Determination device and determination method

Abstract

To provide a determination device which can properly determine a change of a degree of vacuum in a vacuum vessel.SOLUTION: A determination device (1) includes: a vibration part (3) which applies vibration to a vacuum vessel (61); a detection part (4) which detects vibration transmitted from the vacuum vessel when the vibration part applies the vibration to the vacuum vessel; and a determination part (132) which determines a change of a degree of vacuum of the vacuum vessel based on a change of a natural vibration frequency of the vacuum vessel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to a determination device for determining a change in the degree of vacuum in a vacuum vessel.

Background Art

[0002] There is known a vacuum valve (vacuum interrupter) in which a pair of contacts that can contact and separate from each other is provided inside a vacuum vessel. The vacuum valve is installed, for example, in a vacuum circuit breaker provided in a power cutoff facility to cut off an electric circuit. In such a vacuum valve, when the degree of vacuum inside the vacuum vessel decreases, the insulation performance, that is, the interruption performance, deteriorates. Therefore, a technique for determining a decrease in the degree of vacuum inside the vacuum vessel is required.

[0003] Patent Document 1 discloses a technique for detecting an electromagnetic wave generated along with internal discharge of a vacuum valve, specifying a discharge start voltage, and estimating the degree of vacuum of the vacuum valve based on a Paschen curve showing the correlation between the discharge start voltage and the degree of vacuum. Further, Patent Document 2 discloses a technique for determining whether a signal detected by an antenna when discharge occurs in a vacuum valve is based on discharge due to deterioration of the degree of vacuum in the vacuum valve.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technology described in Patent Document 1 has a problem in that it requires a complex filter to distinguish between electromagnetic waves generated by partial discharges occurring inside the vacuum valve and electromagnetic waves generated by partial discharges occurring outside the vacuum valve. Furthermore, the technology described in Patent Document 2 has a problem in that when electromagnetic noise synchronized with commercial frequency generated outside the vacuum valve is mixed in, it may be possible to mistakenly determine that the vacuum level has decreased.

[0006] One aspect of the present invention aims to provide a determination device that can appropriately determine changes in the vacuum level of a vacuum container. [Means for solving the problem]

[0007] To solve the above problems, a determination device according to one aspect of the present invention comprises: an excitation unit that applies vibration to a vacuum vessel; a detection unit that detects vibration transmitted from the vacuum vessel when the excitation unit applies vibration to the vacuum vessel; and a determination unit that determines a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel. The determination device may further include an excitation unit that applies vibration to the vacuum vessel.

[0008] Furthermore, the excitation unit and the detection unit may be the same piezoelectric element. Alternatively, the excitation unit and the detection unit may be separate piezoelectric elements, and these separate piezoelectric elements may be provided at positions that sandwich the vacuum vessel. Furthermore, these separate piezoelectric elements may function as both the excitation unit and the detection unit, and the determination unit may determine the change in the natural frequency of the vacuum vessel based on the vibration detected by each of the separate piezoelectric elements.

[0009] Furthermore, the vacuum container may constitute a vacuum valve together with a pair of contacts in the circuit breaker. The vibration unit and detection unit may also be provided on the outer surface of the tank housing the vacuum valve. Alternatively, the vibration unit and detection unit may be provided inside the tank housing the vacuum valve. Furthermore, the vibration unit and detection unit may be provided on the outer surface of the vacuum valve.

[0010] To solve the above problems, a determination method according to one aspect of the present invention includes an excitation step of applying vibration to a vacuum vessel, a detection step of detecting vibration transmitted from the vacuum vessel when vibration is applied to the vacuum vessel by the excitation step, and a determination step of determining a change in the degree of vacuum of the vacuum vessel based on a change in the natural frequency of the vacuum vessel. [Effects of the Invention]

[0011] According to one aspect of the present invention, changes in the vacuum level of a vacuum container can be appropriately determined. [Brief explanation of the drawing]

