JPH07231558A - Method and apparatus for detecting internal abnormality of gas insulated machine - Google Patents

Abstract

PURPOSE:To detect only the partial discharge in a tank by removing the partial discharge noise in the atmosphere generated on the outside of the tank positively. CONSTITUTION:The internal abnormality detecting apparatus comprises a waveguide 22 fixed to a tank 4, an electromagnetic wave sensor 23 disposed in the waveguide 22 in order to detect electromagnetic wave and to deliver an electric signal to the outside of the waveguide 22, and a signal processing section 8 for processing an output signal from the sensor 23 and notifying an abnormality in the tank 4.

Description

Detailed Description of the Invention

[0001]

This invention relates to a gas circuit breaker and a GIS.
The present invention relates to a method and apparatus for detecting an internal abnormality of SF ₆ gas-insulated equipment by measuring partial discharge.

[0002]

2. Description of the Related Art Gas-insulated equipment cannot detect the inside of a tank from the outside, so that an internal abnormality is detected by measuring partial discharge. FIG. 13 is a partially cutaway side view showing a configuration of a conventional internal abnormality detection device for a gas insulation device. The SF ₆ gas insulation device 1 has a configuration in which a circuit breaker 3 is housed in a tank 4 and both ends of the circuit breaker 3 are connected to an overhead line 5 via bushings 2. SF ₆ gas is enclosed in the tank 4 and the electromagnetic wave sensor 6
Is provided in the manhole portion 4A at the right end of the tank 4 and is connected to the signal processing portion 8 via the airtight terminal 7. Further, the output signal of the signal processing unit 8 is sent to the display unit 9. In addition, the high frequency current transformer 1 is connected to the ground wire 10 of the tank 4.
1, the output of the current transformer 11 is also sent to the display unit 9 via the signal processing unit 8. Further, an electromagnetic wave sensor 12 is installed near the outside of the left side of the tank 4 via a pedestal 13, and an output signal of this electromagnetic wave sensor 12 is also sent to the display unit 9 via the signal processing unit 8.

FIG. 13 shows 3 for measuring partial discharge.
Two methods are shown at the same time. Electromagnetic wave sensor 6, 1
2. The current transformer 11 is a sensor for detecting partial discharge and sending an electric signal to the signal processing unit 8. The electromagnetic wave sensors 6 and 12 are antennas that catch the electromagnetic waves emitted by the partial discharge. The electromagnetic wave sensor 6 captures the electromagnetic waves emitted from the partial discharge generated by the internal abnormality of the tank 4, inside the tank 4.
Captures electromagnetic waves emitted from the partial discharge generated by the internal abnormality of the tank 4 and leaking from the bushing 2 to the outside of the tank 4. The current transformer 11 catches the partial discharge current because the partial discharge current generated by the internal abnormality of the tank 4 flows through the ground line 10.

Even if any of the methods shown in FIG. 13 is used, the tank 4
Of the electromagnetic wave sensors 6 and 12 and the current transformer 11, and outputs a signal notifying that an abnormality has occurred inside the tank 4, The display 9 receives the output signal of the signal processing unit 8 and displays that an abnormality has occurred inside the tank 4 on a display or a cathode ray tube.

[0005]

However, the conventional apparatus as described above has a problem in that the internal abnormality of the tank cannot be detected because it is disturbed by the partial discharge in the atmosphere generated outside the gas-insulated equipment. That is, outside the tank, a partial discharge in the air is likely to occur on the overhead wire or the head of the bushing in the case of rain. Electromagnetic waves and high frequency currents due to this partial discharge in the air become noise and enter the electromagnetic wave sensor and the current transformer. When this noise level becomes large, the level of partial discharge that occurs when the inside of the tank is abnormal is exceeded, and the internal abnormality of the tank may not be detected.

FIG. 14 shows an electromagnetic wave sensor 6 in FIG.
It is a frequency characteristic diagram of the electromagnetic wave which was captured. The horizontal axis shows the frequency F and the vertical axis shows the level of the electromagnetic wave component. Characteristic 13 shows partial discharge in the air in the overhead line 5, and characteristic 14 shows partial discharge in SF ₆ gas when the inside of the tank 4 is abnormal. In this case, the characteristic 15 is a characteristic when the partial discharge in the overhead wire 5 and the internal partial discharge in the tank 4 occur at the same time. In any of the characteristics, the output signal of the electromagnetic wave sensor 6 is output via the frequency analyzer.

