage is stopped depending on the magnitude of the discharge peak value, so that the influence of the applied voltage on the measurement object 2 can be suppressed.

[0100] In the example shown in FIG. 4(a), the discharge peak value suddenly increases when the impulse voltage is greater than RPDIV, but the same phenomenon can occur at voltages lower than RPDIV.

[0101] In such a case, if the impulse voltage continues to increase until the RPDIV is acquired, it may have a negative effect on the object to be measured 2. Therefore, by stopping the increase control of the impulse voltage depending on the magnitude of the discharge peak value, it is possible to avoid applying an excessive voltage to the object to be measured 2.

[0102] Fig. 5 is a diagram for explaining the measurement results of the reference RPDEV and the reference PDEV. In Fig. 5, the start threshold T1, the extinction threshold T2, the boost threshold T1r, and the drop threshold T2r are the same as those shown in Fig. 3. On the other hand, the start voltage value Vs and the end voltage value Ve are different from those shown in Fig. 3.

[0103] Figure 5(a) shows ideal measurement results in which the discharge ratio increases regularly and monotonically until the impulse voltage reaches the turn-around voltage, and then decreases regularly and monotonically at the turn-around voltage. On the other hand, Figure 5(b) shows measurement results in which the frequency and magnitude of partial discharges fluctuate.

[0104] As shown in FIG. 5(a), when the discharge ratio changes regularly as the impulse voltage is swept, RPDEV and the reference RPDEV have the same voltage value, and PDEV and the reference PDEV have the same voltage value.

[0105] However, because the occurrence of partial discharge is a probabilistic phenomenon, the frequency and intensity of partial discharges may accidentally become relatively high or low. In such a situation, RPDEV and PDEV may be measured on the high side. When RPDEV and PDEV are judged as indicators of the partial discharge resistance of the measurement object 2, if these indicators are estimated on the high side, there is a risk of inducing damage to the measurement object 2 due to the application of a voltage exceeding the partial discharge resistance.

[0106] To address this issue, in this embodiment, in addition to RPDEV and PDEV, reference PD indices called reference RPDEV and reference PDEV are acquired.

[0107] As shown in Figure 5(b), the reference RPDEV is set to the smallest voltage value among the impulse voltage values ​​when the discharge ratio becomes less than the step-down threshold T2r in a state where the impulse voltage when the discharge ratio becomes equal to or greater than the step-down threshold T2r is lowered by one step.

[0108] More specifically, the measurement device 1 acquires, as the reference candidate value, the impulse voltage value at which the discharge rate becomes less than the step-down threshold T2r when the impulse voltage whose discharge rate is equal to or greater than the step-down threshold T2r is reduced by one step during the step-down of the impulse voltage. In the example shown in Fig. 5(b), the reference candidate values ​​are 1160 [V] and 1140 [V].

[0109] The measurement device 1 then sets the smallest voltage value among the acquired reference candidate values ​​as the reference RPDEV. In the example shown in Fig. 5(b), 1140 [V] is set as the reference RPDEV as it is the smallest voltage value between 1160 [V] and 1140 [V].

[0110] By setting the reference RPDEV in this way, the reference RPDEV takes into consideration the accidental nature of partial discharges, and therefore is estimated to be lower than the RPDEV in the actual measurement process.

[0111] Similarly, the reference PDEV is set to the smallest voltage value among the impulse voltage values ​​when the discharge ratio becomes less than the extinction threshold T2 in a state where the impulse voltage when the discharge ratio becomes equal to or greater than the extinction threshold T2 is lowered by one step.

[0112] More specifically, the measurement device 1 acquires, as reference candidate values, impulse voltage values ​​at which the discharge ratio becomes less than the extinction threshold T2 when the impulse voltage whose discharge ratio is equal to or greater than the extinction threshold T2 is decreased by one step during the step-down of the impulse voltage, and then sets the smallest voltage value among the acquired reference candidate values ​​as the reference PDEV.

[0113] By setting the reference PDEV in this way, the reference PDEV takes into account the accidental nature of partial discharges, as with the reference RPDEV, and is therefore estimated to be lower than the PDEV.

[0114] Although the example in which the smallest voltage value among the reference candidate values ​​of the impulse voltage is stored as the reference PDEV has been described, a voltage value smaller than the largest voltage value among the plurality of reference candidate values, for example, the second or third smallest voltage value, may be selected as the reference PDEV. Alternatively, the average or median of the plurality of reference candidate values ​​may be used. The same applies to the reference RPDEV.

[0115] As described above, by measuring the reference PDEV and reference RPDEV, it becomes possible to compare them with the PDEV and RPDEV, thereby enabling the user to determine the validity of the PDEV and RPDEV.

[0116] For example, the measurement device 1 may calculate an evaluation value of the validity of the PDEV and RPDEV based on the difference between the reference PDEV and the PDEV and the difference between the reference RPDEV and the RPDEV. As a specific example, the measurement device 1 reduces the evaluation value of the validity of the PDEV as the difference between the reference PDEV and the PDEV increases.

[0117] Alternatively, the measurement device 1 may set the reference PDEV and the average value of PDEV as PDEV, and reset the reference RPDEV and the average value of RPDEV as RPDEV, or may set the reference RPDEV as PDEV, and reset the reference RPDEV as RPDEV.

[0118] FIG. 6 is a diagram showing an example of a display image 11 of the measurement results obtained by the measurement device 1. As shown in FIG.

[0119] In the display image 11, the voltage values ​​and discharge ratios are displayed for each PD index, PDIV, RPDIV, folded voltage, RPDEV, reference RPDEV, PDEV, and reference PDEV.

[0120] This allows the user to, for example, compare the intermediate value of the PDIV and turn-over voltage with the measured value of RPDIV, or the intermediate value of the turn-over voltage and PDEV with the measured value of RPDEV, thereby understanding the magnitude of the partial discharge fluctuations.

[0121] In this example, since the voltage values ​​of the RPDEV and the reference RPDEV are different, the voltage value of the reference RPDEV is displayed in bold and underlined to indicate this. The same is true for the reference PDEV. Furthermore, the evaluation results of the validity of the PDEV and the validity of the RPDEV are displayed as reference information.

[0122] In this way, by using the measured values ​​of the reference RPDEV and the reference PDEV, it is possible to avoid overestimating the partial discharge resistance of the measurement object 2.

[0123] Next, the operation of the measurement device 1 in this embodiment will be described with reference to FIGS.

[0124] FIG. 7 is a flowchart showing an example of a measurement method executed by the measurement device 1.

