Inspection device and method for inspection

Abstract

To provide an inspection device which has an improved detection accuracy.SOLUTION: An inspection device (1) includes: a piezoelectric element (11); an application unit (12) for applying an AC voltage to the piezoelectric element; and a control unit (14) for operating an input voltage and an output current and detecting an abnormality in a facility as an inspect target according to the result of the operation. The control unit corrects the temperature in the operation result on the basis of the measured input voltage and output current.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an inspection device and an inspection method.

Background Art

[0002] Conventionally, a technique for detecting the presence or absence of an abnormality in equipment by detecting the resonance characteristics of the equipment when vibration is applied to the equipment to be inspected is known. For example, in Patent Document 1, when a voltage is swept in frequency and applied to a piezoelectric element provided in the inspection target (that is, when vibration is applied to the equipment), an inspection device for detecting an abnormality in the equipment from the real part of the admittance of the piezoelectric element (indicating the resonance characteristics of the equipment) is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique of Patent Document 1, it is not considered that the output value (real part of admittance) of the piezoelectric element changes with the change in the ambient temperature of the piezoelectric element. That is, depending on the ambient temperature, the detection accuracy of the inspection device may decrease.

[0005] One aspect of the present invention aims to provide an inspection device capable of improving detection accuracy.

Means for Solving the Problems

[0006] In order to solve the above problems, an inspection device according to an aspect of the present invention includes a piezoelectric element provided in a facility to be inspected, an application unit that applies an alternating voltage to the piezoelectric element by frequency-sweeping within a predetermined frequency range, and a control unit that calculates a voltage value applied to the piezoelectric element by the application unit and a current value flowing through the piezoelectric element, and detects an abnormality in the facility to be inspected according to a calculation result. The control unit performs temperature correction of the calculation result based on the measured voltage value and current value.

[0007] In order to solve the above problems, an inspection method according to an aspect of the present invention includes an application step of applying a voltage to a piezoelectric element provided in a facility to be inspected by frequency-sweeping within a predetermined frequency range, and a detection step of calculating a voltage value applied to the piezoelectric element and a current value flowing through the piezoelectric element, and detecting an abnormality in the facility to be inspected according to a calculation result. The inspection method further includes a temperature correction step of performing temperature correction of the calculation result based on the measured voltage value and current value after the application step and before the detection step.

Advantages of the Invention

[0008] According to an aspect of the present invention, the detection accuracy of the inspection device can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0010] 〔Embodiment 1〕 Hereinafter, an embodiment of the present invention will be described in detail. For convenience of explanation, the same members are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0011] (Internal Structure and Appearance Example of Gas Circuit Breaker) FIG. 1 is a diagram showing the internal structure of a gas circuit breaker 100 in which an inspection device 1 according to an embodiment of the present invention is installed. Note that, as an example of a molded product, the case of the epoxy container 101 of the gas circuit breaker 100 will be described, but the present invention is not limited thereto.

[0012] The gas circuit breaker 100 is a device that is installed in a substation, a power plant, etc. and opens and closes an electric current in an insulating gas, and includes an epoxy container 101, a fixed contact 102, a movable contact 103, a current collector 104, an insulating operating rod 106, and an arc drive coil 107. An insulating gas 105 is enclosed inside the epoxy container 101.

[0013] As the insulating gas 105, for example, sulfur hexafluoride (SF6 gas) is used. The SF6 gas has high insulation, and its dielectric strength is three times that of air. In addition, since the SF6 gas is inert and has high thermal conductivity, it can quickly cool the electrodes heated by arc discharge.

[0014] In this gas circuit breaker 100, the opening and closing of the current is performed by using a magnetic drive effect that rotationally drives the arc by the magnetic force generated by the arc drive coil 107 and a heat buffer effect that effectively utilizes the thermal energy of the arc itself.

[0015] The arc generated by the current collector 104 heats the SF6 gas with its own heat to increase the pressure, and blows the SF6 gas against the arc at that pressure to extinguish the arc. By moving the movable contact 103 and the insulating operating rod 106 and separating them from the fixed contact 102, the current is interrupted. FIG. 1 shows a state where the interruption of the current is completed.