[0012] [Figure 1] This is a block diagram showing an example of the main components of a determination system according to one embodiment of the present invention. [Figure 2] This figure shows an example of a measurement circuit in a judgment system. [Figure 3] This flowchart shows an example of a judgment process in which a judgment system determines a decrease in the vacuum level of a vacuum container. [Figure 4] This block diagram shows another example of the main components of a judgment system. [Figure 5] This block diagram shows yet another example of the main components of a judgment system. [Figure 6] This figure shows another example of a measurement circuit in a judgment system. [Modes for carrying out the invention]

[0013] [Embodiment 1] Hereinafter, Embodiment 1 of the present disclosure will be described in detail with reference to Figures 1 to 4. Figure 1 is a block diagram showing the configuration of the main part of the determination system 100. Figure 2 is a diagram showing an example of a measurement circuit in the determination system 100. In the following description, a determination device for determining a decrease in the vacuum degree of a vacuum vessel in a circuit breaker will be used as an example. However, the determination device according to this embodiment is not limited to a vacuum vessel in a circuit breaker, but can be applied to vacuum vessels in various situations.

[0014] Figure 1 is a block diagram showing an example of the main components of the determination system 100. As shown in Figure 1, the determination system 100 includes a determination device 1 and a circuit breaker 2. First, before describing the configuration of the determination device 1, the configuration of the circuit breaker 2 will be explained below.

[0015] (Outline configuration of circuit breaker 2) The circuit breaker 2 (switching device) comprises a tank 50, a vacuum valve 60, and an actuator 70. The circuit breaker 2 is used, for example, to interrupt an electrical circuit in a power interruption system. Examples of circuit breakers 2 include vacuum circuit breakers and gas circuit breakers.

[0016] Tank 50 is a sealed tank that houses the vacuum valve 60, which will be described later. If the circuit breaker 2 is a gas-insulated switchgear, tank 50 is filled with an insulating gas (e.g., dry air). If the circuit breaker 2 is a vacuum circuit breaker, the inside of tank 50 is maintained at a predetermined vacuum level (vacuum state).

[0017] Further, a first electric circuit 51, which is one of the electric circuits (the upper side in FIG. 1) in the power cutoff equipment, and a second electric circuit 52, which is the other electric circuit (the lower side in FIG. 1) in the power cutoff equipment, penetrate through the tank 50 and are introduced into the interior of the tank 50. Inside the tank 50, an insulating member for supporting the vacuum valve 60 while maintaining the insulation between the electric circuit in the power cutoff equipment and the tank 50 is provided. Specifically, inside the tank 50, a first insulating member 53 is provided between the first electric circuit 51 and the upper part of the tank 50. Also, inside the tank 50, a second insulating member 54 is provided between the second electric circuit 52 and the lower part of the tank 50.

[0018] The vacuum valve 60 includes a vacuum container 61, a fixed contact 62, and a movable contact 63. The vacuum container 61 is maintained at a predetermined degree of vacuum and houses the fixed contact 62 and the movable contact 63. The fixed contact 62 is connected to the first electric circuit 51 and has a contact point with the movable contact 63 at the end on the vacuum container 61 side. The fixed contact 62 is fixed to the vacuum container 61. The movable contact 63 is connected to the second electric circuit 52 and has a contact point with the fixed contact 62 at the end on the vacuum container 61 side. The movable contact 63 is provided so as to be movable in the vertical direction with respect to the vacuum container 61.

[0019] The operator 70 can be operated manually or electrically and moves the movable contact 63 in the vertical direction. The operator 70 is provided outside the tank 50, and the joint portion between the operator 70 and the tank 50 penetrates through the tank 50 while maintaining the airtightness of the tank 50.

[0020] During the closing operation of the vacuum valve 60, the movable contact 63 is moved upward by the operator 70, and the fixed contact 62 and the movable contact 63 come into contact with each other. Thereby, the electric circuit in the power cutoff equipment is connected. During the opening operation of the vacuum valve 60, the movable contact 63 is moved downward by the operator 70, and the fixed contact 62 and the movable contact 63 are separated from each other. Thereby, the electric circuit in the power cutoff equipment is cut off.

