Partial discharge detection device

Abstract

[Project] Detect partial discharges with good precision. [Solution] An electrode (101) is attached to the surface (120s) of the main body (120) constituting the case body of the detection sensor (100), and a dielectric is attached to the surface. Additionally, a recess (123) is formed in the four corners of the main body, and a magnet (107) is inserted. When the detection sensor (100) is mounted so that the dielectric contacts the outer surface of an electrical facility containing a transformer or a distribution board, electrostatic coupling occurs between the electrical facility and the electrode, and changes in ground voltage caused by partial discharge generated in the distribution board can be detected with high sensitivity. Furthermore, when in a noisy environment, after mounting the detection sensor (100) so that the rear side contacts the inner surface of the electrical facility, a metal plate antenna plate is mounted on the surface of the electrode (101) and the dielectric. By doing this, partial discharge generated internally can be detected while blocking external noise by the electrical facility. By doing this, partial discharge can be detected with good precision.

Description

Technology Field

[0001] The present invention relates to a technology for detecting partial discharge occurring in electrical equipment covering a transformer or switchboard. Background Technology

[0002] In electrical equipment handling high-voltage electricity, such as transformers or switchboards, wires and various other parts are properly insulated by insulating materials. If this insulating material undergoes aging deterioration or damage, weak, pulsed discharges may occur in these areas due to localized short circuits. To maintain electrical equipment in proper condition, it is desirable to detect these localized discharges and perform maintenance at an early stage.

[0003] Transient Earth Voltage (TEV) sensors are known as sensors for detecting partial discharge. A TEV sensor is a sensor that detects changes in ground voltage occurring in electrical equipment due to partial discharge. Conventionally, TEV sensors have been configured with electrodes formed inside a case body, and when mounted on electrical equipment, changes in the ground voltage of electrical equipment are detected by the electrodes by utilizing the fact that electrostatic coupling occurs between the electrical equipment and the electrodes when they are positioned at a predetermined distance. Patent Document 1 discloses a technology for detecting by lowering the frequency of a waveform signal detected by a TEV sensor. Prior art literature

[0004] Japanese Patent Publication No. 2021-25881 The problem to be solved

[0005] However, conventional TEV sensors suffered from poor sensitivity, making it difficult to ensure the precision of partial discharge detection. There was also the challenge of being susceptible to ambient noise. Furthermore, since partial discharges are very high-frequency pulses, detecting them required high-frequency detection and sampling; consequently, detection devices became expensive and the power consumption required for detection tended to increase.

[0006] The present invention has been made in consideration of these problems, and aims to solve at least some of these problems in the detection of partial discharge. means of solving the problem

[0007] The present invention, in a first embodiment,

[0008] A partial discharge detection device for detecting partial discharge occurring inside electrical equipment covering a transformer or switchboard,

[0009] An electrode composed of a metal plate, and

[0010] A dielectric film attached to the surface of the above electrode, and

[0011] With the above membrane facing the electrical equipment side, it can be configured as a partial discharge detection device having a case body for mounting the electrode to the electrical equipment.

[0012] In the first embodiment, when an electrode is mounted on an electrical facility, a dielectric material is interposed between the electrode and the electrical facility. When a partial discharge occurs inside the electrical facility and the electromagnetic waves generated therefrom reach the electrical facility, a fluctuation in the ground voltage of the electrical facility occurs and is detected by the electrode that is electrostatically coupled with the electrical facility. Here, in the first embodiment, since a dielectric material is interposed between the electrical facility and the electrode, the capacitance of the electrode is increased, and accordingly, the sensitivity is increased. Therefore, according to the first embodiment, it becomes possible to detect partial discharges generated inside the electrical facility with good sensitivity.

[0013] In the present invention, various materials can be used as the dielectric, but

[0014] The above film may be made of fluoropolymer.