[0016] FIG. 2 is a diagram showing an external appearance example of the gas circuit breaker 100 in which the inspection device 1 according to an embodiment of the present invention is installed. The SF6 gas enclosed in the gas circuit breaker 100 has electrical insulation performance, and has insulation performance and current opening and closing performance that are directly proportional to the sealed gas pressure. Therefore, in order to always maintain the performance of the gas circuit breaker 100, it is important to manage the enclosed gas.

[0017] For this management, the operator 200 operates a pressure sensor, a manometer, a gas density switch, etc. for monitoring the gas pressure in the epoxy container 101 filled with gas, and performs management such as outputting an alarm when the gas pressure drops.

[0018] However, there may be a problem that the epoxy container 101 filled with high-pressure SF6 gas cracks. In this case, a rapid gas leak occurs and the opening and closing performance is lost. Therefore, the operator 200 locks the breaker operation.

[0019] In addition, when the gas pressure decreases, events such as the insulation performance during current opening and closing cannot be maintained may occur, which may lead to significant damage. Therefore, it is desirable to detect a crack, which is a stage before the epoxy container 101 cracks. However, among small cracks, it is difficult to find them by visual inspection or gas pressure, and it is difficult to detect an initial state abnormality.

[0020] In this embodiment, before a major problem such as cracking of the epoxy container 101 filled with high-pressure gas occurs, abnormalities such as cracks, small chips, and distortions in the epoxy container 101 can be easily detected. For this purpose, as shown in FIG. 2, a piezoelectric element 11 is provided on a metal frame 120 that connects the gas circuit breaker 100 and the operating device 200.

[0021] FIG. 3 is a diagram showing the position where the piezoelectric element 11 of the inspection device 1 according to this embodiment is installed. An insulating spacer 220 is provided between the GIS (Gas Insulated Switchgears) tank 110 on the gas circuit breaker 100 side and the GIS tank 210 on the operating device 200 side, and a gas compartment of the GIS is configured.

[0022] The piezoelectric element 11 is pressed against the flat surface portion of the insulating spacer 220 or an adjacent metal portion by a cloth band, a magnet, or the like. Also, the piezoelectric element 11 may be pressed against the epoxy container 101, or the piezoelectric element 11 may be pressed against the metal frame 120 as described above.

[0023] (Functional Configuration of Inspection Device) FIG. 4 is a block diagram showing the functional configuration of the inspection device 1 according to an embodiment of the present invention. The inspection device 1 includes a piezoelectric element 11, an application unit 12, a measurement unit 13, a control unit 14, a storage unit 15, and an output unit 16. The inspection device 1 is a device that detects abnormalities in the gas circuit breaker 100, which is an example of the equipment to be inspected.

[0024] The piezoelectric element 11 is provided in the gas circuit breaker 100, which is an example of the equipment to be inspected. The piezoelectric element 11 generates vibrations in the gas circuit breaker 100 when a voltage is applied by the application unit 12 described later. Also, the piezoelectric element 11 outputs an output current corresponding to the vibrations transmitted from the gas circuit breaker 100. The piezoelectric element 11 may be provided at a position where it can generate vibrations in the gas circuit breaker 100 and detect the vibrations (for example, the positions shown in FIGS. 2 and 3).

[0025] The application unit 12 is electrically connected to two electrodes connected to the piezoelectric element 11 via a measurement resistor R. The application unit 12 applies an AC voltage to the piezoelectric element 11 by frequency-sweeping it within a predetermined frequency range. Specifically, the application unit 12 applies an AC voltage to the piezoelectric element 11 while continuously or stepwise changing the AC voltage within a predetermined frequency range. For example, the application unit 12 gradually increases the frequency from F1 [kHz] to F2 [kHz] over a predetermined time T1 [seconds] and applies an AC voltage with a constant amplitude to the piezoelectric element 11. Note that the amplitude of the AC voltage, the frequency range F1 [kHz] to F2 [kHz], and the predetermined time T1 [seconds] may be appropriately changed according to the equipment to be inspected and the characteristics of the piezoelectric element 11. Also, the amplitude of the AC voltage does not necessarily have to be constant. Further, the application unit 12 may switch the frequency randomly between F1 [kHz] and F2 [kHz].