[0125] In step S1, the measurement device 1 executes a PDIV measurement process for measuring the PDIV of the object to be measured 2 while gradually increasing the impulse voltage applied to the object to be measured 2. The PDIV measurement process will be described later with reference to FIG.

[0126] In step S2, the measurement device 1 executes an RPDIV measurement process for measuring the RPDIV of the measurement object 2 while increasing the impulse voltage in a stepwise manner. The RPDIV measurement process will be described later with reference to FIG.

[0127] In step S3, the measuring device 1 determines whether the voltage control of the impulse voltage has been switched from increasing control to decreasing control in either step S1 or step S2.

[0128] In this example, a voltage boost stop flag is used to indicate whether or not the increase control has been stopped in order to switch the voltage control of the impulse voltage to the decrease control. This voltage boost stop flag is set to "TRUE" if the increase control has been stopped in step S1 or S2, and is set to "FALSE" if the increase control has not been stopped.

[0129] If the boost stop flag indicates "FALSE", the measuring device 1 is maintaining the upward control and proceeds to step S4, whereas if the boost stop flag indicates "TRUE", the measuring device 1 has switched to downward control and skips step S4 and proceeds to step S5.

[0130] In step S4, the measurement device 1 executes a turn-around measurement process for switching the voltage control of the impulse voltage from increasing control to decreasing control while measuring the discharge rate of the measurement object 2. The turn-around measurement process will be described later with reference to FIG.

[0131] In step S5, the measuring device 1 determines whether or not there is a voltage value in the PDIV in order to determine whether or not to measure RPDEV and PDEV. In step S1, it is assumed that the increase control of the impulse voltage will be stopped before the impulse voltage reaches PDIV. In such a case, a voltage value is not set in the PDIV, and measurement of RPDEV and PDEV is omitted.

[0132] Therefore, if PDIV indicates "No Data," RPDEV and PDEV cannot be measured, and the measurement device 1 skips steps S6 and S7 and proceeds to step S8. On the other hand, if a voltage value has already been set in PDIV, it is determined that RPDEV and PDEV can be measured, and the measurement device 1 proceeds to step S6.

[0133] In step S6, the measurement device 1 executes an RPDEV measurement process for measuring the RPDEV of the measurement object 2 while gradually decreasing the impulse voltage. The RPDEV measurement process will be described later with reference to FIG.

[0134] In step S7, the measurement device 1 executes a PDEV measurement process for acquiring the PDEV of the measurement object 2 while gradually decreasing the impulse voltage. The PDEV measurement process will be described later with reference to FIG.

[0135] In step S8, the measurement device 1 executes a result output process for outputting the measurement results including PDIV, RPDIV, RPDEV, and PDEV for the measurement object 2. The result output process will be described later with reference to FIG.

[0136] When the process of step S8 is completed, the series of processes for the above measurement method is completed.

[0137] FIG. 8 is a flowchart showing an example of a processing procedure related to the PDIV measurement processing executed in step S1.

[0138] In step S11, the measurement device 1 sets the impulse voltage Vin to a start voltage value Vs. In this embodiment, an initial value V1 is used as the start voltage value Vs.

[0139] In step S12, the measurement device 1 sets the voltage boost stop flag to "FALSE" to start increasing control of the impulse voltage Vin.

[0140] In step S13, the measurement device 1 executes a repetitive discharge measurement process, whereby the measurement device 1 repeatedly applies the set impulse voltage Vin to the measurement object 2 multiple times to obtain a discharge ratio Rd that indicates the occurrence frequency of partial discharge in the measurement object 2. This repetitive discharge measurement process will be described later with reference to FIG.

[0141] In step S14, the measurement device 1 determines whether or not a boost stop condition for stopping the increase control of the impulse voltage Vin is met.

[0142] In this embodiment, the boost stop condition is determined by determining whether the discharge ratio Rd has reached a switching threshold Tsw, which is a threshold for switching the voltage control of the impulse voltage Vin from increasing control to decreasing control, and is set to, for example, 100%.

[0143] If the discharge ratio Rd reaches the switching threshold Tsw, the measurement device 1 determines that the boost stop condition is met and proceeds to step S15, and if the discharge ratio Rd does not reach the switching threshold Tsw, the measurement device 1 proceeds to step S16.

[0144] In step S15, the measurement device 1 sets the boost stop flag to "TRUE", which means that the boost stop condition is met.

[0145] In step S16, the measuring device 1 determines whether the discharge ratio Rd exceeds 0%. That is, the measuring device 1 determines whether the discharge ratio Rd is equal to or greater than the above-mentioned initiation threshold T1. This initiation threshold T1 indicates the discharge ratio when only one partial discharge is detected.

[0146] If the discharge ratio Rd exceeds 0%, the measurement device 1 proceeds to step S19, and if the discharge ratio Rd is 0%, the measurement device 1 proceeds to step S17.

[0147] In step S17, the measurement device 1 determines whether the boost stop flag indicates "TRUE" which means that the increase control of the impulse voltage Vin is stopped.

[0148] If the boost stop flag indicates "TRUE", the voltage control of the impulse voltage Vin has been switched to the decrease control, and the measuring device 1 ends the PDIV measurement process and returns to the processing procedure of the measurement method shown in Fig. 7. On the other hand, if the boost stop flag indicates "FALSE", the measuring device 1 maintains the increase control, and proceeds to step S18.

[0149] In step S18, the measurement device 1 sets a new voltage value for the impulse voltage Vin by adding an increment ΔV to the set value for the impulse voltage Vin. The measurement device 1 then increases the value of the impulse voltage Vin, which is repeatedly applied to the measurement object 2, until the discharge ratio Rd exceeds 0% or the boost stop condition is met.

[0150] That is, steps S13 to S18 correspond to a voltage boost control step in which the impulse voltage Vin is increased stepwise every time the impulse voltage Vin is repeatedly applied to the measurement object 2 multiple times.

[0151] In step S19, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd exceeds 0% as the PDIV. That is, the measurement device 1 acquires the PDIV indicating the value of the impulse voltage Vin when the discharge ratio Rd first becomes equal to or greater than the start threshold T1.

[0152] When the process of step S19 is completed, the process returns to the procedure of the measurement method shown in FIG. 7, and the PDIV measurement process of step S1 in the measurement method is completed.

[0153] In this embodiment, one of the conditions for stopping the boosting in step S14 is to determine whether the discharge ratio Rd has reached the switching threshold value Tsw, but instead, it may be determined whether the discharge peak value exceeds a predetermined allowable value To.

