Partial discharge determining device

Abstract

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

Description

Partial discharge determination device

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

[0002] Conventionally, there have been devices for determining partial discharges occurring 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 (antennas for detecting electromagnetic waves) are provided in the metal cover, and electromagnetic waves accompanying partial discharges are detected by the multiple slot-shaped openings (antennas for detecting electromagnetic waves). This makes it possible to detect partial discharges with a simple configuration.

[0003] Japanese Patent Application Laid-Open No. 2007-263640

[0004] However, in the above-mentioned conventional partial discharge detector, a metal cover is disposed on the outer periphery of the gas-insulated equipment, and therefore the slot-shaped opening for detecting electromagnetic waves is also disposed on the outer periphery of the gas-insulated equipment. As a result, the partial discharge detector detects 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. Therefore, the partial discharge detector 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 influence of external disturbances and detect partial discharges that have occurred in gas-insulated equipment with higher accuracy.

[0006] The partial discharge determination device according to the present disclosure includes a first insulating spacer having 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 external electromagnetic waves, and is 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 or the second tank; a second antenna provided inside the first member and positioned 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 that determines whether or not partial discharge has occurred 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.

[0007] The partial discharge detecting device of the present disclosure has multiple antennas for detecting electromagnetic waves provided inside a first member that is an insulating member, and the first member is covered with a second member that is a conductive member. This allows the conductive member to reduce the disturbance detected by the antennas, enabling partial discharge to be detected with high accuracy.

[0008] FIG. 2( a) is a cross-sectional view of an insulating spacer constituting the partial discharge determining device according to embodiment 1. FIG. 2( b) is a cross-sectional view of an insulating spacer constituting the partial discharge determining device according to embodiment 1. FIG. 2( a) is a plan view of an insulating spacer constituting the partial discharge determining device according to embodiment 1, and FIG. 2( b) is a cross-sectional view of an insulating spacer constituting the partial discharge determining device according to embodiment 1. FIG. 2( b) is a diagram explaining a waveform of a normal electromagnetic wave and a waveform of an abnormal electromagnetic wave. FIG. 2( a) is a process flow for determining partial discharge according to embodiment 1. FIG. 2( b) is a process flow for determining partial discharge according to embodiment 2. 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 an insulating spacer constituting the partial discharge determining device according to embodiment 3. 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 an insulating spacer constituting the partial discharge determining device according to embodiment 4. FIG. 2( b) is a cross-sectional view of an insulating spacer constituting the partial discharge determining device according to embodiment 5.

[0009] Embodiment 1. A partial discharge determining device in embodiment 1 will be described with reference to Figures 1 to 4. Figure 1 is a cross-sectional view of the partial discharge determining device according to embodiment 1. 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 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 with 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 holder 13. A first antenna 14 and a second antenna 15, which is located closer to the second tank than the first antenna, are provided within the first member. The first antenna 14 and the second antenna 15 detect electromagnetic waves generated from the inside of the first tank 21 or the inside of the second tank 22. The first antenna 14 and the second antenna 15 are made of a conductive material 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 the electromagnetic wave detected by the first antenna 14, to the control unit 40. The second antenna 15 transmits a second electromagnetic wave, which is the 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 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 a 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 here is not limited to the internal space of the first tank 21 or the second tank 22, but also refers to 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, taken along the line A-A in FIG. 2( a). The insulating spacer 10 has a disk-like shape and a first member 11 therein. The second member 12 has a hollow disk-like shape and is provided to cover the first member 11. A first antenna 14 and a second antenna 15 are provided inside the first member 11. The second member 12 is made of a conductive material, and therefore reduces the detection of external disturbances such as broadcast waves and wireless communication waves by the first antenna 14 and second antenna 15 inside the second member 12. The conductor holding portion 13 is located approximately at the center of the insulating spacer.

[0013] Furthermore, 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 has a hole through which a cable for connecting to the control unit 40 (not shown) passes. 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 by which the control unit 40 determines whether the first electromagnetic wave and the second electromagnetic wave have an abnormality or not will be described. FIG. 3 is a diagram illustrating the waveform of a normal (abnormal) electromagnetic wave and the waveform of an electromagnetic wave with an abnormality. FIG. 3( a) shows the waveform of a normal (abnormal) electromagnetic wave, and FIG. 3( b) shows the waveform of an electromagnetic wave with an abnormality. In both diagrams, the horizontal axis represents time and the vertical axis represents signal strength, and the waveform represents the change in signal strength over time. A normal (abnormal) electromagnetic wave waveform exhibits a substantially constant signal strength regardless of the passage of time, as shown in FIG. 3( a). On the other hand, a waveform with an abnormality exhibits a sudden change in signal strength, as shown in the area surrounded by the dotted line in FIG. 3( b). The control unit 40 determines whether a sudden change in signal strength has occurred from the waveforms of the first electromagnetic wave and the second electromagnetic wave, and determines whether an abnormality exists or is normal (abnormal).