[0015] Fluoropolymer resin is desirable because it is relatively easy to obtain and handle, and has a sufficient dielectric constant for improving sensitivity. As an example, a material in which a glass fiber sheet substrate is coated with fluoropolymer resin can be used.

[0016] When the dielectric constant is increased, the detection sensitivity of the ground voltage is improved, while the frequency range at which the detection sensitivity increases shifts toward the low frequency side. In this sense, it is not the case that a higher dielectric constant is better; rather, the optimal value can be selected by considering both sensitivity and the frequency range. Fluoropolymer resin can be considered a suitable material for the present invention from this perspective as well.

[0017] In the present invention,

[0018] It may be used that the capacitance in the state of being mounted on the above electrical equipment is 200 pF or more.

[0019] As a result of measuring the improvement in detection sensitivity of ground voltage with increasing capacitance, it was confirmed that overall, sensitivity increases monotonically with increasing capacitance, but while sensitivity increases very rapidly up to a capacitance of about 200 pF, it was confirmed that the increase in sensitivity becomes gradual when it exceeds about 200 pF. Therefore, it is thought that sufficient improvement in sensitivity is obtained by making the capacitance 200 pF or higher.

[0020] To increase capacitance, methods such as increasing the electrode area, increasing the dielectric constant of the dielectric, or narrowing the gap between the electrode and the electrical equipment (making the dielectric thinner) can be considered. Any of these may be adopted, or a combination thereof may be adopted.

[0021] Above all, if one attempts to achieve a capacitance of 200 pF, which is approximately 20 times the conventional capacitance (about 11 pF), solely through the electrode area, it becomes necessary to increase the electrode area by 20 times, resulting in a very large size of the detection sensor. In the present invention, using a dielectric material is also useful for increasing sensitivity while keeping the size of the detection sensor small.

[0022] In the present invention,

[0023] The above case body forms a box shape, and

[0024] The above electrode is attached to one surface of the above case body, and

[0025] The above film may be attached to the outer surface of the electrode.

[0026] By doing so, the case body, electrode, and film can be easily handled as a single sensor. Conventional TEV sensors typically have the electrode inside the case body to ensure a gap between the electrode and the electrical equipment, but in the present invention, since a dielectric film is provided on the surface of the electrode, the electrode can be mounted on the outer surface of the case body. As a result, it is possible to arrange the electrical equipment and the electrode close together by interposing a dielectric film while taking on an easy-to-handle form such as a box-shaped case body, thereby improving the detection sensitivity.

[0027] Various methods can be taken to mount the case body to electrical equipment, such as using magnetic force, adhesive, adhesive, suction cups, screws, or other fasteners. A method of mounting a magnet to the case body and mounting it to electrical equipment using this magnetic force is preferred in terms of ease of handling.

[0028] The present invention, in a second aspect,

[0029] A partial discharge detection device for detecting partial discharge occurring inside electrical equipment covering a transformer or switchboard,

[0030] An electrode composed of a metal plate, and

[0031] An antenna plate composed of a metal plate, and

[0032] It can be configured as a partial discharge detection device having a case body for mounting the electrode to the electrical equipment while maintaining the electrode and the antenna plate parallel at a first interval and maintaining a second interval from the electrical equipment.

[0033] According to the second embodiment, since the case body has electrodes and an antenna plate, electromagnetic waves caused by partial discharge generated inside the electrical equipment can be captured by the antenna plate, and the ground voltage can be detected by the electrodes.

[0034] Conventionally, TEV sensors detected electromagnetic waves caused by partial discharges in electrical equipment and detected the resulting ground voltage. However, when electrical equipment is installed in an environment with significant external noise, the equipment captures both the external noise and the partial discharges; consequently, the partial discharge detection device finds it difficult to distinguish between the partial discharges and the noise, resulting in reduced detection accuracy.

[0035] In contrast, in the second embodiment, if a partial discharge detection device is mounted on the inside of an electrical facility, the antenna plate can capture the internal partial discharge while the electrical facility blocks external noise, so the partial discharge can be detected with good precision without being affected by noise.