[0154] In this case, when the discharge peak value exceeds the allowable value To, the voltage boost stop flag is set to "TRUE" and the increase control of the impulse voltage Vin is stopped.

[0155] Alternatively, when the discharge ratio Rd reaches the switching threshold Tsw or when the discharge peak value exceeds the allowable value To, the boost stop flag may be set to "TRUE" and the increase control of the impulse voltage Vin may be stopped.

[0156] FIG. 9 is a flowchart showing an example of a procedure for the repeated discharge measurement process executed in step S13.

[0157] In step S131, the measurement apparatus 1 repeatedly applies the same impulse voltage Vin to the object to be measured 2. That is, step S131 corresponds to an application step in which the impulse voltage Vin is repeatedly applied to the object to be measured 2.

[0158] In step S132, the measuring device 1 detects, for each impulse voltage Vin, a discharge peak value resulting from a partial discharge occurring in the object to be measured 2 from the voltage signal occurring in the object to be measured 2. In other words, step S132 corresponds to a detection step of detecting a partial discharge occurring in the object to be measured 2 based on the voltage signal occurring in the object to be measured 2 in step S131.

[0159] In step S133, the measurement device 1 calculates a discharge ratio Rd indicating the ratio of the number of times a discharge peak value is detected to the number of times the impulse voltage Vin is repeatedly applied. That is, step S133 corresponds to a processing step of acquiring the number of times a partial discharge is detected in the measurement object 2 for each value of the impulse voltage Vin.

[0160] When the process of step S133 ends, the process returns to the procedure of the PDIV measurement process shown in FIG. 8, and the repeated discharge measurement process of step S13 in the PDIV measurement process is completed.

[0161] Next, the RPDIV measurement process in step S2 of the measurement method shown in FIG. 7 will be described with reference to FIG.

[0162] FIG. 10 is a flowchart showing an example of a processing procedure related to the RPDIV measurement processing executed in step S2.

[0163] In step S21, the measurement device 1 determines whether or not a boost stop condition for stopping the increase control of the impulse voltage Vin is met.

[0164] In this embodiment, if the discharge ratio Rd reaches the switching threshold Tsw, the measurement device 1 determines that the boost stop condition is met and proceeds to step S22, but if the discharge ratio Rd does not reach the switching threshold Tsw, the measurement device 1 skips step S22 and proceeds to step S23. Alternatively, the measurement device 1 may determine that the boost stop condition is met if the discharge peak value exceeds a predetermined allowable value To.

[0165] In step S22, the measurement device 1 sets the boost stop flag to "TRUE", which means that the boost stop condition is met.

[0166] In step S23, the measurement device 1 determines whether the discharge ratio Rd is equal to or greater than the boost threshold T1r. If the discharge ratio Rd is less than the boost threshold T1r, the measurement device 1 proceeds to step S24.

[0167] In step S24, the measurement device 1 determines whether the boost stop flag indicates "TRUE" which means that the increase control of the impulse voltage Vin is stopped.

[0168] If the boost stop flag indicates "TRUE", the voltage control of the impulse voltage Vin has been switched to decrease control, and the measurement device 1 ends the RPDIV measurement process and returns to the processing procedure of the measurement method shown in Fig. 7. On the other hand, if the boost stop flag indicates "FALSE", the measurement device 1 maintains increase control, and proceeds to step S25.

[0169] In step S25, the measurement device 1 sets a new voltage value for the impulse voltage Vin by adding the increase amount ΔV to the value set for the impulse voltage Vin. That is, the measurement device 1 executes control of increasing the impulse voltage Vin using the boost control unit 31.

[0170] In step S13, the measurement device 1 executes the repeated discharge measurement process shown in FIG.

[0171] In this way, the measuring device 1 increases the impulse voltage Vin applied to the object 2 until the discharge ratio Rd becomes equal to or greater than the boost threshold T1r or the boost stop condition is met. That is, steps S21 to S25 correspond to a boost control step in which the impulse voltage Vin is increased stepwise each time the impulse voltage Vin is repeatedly applied to the object 2.

[0172] If the discharge ratio Rd becomes equal to or greater than the boost threshold T1r in step S23, the measurement device 1 proceeds to step S26.

[0173] In step S26, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd becomes equal to or greater than the boost threshold T1r to RPDIV. That is, the measurement device 1 acquires RPDIV indicating the value of the impulse voltage Vin when the discharge ratio Rd first becomes equal to or greater than the boost threshold T1r.

[0174] When the process of step S26 is completed, the process returns to the procedure of the measurement method shown in FIG. 7, and the RPDIV measurement process of step S2 in the measurement method is completed.

[0175] FIG. 11 is a flowchart showing an example of a processing procedure regarding the return measurement processing executed in step S4.

[0176] In step S41, the measurement device 1 sets a new voltage value for the impulse voltage Vin by adding an increase amount ΔV to the value set for the impulse voltage Vin, similar to step S14 shown in Fig. 8. That is, the measurement device 1 executes control of increasing the impulse voltage Vin using the boost control unit 31.

[0177] In step S13, the measurement device 1 executes the repeated discharge measurement process shown in FIG.

[0178] In step S42, the measurement device 1 determines whether a boost stop condition for stopping the increase control of the impulse voltage Vin is met. In this embodiment, a switching threshold value Tsw related to the discharge ratio Rd is set as the boost stop condition. For example, the switching threshold value Tsw is set to a value greater than the boost threshold value T1r.

[0179] In this embodiment, if the discharge ratio Rd has not reached the switching threshold Tsw, the measurement device 1 returns to step S41 and increases the value of the impulse voltage Vin repeatedly applied to the measurement object 2 until the discharge ratio Rd reaches the switching threshold Tsw. Alternatively, the measurement device 1 may return to step S41 if the impulse voltage Vin has not reached the predetermined upper limit voltage Vt and the discharge ratio Rd has not reached the switching threshold Tsw.

[0180] That is, steps S41, S13, and S42 correspond to a voltage boost control step in which the impulse voltage Vin is increased stepwise every time the impulse voltage Vin is repeatedly applied to the measurement object 2 multiple times.

[0181] If the discharge ratio Rd reaches the switching threshold value Tsw in step S42, the measurement device 1 determines that the boost stop condition is met and proceeds to step S43. Alternatively, the measurement device 1 may determine that the boost stop condition is met when the discharge peak value exceeds a predetermined allowable value To.

[0182] In step S43, the measurement device 1 stops the increase control of the impulse voltage Vin in the state of the impulse voltage Vin when the discharge ratio Rd reaches the switching threshold Tsw, and switches to the decrease control of the impulse voltage Vin.