[0015] Next, a process will be described in which the control unit 40 of the partial discharge determining device 100 determines 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 determines whether the first electromagnetic wave and the second electromagnetic wave acquired during the same time period in step S101 are abnormal or normal (no abnormality) (step S102). Next, if the control unit 40 determines that the first electromagnetic wave and the second electromagnetic wave are abnormal (step S103: YES) based on the result of the abnormality determination in step S102, the control unit 40 determines whether a partial discharge exists inside the first tank 21 or the second tank 22 (step S104). On the other hand, if either the first electromagnetic wave or the second electromagnetic wave is normal (no abnormality) in the process of step S103 (step S103: NO), the control unit 40 determines that no partial discharge exists and ends the process.

[0017] As described above, in the partial discharge determining device 100, the first antenna 14 and the second antenna 15, which detect electromagnetic waves generated from inside the first tank 21 or the second tank 22, are provided inside the first member 11, which is an insulating member, and are surrounded by 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 equipment 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, it is possible to obtain the effect of reducing costs.

[0019] In addition, if it is determined in the determination process of step S103 that there is an abnormality in only one of the first electromagnetic wave or the second electromagnetic wave, it may not be determined that a partial discharge has occurred in the gas insulated device, but may be determined that there is simply a sensor abnormality.

[0020] Embodiment 2 A partial discharge determining device 100 in embodiment 2 will be described using Figure 5. In Figure 5, the same reference numerals as in Figure 4 indicate the same or corresponding parts. While the partial discharge determining device in embodiment 1 determines whether a partial discharge has occurred inside the first tank 21 or the second tank 22, the partial discharge determining device in embodiment 2 is configured to determine whether a partial discharge has occurred inside the first tank 21 or the second tank.

[0021] 5 shows 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 an abnormality is detected 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 control unit 40 acquires the first time and the second time, which are the times when the abnormal waveforms shown in FIG. 3B are detected. 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, a time between the occurrence of the abnormal waveform, or any other time during the occurrence of the abnormal waveform.

[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 processing 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 possible to determine 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, for example. In this case, it is determined that a partial discharge has occurred inside the tank closer to the antenna that detected the electromagnetic waves with the larger peak value. For example, if the peak value of the first electromagnetic waves is larger than the peak value of the second electromagnetic waves, it is determined that a partial discharge has occurred inside the first tank 21, which is closer to the first antenna 14 that detected the first electromagnetic waves. On the other hand, if the peak value of the second electromagnetic waves is larger than the peak value of the first electromagnetic waves, it is determined that a partial discharge has occurred inside the second tank 22, which is closer to the second antenna 15 that detected the second electromagnetic waves.

[0025] Embodiment 3 A partial discharge determining apparatus 100 in embodiment 3 will be described with reference to Figure 6. In Figure 6, the same reference numerals as in Figure 2 indicate the same or corresponding parts. While the insulating spacer in the partial discharge determining apparatus in embodiment 1 has one conductor holding portion, the insulating spacer in the partial discharge determining apparatus in embodiment 3 has a configuration that includes multiple conductor holding portions.

[0026] 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, taken along the line A-A in Fig. 6(a). The insulating spacer 10 according to embodiment 3 has three conductor holding portions: a first conductor holding portion 131, a second conductor holding portion 132, and a third conductor holding portion 133. These conductor holding portions hold conductors 30, but the currents in each conductor are out of phase with each other.

[0027] As described above, in the partial discharge determining device 100 according to the third embodiment, each insulating spacer 10 holds a plurality of conductors with different current phases. 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 A partial discharge determining device 100 in embodiment 4 will be described using Figure 7. In Figure 7, the same reference numerals as in Figure 6 indicate the same or corresponding parts. The partial discharge determining devices in embodiments 1 and 3 determine whether a partial discharge has occurred inside the first tank or inside the second tank, whereas the partial discharge determining device in embodiment 4 determines the occurrence of a partial discharge in the circumferential direction when multiple conductors are held, as in embodiment 3.

[0029] 7A is a plan view of an insulating spacer constituting the partial discharge determining device according to embodiment 4, and FIG. 7B is an enlarged view of each cross section of the insulating spacer constituting the partial discharge determining device according to embodiment 4. As shown in FIG. 7A, multiple 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] 7(b) is an enlarged view of each cross section shown in FIG. 7(a), in which the multiple antennas 141, 142, and 143 are arranged at different positions in the conductor axial direction. From the above, when a partial discharge occurs in a conductor held by one of the conductor holders 131 to 133, it is possible to determine which conductor holder the partial discharge occurred in. For example, a method can be considered in which the conductor held by the conductor holder closest to the antenna that detected the electromagnetic wave with the highest peak value of the abnormal waveform is determined to be abnormal, i.e., a partial discharge has occurred. In this case, abnormal waveforms are detected by the first antenna 141, the second antenna 142, and the third antenna 143, and if the electromagnetic wave peak value of the first antenna 141 is the highest, it is determined that the conductor held by the first conductor holder 131 closest to the first antenna 141 is abnormal, i.e., a partial discharge has occurred. On the other hand, if 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, if 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 positions in the circumferential direction of the insulating spacer, with each antenna arranged close to a different conductor, thereby making 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 and the number of antennas are three, i.e., the same number, but the number of conductors and the number of antennas may be different. For example, in Fig. 7, even if the second antenna 142 is not present near the second conductor holding portion 132 and a partial discharge occurs in the conductor held by the second conductor holding portion 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 portion 132, which is located at approximately the same distance from the first antenna 141 and the third antenna 143.