[0026] The measurement unit 13 is connected to two electrodes connected to the piezoelectric element 11 and both ends of the measurement resistor R. The measurement unit 13 measures the input voltage input to the piezoelectric element 11 and the output current flowing through the piezoelectric element 11 when vibration is generated in the gas circuit breaker 100 via the piezoelectric element 11. Specifically, the measurement unit 13 measures the voltage between the two electrodes connected to the piezoelectric element 11 as the input voltage when the application unit 12 is applying an AC voltage to the piezoelectric element 11. Also, the measurement unit 13 measures the current flowing through the measurement resistor R as the output current when the application unit 12 is applying an AC voltage to the piezoelectric element 11. The measurement unit 13 performs A / D conversion on the measurement results of the input voltage and the output current and outputs them to the control unit 14. Note that since the resistance value of the measurement resistor R is sufficiently small compared to the impedance of the piezoelectric element 11, the measured input voltage can be regarded as the voltage applied to the piezoelectric element 11. Also, a value obtained by subtracting the voltage across both ends of the measurement resistor R from the measured input voltage may be used as the input voltage input to the piezoelectric element 11 for subsequent calculations. Further, when the upper limit of the sweep frequency range is high (i.e., when the impedance of the piezoelectric element 11 is low and the resistance value of the measurement resistor R cannot be ignored), the four-terminal method may be used for the measurement.

[0027] The control unit 14 comprehensively controls each member of the inspection device 1. For example, the control unit 14 controls the voltage supply to the piezoelectric element 11 by the application unit 12. Further, the control unit 14 stores the data input from the measurement unit 13 in a storage unit 15 described later. In the present embodiment, the control unit 14 includes an acquisition unit 141, a correction unit 142, and a detection unit 143.

[0028] The acquisition unit 141 acquires, from the measurement unit 13, the value of the input voltage and the value of the output current during a predetermined time T1, which are the measurement values measured by the measurement unit 13. Then, the acquisition unit 141 calculates the admittance of the piezoelectric element 11 when an AC voltage is applied to the piezoelectric element 11 with frequency sweeping from the measurement values.

[0029] Specifically, the acquisition unit 141 acquires the waveforms of the input voltage and the output current in the frequency domain obtained by performing Fourier transform on the waveforms of the input voltage and the output current (waveforms over time; waveforms in the time domain) measured by the measurement unit 13. That is, the acquisition unit 141 calculates the values of the input voltage and the output current for each frequency in the frequency range F1 to F2. Fourier transform is an example of frequency analysis (frequency conversion) for converting a waveform in the time domain into a waveform in the frequency domain. Hereinafter, the values and waveforms etc. after performing this conversion are referred to as the values and waveforms etc. after frequency conversion.

[0030] The acquisition unit 141 obtains the admittance waveform by dividing each value of the output current after frequency conversion by each value of the input voltage after frequency conversion. That is, the acquisition unit 141 calculates the admittance after frequency conversion. Specifically, the acquisition unit 141 calculates the admittance for each frequency in the frequency range F1 to F2. The value of the real part of the admittance acquired by the acquisition unit 141 is, for example, data with a 1 Hz step in the frequency range F1 [kHz] to F2 [kHz]. Hereinafter, unless otherwise specified, the admittance for each frequency in the frequency range F1 to F2 is simply referred to as "admittance". Also, the real part of the admittance calculated by the acquisition unit 141 is referred to as the "measured value of the real part of the admittance".

[0031] The correction unit 142 performs temperature correction on the measured value of the real part of the admittance. Temperature correction means considering that the value of the output current output from the piezoelectric element 11 changes as the ambient temperature of the piezoelectric element 11 changes, and converting the calculation result obtained from the output current (the measured value of the real part of the admittance) into the calculation result when the ambient temperature of the piezoelectric element 11 is the reference temperature. Details of the temperature correction will be described later.

[0032] FIG. 5 is a graph showing the frequency characteristics of the value of the real part of the admittance when the ambient temperature is 0° C. (in this embodiment, a temperature other than the reference temperature) and 20° C. (in this embodiment, the reference temperature). In FIG. 5, the vertical axis represents the value of the real part of the admittance [S], and the horizontal axis represents the frequency [kHz].