[0183] That is, steps S42 and S43 correspond to a stopping step of stopping the increase control of the impulse voltage Vin based on the state index indicating the occurrence state of partial discharge detected for each value of the impulse voltage Vin.

[0184] When the process of step S43 is completed, the process returns to the procedure of the measurement method shown in FIG. 7, and the return measurement process of step S4 in the measurement method is completed.

[0185] FIG. 12 is a flowchart showing an example of a processing procedure related to the RPDEV measurement processing executed in step S6.

[0186] In step S61, the measuring device 1 determines whether the impulse voltage Vin is below a predetermined lower limit. This lower limit is set to a value (V1+ΔV) obtained by adding a decrease ΔV to the initial value V1 so that the lower limit does not fall below the initial value V1 when the impulse voltage Vin is reduced by one step.

[0187] If the impulse voltage Vin is below the lower limit (V1+ΔV), the measurement device 1 returns to the procedure of the measurement method shown in Fig. 7 and completes the RPDEV measurement process of step S6 in the measurement method. On the other hand, if the impulse voltage Vin is equal to or greater than the lower limit (V1+ΔV), the measurement device 1 proceeds to step S62.

[0188] In step S62, the measurement device 1 sets a new voltage value obtained by subtracting the decrease amount ΔV from the value set for the impulse voltage Vin. That is, the measurement device 1 executes the step-down control unit 32 to decrease the impulse voltage Vin.

[0189] In step S13, the measurement device 1 executes the repeated discharge measurement process shown in FIG.

[0190] In step S63, the measurement device 1 determines whether the discharge ratio Rd has become less than the above-mentioned step-down threshold T2r.

[0191] When the discharge ratio Rd is equal to or greater than the step-down threshold T2r, the measurement device 1 reduces the value of the impulse voltage Vin repeatedly applied to the measurement object 2 until the discharge ratio Rd becomes less than the step-down threshold T2r.

[0192] That is, steps S62, S13, and S63 correspond to a step-down control step in which the impulse voltage Vin is reduced stepwise each time the impulse voltage Vin is repeatedly applied to the measurement object 2 multiple times.

[0193] If the discharge ratio Rd is less than the step-down threshold T2r in step S63, the measurement device 1 proceeds to step S64.

[0194] In step S64, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd becomes less than the step-down threshold T2r to RPDEV. That is, the measurement device 1 acquires RPDEV indicating the value of the impulse voltage Vin when the discharge ratio Rd first becomes equal to or greater than the step-down threshold T2r.

[0195] In step S65, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd becomes less than the step-down threshold T2r as the reference RPDEV for determining the validity of RPDEV.

[0196] When the process of step S65 ends, the measurement device 1 returns to the processing procedure of the measurement method shown in FIG. 7, and completes the RPDEV measurement process of step S6 in the measurement method.

[0197] FIG. 13 is a flowchart showing an example of a processing procedure related to the PDEV measurement processing executed in step S7.

[0198] First, in step S71, the measurement device 1 determines whether the impulse voltage Vin is below the initial value V1, and if the impulse voltage Vin is below the initial value V1, the measurement device 1 returns to the processing procedure of the measurement method shown in Fig. 7 and completes the PDEV measurement process of step S7 in the measurement method. On the other hand, if the impulse voltage Vin is equal to or greater than the initial value V1, the measurement device 1 proceeds to step S72.

[0199] In step S72, the measurement device 1 determines whether the discharge ratio Rd has become 0% in order to measure PDEV.

[0200] That is, the measuring device 1 determines whether the discharge ratio Rd is less than the extinction threshold T2. This extinction threshold T2 indicates the discharge ratio when only one partial discharge is detected among the number of repeated applications. If the discharge ratio Rd is 0%, the measuring device 1 proceeds to step S73.

[0201] In step S73, the measurement device 1 determines whether or not there is a voltage value in PDEV in order to identify the value of the impulse voltage Vin when the discharge ratio Rd becomes 0% for the first time during the decrease control.

[0202] If PDEV indicates "No Data," the measurement device 1 determines that the value of the impulse voltage Vin is the voltage value when the discharge ratio Rd became 0% for the first time, and proceeds to step S74. On the other hand, if a voltage value has already been set in PDEV, this means that the discharge ratio Rd has become 0% two or more times, and so the measurement device 1 skips step S74 and proceeds to step S75.

[0203] In step S74, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd first becomes 0% as PDEV. That is, the measurement device 1 acquires PDEV indicating the value of the impulse voltage Vin when the discharge ratio Rd first becomes less than the extinction threshold T2.

[0204] In step S75, the measurement device 1 executes a reference voltage update process to update, as necessary, the voltage value of the reference PDEV set in step S73 and the voltage value of the reference RPDEV set in step S65 of Fig. 12. This reference voltage update process will be described later with reference to Fig. 14.

[0205] In step S76, the measurement device 1 sets a new voltage value for the impulse voltage Vin, which is obtained by subtracting the decrease amount ΔV from the value set for the impulse voltage Vin. That is, the measurement device 1 executes the control to decrease the impulse voltage Vin.

[0206] In step S77, the measurement apparatus 1 determines whether the impulse voltage Vin has decreased to the end voltage value Ve. The end voltage value Ve may be the same as or different from the start voltage value Vs.

[0207] In this embodiment, the end voltage value Ve is the initial value V1 in step S11 in Fig. 8. If the impulse voltage Vin is equal to or greater than the initial value V1, the measurement device 1 proceeds to step S13.

[0208] In step S13, the measurement device 1 executes the repeated discharge measurement process shown in FIG.

[0209] In step S78, the measurement device 1 determines whether the non-discharge voltage drop amount, which indicates the size of the voltage range of the impulse voltage Vin where the discharge ratio Rd is continuously 0%, is greater than the stop threshold value Ts. The stop threshold value Ts is a predetermined value, and is set to, for example, the voltage amount (=ΔV×5) when the impulse voltage Vin is reduced five times.

[0210] When the non-discharge step-down amount is greater than the stop threshold Ts, the measuring device 1 stops the decrease control of the impulse voltage Vin. That is, when the non-discharge step-down amount is greater than a predetermined value while the impulse voltage Vin is being gradually decreased by the step-down control unit 32, the circuit control unit 33 in the measuring device 1 stops the step-down control of the impulse voltage.

[0211] On the other hand, if the non-discharge voltage drop amount is equal to or less than the stop threshold Ts, the measuring device 1 repeats the processes of steps S71 to S77 until the non-discharge voltage drop amount exceeds the stop threshold Ts or until the impulse voltage Vin drops to the initial value V1.

