Partial discharge determination device

Abstract

The partial discharge determination device (100) has a first member (11) which is an insulating member, and a second member (12) which is a conductive member that covers the side surface of the first member and reduces the influence of electromagnetic waves from the outside, and has a first insulating spacer (10) sandwiched between and connected to a first tank (21) and a second tank (22), a first antenna (14) provided inside the first member and configured to detect electromagnetic waves generated from at least one of the first tank or the second tank, a second antenna (15) provided inside the first member and configured closer to the second tank than the first antenna and configured to detect electromagnetic waves generated from at least one of the first tank or the second tank, and a control unit (40) which determines the presence or absence of partial discharge inside the first tank or the second tank from the first electromagnetic waves detected by the first antenna and the second electromagnetic waves detected by the second antenna.

Description

[Technical field]

[0001] The present disclosure relates to a partial discharge determining device. [Background technology]

[0002] Conventionally, there are devices for determining partial discharges that occur inside gas-insulated equipment. As in the partial discharge detection device described in Patent Document 1, an insulating spacer is covered with a metal cover, and multiple slot-shaped openings (antenna parts for detecting electromagnetic waves) are provided in the metal cover, and electromagnetic waves accompanying partial discharge occurrence are detected by the multiple slot-shaped openings (antenna parts for detecting electromagnetic waves). This makes it possible to detect partial discharges with a simple configuration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-263640 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional partial discharge detection device, a metal cover is arranged on the outer periphery of the gas-insulated equipment, and therefore the slot-shaped opening for detecting electromagnetic waves is also arranged on the outer periphery of the gas-insulated equipment. Therefore, not only electromagnetic waves caused by partial discharges generated inside the gas-insulated equipment, but also disturbances such as broadcast waves and wireless communication waves arriving from outside the gas-insulated equipment are detected. Therefore, the partial discharge detection device disclosed in Patent Document 1 may not be able to accurately detect partial discharges in the gas-insulated equipment due to disturbances.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a partial discharge detection device that can reduce the effects of disturbances and detect partial discharges that have occurred in gas-insulated equipment with higher accuracy. [Means for solving the problem]

[0006] The partial discharge determination device according to the present disclosure has a first member which is an insulating member and a second member which is a conductive member that covers the side surface of the first member and reduces the influence of electromagnetic waves from the outside, and is equipped with a first insulating spacer which is sandwiched between and connected to the first tank and the second tank, a first antenna which is provided inside the first member and detects electromagnetic waves generated from at least one of the first tank or the second tank, a second antenna which is provided inside the first member and is provided on the second tank side of the first antenna and detects electromagnetic waves generated from at least one of the first tank or the second tank, and a control unit which determines the presence or absence of partial discharge occurring inside the first tank or the second tank from the first electromagnetic waves detected by the first antenna and the second electromagnetic waves detected by the second antenna. Effect of the Invention

[0007] The partial discharge detection device disclosed herein has multiple antennas for detecting electromagnetic waves provided inside a first member, which is an insulating member, and the first member is covered with a second member, which is a conductive member. This allows the conductive member to reduce disturbances detected by the antennas, making it possible to detect partial discharge with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a partial discharge determining device according to a first embodiment. [Diagram 2] FIG. 2(a) is a plan view of an insulating spacer constituting the partial discharge determining device of embodiment 1, and FIG. 2(b) is a cross-sectional view of the insulating spacer constituting the partial discharge determining device of embodiment 1. [Diagram 3] 1A and 1B are diagrams illustrating a normal electromagnetic wave waveform and an abnormal electromagnetic wave waveform. [Figure 4] 4 is a process flow for determining partial discharge according to the first embodiment. [Diagram 5] 11 is a process flow of partial discharge determination according to the second embodiment. [Figure 6]FIG. 6(a) is a plan view of an insulating spacer constituting the partial discharge determining device according to embodiment 3, and FIG. 6(b) is a cross-sectional view of the insulating spacer constituting the partial discharge determining device according to embodiment 3. [Figure 7] FIG. 7(a) is a plan view of an insulating spacer constituting the partial discharge determining device according to embodiment 4, and FIG. 7(b) is an enlarged view of each cross section of the insulating spacer constituting the partial discharge determining device according to embodiment 4. [Figure 8] FIG. 11 is a cross-sectional view of a partial discharge determining device according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Embodiment 1 The partial discharge determining device in the first embodiment will be described with reference to Fig. 1 to Fig. 4. Fig. 1 is a cross-sectional view of the partial discharge determining device according to the first embodiment. The partial discharge determining device 100 includes an insulating spacer 10 and a control unit 40. The insulating spacer 10, the first tank 21, the second tank 22 and the conductor 30 form a part of a gas insulation device 200. The insulating spacer 10 is also referred to as a first insulating spacer.