[0021] Here, as long as the vacuum container 61 maintains a vacuum state, the arc generated between the fixed contact 62 and the movable contact 63 when the vacuum valve 60 is opened diffuses and is extinguished. In other words, the electrical circuit can be interrupted. On the other hand, if the vacuum level inside the vacuum container 61 decreases, the insulation performance, i.e., the interruption performance, of the vacuum valve 60 decreases. To prevent such a decrease in the interruption performance of the vacuum valve 60 due to a decrease in the vacuum level inside the vacuum container 61, the determination system 100 according to this embodiment is provided with a determination device 1 that determines the decrease (change) in the vacuum level of the vacuum container 61.

[0022] (Configuration of the determination device 1) Next, the configuration of the determination device 1 will be described below. The determination device 1 comprises an excitation unit 3, a detection unit 4, an application unit 11, a measurement unit 12, a control unit 13, a storage unit 14, and an alarm unit 15. The determination device 1 determines the decrease in the vacuum level of the vacuum container 61 in the circuit breaker 2. Hereinafter, the vacuum container 61 in which the vacuum state is maintained will be referred to as the normal vacuum container 61.

[0023] The vibration excitation unit 3 applies vibration to the vacuum vessel 61. The vibration excitation unit 3 is located near the vacuum vessel 61. In the example shown in Figure 1, the vibration excitation unit 3 is located at a position corresponding to the first insulating member 53 on the outer surface of the tank 50. The vibration excitation unit 3 is, for example, a piezoelectric element. In this case, the vibration excitation unit 3 generates vibration when a voltage is applied by the application unit 11, which will be described later. Alternatively, vibration may be generated by an excitation source that transmits vibration to the vacuum vessel 61 from a position away from the vacuum vessel 61, instead of the vibration excitation unit 3.

[0024] The detection unit 4 detects vibrations transmitted from the vacuum vessel 61 when vibrations are applied to the vacuum vessel 61. The detection unit 4 is provided in the vicinity of the vacuum vessel 61. In the example shown in Figure 1, the detection unit 4 is provided at a position corresponding to the second insulating member 54 on the outer surface of the tank 50. The detection unit 4 is, for example, a piezoelectric element. In this case, the detection unit 4 outputs a voltage corresponding to the vibrations transmitted from the vacuum vessel 61. The detection unit 4 only needs to be able to detect vibrations transmitted from the vacuum vessel 61, and may be, for example, an acceleration sensor.

[0025] As shown in Figure 1, the excitation unit 3 and the detection unit 4 are separate piezoelectric elements and are positioned on either side of the vacuum vessel 61. Therefore, the detection unit 4 detects vibrations transmitted from the excitation unit 3 via the vacuum vessel 61, and can appropriately detect the amplitude of vibrations amplified by the resonance of the vacuum vessel 61. Furthermore, the excitation unit 3 and the detection unit 4 are positioned opposite the first insulating member 53 and the second insulating member 54 that support the vacuum valve, with the tank 50 in between. Therefore, the excitation unit 3 can efficiently vibrate the vacuum vessel 61, and the detection unit 4 can efficiently detect vibrations transmitted from the vacuum vessel 61.

[0026] However, the installation positions of the vibration excitation unit 3 and the detection unit 4 are not limited to these. For example, the installation positions of the vibration excitation unit 3 and the detection unit 4 may be swapped. Alternatively, the vibration excitation unit 3 and the detection unit 4 may be provided on the side of the tank 50.

[0027] The application unit 11 applies an input voltage to the excitation unit 3. Specifically, as shown in Figure 2, the excitation unit 3 and the application unit 11 are electrically connected. The application unit 11 applies an AC voltage having a predetermined frequency (determination frequency) as an input voltage to both poles connected to the excitation unit 3. Alternatively, the application unit 11 sweeps the AC voltage within a predetermined frequency range and applies it to the excitation unit 3. As a result, the excitation unit 3 applies vibrations of the determination frequency or vibrations of a predetermined frequency range to the vacuum container 61.