[0212] If the non-discharge voltage drop amount exceeds the stop threshold value Ts in step S78, or if the impulse voltage Vin falls below the initial value V1 in step S76, the measurement device 1 returns to the processing procedure of the measurement method shown in FIG. 7 and completes the PDEV measurement process of step S7 in the measurement method.

[0213] In this embodiment, the process of step S77 is executed to shorten the measurement time, but the process of step S78 may be omitted.

[0214] FIG. 14 is a flowchart showing an example of the processing procedure of the reference voltage update processing executed in step S75.

[0215] In step S751, the measurement device 1 checks whether the discharge ratio Rd has become 0% to determine whether the reference RPDEV needs to be updated. That is, the measurement device 1 determines whether the discharge ratio Rd has become less than the extinction threshold T2. If the discharge ratio Rd has exceeded the discharge ratio Rd, the measurement device 1 proceeds to step S742.

[0216] In step S752, the measurement device 1 erases the voltage value in the reference PDEV to record that the discharge ratio Rd is greater than 0%, i.e., the measurement device 1 resets the reference PDEV.

[0217] On the other hand, if the discharge ratio Rd becomes 0% in step S751, the measurement device 1 proceeds to step S753.

[0218] In step S753, the measuring device 1 determines whether or not the discharge ratio Rd has reached 0% when the impulse voltage Vin is lowered by one step when the discharge ratio Rd is greater than 0%.

[0219] If PDEV indicates "No Data," the measurement device 1 determines that the discharge ratio Rd has reached 0% when the impulse voltage Vin is lowered by one level when the discharge ratio Rd is above 0%, and proceeds to step S744. On the other hand, if a voltage value has already been set in PDEV, the measurement device 1 skips step S744 and proceeds to step S745.

[0220] In step S754, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd becomes 0% in a state where the impulse voltage Vin is reduced by one step when the discharge ratio Rd is above 0% as the reference PDEV.

[0221] In this way, the measurement device 1 updates the voltage value of the reference PDEV when the discharge ratio Rd becomes less than the extinction threshold T2 in a state where the impulse voltage Vin when the discharge ratio Rd becomes 0% is reduced by one step.

[0222] Ultimately, the smallest voltage value among the impulse voltage Vin values ​​when the discharge ratio Rd becomes less than the extinction threshold T2 in a state where the impulse voltage Vin is lowered by one step when the discharge ratio Rd becomes equal to or greater than the extinction threshold T2 is stored in the reference PDEV.

[0223] In step S755, the measurement device 1 determines whether the discharge ratio Rd has become less than the step-down threshold T2r. If the discharge ratio Rd has become equal to or greater than the step-down threshold T2r, the measurement device 1 proceeds to step S756.

[0224] In step S756, the measurement device 1 erases the voltage value at the reference PDEV in order to record that the discharge ratio Rd has become equal to or greater than the step-down threshold T2r.

[0225] On the other hand, if the discharge ratio Rd becomes less than the step-down threshold T2r in step S745, the measurement device 1 proceeds to step S757.

[0226] In step S757, the measuring device 1 determines whether or not the discharge ratio Rd becomes less than the step-down threshold T2r when the impulse voltage Vin at which the discharge ratio Rd becomes equal to or greater than the step-down threshold T2r is lowered.

[0227] If the reference RPDEV indicates "No Data", the measuring device 1 determines that the discharge ratio Rd has become less than the step-down threshold T2r when the impulse voltage Vin at which the discharge ratio Rd becomes equal to or greater than the step-down threshold T2r is lowered, and proceeds to step S748.

[0228] In step S758, the measurement device 1 sets the value of the impulse voltage Vin when the discharge ratio Rd becomes less than the step-down threshold T2r in a state where the impulse voltage Vin is lowered by one step when the discharge ratio Rd becomes equal to or greater than the step-down threshold T2r as the reference RPDEV.

[0229] In this way, when the impulse voltage Vin is lowered by one step when the discharge ratio Rd becomes equal to or greater than the step-down threshold T2r, the measurement device 1 updates the voltage value of the reference RPDEV when the discharge ratio Rd becomes less than the step-down threshold T2r.

[0230] Ultimately, when the impulse voltage Vin is lowered by one step when the discharge ratio Rd becomes equal to or greater than the step-down threshold T2r, the smallest voltage value of the impulse voltage Vin when the discharge ratio Rd becomes less than the step-down threshold T2r is stored in the reference RPDEV.

[0231] When the processing of step S756 or S758 is completed, or when the reference RPDEV indicates a voltage value in step S757, the measurement device 1 returns to the PDEV measurement processing shown in FIG. 13 and completes the reference voltage update processing of step S75 in the PDEV measurement processing.

[0232] Next, the result output process of step S8 in the measurement method shown in FIG. 7 will be described with reference to FIG.

[0233] FIG. 15 is a flowchart showing an example of a processing procedure for the result output processing executed in step S8.

[0234] In step S81, the measurement device 1 records in the storage unit 60 the measurement results obtained in the processes of steps S1 to S7.

[0235] The measurement results include the discharge ratio Rd obtained for each value of the impulse voltage Vin, the partial discharge peak value, PDIV, RPDIV, the turn-back voltage value, PDEV, RPDEV, reference PDEV, reference RPDEV, and the like.

[0236] In step S82, the measuring device 1 displays the above measurement results on the screen of the display unit 10. For example, the display unit 10 displays the number of discharges or the discharge ratio Rd among the number of repeated applications of the impulse voltage Vin for each of PDIV, RPDIV, turn-back voltage value, PDEV, and RPDEV.

[0237] In step S83, the measurement device 1 determines whether the voltage values ​​of the reference RPDEV and RPDEV are equal. If the voltage values ​​are equal, the measurement device 1 proceeds to step S84, and if the voltage values ​​are different, the measurement device 1 skips step S84 and proceeds to step S85.

[0238] In step S84, the measuring device 1 displays on the screen of the display unit 10 that there is a difference between the voltage values ​​of the reference RPDEV and RPDEV. This allows the user to understand the validity of the voltage value of RPDEV by referring to the voltage value of the reference RPDEV.

[0239] For example, if the difference between the voltage value of the reference RPDEV and the voltage value of RPDEV is large, the user can understand the trend of the discharge ratio Rd while the impulse voltage Vin is being stepped down and then treat the voltage value of the reference RPDEV as RPDEV.