[0033] As shown in FIG. 5, as the ambient temperature of the piezoelectric element 11 changes, the value of the real part of the admittance of the piezoelectric element 11 also changes. Specifically, the baseline of the graph showing the value of the real part of the admittance when the ambient temperature is 0° C. is overall lower compared to the baseline of the graph showing the value of the real part of the admittance when the ambient temperature is 20° C. Also, the frequency at which the peak value is taken is different between the case where the ambient temperature is 0° C. and the case where the ambient temperature is 20° C.

[0034] The detection unit 143 detects an abnormality of the gas circuit breaker 100 (specifically, the occurrence of cracks or the like in the epoxy container 101) according to the calculation result. In this embodiment, the calculation result is the value of the real part of the admittance subjected to temperature correction by the correction unit 142 (hereinafter referred to as the corrected value of the real part of the admittance). The detection unit 143 checks whether there is an abnormality in the gas circuit breaker 100 by comparing the frequency characteristics of the real part of the admittance during normal times with the frequency characteristics of the measured real part of the admittance. Here, the data showing the frequency characteristics of the real part of the admittance during normal times is stored in the storage unit 15 in advance.

[0035] The detection unit 143 detects an abnormality of the gas circuit breaker 100 according to the peak value of the real part of the admittance. For example, the detection unit 143 detects an abnormality of the gas circuit breaker 100 according to the change in the magnitude of the peak in a predetermined frequency band. Specifically, the detection unit 143 may subtract the component of the real part of the admittance measured from the component of the real part of the admittance in the normal state while monotonically increasing the frequency, and detect a location where the difference in the peak value becomes large based on the value. Also, the values of peak A and peak B in a predetermined frequency band in the normal state are extracted, and a threshold value for determining an abnormality is determined in advance from the ratio of the values of peak A and peak B. Then, the detection unit 143 may calculate the ratio of the value of peak A to the value of peak B in the graph of the object to be inspected, and detect an abnormality of the gas circuit breaker 100 by comparing the ratio with the above threshold value.

[0036] The storage unit 15 stores various data used by the control unit 14. For example, the storage unit 15 stores a temperature correction method. Also, the storage unit 15 stores the frequency characteristics of the real part of the admittance in the normal state and a method for detecting an abnormality of the gas circuit breaker 100.

[0037] The output unit 16 notifies an abnormality of the gas circuit breaker 100 based on the detection result of the detection unit 143. The output unit 16 may be a speaker. In this case, the output unit 16 may output a predetermined alert sound based on the detection result of the detection unit 143.

[0038] Note that instead of correcting the measured value of the real part of the admittance, the threshold value used for detecting an abnormality of the gas circuit breaker 100 may be corrected.

[0039] (Details of Temperature Correction) FIG. 6 is a graph showing the frequency characteristics of the measured value of the real part of the admittance. FIG. 7 is a graph showing the temperature characteristics of the value of the real part of the admittance. With reference to FIGS. 6 and 7, an example of the temperature correction performed by the correction unit 142 will be described below.

[0040] The correction unit 142 extracts (2001) measurement values of the real part of the admittance in the first frequency range Fa1[kHz] - 1kHz to Fa1[kHz] + 1kHz (see FIG. 6) within the frequency range F1[kHz] to F2[kHz]. Then, the correction unit 142 calculates a statistical value (for example, an average value) corresponding to the measurement value of the real part of the admittance in the first frequency range.

[0041] The first frequency range is selected such that the difference between the maximum value and the minimum value of the real part of the admittance in the first frequency range is smaller than the difference between the maximum value and the minimum value of the real part of the admittance in the second frequency range. Here, the second frequency range is a range within the frequency range F1[kHz] to F2[kHz] that is different from the first frequency range, temperature correction is performed, and it includes measurement values (that is, peak values) used for detecting abnormalities in the gas circuit breaker 100. That is, the first frequency range is compared with the second frequency range that includes the measurement values used for detecting abnormalities in the gas circuit breaker 100, and includes a graph closer to the baseline of the graph showing the measurement values of the real part of the admittance.

[0042] By selecting the first frequency range in this way, the first frequency range becomes a range where the real part of the admittance has as few peak value portions as possible. In other words, the first frequency range becomes a range that contains as few components contributing to the resonance characteristics of the facility to be inspected as possible.

[0043] The first frequency range may be selected such that the difference between the maximum value and the minimum value of the real part of the admittance in the first frequency range is equal to or less than a predetermined threshold value.