[0028] The measurement unit 12 measures the output voltage output by the detection unit 4. Specifically, as shown in Figure 2, the measurement unit 12 measures the output voltage between the two electrodes connected to the detection unit 4 when the application unit 11 is applying an input voltage to the excitation unit 3.

[0029] The control unit 13 comprehensively controls each component of the determination device 1. For example, the control unit 13 controls the voltage supply from the application unit 11 to the excitation unit 3. The control unit 13 includes a calculation unit 131 and a determination unit 132.

[0030] The calculation unit 131 calculates the amplitude of vibration transmitted from the vacuum vessel from the output voltage measured by the measurement unit 12. For example, the calculation unit 131 calculates the maximum amplitude in the waveform of the output voltage measured by the measurement unit 12 as the amplitude of vibration.

[0031] The determination unit 132 determines, based on the amplitude of the vibration detected by the detection unit 4, the change in the natural frequency of the vacuum container 61, which correlates with the vacuum level of the vacuum container 61. In other words, the determination unit 132 determines, based on the change in the natural frequency of the vacuum container 61, whether or not the vacuum level of the vacuum container 61 has changed (decreased).

[0032] The application unit 11 applies an AC voltage with a determination frequency close to the natural frequency of the vacuum vessel 61 under normal conditions (normal natural frequency) as an input voltage to the excitation unit 3. At this time, the excitation unit 3 applies vibrations of the aforementioned determination frequency to the vacuum vessel 61. When the vacuum vessel 61 maintains a vacuum state, the vacuum vessel 61 resonates at the normal natural frequency. The detection unit 4 detects vibrations amplified by such resonance of the vacuum vessel 61. That is, the amplitude of the sine wave of the determination frequency included in the output voltage waveform becomes sufficiently larger than a predetermined threshold. Also, the maximum amplitude calculated by the calculation unit 131 becomes larger than a predetermined threshold.

[0033] On the other hand, when the vacuum level of the vacuum container 61 decreases, the natural frequency of the vacuum container 61 changes from the natural frequency under normal conditions. Therefore, even if vibrations of the judgment frequency are applied to the vacuum container 61, the vacuum container 61 will not resonate. In other words, the amplitude of the sine wave of the judgment frequency included in the output voltage waveform changes less than the amplitude of the input voltage. Consequently, when the vacuum level of the vacuum container 61 decreases compared to when the vacuum container 61 maintains a vacuum state, the maximum amplitude calculated by the calculation unit 131 also decreases.

[0034] The determination unit 132 determines, for example, whether the maximum amplitude calculated by the calculation unit 131 is below a predetermined threshold. The predetermined threshold is, for example, a voltage value smaller than the normal maximum amplitude. If the maximum amplitude calculated by the calculation unit 131 is greater than the predetermined threshold, that is, if the natural frequency of the vacuum vessel 61 has not changed from the normal natural frequency, the determination unit 132 determines that the vacuum level of the vacuum vessel 61 has not changed (is normal). If the maximum amplitude calculated by the calculation unit 131 is below the predetermined threshold, the determination unit 132 determines that the natural frequency of the vacuum vessel 61 has changed from the normal natural frequency, and that the vacuum level of the vacuum vessel 61 has decreased (changed).

[0035] The calculation unit 131 may also extract a sine wave of the determination frequency from the output voltage waveform. In this case, the determination unit 132 determines whether the amplitude of the extracted sine wave of the determination frequency is below a predetermined threshold.

[0036] The application unit 11 may also apply an AC voltage to the excitation unit 3 while sweeping the frequency within a predetermined range. In this case, the calculation unit 131 calculates the amplitude of the output voltage at each frequency. The determination unit 132 determines that the frequency with the highest amplitude of the output voltage (peak frequency) is the natural frequency of the vacuum vessel 61. The determination unit 132 also determines that the vacuum level of the vacuum vessel 61 has decreased if the natural frequency of the vacuum vessel 61 has changed from the normal natural frequency.