[0010] The first tank 21 and the second tank 22 are connected to the insulating spacer 10. The first tank 21 and the second tank 22 are fixed by bolts in a manner that sandwiches the insulating spacer 10 therebetween.

[0011] The insulating spacer 10 includes a first member 11 which is an insulating member, a second member 12 which is a conductive member covering the outer peripheral side surface of the first member 11, and a conductor holding portion 13. Inside the first member, a first antenna 14 and a second antenna 15 which is provided on the second tank side of the first antenna are provided. The first antenna 14 and the second antenna 15 detect electromagnetic waves generated from inside the first tank 21 or inside the second tank 22. The first antenna 14 and the second antenna 15 are made of a conductive member such as aluminum. The first antenna 14 and the second antenna 15 are connected to a control unit 40. The first antenna 14 transmits a first electromagnetic wave, which is an electromagnetic wave detected by the first antenna 14, to the control unit 40. The second antenna 15 transmits a second electromagnetic wave, which is an electromagnetic wave detected by the second antenna 15, to the control unit 40. The control unit 40 determines whether or not partial discharge has occurred inside the first tank 21 or inside the second tank 22 from the first electromagnetic wave and the second electromagnetic wave acquired from the first antenna 14 and the second antenna 15. The conductor holding unit 13 holds the conductor 30 through which high-voltage electricity flows. The conductor holding unit 13 is made of a conductive material. Note that the inside of the first tank 21 or the inside of the second tank 22 mentioned here is not limited to the internal space of the first tank 21 or the second tank 22, but also indicates the internal surface of the first tank 21 or the second tank 22, the conductor 30 disposed therein, and the like.

[0012] Next, the structure of the insulating spacer according to the first embodiment will be described. FIG. 2(a) is a plan view of the insulating spacer constituting the partial discharge determining device according to the first embodiment, and FIG. 2(b) is a cross-sectional view of the insulating spacer constituting the partial discharge determining device according to the first embodiment, which is a cross-sectional view taken along the line AA in FIG. 2(a). The insulating spacer 10 has a first member 11 therein and is in a disk-like shape. The second member 12 has a hollow disk-like shape and is provided so as to cover the first member 11. The first antenna 14 and the second antenna 15 are provided inside the first member 11. Since the second member 12 is made of a conductive member, the second member 12 reduces the detection of disturbances such as broadcast waves and wireless communication waves by the first antenna 14 and the second antenna 15 inside the second member 12. The conductor holding portion 13 is located approximately at the center of the insulating spacer.

[0013] In addition, a first base 140 which is the base of the first antenna 14 and a second base 150 which is the base of the second antenna 15 are connected to the second member 12. The second member 12 is provided with a hole for passing a cable for connecting to a control unit 40 (not shown). The first antenna 14 and the second antenna 15 are connected to the control unit 40 through the cable. The first antenna 14 and the second antenna 15 are the same component.

[0014] Next, a method in which the control unit 40 judges whether the first electromagnetic wave and the second electromagnetic wave are abnormal or not will be described. FIG. 3 is a diagram for explaining the waveform of a normal (abnormal) electromagnetic wave and the waveform of an electromagnetic wave with an abnormality. FIG. 3(a) is a waveform of a normal (abnormal) electromagnetic wave, and FIG. 3(b) is a waveform diagram of an electromagnetic wave with an abnormality. In both figures, the horizontal axis indicates time and the vertical axis indicates signal strength, and the waveform indicates the change in signal strength over time. A normal (abnormal) electromagnetic wave waveform shows a substantially constant signal strength regardless of the passage of time as shown in FIG. 3(a). On the other hand, an abnormal waveform has a sudden change in signal strength as shown in the area surrounded by a dotted line in FIG. 3(b). The control unit 40 judges whether a sudden change in signal strength occurs from the waveforms of the first electromagnetic wave and the second electromagnetic wave, and judges whether an abnormality exists or not, i.e., whether the first electromagnetic wave and the second electromagnetic wave are abnormal or normal (abnormal).

[0015] Next, a description will be given of the process performed by the control unit 40 of the partial discharge determination device 100 to determine whether or not a partial discharge has occurred inside the first tank 21 or the second tank 22. Fig. 4 shows a process flow for determining partial discharge performed by the control unit 40 according to the first embodiment.