[0036] The first gap between the electrode and the antenna plate can be set arbitrarily, but from the perspective of increasing detection sensitivity, it is preferable for the first gap to be narrow.

[0037] In addition, the second gap between the electrical equipment and the electrode can be set arbitrarily, but from the perspective of avoiding the influence of noise, it is preferable for the second gap to be wide.

[0038] In the second aspect of the present invention,

[0039] It may also have a dielectric film provided between the electrode and the antenna plate.

[0040] By doing this, detection sensitivity can be increased, just like in the first embodiment.

[0041] In the second aspect of the present invention,

[0042] The above antenna plate is detachably mounted, and

[0043] The above case body may be configured such that when the antenna plate is removed, the electrode can be mounted on the electrical equipment with a third gap narrower than the second gap.

[0044] The partial discharge detection device can detect partial discharge by mounting it on the inside of electrical equipment when equipped with an antenna plate. This embodiment is useful in noisy environments.

[0045] Meanwhile, when the antenna plate is removed, partial discharge can be detected by utilizing the electrical equipment itself as an antenna by mounting it on the outside (or inside) of the electrical equipment. This embodiment is useful in environments with low noise.

[0046] By making the antenna detachable in this way, it becomes possible to switch the mode of use by mounting it on the inside or outside of the electrical equipment depending on the environment.

[0047] The third interval can be arbitrarily determined within the range where the electrical equipment and the electrode can be electrostatically coupled. It may be the same as the first interval or different.

[0048] In one embodiment, the partial discharge detection device of the present invention may be mounted such that the surface facing the electrode is attached to the electrical equipment when the antenna plate is mounted, and when the antenna plate is removed, the device may be inverted and the electrode side is attached to the electrical equipment.

[0049] In addition, the partial discharge detection device may be configured to allow the thickness of the case body to be changed in another embodiment. In this embodiment, when mounted on the inside of an electrical facility, the case body may be mounted in a thick state to avoid noise interference, and when mounted on the outside of an electrical facility, the case body may be mounted in a thin state to enable electrostatic coupling.

[0050] In the second aspect of the present invention,

[0051] The above case body forms a box shape and has a magnet extending from the surface to the back surface, and

[0052] The above electrode may be attached at a position avoiding the magnet on the surface.

[0053] According to the above embodiment, it becomes possible to mount the case body to an electrical installation facing either the front or the back. Additionally, since a magnet extending from the surface to the back is used, there is an advantage of a simplified structure.

[0054] Above all, the structure is not limited to the above, and a configuration in which magnets are provided on the front and back surfaces of the case body may also be used.

[0055] In the second aspect of the present invention,

[0056] The above antenna plate may be detachably mounted by the above magnet.

[0057] By doing this, the antenna plate can be attached and detached relatively easily. As described above, if a magnet extending from the surface to the back surface is used, this magnet may be used.

[0058] In the first and second embodiments of the present invention, additionally,

[0059] It may be provided with a conversion circuit that reduces the frequency of the detection signal detected by the above electrode.

[0060] Partial discharge typically results in very high-frequency pulses. Consequently, detection and transmission of the detection results must also be performed at high frequencies, leading to increased power consumption. In contrast, according to the above embodiment, the frequency of the detection signal can be reduced by a conversion circuit, making it possible to suppress power consumption.

[0061] In the second aspect of the present invention,

[0062] The above conversion circuit may be a circuit that tunes to a detection signal of 10 to 20 MHz.

[0063] It is known that the partial discharge signal detected by the partial discharge detection device has peaks at 10 to 20 MHz and 50 to 100 MHz. When reducing the frequency to suppress power consumption, the 10 to 20 MHz range is easier to convert than the 50 to 100 MHz range. According to the above embodiment, there is an advantage in that the frequency of the partial discharge can be detected and the conversion to a low frequency can also be performed efficiently.