[0044] Next, the correction unit 142 acquires from the storage unit 15 data (see FIG. 7) showing the temperature characteristics of the value of the real part of the admittance at the frequency Fa1. In FIG. 7, the vertical axis represents the value y[S] of the real part of the admittance, and the horizontal axis represents the temperature difference x[°C] with respect to the reference temperature of the ambient temperature. In the present embodiment, the value y of the real part of the admittance is approximately represented by a fourth-order polynomial (in the present embodiment, the following formula (1)) with respect to the temperature difference x.

Equation

[0045] Note that the approximate equation showing the relationship between the value y of the real part of the admittance and the temperature difference x is created in advance by providing the piezoelectric element 11 to the normal gas circuit breaker 100 (as shown in FIG. 3) and plotting several values of the real part of the admittance with respect to the ambient temperature of the piezoelectric element 11. The approximate equation is created using a known method (for example, the least squares method). Further, the approximate equation is not limited to the above-described fourth-degree polynomial, and may be other polynomials, exponential equations, or logarithmic equations.

[0046] Next, the correction unit 142 corrects the measured value of the real part of the admittance in the frequency range F1 [kHz] to F2 [kHz] according to the following Equation (2) based on the temperature difference x = -20°C.

Equation

Equation

[0047] As described above, as temperature correction, the correction unit 142 corrects the measured value of the real part of admittance in a second frequency range different from the first frequency range based on the measured value of the real part of admittance in the first frequency range.

[0048] FIG. 8 is a graph showing the frequency characteristics of the measured value of the real part of admittance and the corrected value of the real part of admittance. FIG. 9 is a graph showing the frequency characteristics of the value of the real part of admittance and the corrected value of the real part of admittance when the ambient temperature is the reference temperature.

[0049] As shown in FIG. 8, the baseline of the graph showing the corrected value of the real part of admittance is overall rising as compared with the baseline of the graph showing the measured value of the real part of admittance. Further, as shown in FIG. 9, the graph showing the corrected value of the real part of admittance substantially coincides with the graph showing the value of the real part of admittance when the ambient temperature is the reference temperature. This indicates that the decrease in the baseline (see FIG. 5) due to the ambient temperature of 0°C being lower than the reference temperature of 20°C can be restored to the original by temperature correction. That is, by temperature correction, the measured value of the real part of admittance when the ambient temperature is a temperature other than the reference temperature can be converted into the measured value when the ambient temperature is the reference temperature. Therefore, by detecting the abnormality of the gas circuit breaker 100 using the corrected value of the real part of admittance, the detection accuracy of the inspection device 1 can be improved.

[0050] <Processing of the inspection device 1> FIG. 10 is a flowchart showing an example of the process in which the inspection device 1 detects an abnormality of the gas circuit breaker 100. With reference to FIG. 10, an example of the operation in which the inspection device 1 calculates the input voltage and the output current and detects an abnormality of the equipment of the gas circuit breaker 100 according to the calculation result will be described below.

[0051] As shown in FIG. 10, first, the application unit 12 applies an AC voltage to the piezoelectric element 11 by frequency-sweeping it within a predetermined frequency range (application step S1). Specifically, the application unit 12 gradually increases the frequency from F1 to F2 during a predetermined time T1 and applies an AC voltage having a constant amplitude to the piezoelectric element 11. As a result, the piezoelectric element 11 gradually increases the vibration frequency from F1 to F2 and applies the vibration to the gas circuit breaker 100.

[0052] Next, the measurement unit 13 measures the input voltage generated in the piezoelectric element 11 and the output current flowing through the piezoelectric element 11 when the gas circuit breaker 100 generates vibration via the piezoelectric element 11 (S2). The measurement unit 13 performs A / D conversion on the measurement results of the input voltage and the output current and outputs them to the control unit 14. The control unit 14 stores the measurement results of the input voltage and the output current in the storage unit 15 over time.

[0053] Next, the acquisition unit 141 acquires the measurement results of the input voltage and the output current from the storage unit 15. The acquisition unit 141 performs Fourier transform on each of the waveforms of the input voltage and the output current (S3). Next, the acquisition unit 141 calculates the measured value of admittance by dividing each value constituting the waveform of the output current after Fourier transform by each value constituting the waveform of the input voltage after Fourier transform (S4).