[0016] The control unit 40 performs a process of acquiring the first electromagnetic wave and the second electromagnetic wave (step S101). Next, the control unit 40 judges whether the first electromagnetic wave and the second electromagnetic wave acquired in the same time zone in step S101 are abnormal or normal (absent) (step S102). Next, if the first electromagnetic wave and the second electromagnetic wave are abnormal based on the result of the abnormality judgment in step S102 (step S103: YES), the control unit 40 judges whether or not a partial discharge exists inside the first tank 21 or inside the second tank 22 (step S104). On the other hand, if either the first electromagnetic wave or the second electromagnetic wave is normal (absent) in the process of step S103 (step S103: NO), it is determined that no partial discharge exists and the process ends.

[0017] As described above, in the partial discharge determining device 100, the first antenna 14 and the second antenna 15 that detect electromagnetic waves generated from inside the first tank 21 or the second tank 22 are provided in the first member 11, which is an insulating member, and are covered with the second member 12, which is a conductive member. In this way, the second member 12 reduces the detection of disturbances such as broadcast waves and wireless communication waves by the first antenna 14 and the second antenna 15. This allows the control unit 40 to determine with high accuracy whether or not partial discharge has occurred in the gas insulated device based on the electromagnetic waves detected by the first antenna 14 and the second antenna 15, which are less affected by disturbances.

[0018] Furthermore, by using the same component for the first antenna 14 and the second antenna 15, an effect of reducing costs can be obtained.

[0019] In addition, if it is determined in the determination process of step S103 that only one of the first electromagnetic wave or the second electromagnetic wave is abnormal, it may be determined that there is simply a sensor abnormality without determining that a partial discharge has occurred in the gas insulated device.

[0020] Embodiment 2 The partial discharge determining device 100 in the second embodiment will be described with reference to Fig. 5. In Fig. 5, the same reference numerals as in Fig. 4 indicate the same or corresponding parts. While the partial discharge determining device in the first embodiment determines whether or not a partial discharge has occurred inside the first tank 21 or inside the second tank 22, the partial discharge determining device in the second embodiment is configured to determine whether a partial discharge has occurred inside the first tank 21 or inside the second tank.

[0021] 5 is a process flow of partial discharge determination performed by the control unit 40 according to the second embodiment. In the process of step S103, if there is an abnormality in the first electromagnetic wave and the second electromagnetic wave (step S103: YES), the control unit 40 acquires the first time when the first antenna 14 detects the abnormality in the first electromagnetic wave and the second time when the second antenna 15 detects the abnormality in the second electromagnetic wave (step S111). That is, for the first electromagnetic wave and the second electromagnetic wave, the first time and the second time that are the times when the abnormal waveform in FIG. 3(b) is detected are acquired. The time when the abnormal waveform is detected may be the time when the abnormal waveform starts, the time when the peak value of the abnormal waveform is detected, the time in the middle of the occurrence of the abnormal waveform, or any other time while the abnormal waveform is occurring.

[0022] Next, the control unit 40 compares the first time with the second time (step S112). If the first time is earlier than the second time (step S112: YES), it is determined that a partial discharge has occurred inside the first tank 21, which is closer to the first antenna 14 than the second tank 22 (step S113). On the other hand, if the second time is later than the second time in the process of step S112 (step S113: NO), it is determined that a partial discharge has occurred inside the second tank 22, which is closer to the second antenna 15 than the first tank 21 (step S114).

[0023] As described above, the partial discharge determining device 100 according to the second embodiment determines whether a partial discharge has occurred inside the first tank 21 or the second tank 22, based on the first time when the first antenna 14 detects a first electromagnetic wave abnormality and the second time when the second antenna 15 detects a second electromagnetic wave abnormality. This identifies the tank that requires maintenance, improving the efficiency of the maintenance work.

[0024] The determination is not limited to time, and it may be determined whether a partial discharge has occurred inside the first tank 21 or the second tank 22 by comparing the peak values ​​of the abnormal waveforms. In this case, it is determined that a partial discharge has occurred inside the tank closer to the antenna that detected the electromagnetic wave with the larger peak value. For example, if the peak value of the first electromagnetic wave is larger than the peak value of the second electromagnetic wave, it is determined that a partial discharge has occurred inside the first tank 21 that is closer to the first antenna 14 that detected the first electromagnetic wave. On the other hand, if the peak value of the second electromagnetic wave is larger than the peak value of the first electromagnetic wave, it is determined that a partial discharge has occurred inside the second tank 22 that is closer to the second antenna 15 that detected the second electromagnetic wave.