In FIG. 14, it is understood from the characteristic 13 that the partial discharge in the air has few frequency components of 0.5 GHz or more. On the other hand, from characteristic 14, the partial discharge in SF ₆ gas is 0.8.
It can be seen that there are many frequency components above GHz. Since each partial discharge detection device in FIG. 13 does not include a frequency analyzer, when an electromagnetic wave having the characteristics shown in FIG. 14 is generated,
Only that peak value is detected. That is, in the case of the characteristic 14, the partial discharge inside the tank can be accurately measured, but in the cases of the characteristics 13 and 15, the noise due to the partial discharge in the air interferes and the partial discharge inside the tank is accurately measured. I can't. That is, regardless of whether or not there is an internal abnormality in the tank, only the noise level is detected, and the abnormality detection is erroneously determined.

In order to eliminate the above-mentioned erroneous determination of abnormality detection, it is conceivable to cut the electromagnetic wave component of 0.7 GHz or less. As a method to do so, it is conceivable to interpose a filter circuit that cuts off a frequency of 0.7 GHz or lower or a bandpass filter circuit that passes only a specific frequency of 0.8 GHz or higher on the output side of the electromagnetic wave sensor or current transformer. . Although noise removal by this filter circuit is not impossible, it is very difficult to obtain the attenuation characteristics shown in the catalog even with a commercially available filter circuit. The reason is that since high frequencies are handled, the components of the frequency to be cut off bypass between the input and output wirings of the filter circuit unless careful attention is paid to the installation location and wiring of the filter circuit. If the grounding method of the filter circuit is not devised, the cutoff frequency component will be transmitted to the output side of the filter circuit through the ground wire.

An object of the present invention is to reliably remove the components of the partial air discharge generated outside the tank and to detect only the partial discharge generated inside the tank.

[0010]

In order to achieve the above object, according to the method of the present invention, there is provided a method for detecting an internal abnormality of a gas-insulated device in which an electric device is housed in a tank filled with SF ₆ gas. The axial end of the waveguide, which is formed of a conductor tube whose axial length is longer than the width or diameter of the lumen, is attached to the tank wall in a state where one end of the waveguide in the axial direction communicates with the inside of the tank. An electromagnetic wave sensor installed in the converter converts the electromagnetic wave that has propagated inside the waveguide into an electrical signal,
It is preferable that the electric signal is processed by the signal processing unit to notify that an abnormality has occurred inside the tank.

Further, in order to achieve the above object, according to the present invention, a waveguide having an axial length longer than the width or diameter of the inner cavity is formed, and one axial end communicates with the inside of the tank. In this state, the waveguide is attached to the tank wall, and the other end in the axial direction is gas-sealed, and an electromagnetic wave is detected inside the waveguide and an electric signal is output to the outside of the waveguide. The electromagnetic wave sensor and the signal processing unit that processes the output signal of the electromagnetic wave sensor and notifies that an abnormality has occurred inside the tank.

Further, in such a configuration, a branch pipe is provided in communication with the waveguide between the tank side opening of the waveguide and the electromagnetic wave sensor, and the opposite waveguide side of the branch pipe is gas-sealed. At the same time, a conductive terminal plate that closes the inner cavity may be provided inside the branch pipe. In addition, the end plate is slidably arranged in the axial direction of the branch pipe lumen, one end is attached to the end plate and the other end is pulled out of the branch pipe, and the drive rod is grasped by the branch pipe part. A drive unit for sliding the terminal plate in the axial direction of the branch pipe may be provided.

Further, in such a construction, instead of the branch pipe, an expansion pipe having a partially enlarged width or diameter of the lumen is interposed between the tank-side opening of the waveguide and the electromagnetic wave sensor. It is good to Further, the expansion pipe may be a flexible pipe whose axial direction can be changed. In addition, in such a configuration, the lumen of the waveguide is filled with a solid insulator instead of the expansion tube, or the waveguide of the waveguide is provided between the tank-side opening of the waveguide and the electromagnetic wave sensor. It is preferable that a wire net that closes the inner cavity is provided.