[0064] In the second aspect of the present invention,

[0065] The above conversion circuit may be an AM modulation circuit equipped with a tuning circuit, a high-frequency amplifier circuit, a detection circuit, and a low-frequency amplifier circuit.

[0066] By doing this, the frequency can be lowered. In addition, the AM modulation circuit described above has the advantage of being available as a single IC chip, making it relatively inexpensive to obtain.

[0067] The present invention, in a third aspect,

[0068] A partial discharge detection system for detecting partial discharge occurring inside electrical equipment covering a transformer or switchboard,

[0069] A partial discharge detection device of any embodiment described above, and

[0070] It can be configured as a partial discharge detection system having an analysis device that analyzes the presence or absence of partial discharge based on the output of the partial discharge detection device.

[0071] According to the third embodiment, partial discharge can be detected by analysis using an analysis device. The analysis can be performed in various ways.

[0072] In the third aspect of the present invention, additionally,

[0073] The above partial discharge detection device may be equipped with a wireless communication device for wirelessly communicating its output to the analysis device.

[0074] According to the above embodiment, since the output can be transmitted wirelessly, the convenience of the partial discharge detection device can be improved.

[0075] In the present invention, the various features described above do not necessarily have to be fully present, and parts thereof may be appropriately omitted or combined. Brief explanation of the drawing

[0076] Figure 1 is an explanatory diagram showing the configuration of a partial discharge detection system. Figure 2 is an explanatory diagram showing the configuration of a detection sensor. Figure 3 is an explanatory diagram showing the usage mode of the detection sensor. Figure 4 is a graph showing the effect of noise according to the thickness of the case body. Figure 5 is a graph showing the relationship between capacitance and sensitivity. Figure 6 is an explanatory diagram showing the relationship between the material of the dielectric and the capacitance. Figure 7 is an explanatory diagram showing the configuration of a communication device. Figure 8 is an explanatory diagram showing the operation of the conversion circuit. Figure 9 is a flowchart of the discharge detection process. Specific details for implementing the invention

[0077] Hereinafter, regarding embodiments of the present invention, a system for detecting partial discharge occurring in a switchboard is described as an example.

[0078] Figure 1 is an explanatory diagram showing the configuration of a partial discharge detection system. The electrical equipment (10) is a facility that houses a distribution panel in a box that transforms high voltage sent from a power company.

[0079] The door of the electrical equipment (10) is equipped with a detection sensor (100) for detecting partial discharge and a communication device (190) for wirelessly communicating the detected signal. The detection sensor (100) and the communication device (190) correspond to a partial discharge detection device.

[0080] The detected signal is transmitted from the communication device (190) to the analysis device (200) via the network (NE) through the relay (20). The relay (20) is a device for connecting the communication device (190) to the network (NE), and various known devices may be used.

[0081] The detection sensor (100) and the analysis device (200) can be connected in various ways, and the communication device (190) and the analysis device (200) may be directly connected wirelessly or via a wire. Also, both may be integrated into a single unit.

[0082] The detection sensor (100) may be mounted on the outside of the electrical equipment (10) as indicated by the solid line in the drawing, or mounted on the inside as indicated by the dashed line. If mounted on the inside, the communication device (190A) is also mounted on the inside. However, it is preferable that the communication device (190A) be configured to be capable of communication even when mounted on the inside of the electrical equipment (10). For example, a configuration may be added in which the detection signal is transmitted to the communication device (190) by electricity, light, sound, etc. through the door of the electrical equipment (10).

[0083] The configuration of the detection sensor (100) and the communication device (190) will be described later.

[0084] The interpretation device (200) is constructed in software by installing a program that implements each function shown on the server. Some or all of the functions may be configured in hardware.

[0085] Explain each function of the city.

[0086] The transmitting and receiving unit (201) has the function of transmitting and receiving signals through a network (NE) with the detection sensor (100), etc.