[0240] In step S85, the measurement apparatus 1 determines whether or not the voltage values ​​of the reference PDEV and the PDEV are equal, and if the voltage values ​​of the reference PDEV and the PDEV are equal, the measurement apparatus 1 proceeds to step S85.

[0241] In step S86, the measuring device 1 displays a message that there is a difference between the voltage values ​​of the reference PDEV and the PDEV on the screen of the display unit 10. This allows the user to understand the validity of the voltage value of the PDEV by referring to the voltage value of the reference PDEV.

[0242] For example, if the difference between the voltage value of the reference PDEV and the voltage value of the PDEV is large, the user may understand the trend of the discharge ratio Rd while the impulse voltage Vin is being stepped down and then treat the voltage value of the reference PDEV as the PDEV.

[0243] When the processing of step S86 is completed, or when the voltage values ​​of the reference PDEV and the PDEV are equal in step S85, the measuring device 1 returns to the measurement method shown in FIG. 7, completes the result output processing of step S8, and ends the series of processing procedures for the measurement method.

[0244] The effects of this embodiment will be described in detail below.

[0245] In this embodiment, the measuring device 1 measures a voltage associated with the occurrence of a partial discharge in a measurement object 2 configured with one or more coils L1 to L3. The measuring device 1 includes an application circuit 40 that repeatedly applies an impulse voltage Vin to the measurement object 2 multiple times, and a detection circuit 50 that detects a partial discharge occurring in the measurement object 2 based on a voltage signal generated in the measurement object 2 by the application circuit 40. The measuring device 1 further includes a calculation unit 30B, a step-up control unit 31, a step-down control unit 32, and a circuit control unit 33.

[0246] The boost control unit 31 functions as a boost control means that controls the operation of the application circuit 40 so that the impulse voltage Vin increases stepwise each time the impulse voltage Vin is repeatedly applied multiple times to the measurement object 2. The circuit control unit 33 functions as a stopping means that stops the increase control of the impulse voltage Vin by the boost control unit 31, based on a state index that indicates the occurrence state of partial discharge detected for each value of the impulse voltage Vin.

[0247] The step-down control unit 32 functions as step-down control means that controls the operation of the application circuit 40 so that the impulse voltage Vin decreases stepwise when the increase control is stopped by the circuit control unit 33. The calculation unit 30B functions as processing means that acquires the number of times partial discharges are detected in the measurement object 2 out of multiple times for each value of the impulse voltage Vin.

[0248] In this embodiment, the measurement method for measuring the voltage related to the occurrence of partial discharge in the measurement object 2 includes steps S18, S25 and S41, steps S42 and S43, steps S62 and S76, and steps S131 to S133.

[0249] Step S131 corresponds to an application step of repeatedly applying an impulse voltage to the object to be measured 2, and step S132 corresponds to a detection step of detecting a partial discharge occurring in the object to be measured 2 based on a voltage signal generated in the object to be measured 2 by step S131. Steps S18, S25, and S41 correspond to a boost control step of increasing the impulse voltage Vin stepwise every time the impulse voltage Vin is repeatedly applied to the object to be measured 2.

[0250] Furthermore, steps S42 and S43 correspond to a stopping step of stopping the increase control of the impulse voltage Vin based on a state index indicating the occurrence state of partial discharge detected for each value of the impulse voltage Vin. Steps S62 and S76 correspond to a step-down control step of gradually decreasing the impulse voltage Vin when the increase control is stopped by steps S42 and S43. Furthermore, step S133 corresponds to a processing step of acquiring the number of times partial discharge has been detected in the measurement object 2 out of multiple times for each value of the impulse voltage Vin.

[0251] In this embodiment, the program is executed by a computer that controls the application circuit 40 and the detection circuit 50 to measure the voltage related to the occurrence of partial discharge in the measurement object 2. This program includes steps S18, S25, and S41, steps S42 and S43, steps S62 and S76, and step S133.

[0252] Steps S18, S25, and S41 correspond to a boost control step of controlling the operation of the application circuit 40 so that the impulse voltage Vin increases stepwise each time the impulse voltage Vin is repeatedly applied to the measurement object 2. Steps S42 and S43 correspond to a stop step of stopping the increase control of the impulse voltage based on a state index indicating the occurrence state of partial discharge detected for each value of the impulse voltage Vin.

[0253] Furthermore, steps S62 and S76 correspond to a step-down control step for controlling the operation of the application circuit 40 so that the impulse voltage Vin decreases stepwise when the increase control is stopped by steps S42 and S43. Also, step S133 corresponds to a processing step for acquiring the number of times partial discharges have been detected in the measurement object 2 out of multiple times for each value of the impulse voltage Vin.

[0254] According to these configurations, the increase control of the impulse voltage Vin applied to the object to be measured 2 is stopped by utilizing a state indicator that indicates the occurrence state of partial discharge in the object to be measured 2. Therefore, it becomes possible to stop the increase control of the impulse voltage Vin when the occurrence state of partial discharge in the object to be measured 2 is in a state that adversely affects the characteristics of the object to be measured 2.

[0255] Therefore, it is possible to prevent excessive voltage application according to the characteristics of the object to be measured 2. As a result, even when controlling the decrease of the impulse voltage Vin, it is possible to measure the voltage related to partial discharge of the object to be measured 2 while suppressing the influence of excessive applied voltage on the object to be measured 2.

[0256] Therefore, it is possible to measure the occurrence state of partial discharge in the object to be measured 2 while suppressing application of an excessive voltage depending on the characteristics of the object to be measured 2.

[0257] Furthermore, the calculation unit 30B in this embodiment calculates the discharge ratio Rd for each value of the impulse voltage Vin by the boost control unit 31, and obtains a first voltage value indicating the magnitude of the impulse voltage when the discharge ratio Rd becomes equal to or greater than a first threshold. Examples of the first voltage value include PDIV indicating a partial discharge inception voltage and RPDIV indicating a repetitive partial discharge inception voltage. When the first voltage value corresponds to PDIV, the first threshold corresponds to the inception threshold T1 described above, and when the first voltage value corresponds to RPDIV, the first threshold corresponds to the boost threshold T1r described above.

[0258] Then, when the impulse voltage Vin is increased by the boost control unit 31 to a value greater than the first voltage value, the circuit control unit 33 stops the increase control of the impulse voltage Vin based on the state index of partial discharge in the object to be measured 2.