[0037] The memory unit 14 stores various data used by the control unit 13. For example, the memory unit 14 stores the normal natural frequency and predetermined threshold values ​​in advance. The memory unit 14 also stores the output voltage measured by the measurement unit 12 over time. The alarm unit 15 notifies that the vacuum level of the vacuum container 61 is decreasing based on the determination result of the determination unit 132. The alarm unit 15 may be a speaker. In this case, the alarm unit 15 may output a predetermined alert sound based on the determination result of the determination unit 132.

[0038] (Example of operation of the determination device 1) Figure 3 is a flowchart showing an example of a determination process in which the determination device 1 determines a decrease in the vacuum level of the vacuum container 61. Referring to Figure 3, an example of operation in which the determination device 1 determines a decrease in the vacuum level of the vacuum container 61 based on the amplitude of vibration transmitted from the vacuum container 61 when vibration of a determination frequency is applied to the vacuum container 61 will be described below.

[0039] As shown in Figure 3, first, the application unit 11 applies an input voltage to the excitation unit 3 (excitation step S1). Specifically, the application unit 11 applies an AC voltage with a determination frequency close to the normal natural frequency as the input voltage to the excitation unit 3. At this time, the excitation unit 3 applies vibrations of the aforementioned determination frequency to the vacuum container 61.

[0040] Next, the detection unit 4 detects the vibration transmitted from the vacuum vessel 61 when vibration is applied to the vacuum vessel 61. Specifically, the detection unit 4 outputs a voltage corresponding to the vibration transmitted from the vacuum vessel 61. The measurement unit 12 measures this voltage as the output voltage (detection step S2). The measurement unit 12 stores the measured output voltage in the storage unit 14 over time. The calculation unit 131 obtains the waveform of the output voltage measured by the measurement unit 12 from the storage unit 14. The calculation unit 131 calculates the maximum amplitude in this waveform as the amplitude of the vibration (detection step S3).

[0041] Next, the determination unit 132 determines, based on the amplitude of the vibration detected by the detection unit 4, that the natural frequency of the vacuum vessel 61, which correlates with the vacuum level of the vacuum vessel 61, has changed (determination step S4). Specifically, the determination unit 132 determines that the natural frequency of the vacuum vessel 61 has changed if the maximum amplitude calculated by the calculation unit 131 is below a predetermined threshold (YES in S4). In other words, it determines that the vacuum level of the vacuum vessel 61 has decreased (changed). Subsequently, the alarm unit 15 notifies that the vacuum level of the vacuum vessel 61 has decreased (S5), and the operation of the determination device 1 ends. On the other hand, the determination unit 132 determines that the natural frequency of the vacuum vessel 61 has not changed if the maximum amplitude calculated by the calculation unit 131 is not below a predetermined threshold (YES in S4). In other words, it determines that the vacuum level of the vacuum vessel 61 has not changed (is normal). Subsequently, the operation of the determination device 1 ends.

[0042] As described above, the determination device 1 can determine a decrease in the vacuum level of the vacuum container 61 by detecting the amplitude of vibration transmitted from the vacuum container 61 when vibration is applied to the vacuum container 61. Therefore, the determination device 1 can determine a decrease in the vacuum level of the vacuum container 61 with a simple configuration, such as providing a detection unit 4 for detecting the amplitude of vibration near the vacuum container 61. Furthermore, it can detect a decrease in the vacuum level of the vacuum container 61 even in situations where vacuum leakage from the vacuum container 61 cannot be directly detected by a gas sensor or the like.

[0043] Furthermore, in a method that determines the decrease in vacuum level of a vacuum container installed in a circuit breaker by detecting electromagnetic waves associated with partial discharge occurring between the electrodes of the circuit breaker, there is a possibility that electromagnetic noise synchronized with the commercial frequency generated externally may be mixed in, leading to a false determination that the vacuum level has decreased. On the other hand, the determination device 1 according to this embodiment detects the amplitude of vibrations transmitted from the vacuum container 61, and therefore does not have the problem of false determination due to electromagnetic noise as described above.

[0044] Furthermore, in a method that determines the decrease in vacuum level of a vacuum container installed in a circuit breaker by detecting electromagnetic waves associated with partial discharge occurring between the electrodes of the circuit breaker, partial discharge ceases to occur when the vacuum container is filled with insulating gas, making it difficult to detect the decrease in vacuum level. On the other hand, the determination device 1 according to this embodiment can appropriately detect the decrease in vacuum level even when the vacuum container 61 is filled with insulating gas.