[0025] Embodiment 3 The partial discharge determining device 100 in the third embodiment will be described with reference to Fig. 6. In Fig. 6, the same reference numerals as in Fig. 2 indicate the same or corresponding parts. The insulating spacer in the partial discharge determining device in the first embodiment has one conductor holding portion, whereas the insulating spacer in the partial discharge determining device in the third embodiment has a configuration having a plurality of conductor holding portions.

[0026] Fig. 6(a) is a plan view of an insulating spacer constituting the partial discharge determining device according to the third embodiment, and Fig. 6(b) is a cross-sectional view of the insulating spacer constituting the partial discharge determining device according to the third embodiment, taken along the line AA in Fig. 6(a). The insulating spacer 10 according to the third embodiment has three conductor holding parts, namely a first conductor holding part 131, a second conductor holding part 132, and a third conductor holding part 133. These conductor holding parts hold a conductor 30, but the currents of the respective conductors are in different phases.

[0027] As described above, in the partial discharge determining device 100 according to the third embodiment, a plurality of conductors with different current phases are held by each insulating spacer 10. This eliminates the need to prepare an insulating spacer 10 for each phase, reducing the number of parts and the overall cost of the gas insulated device.

[0028] Embodiment 4 The partial discharge determining device 100 in the fourth embodiment will be described with reference to Fig. 7. In Fig. 7, the same reference numerals as in Fig. 6 indicate the same or corresponding parts. The partial discharge determining devices in the first and third embodiments determine whether a partial discharge has occurred inside the first tank or inside the second tank, whereas the partial discharge determining device in the fourth embodiment determines the occurrence of a partial discharge in the circumferential direction in which conductor a partial discharge has occurred when multiple conductors are held as in the third embodiment.

[0029] Fig. 7(a) is a plan view of an insulating spacer constituting the partial discharge determining device according to the fourth embodiment, and Fig. 7(b) is an enlarged view of each cross section of the insulating spacer constituting the partial discharge determining device according to the fourth embodiment. As shown in Fig. 7(a), a plurality of antennas 141, 142, and 143 are provided at different positions in the circumferential direction of the insulating spacer. The first antenna 141 is provided at a position closer to the first conductor holding portion 131 than the second conductor holding portion 132 and the third conductor holding portion 133, the second antenna 142 is provided at a position closer to the second conductor holding portion 132 than the first conductor holding portion 131 and the third conductor holding portion 133, and the third antenna 143 is provided at a position closer to the third conductor holding portion 133 than the first conductor holding portion 131 and the second conductor holding portion 132.

[0030] FIG. 7(b) is an enlarged view of each cross section shown in FIG. 7(a), and each of the multiple antennas 141, 142, and 143 is disposed at a different position in the conductor axial direction. As described above, when a partial discharge occurs in a conductor held by any of the conductor holding parts 131 to 133, it is possible to determine which conductor holding part the partial discharge occurred in. For example, a method of determining that an abnormality exists in the conductor held by the conductor holding part close to the antenna that detects the electromagnetic wave with the highest peak value of the abnormal waveform, that is, that a partial discharge has occurred, is considered. In this case, abnormal waveforms are detected in each of the first antenna 141, the second antenna 142, and the third antenna 143, and when the peak value of the electromagnetic wave of the first antenna 141 is the highest, it is determined that an abnormality exists in the conductor held by the first conductor holding part 131 close to the first antenna 141, that is, that a partial discharge has occurred. On the other hand, when the peak value of the electromagnetic waves from the second antenna 142 is the highest, it is determined that there is an abnormality, i.e., a partial discharge, in the conductor held by the second conductor holding part 132 closest to the second antenna 142. On the other hand, when the peak value of the electromagnetic waves from the third antenna 143 is the highest, it is determined that there is an abnormality, i.e., a partial discharge, in the conductor held by the third conductor holding part 133 closest to the third antenna 143.

[0031] As described above, the partial discharge determining device 100 according to the fourth embodiment has multiple antennas arranged at different circumferential positions of the insulating spacer, and each of the multiple antennas is arranged close to a different conductor. This makes it possible to determine in which conductor an abnormality, i.e., a partial discharge, is occurring.