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

[0034] 8 is a cross-sectional view of a partial discharge determining apparatus according to a fifth embodiment. If the insulating spacer 10 in the first embodiment is referred to as the first insulating spacer 10, the partial discharge determining apparatus 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 apparatus 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 connected to the second insulating spacer 50 and sandwiching the second insulating spacer 50 between the second tank 22. Furthermore, there is a third insulating spacer 60 connected to the third tank 23 separately from the second insulating spacer 50. Furthermore, there is a fourth tank 24 connected to the third insulating spacer 60 and sandwiching the third insulating spacer 60 between 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 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 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. It should be noted that the interior of the third tank 23 or the interior 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 refers to 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, as are the first insulating spacer 10. The control unit 40 determines whether or not partial discharge has occurred inside the third tank 23 or the fourth tank 24 connected to the third insulating spacer 10, 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, which reduces the number of parts and the overall cost of the gas insulated apparatus.

[0038] REFERENCE SIGNS LIST 10 Insulating spacer (first insulating spacer) 11 First member 12 Second member 13 Conductor holding portion 14, 141 First antenna 15, 142 Second antenna 16 Fourth antenna 17 Fifth antenna 21 First tank 22 Second tank 23 Third tank 34 Fourth tank 30 Conductor 40 Control unit 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 portion 143 Third antenna

Claims

1. A partial discharge determination device having a first member that is an insulating member, and a second member that is a conductive member covering a side surface of the first member and reducing the influence of external electromagnetic waves, a first insulating spacer sandwiched and connected between a first tank and a second tank, a first antenna provided inside the first member for detecting electromagnetic waves generated from at least one of the first tank or the second tank, a second antenna provided inside the first member on the side of the second tank rather than the first antenna for detecting electromagnetic waves generated from at least one of the first tank or the second tank, and a control unit for determining the presence or absence of partial discharge in the first tank or the second tank from a first electromagnetic wave that is the electromagnetic wave detected by the first antenna and a second electromagnetic wave that is the electromagnetic wave detected by the second antenna.

2. The control unit determines the presence or absence of abnormality of the electromagnetic wave from the waveforms of the first electromagnetic wave and the second electromagnetic wave, and if a first time when an abnormality of the first electromagnetic wave determined to be abnormal is detected is earlier than a second time when an abnormality of the second electromagnetic wave determined to be abnormal is detected, it is determined that partial discharge is occurring inside the first tank, and if the first time is later than the second time, it is determined that partial discharge is occurring inside the second tank. The partial discharge determination device according to claim 1.

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

4. The first insulating spacer holds a plurality of conductors having different current phases from each other, and the plurality of conductors are located inside the first tank or the second tank. The partial discharge determination device according to any one of claims 1 to 3.

5. The first antenna is provided at a position different from the second antenna in the circumferential direction of the first insulating spacer, and the control unit determines in which of the plurality of conductors partial discharge is occurring from the first electromagnetic wave and the second electromagnetic wave. The partial discharge determination 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, for detecting an electromagnetic wave generated from at least one of the first tank and the second tank; first conductor holding portions, second conductor holding portions, and third conductor holding portions provided on the first member for holding the conductors respectively; wherein the first antenna is disposed closer to the first conductor holding portion than the second conductor holding portion and the third conductor holding portion; the second antenna is disposed closer to the second conductor holding portion than the first conductor holding portion and the third conductor holding portion; the third antenna is disposed closer to the third conductor holding portion than the first conductor holding portion and the second conductor holding portion; and the control unit determines in which conductor of the conductor held by the first conductor holding portion, the conductor held by the second conductor holding portion, or the conductor held by the third conductor holding portion partial discharge is occurring, from the first electromagnetic wave, the second electromagnetic wave, and a third electromagnetic wave detected by the third antenna. The partial discharge determination device according to claim 5.

7. A second insulating spacer having the first member and the second member covering the side surface of the first member is sandwiched and connected between a third tank and a fourth tank that are sandwiched and connected to the second tank, a third insulating spacer having the first member and the second member covering the side surface of the first member, a fourth antenna provided inside the first member of the third insulating spacer for detecting electromagnetic waves generated from at least one of inside the third tank and inside the fourth tank, and a fifth antenna provided inside the first member of the third insulating spacer on the side of the fourth tank relative to the fourth antenna for detecting electromagnetic waves generated from at least one of inside the third tank and inside the fourth tank. The control unit determines the presence or absence of partial discharge inside the first tank or inside the second tank from a first electromagnetic wave which is an electromagnetic wave detected by the first antenna and a second electromagnetic wave which is an electromagnetic wave detected by the second antenna, and determines the presence or absence of partial discharge inside the third tank or inside the fourth tank from a fourth electromagnetic wave which is an electromagnetic wave detected by the fourth antenna and a fifth electromagnetic wave which is an electromagnetic wave detected by the fifth antenna. The partial discharge determination device according to any one of claims 1 to 6.

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