[0087] The discharge detection unit (202) determines whether it corresponds to a partial discharge based on the signal detected by the detection sensor (100).

[0088] The alert unit (203) outputs an alert when partial discharge is detected and it is determined that there is an abnormality in the distribution panel. The alert can be output in various ways, such as by sending an email to a designated notification recipient.

[0089] The switchboard database (204) is a database that stores information about switchboards, i.e., electrical equipment (10). For example, information that identifies a switchboard, such as its location and name, is stored by corresponding it to an identifier assigned to the switchboard. By doing this, by receiving a detection result along with an identifier from the detection sensor (100), it is easy to identify which switchboard the detection result is from.

[0090] The detection log memory unit (205) stores past detection results for each distribution panel. By storing past detection results, for example, it is possible to check how often partial discharge occurs, and thus it is possible to determine whether there is an abnormality in the distribution panel.

[0091] The partial discharge detection system is not limited to the configuration shown in FIG. 1 and can take various configurations. Functions other than those shown may also be added.

[0092] FIG. 2 is an explanatory diagram showing the configuration of a detection sensor (100).

[0093] FIG. 2(a) shows a perspective view. The case body of the detection sensor (100) consists of a main body (120) and a cover body (140). For convenience of explanation, the upper side of the case body in the drawing will be referred to as the front side and the lower side as the back side.

[0094] A metal plate electrode (101) is attached to the surface (120s) of the main body (120) constituting the case body. Also, a dielectric material is attached to the surface of the electrode (101). Hereinafter, the side to which the electrode (101) is attached will be referred to as the surface, and the opposite side will be referred to as the back side.

[0095] In the four corners of the case body, magnets (107) extending from the surface to the back are embedded. Due to the magnetic force of the magnets (107), the detection sensor (100) can be mounted on the electrical equipment (10) in either the surface or the back direction.

[0096] Additionally, the main body (120) of the case body is equipped with a terminal (104) for outputting a detection signal. The terminal (104) and the electrode (101) are connected by a wire inside the main body (120).

[0097] FIG. 2(b) shows the internal structure of the detection sensor (100) with the main body (120) and cover (140) removed. A mounting portion (122) for mounting a terminal (104) is formed on the side (121) of the main body (120). The electrode and the terminal (104) are connected by a wire (105).

[0098] In the four corners of the main body (120), concave portions (123) are formed, and cylindrical magnets (107) are inserted into each. In the cover body (140), a mounting portion (142) for pressing the terminal (104) is formed on its side (141). Also, in the four corners, convex portions (143) for pressing the magnets (107) are formed.

[0099] In this way, by pressing the magnet (107) and terminal (104) with the cover body (140), there is an advantage in that the detection sensor (100) can be constructed simply without the need to use parts such as screws.

[0100] The shape and structure of the detection sensor (100) are not limited to the examples described above. The magnet (107) may be mounted on the surface and the back surface in sections.

[0101] Figure 3 is an explanatory diagram showing the usage mode of the detection sensor.

[0102] FIG. 3(a) shows a state in which the detection sensor (100) is mounted on the outside of the door (11) of the electrical equipment (10). At this time, the detection sensor (100) is mounted with its surface facing the door (11) by means of the magnetic force (F) of the magnet (107). Since a dielectric (102) is attached to the surface of the electrode (101), by mounting the detection sensor (100) on the door (11), a configuration is formed in which the dielectric (102) is placed between the door (11) and the electrode (101).

[0103] As a result, when partial discharge occurs in the distribution panel within the electrical equipment (10), the electromagnetic waves are captured by the door (11) and detected by the detection sensor (100). Also, as the dielectric (102) is interposed, the capacitance of the electrode (101) is increased, and the sensitivity of the detection is increased.