[0259] This configuration makes it possible to grasp the increasing trend of the discharge ratio Rd when the impulse voltage Vin is a voltage value higher than the first voltage value, thereby enabling the user to confirm whether the acquired first voltage value is a voltage value when the discharge ratio Rd is increasing monotonically, a voltage value when the discharge ratio Rd suddenly increases, or a voltage value when the increase in the discharge ratio Rd is gradually increasing or decreasing.

[0260] Furthermore, by using the state indicator of partial discharge in the measurement object 2, it is possible to avoid continuous application of an excessive impulse voltage to the measurement object 2. Therefore, it is possible to grasp the validity of the acquired first voltage value while suppressing application of an excessive voltage to the measurement object 2.

[0261] Furthermore, in this embodiment, the PD frequency acquisition unit 35 of the calculation unit 30B acquires the discharge ratio Rd for each value of the impulse voltage Vin by the boost control unit 31 as the above-mentioned state index, and the circuit control unit 33 stops the increase control of the impulse voltage Vin when the discharge ratio Rd reaches the switching threshold Tsw, which is a predetermined threshold greater than the first threshold.

[0262] According to this configuration, the discharge ratio Rd is used as a state index for determining whether to stop the increase control of the impulse voltage Vin. Since the discharge ratio Rd is a state index that indicates the average occurrence state of partial discharge, noise components caused by the randomness of partial discharge are reduced.

[0263] Therefore, it is possible to accurately determine the effect of the applied voltage on the measurement object 2. Therefore, it is possible to avoid a situation in which the increase control of the impulse voltage Vin is stopped due to an accidental partial discharge.

[0264] Furthermore, the PD frequency acquisition unit 35 in this embodiment measures, as a state index, the peak of the voltage signal caused by partial discharge in the measurement object 2 for each value of the impulse voltage Vin by the boost control unit 31. Then, when the discharge peak value indicating the peak of the voltage signal caused by partial discharge exceeds the allowable value To, the circuit control unit 33 stops the increase control of the impulse voltage Vin.

[0265] According to this configuration, the discharge peak value is used as a state indicator for determining whether to stop the increase control of the impulse voltage Vin. The discharge peak value is a state indicator that indicates the occurrence state of each partial discharge, and can directly detect the risk of damage to the measurement object 2 due to the applied voltage.

[0266] Therefore, it is possible to accurately determine the adverse effect of the applied voltage on the measurement object 2. Therefore, it is possible to avoid the occurrence of dielectric breakdown or damage to the measurement object 2 due to the applied voltage.

[0267] Furthermore, the calculation unit 30B in this embodiment acquires, as the second voltage value, the value of the impulse voltage when the discharge ratio Rd first becomes less than the second threshold. Examples of the second voltage value include PDEV, which indicates a partial discharge extinction voltage, and RPDEV, which indicates a repeated partial discharge extinction voltage. When the second voltage value corresponds to PDEV, the second threshold corresponds to the extinction threshold T2 described above, and when the second voltage value corresponds to RPDIV, the second threshold corresponds to the step-down threshold T2r described above.

[0268] Then, the calculation unit 30B acquires the lowest voltage value among the multiple impulse voltages when the discharge ratio Rd becomes less than the second threshold value in a state in which the impulse voltage Vin when the discharge ratio Rd becomes equal to or greater than the second threshold value is lowered by one step by the step-down control unit 32, as a related voltage value related to the second voltage value.

[0269] According to this configuration, by comparing the second voltage value with the related voltage value, it is possible to infer whether the acquired second voltage value is a voltage value when partial discharges become weaker regularly as the impulse voltage decreases, a voltage value when a weak partial discharge occurs accidentally, or a voltage value when the degree of decrease in the discharge ratio Rd gradually increases or decreases. In other words, the validity of the second voltage can be evaluated.

[0270] Furthermore, the measuring device 1 in this embodiment further includes a display unit 10 as a display means for displaying the second voltage value and the related voltage value, thereby enabling the user to understand the validity of the second voltage value.

[0271] In addition, the second voltage value in this embodiment is RPDEV (repeated partial discharge extinction voltage). Therefore, the above-mentioned related voltage value corresponds to the reference RPDEV, and a user can understand the validity of RPDEV by comparing the reference RPDEV with RPDEV.

[0272] In addition, the second voltage value in this embodiment is a partial discharge extinction voltage (PDEV). Therefore, the above-mentioned related voltage value corresponds to a reference PDEV, and a user can understand the validity of the PDEV by comparing the reference PDEV with the PDEV.

[0273] Furthermore, in this embodiment, the measurement device 1 includes a display unit 10 as output means for outputting the results obtained by the calculation unit 30B. The calculation unit 30B acquires a third voltage value, which is a folded voltage value indicating the magnitude of the impulse voltage Vin when the increase control of the impulse voltage Vin is stopped by the circuit control unit 33. The display unit 10 displays the number of discharges or the discharge ratio Rd among the number of repeated applications of the impulse voltage Vin for each of the first to third voltage values ​​acquired by the calculation unit 30B.

[0274] According to this configuration, the number of discharges or the discharge ratio Rd at the first voltage value to the third voltage value acquired by the calculation unit 30B is displayed, so that the user can grasp the validity of these, for example, based on the symmetry of the first voltage value and the third voltage value.

[0275] Furthermore, the circuit control unit 33 in this embodiment determines whether the magnitude of the voltage range of the impulse voltage Vin in which the discharge ratio Rd is continuously 0 percent (e.g., the above-mentioned step-down amount) is greater than a predetermined value when the impulse voltage Vin is being gradually lowered by the step-down control unit 32. If the magnitude of the voltage range of the impulse voltage Vin in which the discharge ratio Rd is continuously 0 percent is greater than the predetermined value, the circuit control unit 33 stops the step-down control of the impulse voltage Vin.

[0276] This configuration makes it possible to end the measurement process without lowering the impulse voltage Vin to the end voltage value of the sweep range, thereby reducing the measurement time while avoiding unnecessary application of the impulse voltage Vin to the measurement object 2.

[0277] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0278] For example, it is possible that the impulse voltage Vin is equivalent to RPDEV when the boost control unit 31 stops increasing the impulse voltage Vin. In such a case, the circuit control unit 33 controls the operation of the application circuit 40 so that the impulse voltage Vin becomes a predetermined voltage value greater than RPDEV, and the PD index acquisition unit 36 ​​acquires the discharge ratio Rd at the predetermined voltage value. By acquiring the discharge ratio Rd at the predetermined voltage value, the validity of RPDEV can be evaluated to some extent.