[0032] In the fourth embodiment, for convenience, the number of conductors is three and the number of antennas is three, so that the numbers of conductors and antennas are the same, but the number of conductors and antennas may be different. For example, in FIG. 7, even if there is no second antenna 142 in the vicinity of the second conductor holding part 132 and a partial discharge occurs in the conductor held by the second conductor holding part 132, if the peak values ​​of the abnormal waveforms detected by the first antenna 141 and the third antenna 143 are the same, it is possible to determine that a partial discharge has occurred in the conductor held by the second conductor holding part 132, which is located at approximately the same distance as the first antenna 141 and the third antenna 143.

[0033] Embodiment 5. The partial discharge determining device 100 in the fifth embodiment will be described with reference to Fig. 8. In Fig. 8, the same reference numerals as in Fig. 1 indicate the same or corresponding parts. The partial discharge determining device in the first embodiment is configured by connecting one insulating spacer to a first tank and a second tank that sandwich the spacer, whereas the partial discharge determining device in the fifth embodiment is configured by connecting a plurality of insulating spacers and tanks.

[0034] FIG. 8 is a cross-sectional view of the partial discharge determining device according to the fifth embodiment. If the insulating spacer 10 in the first embodiment is referred to as the first insulating spacer 10, the partial discharge determining device 100 according to the fifth embodiment includes a third insulating spacer 60 in addition to the first insulating spacer 10 and the control unit 40. In addition, in the gas insulation device 200 according to the fifth embodiment, the second tank 22 is connected to the second insulating spacer 50 separately from the first insulating spacer 10. Furthermore, there is a third tank 23 that is connected to the second insulating spacer 50 and sandwiches the second insulating spacer 50 with the second tank 22. Furthermore, there is a third insulating spacer 60 that is connected to the third tank 23 separately from the second insulating spacer 50. Furthermore, there is a fourth tank 24 that is connected to the third insulating spacer 60 and sandwiches the third insulating spacer 60 with the third tank 23. In this case, both the second insulating spacer 50 and the third insulating spacer 6 have a first member 11 which is an insulating member, a second member 12 which is a conductive member covering the outer peripheral side surface of the first member 11, and a conductor holding portion 13.

[0035] A fourth antenna 16 and a fifth antenna 17 are provided inside the first member 11 of the third insulating spacer 60. The fourth antenna 16 and the fifth antenna 17 detect electromagnetic waves generated from inside the third tank 23 or the fourth tank 24. The fourth antenna 16 and the fifth antenna 17 are made of a conductive material such as aluminum. The fourth antenna 16 and the fifth antenna 17 are connected to the control unit 40. The fourth antenna 16 transmits a fourth electromagnetic wave, which is the electromagnetic wave detected by the fourth antenna 16, to the control unit 40. The fifth antenna 17 transmits a fifth electromagnetic wave, which is the electromagnetic wave detected by the fifth antenna 17, to the control unit 40. The control unit 40 determines whether or not partial discharge has occurred inside the third tank 23 or the fourth tank 24 from the fourth electromagnetic wave and the fifth electromagnetic wave acquired from the fourth antenna 16 and the fifth antenna 17. The inside of the third tank 23 or the inside of the fourth tank 24 mentioned here is not limited to the internal space of the third tank 23 or the fourth tank 24, but also indicates the internal surface of the third tank 23 or the fourth tank 24, the conductor 30 disposed therein, etc. On the other hand, the second insulating spacer 50 does not have an antenna.

[0036] The fourth antenna 16 and the fifth antenna 17 are connected to the control unit 40, similarly to the first insulating spacer 10. The control unit 40 determines the presence or absence of partial discharge inside the third tank 23 or the fourth tank 24 connected to the third insulating spacer, based on the fourth electromagnetic wave detected by the fourth antenna 16 of the third insulating spacer 60 and the fifth electromagnetic wave detected by the fifth antenna 17.