[0104] FIG. 3(b) shows a state in which the detection sensor (100) is mounted on the inside of the door (11) of the electrical equipment (10). At this time, the detection sensor (100) is mounted so that its back side faces the door (11) by the magnetic force F1 of the magnet (107). Also, on the surface, an antenna plate (103) is mounted on the surface of the electrode (101) and dielectric (102) by the magnetic force F2 of the magnet (107). The antenna plate (103) is a metal plate larger than the electrode (101). When mounted inside the electrical equipment (10), the configuration is such that the dielectric (102) is placed between the electrode (101) and the antenna plate (103).

[0105] As a result, when partial discharge occurs in the distribution board within the electrical equipment (10), the electromagnetic waves are captured by the antenna plate (103) and detected by the detection sensor (100). Also, as the dielectric (102) is interposed, the capacitance of the electrode (101) is increased, and the sensitivity of the detection is increased.

[0106] When the electrical equipment (10) is installed in a noisy environment, the noise is captured by the door (11) of the electrical equipment (10) as shown in the illustration. Also, the door (11) also has the function of shielding the noise. Additionally, the case body of the detection sensor (100) also has the function of isolating the antenna plate (103) that captures partial discharge at a distance t from the door (11). Therefore, as shown in FIG. 3(b), the detection sensor (100) of the embodiment can detect partial discharge by suppressing the influence of noise by mounting it on the inside of the door (11).

[0107] The distance t (referred to as the case thickness t) from the door (11) to the antenna plate (103) can be arbitrarily determined by taking into account the influence of noise, etc.

[0108] FIG. 4 is a graph showing the effect of noise according to the thickness of the case body. As shown, as the thickness t of the case body increases, the noise incorporation rate decreases monotonically. To sufficiently reduce noise, it is desirable to make the thickness t of the case body 10 mm or more. Above all, since increasing the thickness of the case body makes the detection sensor (100) larger, it is desirable to determine the thickness of the case body taking this into consideration.

[0109] As previously explained, the detection sensor (100) has a dielectric (102) attached to the surface of the electrode (101), thereby improving the detection sensitivity.

[0110] FIG. 5 is a graph showing the relationship between capacitance and sensitivity. The vertical axis represents the sensitivity multiplier based on the sensitivity of a conventional TEV sensor (combined capacitance of about 11 pF). As shown, as the capacitance increases, the sensitivity of the detection sensor (100) increases monotonically. However, the sensitivity of the detection sensor (100) does not increase linearly; in the range of capacitance up to 204 pF, the sensitivity improves significantly by about 5 times due to a slight increase in capacitance, and in the range exceeding this, the effect of the increase in capacitance becomes gradual, so even if the capacitance is increased, the sensitivity does not increase significantly. Therefore, in order to obtain sufficient sensitivity as a detection sensor (100), it is desirable to have a capacitance of about 200 pF or more.

[0111] In the detection sensor (100), the dielectric (102) can be made of various materials. In the example, three types of materials shown below were tested, and a material suitable for the detection sensor (100) was selected.

[0112] Figure 6 is an explanatory diagram showing the relationship between the dielectric material and capacitance. As shown in Figure 6(a), CS-3945, ES-3346, and AD-3396 (all trademarks) were used in the examples. Characteristics such as relative permittivity and sheet thickness are as shown in the table in Figure 6(a).

[0113] The capacitance when using these materials is shown in FIG. 6(b). In the table, curve A represents the capacitance of a conventional TEV sensor. As shown, from largest to smallest capacitance, the order is CS-3945, ES-3346, and AD-3396, and it can be seen that the capacitance of CS-3945 exceeds 200 pF.

[0114] As shown in Fig. 6(a), the relative permittivity increases in the order of CS-3945, ES-3346, and AD-3396, but the thickness of the material decreases in this order, so the total capacitance is greatest in CS-3945. As such, both the relative permittivity and the thickness of the material are involved in the capacitance. The example shown is merely an illustration, and materials with various relative permittivity and various thicknesses can be selected.