[0054] Next, the correction unit 142 performs temperature correction on the measured value of the real part of the admittance and calculates the corrected value of the real part of the admittance (temperature correction step S5). Specifically, the correction unit 142 extracts the measured value of the real part of the admittance in the first frequency range. The first frequency range is a range where the real part of the admittance has as few peak values as possible. The first frequency range may be determined by the correction unit 142 or by an operator. Next, the correction unit 142 calculates a statistical value corresponding to the measured value of the real part of the admittance in the first frequency range. Next, the correction unit 142 acquires data indicating the temperature characteristics of the value of the real part of the admittance at the frequency Fa1 corresponding to the first frequency range, and calculates the ambient temperature of the piezoelectric element 11 from the statistical value based on the data. Next, the correction unit 142 corrects the measured value of the real part of the admittance based on the temperature difference with respect to the reference temperature of the ambient temperature, and calculates the corrected value of the real part of the admittance.

[0055] Next, the detection unit 143 detects an abnormality of the gas circuit breaker 100 according to the corrected value of the real part of the admittance (detection step S6). Specifically, the detection unit 143 checks whether there is an abnormality in the gas circuit breaker 100 by comparing the frequency characteristics of the real part of the admittance in the normal state with the frequency characteristics of the measured real part of the admittance. When the detection unit 143 detects an abnormality of the gas circuit breaker 100 (YES in S6), the output unit 16 outputs an alarm indicating that there is an abnormality in the gas circuit breaker 100 (S7). Then, the operation of the inspection device 1 ends. When the detection unit 143 does not detect an abnormality of the gas circuit breaker 100 (NO in S6), the operation of the inspection device 1 ends.

[0056] (Advantages of the inspection device 1) As described above, in the inspection device 1 that detects an abnormality of the facility to be inspected (gas circuit breaker 100) according to the calculation result (value of the real part of the admittance) obtained by calculating the input voltage and the output current, temperature correction is performed on the calculation result. Thereby, an abnormality of the inspection device can be detected in consideration of the change in the output current accompanying the change in the ambient temperature of the piezoelectric element 11. Therefore, the detection accuracy of the inspection device can be improved.

[0057] Further, the temperature correction is performed based on the input voltage and the output current (the measured value of the real part of the admittance obtained from the input voltage and the output current). That is, it is not necessary to provide a temperature sensor near the piezoelectric element 11 for the temperature correction. Therefore, an increase in the cost and size of the inspection device 1 due to providing a temperature sensor near the piezoelectric element 11 can be avoided.

[0058] Also, in the temperature correction method described above, the measured value of the real part of the admittance is corrected based on the statistical value corresponding to the measured value of the real part of the admittance in the first frequency range. Therefore, the computational amount related to the temperature correction can be reduced.

[0059] 〔Modification Example 1〕 The method of temperature correction performed by the correction unit 142 is not limited to the method described above. Other examples of the temperature correction performed by the correction unit 142 will be described below.

[0060] The correction unit 142 creates an approximation curve of a graph (see FIG. 6) showing the frequency characteristics of the measured value of the real part of the admittance. The approximation curve is a curve representing a component obtained by removing the contribution of the resonance characteristics from the measured value of the real part of the admittance. In the present embodiment, the approximation curve is the baseline of the graph. Specifically, the approximation curve is, for example, an envelope curve on the lower side of the graph. The correction unit 142 creates an envelope curve from the graph by a known method (for example, Hilbert transform). The approximation curve may be, for example, a spline curve connecting the minimum points of the graph.

[0061] Next, as the temperature correction, the correction unit 142 corrects the value of the real part of the admittance so that the approximation curve showing the frequency characteristics of the measured value of the real part of the admittance substantially coincides with a predetermined curve. The predetermined curve is, for example, an approximation curve (in the present embodiment, the baseline) showing the frequency characteristics of the value of the real part of the admittance when the ambient temperature of the piezoelectric element 11 is the reference temperature. Note that it is not always necessary for the approximation curve (of the measured value of the real part of the admittance) to substantially coincide with the predetermined curve, and the value of the real part of the admittance may be corrected so that at least the approximation curve approaches the predetermined curve.