[0037] As described above, the partial discharge determining device 100 according to the fifth embodiment determines whether or not a partial discharge has occurred inside the first tank 21 or the second tank 22 based on the electromagnetic waves detected by the first antenna 14 and the second antenna 15. Also, whether or not a partial discharge has occurred inside the third tank 23 or the fourth tank 24 is determined based on the electromagnetic waves detected by the fourth antenna 16 and the fifth antenna 17. This makes it possible to determine whether or not a partial discharge has occurred inside the first tank 21 to the fourth tank 24 even if the second insulating spacer 50 does not have an antenna. Therefore, there is no need to provide an antenna on the second insulating spacer 50, and the number of parts can be reduced, thereby reducing the cost of the entire gas insulation device. [Explanation of symbols]

[0038] 10 Insulating spacer (first insulating spacer) 11 First Component 12 Second member 13 Conductor holding part 14, 141 First Antenna 15, 142 Second Antenna 16 The Fourth Antenna 17 The Fifth Antenna 21 First Tank 22 Second Tank 23 Third Tank 34 The Fourth Tank 30 Conductor 40 Control section 50 Second insulating spacer 60 Third insulating spacer 100 Partial discharge determination device 131 first conductor holding portion 132 second conductor holding portion 133 Third conductor holding part 143 The Third Antenna

Claims

1. a first insulating spacer including a first member that is an insulating member and a second member that is a conductive member that covers a side surface of the first member and reduces the influence of external electromagnetic waves, the first insulating spacer being sandwiched between and connected to the first tank and the second tank; a first antenna provided inside the first member and configured to detect electromagnetic waves generated from at least one of the first tank and the second tank; a second antenna provided inside the first member and closer to the second tank than the first antenna, the second antenna detecting electromagnetic waves generated from at least one of the first tank and the second tank; a control unit that determines whether or not a partial discharge has occurred inside the first tank or the second tank based on a first electromagnetic wave that is an electromagnetic wave detected by the first antenna and a second electromagnetic wave that is an electromagnetic wave detected by the second antenna; A partial discharge determination device having the same.

2. The control unit determining whether or not there is an abnormality in the electromagnetic waves from the waveforms of the first electromagnetic wave and the second electromagnetic wave; If the first time at which the abnormality in the first electromagnetic wave determined to be abnormal is detected is before the second time at which the abnormality in the second electromagnetic wave determined to be abnormal is detected, it is determined that a partial discharge has occurred inside the first tank, and if the first time is after the second time, it is determined that a partial discharge has occurred inside the second tank. The partial discharge determining device according to claim 1.

3. The first antenna and the second antenna have the same shape. The partial discharge determining device according to claim 1 or 2.

4. the first insulating spacer holds a plurality of conductors whose currents are out of phase with one another; The plurality of conductors are located inside the first tank or inside the second tank. The partial discharge determining device according to claim 1 or 2.

5. the first antenna is provided at a position different from the second antenna in the circumferential direction of the first insulating spacer, The control unit determines in which of the plurality of conductors a partial discharge is occurring, based on the first electromagnetic wave and the second electromagnetic wave. The partial discharge determining device according to claim 4.

6. a third antenna provided at a position different from the first antenna and the second antenna in the circumferential direction of the first insulating spacer, the third antenna detecting electromagnetic waves generated from at least one of the first tank and the second tank; a first conductor holding portion, a second conductor holding portion, and a third conductor holding portion provided on the first member and configured to hold the conductors, respectively; and a first antenna is disposed at a position closer to the first conductor holding portion than the second conductor holding portion and the third conductor holding portion; the second antenna is disposed at a position closer to the second conductor holding portion than the first conductor holding portion and the third conductor holding portion; a third antenna is disposed at a position closer to the third conductor holding portion than the first conductor holding portion and the second conductor holding portion; The control unit determines whether a partial discharge has occurred in the conductor held by the first conductor holding unit, the conductor held by the second conductor holding unit, or the conductor held by the third conductor holding unit, based on the first electromagnetic wave, the second electromagnetic wave, and a third electromagnetic wave that is an electromagnetic wave detected by the third antenna. The partial discharge determining device according to claim 5.

7. a third insulating spacer having the first member and the second member covering a side surface of the first member, the third tank and the fourth tank being sandwiched and connected to the second tank, the third insulating spacer having the first member and the second member covering a side surface of the first member; a fourth antenna provided inside the first member of the third insulating spacer, the fourth antenna detecting electromagnetic waves generated from at least one of the third tank and the fourth tank; a fifth antenna provided inside the first member of the third insulating spacer, closer to the fourth tank than the fourth antenna, and configured to detect electromagnetic waves generated from at least one of the third tank and the fourth tank; and The control unit determining whether or not a partial discharge has occurred inside the first tank or the second tank from a first electromagnetic wave detected by the first antenna and a second electromagnetic wave detected by the second antenna; The presence or absence of partial discharge occurring inside the third tank or the fourth tank is determined from a fourth electromagnetic wave detected by the fourth antenna and a fifth electromagnetic wave detected by the fifth antenna. The partial discharge determining device according to claim 1 or 2.

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