[0014]

According to the structure of the present invention, the waveguide communicating with the tank is provided, and the electromagnetic wave sensor is housed in the waveguide. In the waveguide, the cutoff frequency component of the electromagnetic wave traveling axially in the lumen varies depending on the width or diameter of the lumen. All electromagnetic waves below the cutoff frequency are attenuated and do not propagate in the axial direction. Therefore, if a waveguide having a cutoff frequency of at least 0.7 GHz is used, the components of the partial air discharge generated outside the tank are reliably attenuated, and only the partial discharge in the SF ₆ gas generated inside the tank is detected. be able to.

Further, in such a structure, a branch pipe having a built-in end plate is provided in the middle of the waveguide. The depth from the inlet of the branch pipe to the end plate specifies the frequency component of the electromagnetic wave that can travel axially in the lumen of the waveguide. That is, the branch pipe functions as a bandpass filter for electromagnetic waves. Therefore, even if the cutoff frequency of the waveguide is not set to 0.7 GHz, it can be adjusted to 0.8G by adjusting the depth of the branch pipe.
Only specific frequency components above Hz can be passed, and only partial discharge in SF ₆ gas generated inside the tank can be detected.

Further, the end plate is made slidable in the axial direction of the branch pipe by the drive unit from the outside of the tank via the drive rod. As a result, the depth of the branch pipe can be easily adjusted from outside the tank, and 0.8G other than partial discharge in the air can be adjusted.
If ambient noise having a specific frequency component of Hz or higher is incident, it is possible to avoid the specific frequency component and detect only the partial discharge in the SF ₆ gas.

Further, in such a construction, an expansion tube is inserted in the middle of the waveguide instead of the branch tube. The axial length of the expansion tube specifies the frequency component of the electromagnetic wave that can travel axially through the lumen of the waveguide. That is, the expansion tube also serves as a bandpass filter for electromagnetic waves. Therefore, it is possible to detect only the partial discharge in the SF ₆ gas generated inside the tank in the same manner as the branch pipe described above.

Further, by diverting the flexible pipe as the expansion pipe, even if the position on the terminal end side of the waveguide slightly shifts from the tank side, it is absorbed and the installation work of the waveguide becomes easy. At the same time, the earthquake resistance is improved. Also,
In such a configuration, the solid insulator is filled in the lumen of the waveguide instead of the expansion tube. In general, the cutoff frequency of electromagnetic waves greatly depends on the dielectric constant. Letting the relative permittivity be ε, the lumen is filled with one having a larger ε than the gas (ε = 1). In order for a waveguide filled with solid insulator to have the same value as the cutoff frequency of a gas-filled waveguide, the lumen width or diameter of the gas-filled waveguide divided by ε ^0.5 It may be of width or diameter. Therefore, even if the cutoff frequency does not always match 0.7 GHz, the cutoff frequency can be reduced to 0.7 GH by filling with a solid insulator having an appropriate value of ε.
Can be changed to z. Moreover, the waveguide can be made more compact by filling the solid insulator having a large ε.

Further, in such a structure, instead of filling the waveguide with the solid insulator, the wire mesh is provided so as to close the inner cavity. Since the wire net cuts off the low frequency side of the electromagnetic wave, even if the cut-off frequency of the waveguide is not necessarily set to 0.7 GHz, it is possible to cut off components below 0.5 GHz by making the mesh of the wire mesh appropriate. Only partial discharge in ₆ gases can be detected.

[0020]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a cross-sectional view of essential parts showing the configuration of an internal abnormality detection device for a gas insulation device according to an embodiment of the present invention. The gas insulation device 1 has the same structure as that of FIG. 13, in which the circuit breaker 3 is housed in the tank 4 and the bushing 2 is attached. A cylindrical waveguide 22 is attached to the manhole portion 4A of the tank 4 and SF ₆ gas is sealed therein. An electromagnetic wave sensor 23 is provided at the right end of the waveguide 22 and is connected to the signal processing unit 8 via an airtight terminal 24. Further, the output signal of the signal processing unit 8 is sent to the display unit 9.

In FIG. 1, when a partial discharge in SF ₆ gas occurs due to an internal abnormality of the tank 4, electromagnetic waves radiated from the partial discharge enter the waveguide 22 from the tank 4 and enter the waveguide 22. Propagate in the axial direction. Electromagnetic wave sensor 2
3 captures the propagating electromagnetic wave, converts it into an electric signal, and sends it to the signal processing unit 8. The signal processing unit 8 processes the electric signal and outputs a signal notifying that an internal abnormality has occurred, and the display 9 indicates that an abnormality has occurred inside the tank 4 on a display or a cathode ray tube. Waveguide 22
Intercepts electromagnetic wave components below a specific frequency determined by its diameter.