[0062] For example, the correction unit 142 determines the correction coefficient K(f) such that the approximate curve (of the measured value of the real part of the admittance) substantially coincides with a predetermined curve. For example, the correction unit 142 calculates, as the correction coefficient K(f), the ratio of the value of the predetermined curve to the value of the approximate curve at each frequency f. The correction unit 142 calculates the corrected value of the real part of the admittance at each frequency f by multiplying the measured value of the real part of the admittance at each frequency f by the correction coefficient K(f). Thereby, the measured value of the real part of the admittance when the ambient temperature is a temperature other than the reference temperature can be converted into the measured value when the ambient temperature is the reference temperature.

[0063] The temperature correction method shown in Modification 1 does not require determining a first frequency range that does not include a component contributing to the resonance characteristics of the facility to be inspected from the frequency characteristics of the measured value of the real part of the admittance, as compared with the temperature correction method described in Embodiment 1. Therefore, by previously storing in the storage unit 15 an approximate curve (predetermined curve) showing the frequency characteristics of the value of the real part of the admittance of the piezoelectric element 11 at a certain temperature, the inspection device 1 can automatically perform temperature correction. For example, the above-mentioned predetermined curve can be obtained by measuring the input voltage and output current at the reference temperature after installing the piezoelectric element 11 in the facility to be inspected. Also, for example, the above-mentioned predetermined curve can be obtained by measuring the input voltage and output current at the reference temperature in a state where the piezoelectric element 11 is installed in a sample having characteristics (such as rigidity or resonance frequency) similar to those of the facility to be inspected before installing the piezoelectric element 11 in the facility to be inspected.

[0064] 〔Modification 2〕 Still another example of the temperature correction performed by the correction unit 142 will be described below. The point that the correction unit 142 creates an approximate curve showing the frequency characteristics of the measured value of the real part of the admittance is the same as in Modification 1.

[0065] The correction unit 142 may adjust the input voltage so that an approximate curve showing the frequency characteristics of the measured value of the real part of the admittance substantially coincides with a predetermined curve as temperature correction. Note that it is not always necessary for the approximate curve (of the measured value of the real part of the admittance) to substantially coincide with the predetermined curve, and the input voltage may be adjusted as long as the approximate curve at least approaches the predetermined curve. For example, the correction unit 142 adjusts the input voltage so that the difference between the value of the approximate curve at a predetermined frequency and the value of the predetermined curve is equal to or less than a predetermined threshold. Also, for example, the correction unit 142 adjusts the input voltage based on fitting by the least squares method.

[0066] Thereby, the deviation of the value of the real part of the admittance corresponding to the deviation of the ambient temperature from the reference temperature can be restored by adjusting the input voltage. Therefore, even when the ambient temperature is a temperature other than the reference temperature, by adjusting the input voltage, the measured value of the real part of the admittance can be obtained as the value of the real part of the admittance when the ambient temperature is the reference temperature.

[0067] 〔Example of Realization by Software〕 The functions of the inspection device 1 (hereinafter referred to as the "device") can be realized by a program for causing a computer to function as the device and by programs for causing a computer to function as each control block (particularly each part included in the control unit 14) of the device.

[0068] In this case, the above device includes a computer having at least one control device (for example, a processor) and at least one storage device (for example, a memory) as hardware for executing the above program. By executing the above program with this control device and storage device, each function described in each of the above embodiments is realized.

[0069] The above program may be recorded on one or more computer-readable recording media, not temporarily. This recording medium may or may not be provided in the above device. In the latter case, the above program may be supplied to the above device via any wired or wireless transmission medium.

[0070] In addition, part or all of the functions of each of the above control blocks can also be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the above control blocks is formed is also included in the scope of the present invention. In addition to this, for example, it is also possible to realize the functions of each of the above control blocks by a quantum computer.

[0071] (Summary) The inspection device according to Aspect 1 of the present invention includes a piezoelectric element provided in equipment to be inspected, an application unit that applies an alternating voltage to the piezoelectric element with frequency sweeping within a predetermined frequency range, a voltage value applied to the piezoelectric element by the application unit, and a current value flowing through the piezoelectric element, and a control unit that calculates the voltage value and the current value and detects an abnormality in the equipment to be inspected according to the calculation result. The control unit performs temperature correction of the calculation result based on the measured voltage value and current value.