[0115] FIG. 7 is an explanatory diagram showing the configuration of a communication device (190). FIG. 7(a) shows the schematic configuration of a communication device (190). As shown, the communication device (190) is equipped with a conversion circuit (191), an AD converter (198), and a wireless communication unit (199).

[0116] The conversion circuit (191) is a circuit for converting a high-frequency input to a low frequency. The conversion circuit (191) is equipped with a tuning circuit (192), a high-frequency amplifier circuit (193), a detection circuit (194), and a low-frequency amplifier circuit (195).

[0117] Figure 7(b) shows a specific circuit configuration. The tuning circuit (192) can be tuned to a wide range of frequencies by increasing the Q value, but in the embodiment, the circuit is designed to tune to 10 to 20 MHz as described below.

[0118] In this embodiment, an AM modulation IC chip is used to form the conversion circuit (191). By doing so, the conversion circuit can be constructed inexpensively and simply. In addition, the conversion circuit (191) is not limited to this configuration, and various configurations for converting a high-frequency input to a low frequency can be applied.

[0119] The AD converter (198) converts the output converted to a low frequency by the conversion circuit (191) into a digital signal.

[0120] The wireless communication unit (199) transmits the converted digital signal wirelessly.

[0121] FIG. 8 is an explanatory diagram showing the operation of the conversion circuit (191). FIG. 8(a) shows the output signal from the detection sensor (100) when partial discharge is detected. As shown, the output signal has components of various frequencies.

[0122] FIG. 8(b) shows the intensity distribution of each frequency included in the output signal. As shown, it can be seen that the output signal of the partial discharge has intensity peaks at 10 to 20 MHz and 50 to 100 MHz. Therefore, in order to detect the partial discharge with good precision, it is desirable to detect the frequency of one or both of these two peaks by the tuning circuit (192). In this embodiment, the circuit is configured to tune to 10 to 20 MHz. This is because it is more efficient to convert the low frequency of 10 to 20 MHz to a low frequency than to convert the high frequency of 50 to 100 MHz to a low frequency, and also because the tuning circuit for 10 to 20 MHz can be realized more cheaply.

[0123] FIG. 8(c) shows the input and output waveforms for the conversion circuit (191). The detection signal from partial discharge includes various frequencies as shown in FIG. 8(a) and (b), but as shown in the input waveform of FIG. 8(c), it is a very high-frequency pulsed waveform. However, in the embodiment, this detection signal is converted to a low frequency. The frequency after conversion can be selected arbitrarily, but as an example, it may be several tens of KHz, for example, about 50 KHz.

[0124] The reason for converting to a low frequency is as follows. In order to detect a high-frequency pulsed detection signal as shown in FIG. 8(c), it is necessary to sample at a high frequency of the same degree and transmit the detected result at a high frequency. Such a circuit is expensive, and the amount of data transmitted is large, which increases power consumption accordingly. In the embodiment, by reducing this to a low frequency, these problems are avoided, and it becomes possible to detect partial discharge at a low cost while suppressing power consumption.

[0125] The transmitted detection signal is detected by an analysis device (200) to determine whether it is a partial discharge.

[0126] FIG. 9 is a flowchart of the discharge detection process. It is a process performed by the analysis device (200).

[0127] When processing is initiated, the analysis device (200) receives a detection signal (step S10) and determines whether it is a discharge (step S11). A method for determining a discharge is shown in the drawing. As shown, for example, it can be determined that it is a partial discharge when the intensity of the detection signal exceeds a predetermined threshold value. The determination is not limited to this method and various other methods may be taken.

[0128] When no partial discharge is detected (Step S12), the discharge detection process is terminated.

[0129] When partial discharge is detected (step S12), the analysis device (200) reads past detection logs (step S13) and outputs an alert based on the determination of whether an alert is necessary (step S14). The determination of whether an alert is necessary can be based, for example, on the number of past partial discharge detections, detection frequency, etc. The output of the alert can be carried out, for example, by sending an email to a predetermined notification recipient.