[0045] Furthermore, in a method that determines a decrease in the vacuum level of a vacuum container installed in a circuit breaker by applying high voltage between the electrodes of the circuit breaker and detecting whether a continuous discharge occurs between the electrodes, it is necessary to stop the operation of the circuit breaker and open the contacts for the determination. On the other hand, the determination device 1 according to this embodiment can determine a decrease in the vacuum level regardless of the operating state of the circuit breaker 2 (it is not necessary to open the contacts for the determination).

[0046] [Variation 1] The separate piezoelectric elements may function as both an excitation unit and a detection unit. That is, the excitation unit 3 may function as a detection unit. Also, the detection unit 4 may function as an excitation unit. For example, after performing the determination process shown in Figure 3, the determination device 1 may swap the functions of the excitation unit 3 and the detection unit 4 and perform the determination process again. That is, the application unit 11 applies a voltage to the piezoelectric element that was functioning as a detection unit in the previous determination process. The measurement unit 12 measures the voltage output by the piezoelectric element that was functioning as an excitation unit in the previous determination process. The determination unit 132 determines the change in the natural frequency of the vacuum vessel 61 based on the amplitude of vibration detected by each of the separate piezoelectric elements. With this configuration, the determination unit 132 can improve the accuracy of determining the decrease in vacuum by detecting the amplitude of vibration transmitted from the vacuum vessel 61 through two different paths.

[0047] [Variation 2] Figure 4 is a block diagram showing another example of the main components of the determination system 100. As shown in Figure 4, the excitation unit 3 and the detection unit 4 may be provided inside the tank 50 that houses the vacuum valve 60. In the example shown in Figure 4, the excitation unit 3 is provided at a position corresponding to the first insulating member 53 on the inner surface of the tank 50. The detection unit 4 is provided at a position corresponding to the second insulating member 54 on the inner surface of the tank 50. The excitation unit 3 and the detection unit 4 may be provided at a distance from the inner surface of the tank 50, on the first insulating member 53 and the second insulating member 54, respectively.

[0048] [Example 3] Figure 5 is a block diagram showing yet another example of the main components of the determination system 100. As shown in Figure 5, the vibration unit 3 and the detection unit 4 may be provided on the outer surface of the vacuum valve 60.

[0049] [Variation 4] Figure 6 shows another example of a measurement circuit in the judgment system 100. As shown in Figure 6, the excitation unit 3 and the detection unit 4 may be the same (common) piezoelectric element. In this case, the excitation unit 3 (detection unit 4) and the application unit 11 are electrically connected via a resistor R2. The measurement unit 12 measures the output voltage of the resistor R2 (voltage across its terminals) when the application unit 11 applies an input voltage to the excitation unit 3 (detection unit 4). The calculation unit 131 calculates the impedance of the excitation unit 3 (detection unit 4) from the output voltage measured by the measurement unit.

[0050] The application unit 11 applies an AC voltage to the excitation unit 3. When the vacuum vessel 61 resonates at the frequency of the vibration generated in the excitation unit 3 (the frequency of the AC voltage), the impedance of the excitation unit 3 decreases. Therefore, if the impedance is less than a predetermined threshold, the determination unit 132 determines that the natural frequency of the vacuum vessel 61 has not changed and that the vacuum level of the vacuum vessel 61 has not changed. If the impedance is greater than or equal to the predetermined threshold, the determination unit 132 determines that the natural frequency of the vacuum vessel 61 has changed from the normal natural frequency and that the vacuum level of the vacuum vessel 61 has decreased.

[0051] [Examples of implementation using software] The function of the determination device 1 (hereinafter referred to as "the device") is a program that causes the device to function as a computer, and can be realized by a program that causes the computer to function as each control block of the device (particularly each part included in the control unit 13).

[0052] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, the functions described in each of the embodiments are realized.