[0072] In the inspection device according to Aspect 2 of the present invention, in the above Aspect 1, the control unit may detect an abnormality in the equipment to be inspected according to the peak value of the real part of the admittance obtained by dividing the current value by the voltage value.

[0073] In the inspection device according to Aspect 3 of the present invention, in the above Aspect 2, the control unit may perform Fourier transform on the voltage value and the current value, and detect an abnormality in the equipment to be inspected according to the peak value of the real part of the admittance calculated for each frequency component.

[0074] In the inspection device according to Aspect 4 of the present invention, in the above Aspect 3, as the temperature correction, the control unit corrects the value of the real part of the admittance in a second frequency range different from the first frequency range based on the value of the real part of the admittance in the first frequency range, and the difference between the maximum value and the minimum value of the real part of the admittance in the first frequency range may be smaller than the difference between the maximum value and the minimum value of the real part of the admittance in the second frequency range.

[0075] In the inspection device according to aspect 5 of the present invention, in the above aspect 3, as the temperature correction, the control unit may correct the value of the real part of the admittance so that an approximate curve showing the frequency characteristics of the real part of the admittance substantially coincides with a predetermined curve.

[0076] In the inspection device according to aspect 6 of the present invention, in the above aspect 3, as the temperature correction, the control unit may adjust the voltage value so that an approximate curve showing the frequency characteristics of the real part of the admittance substantially coincides with a predetermined curve.

[0077] The inspection method according to aspect 7 of the present invention includes an application step of applying a voltage to a piezoelectric element provided in equipment to be inspected by frequency-sweeping within a predetermined frequency range, and a detection step of calculating a voltage value applied to the piezoelectric element and a current value flowing through the piezoelectric element, and detecting an abnormality of the equipment to be inspected according to the calculation result. The inspection method further includes a temperature correction step of performing temperature correction of the calculation result based on the measured voltage value and current value after the application step and before the detection step.

[0078] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0079] 1 Inspection device 11 Piezoelectric element 12 Application unit 13 Measurement unit 14 Control unit 100 Gas circuit breaker (an example of equipment to be inspected)

Claims

1. A piezoelectric element provided in the equipment to be inspected, An application unit that applies an alternating voltage to the piezoelectric element by frequency-sweeping within a predetermined frequency range, A control unit that calculates the voltage value applied to the piezoelectric element by the application unit and the current value flowing through the piezoelectric element, and detects an abnormality in the equipment to be inspected according to the calculation result, The control unit performs temperature correction of the calculation result based on the measured voltage value and current value, and it is an inspection device.

2. The control unit detects an abnormality in the equipment to be inspected according to the peak value of the real part of the admittance obtained by dividing the current value by the voltage value, and it is the inspection device according to Claim 1.

3. The control unit performs Fourier transform on the voltage value and the current value, and detects an abnormality in the equipment to be inspected according to the peak value of the real part of the admittance calculated for each frequency component, and it is the inspection device according to Claim 2.

4. As the temperature correction, the control unit corrects the value of the real part of the admittance in a second frequency range different from the first frequency range based on the value of the real part of the admittance in the first frequency range, The difference between the maximum value and the minimum value of the real part of the admittance in the first frequency range is smaller than the difference between the maximum value and the minimum value of the real part of the admittance in the second frequency range, and it is the inspection device according to Claim 3.

5. As the temperature correction, the control unit corrects the value of the real part of the admittance so that the approximate curve showing the frequency characteristics of the real part of the admittance approaches a predetermined curve, and it is the inspection device according to Claim 3.

6. As the temperature correction, the control unit adjusts the voltage value so that the approximate curve showing the frequency characteristics of the real part of the admittance approaches a predetermined curve, and it is the inspection device according to Claim 3.

7. An application step of applying a voltage to a piezoelectric element provided in the equipment to be inspected by frequency-sweeping within a predetermined frequency range, An inspection method including a detection step of calculating the voltage value applied to the piezoelectric element and the current value flowing through the piezoelectric element, and detecting an abnormality in the equipment to be inspected according to the calculation result, After the application step and before the detection step, it further includes a temperature correction step of performing temperature correction of the calculation result based on the measured voltage value and current value.

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