[0130] According to the partial discharge detection device and partial discharge detection system of the embodiment described above, partial discharges occurring at high frequencies can be detected with good precision at low cost and power consumption. In addition, when used in a low-noise environment, it is mounted outside the electrical equipment, and when used in a high-noise environment, it is mounted inside the electrical equipment, thereby enabling detection while suppressing the influence of noise.

[0131] The partial discharge detection device and partial discharge detection system do not necessarily have to possess all of the various features described in the embodiments, and may be configured by appropriately omitting or combining some of them.

[0132] Industrial applicability

[0133] The present invention can be used to detect partial discharge occurring in electrical equipment covering a transformer or switchboard. Explanation of the symbols

[0134] 10: Electrical Installations 11 : Door 20 : Repeater 100 : Detection sensor 101 : Electrode 102 : Genome 103 : Antenna board 104 : Terminal 105 : Wire 107 : Magnet 120 : Main body 120s : Surface 121 : Side 122 : Mounting part 123 : Concave part 140 : Cover body 141 : Side 142 : Mounting part 143: Convex part 190, 190A: Communication device 191 : Conversion circuit 192 : Tuning circuit 193 : High-frequency amplifier circuit 194 : Detector circuit 195 : Low-frequency amplifier circuit 198 : AD converter 199 : Wireless Communications Department 200 : Analysis unit 201 : Transmitter / Receiver 202 : Discharge detection unit 203 : Alert Department 204 : Switchboard Database 205 : Detection log memory

Claims

Claim 1 A partial discharge detection device for detecting partial discharge occurring inside an electrical facility covering a transformer or a switchboard, comprising: an electrode composed of a metal plate; a dielectric film attached to the surface of the electrode; a case body for mounting the electrode to the electrical facility with the film facing toward the switchboard side from the outside of the electrical facility; and a detachable antenna plate composed of a metal plate, wherein the case body is box-shaped, the electrode is attached to one surface of the case body, and the film is attached to the outer surface of the electrode, and the case body is mounted such that the surface opposite to the surface to which the electrode is attached contacts the inside of the electrical facility, and in the mounted state, the electrode and the antenna plate are maintained parallel at a first distance, and the electrode is maintained at a second distance from the electrical facility. Claim 2 A partial discharge detection device according to claim 1, wherein the film is a fluoropolymer. Claim 3 A partial discharge detection device according to claim 1, wherein the capacitance when mounted on the electrical equipment is 200 pF or more. Claim 4 delete Claim 5 A partial discharge detection device according to claim 1, having a dielectric film provided between the electrode and the antenna plate. Claim 6 A partial discharge detection device according to claim 1, wherein the case body has a magnet extending from the surface to the back surface, and the electrode is attached at a position avoiding the magnet on the surface. Claim 7 In claim 6, the antenna plate is a partial discharge detection device detachably mounted by the magnet. Claim 8 A partial discharge detection device according to claim 1, further comprising a conversion circuit that reduces the frequency of a detection signal detected by the electrode. Claim 9 In claim 8, the conversion circuit is a partial discharge detection device that is a circuit tuned to a detection signal of 10 to 20 MHz. Claim 10 In claim 8, the conversion circuit is a partial discharge detection device that is an AM modulation circuit equipped with a tuning circuit, a high-frequency amplifier circuit, a detection circuit, and a low-frequency amplifier circuit. Claim 11 A partial discharge detection system for detecting partial discharge occurring inside an electrical facility covering a transformer or a switchboard, comprising a partial discharge detection device described in any one of claims 1 to 3 and claims 5 to 10, and an analysis device that analyzes the presence or absence of partial discharge based on the output of the partial discharge detection device. Claim 12 In claim 11, additionally, the partial discharge detection device comprises a wireless communication device for wirelessly communicating the output to the analysis device, thereby forming a partial discharge detection system.

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