[0279] In addition, in the present embodiment, the boost stop condition in steps S14, S21, and S41 is determined to be whether the discharge ratio Rd has reached the switching threshold Tsw, but the boost stop condition in this embodiment is not limited to this. For example, at least one of the following may be determined: whether the impulse voltage Vin has reached a predetermined upper limit voltage Vt; or whether the discharge ratio Rd has reached the switching threshold Tsw. In this case, when the measurement device 1 determines that the impulse voltage Vin has reached the predetermined upper limit voltage Vt or that the discharge ratio Rd has reached the switching threshold Tsw, it determines that the boost stop condition is met and stops the increase control of the impulse voltage Vin.

[0280] Alternatively, the boost stop condition may be at least one of determining whether the impulse voltage Vin has reached a predetermined upper limit voltage Vt and determining whether the discharge peak value has exceeded a predetermined allowable value To. In this case, when the measurement device 1 determines that the impulse voltage Vin has reached the predetermined upper limit voltage Vt or that the discharge peak value has exceeded the predetermined allowable value To, it determines that the boost stop condition is met and stops the increase control of the impulse voltage Vin.

[0281] Alternatively, the boost stop condition may be determined by determining whether the discharge ratio Rd has reached the switching threshold Tsw and whether the discharge peak value has exceeded a predetermined allowable value To. In this case, when the measurement device 1 determines that the discharge ratio Rd has reached the switching threshold Tsw or that the discharge peak value has exceeded the predetermined allowable value To, it determines that the boost stop condition is met and stops the increase control of the impulse voltage Vin.

[0282] In addition, in this embodiment, the measurement device 1 is provided with a display unit 10, an operation unit 20, a memory unit 60, and a communication unit 70, but all or at least one of the display unit 10, operation unit 20, memory unit 60, and communication unit 70 may be omitted from the measurement device 1. [Explanation of symbols]

[0283] 1. Measuring equipment 2. Measurement object 10 Display section (output means, display means) 30B Calculation unit (processing means) 31 Boost control section (boost control means) 32 Step-down control section (step-down control means) 33 Circuit control unit (stop means) 40 Application circuit 50 Detection circuit T1 Start threshold (first threshold) T1r Pressure increase threshold (first threshold) T2 extinction threshold (second threshold) T2r Blood Pressure Drop Threshold (Second Threshold) Tsw switching threshold To tolerance

Claims

1. A measuring device for measuring the voltage involved in the occurrence of partial discharge in an object to be measured, which is composed of one or more coils, An application circuit that applies an impulse voltage to the object to be measured multiple times, A detection circuit that detects partial discharge occurring in the object to be measured based on a voltage signal generated in the object by the application circuit, A boost control means controls the operation of the application circuit so that the impulse voltage increases in steps each time the impulse voltage is repeatedly applied to the object to be measured, A stopping means for stopping the boost control means's control of increasing the impulse voltage based on a state index indicating the occurrence state of the partial discharge detected for each value of the impulse voltage, A step-down control means controls the operation of the application circuit so that the impulse voltage decreases in steps when the upward control is stopped by the stopping means, The processing means includes a method for obtaining the number of times a partial discharge was detected in the object being measured out of the multiple times for each value of the impulse voltage, The processing means determines the ratio of the number of times for each value of the impulse voltage by the boost control means, and obtains a first voltage value indicating the magnitude of the impulse voltage when the acquisition criterion is met such that the ratio is equal to or greater than the first threshold included in the state index. The stop means stops the impulse voltage increase control even if the acquisition criterion is not met while the impulse voltage increase control is being continued by the boost control means, if at least one of the stop criteria different from the acquisition criterion is met. Measuring device.

2. A measuring device according to claim 1, The processing means determines the ratio of the number of times for each value of the impulse voltage by the boost control means, One of the aforementioned termination criteria is that the ratio of the number of occurrences reaches a predetermined threshold that is greater than the first threshold. Measuring device.

3. A measuring device according to claim 1, The processing means measures the peak of the voltage signal caused by the partial discharge for each value of the impulse voltage by the boost control means as the state index, One of the aforementioned termination criteria is that the peak of the voltage signal resulting from the partial discharge exceeds an acceptable value. Measuring device.

4. A measurement method for measuring the voltage involved in the occurrence of partial discharge in an object to be measured, which is composed of one or more coils, An application step of repeatedly applying an impulse voltage to the object to be measured multiple times, A detection step for detecting a partial discharge occurring in the object to be measured based on the voltage signal generated in the object to be measured by the application step, A boost control step is performed to gradually increase the impulse voltage each time the impulse voltage is applied to the object to be measured multiple times. A stop step that stops the boost control step from raising the impulse voltage based on a state index indicating the occurrence state of the partial discharge detected for each value of the impulse voltage, A step-down control step that gradually lowers the impulse voltage when the upward control is stopped by the stop step, The process includes a step of obtaining the number of times a partial discharge was detected in the object being measured out of the multiple times for each value of the impulse voltage, The processing step involves determining the ratio of the number of times for each value of the impulse voltage obtained by the boost control step, and obtaining a first voltage value that indicates the magnitude of the impulse voltage when the acquisition criterion is met such that the ratio is equal to or greater than a first threshold included in the state index. The stop step stops the impulse voltage increase control even if the acquisition criterion is not met while the impulse voltage increase control is being continued by the boost control step, if at least one of the stop criteria different from the acquisition criterion is met. Measurement method.

5. A computer controls an application circuit that repeatedly applies an impulse voltage to an object to be measured, which is composed of one or more coils, and a detection circuit that detects a partial discharge occurring in the object to be measured based on the voltage signal generated in the object by the application circuit, in order to measure the voltage related to the occurrence of a partial discharge in the object to be measured. A boost control step controls the operation of the application circuit so that the impulse voltage increases in steps each time the impulse voltage is repeatedly applied to the object to be measured. A stop step that stops the boost control step from raising the impulse voltage based on a state index indicating the occurrence state of the partial discharge detected for each value of the impulse voltage, A step-down control step controls the operation of the application circuit so that the impulse voltage decreases in stages when the upward control is stopped by the stop step, A program for causing a process to execute a processing step of obtaining the number of times a partial discharge was detected in the object to be measured out of the multiple times for each value of the impulse voltage, The processing step involves determining the ratio of the number of times for each value of the impulse voltage obtained by the boost control step, and obtaining a first voltage value that indicates the magnitude of the impulse voltage when the acquisition criterion is met such that the ratio is equal to or greater than a first threshold included in the state index. The stop step stops the impulse voltage increase control even if the acquisition criterion is not met while the impulse voltage increase control is being continued by the boost control step, if at least one of the stop criteria different from the acquisition criterion is met. program.

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