[0053] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0054] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in the scope of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0055] Furthermore, each process described in the above embodiments may be performed by AI (Artificial Intelligence). In this case, the AI ​​may operate on the control device described above, or it may operate on other devices (for example, an edge computer or a cloud server).

[0056] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of Symbols]

[0057] 1 Judgment device 2 Circuit breakers 3. Vibration section 4. Detection Unit 13 Control Unit 132 Judgment section 14 Storage section 15 Alarm section 50 tanks 60 Vacuum Valves 61 Vacuum container

Claims

1. A vibration unit that applies vibration to a vacuum vessel, A detection unit for detecting vibrations transmitted from the vacuum vessel when the vibration excitation unit applies vibration to the vacuum vessel, The system includes a determination unit that determines a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel, The vibration unit and the detection unit are separate piezoelectric elements, and the separate piezoelectric elements are provided at positions that sandwich the vacuum container, The separate piezoelectric elements mentioned above function as both the excitation unit and the detection unit. The determination unit is a determination device that determines the change in the natural frequency of the vacuum vessel based on the vibration detected by each of the separate piezoelectric elements.

2. A vibration unit that applies vibration to a vacuum vessel, A detection unit for detecting vibrations transmitted from the vacuum vessel when the vibration excitation unit applies vibration to the vacuum vessel, The system includes a determination unit that determines a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel, The vacuum container, together with a pair of contacts in the circuit breaker, constitutes a vacuum valve. A determination device in which the vibration unit and the detection unit are provided on the outer surface of a tank housing the vacuum valve.

3. A vibration unit that applies vibration to a vacuum vessel, A detection unit for detecting vibrations transmitted from the vacuum vessel when the vibration excitation unit applies vibration to the vacuum vessel, The system includes a determination unit that determines a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel, The vacuum container, together with a pair of contacts in the circuit breaker, constitutes a vacuum valve. A determination device in which the vibration unit and the detection unit are provided inside a tank that houses the vacuum valve.

4. The determination device according to claim 2 or 3, wherein the excitation unit and the detection unit are the same piezoelectric element.

5. The determination device according to claim 2 or 3, wherein the excitation unit and the detection unit are separate piezoelectric elements, and the separate piezoelectric elements are provided at positions that sandwich the vacuum container.

6. The determination device according to claim 1, wherein the vacuum container, together with a pair of contacts in the circuit breaker, constitutes a vacuum valve.

7. The determination device according to claim 6, wherein the vibration unit and the detection unit are provided on the outer surface of the vacuum valve.

8. A vibration step of applying vibration to a vacuum vessel with a vibration unit, A detection step in which a detection unit detects vibrations transmitted from the vacuum vessel when vibrations are applied to the vacuum vessel by the excitation step, The process includes a determination step of determining a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel, The vibration unit and the detection unit are separate piezoelectric elements, and the separate piezoelectric elements are provided at positions that sandwich the vacuum container, The separate piezoelectric elements mentioned above function as both the excitation unit and the detection unit. The determination step involves determining a change in the natural frequency of the vacuum vessel based on the vibration detected by each of the separate piezoelectric elements.

9. A vibration step in which vibration is applied to a vacuum vessel by a vibration unit, A detection step in which a detection unit detects vibrations transmitted from the vacuum vessel when vibrations are applied to the vacuum vessel by the excitation step, The process includes a determination step of determining a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel, The vacuum container, together with a pair of contacts in the circuit breaker, constitutes a vacuum valve. A determination method wherein the vibration unit and the detection unit are provided on the outer surface of a tank housing the vacuum valve.

10. A vibration step in which vibration is applied to a vacuum vessel by a vibration unit, A detection step in which a detection unit detects vibrations transmitted from the vacuum vessel when vibrations are applied to the vacuum vessel by the excitation step, The process includes a determination step of determining a change in the vacuum level of the vacuum vessel based on a change in the natural frequency of the vacuum vessel, The vacuum container, together with a pair of contacts in the circuit breaker, constitutes a vacuum valve. A determination method wherein the vibration unit and the detection unit are provided inside a tank that houses the vacuum valve.

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