FIG. 2 is a frequency characteristic diagram of electromagnetic waves propagating in the waveguide 22 in the axial direction. The horizontal axis represents the frequency F, and the vertical axis represents the attenuation amount of the electromagnetic wave level per unit length. Characteristic 25 is when the waveguide 22 has a cylindrical shape and its inner diameter d is 250 mm, and Fc = 0.7 GH.
The attenuation becomes infinite at z. This Fc is called the cutoff frequency and depends on the diameter d.

FIG. 3 is a characteristic diagram showing the relationship between the lumen diameter d of the waveguide and the cutoff frequency Fc, and the characteristic 26 shows the characteristic of the fundamental mode electromagnetic wave in the cylinder. The cut-off frequency Fc decreases as the lumen diameter d increases. FIG. 4 is a frequency characteristic diagram of an electromagnetic wave captured by the electromagnetic wave sensor, in which the horizontal axis represents frequency and the vertical axis represents the level of the electromagnetic wave component. Characteristic 2
Nos. 7 and 28 both output an electromagnetic wave sensor output signal through a frequency analyzer when a partial discharge in the air occurs on the overhead wire outside the tank and a partial discharge in the SF ₆ gas also occurs inside the tank. It is a thing. Characteristic 27 is
The characteristic 28 is detected by the electromagnetic wave sensor 6 in the conventional configuration shown in FIG. 13, and the characteristic 28 is detected by the electromagnetic wave sensor 23 in the configuration shown in FIG. Characteristic 27 of FIG.
Is the same as the characteristic 15 in FIG. 14, and the frequency is 0.5.
Noise of partial discharge in the air can be seen below GHz, 0.8 GHz
This is an obstacle to the detection of the partial discharge in the SF ₆ gas. The characteristic 28 of FIG. 4 is that the waveguide 2 having a diameter d of 250 mm is
When 2 is used (cutoff frequency Fc is 0.7 GHz)
Therefore, only partial discharge in SF ₆ gas is detected. That is, since the frequency component of 0.7 GHz or less is greatly attenuated by the intervention of the waveguide 22, the electromagnetic wave sensor 2
By sending the output signal of No. 3 to the signal processing unit 8, the internal abnormality of the tank can be reliably detected.

In FIG. 3, the cutoff frequency F is added to the waveguide.
In order to set c to 0.7 GHz, the lumen diameter d should be set to 250 mm. Therefore, in order to remove the noise and set the cutoff frequency to at least 0.7 GHz, the inner diameter d of the waveguide may be set to 250 mm or less. In FIG. 1, the waveguide 22 may be a waveguide of any shape such as a rectangular tube or an elliptic tube, and is not necessarily a cylinder. Here, although it is omitted to show the characteristics of other shapes of the conductive tube,
Cutoff frequency F determined by the shape and thickness of the lumen
It has c. However, in any shape of the conductive tube, unless the axial length is secured to some extent, the attenuation characteristic of the electromagnetic wave at the cutoff frequency Fc does not become as shown in FIG. The axial length of the waveguide 22 is at least the width of the lumen
It must be longer than the width (long side width for rectangular tubes) or diameter (long diameter for elliptical tubes). This is the minimum condition for the conductor tube to function as the waveguide 22. In the conventional configuration of FIG. 13, the electromagnetic wave sensor 6 is housed in the manhole portion 4A at the right end of the tank 4,
The conductor tube of the manhole portion 4A does not function as a waveguide at all because the axial length thereof is extremely short with respect to the diameter.

FIG. 5 is a partially cutaway side view showing the structure of an internal abnormality detecting device for a gas insulation device according to a different embodiment of the present invention. A branch pipe 30 is attached between the tank 4 and the electromagnetic wave sensor 23 in the middle of the waveguide 29, and a conductive terminal plate 31 is housed inside. The end plate 31 includes
An L-shaped groove 32 is formed around the outer peripheral wall, and the other end is provided with a drive rod 33 that is airtightly drawn to the outside of the branch pipe 30. The drive rod 33 is connected to a drive unit 34 provided outside the branch pipe 30, and the end plate 31 can be slid in the axial direction of the branch pipe 30 by rotating the drive unit 34. Others are the same as the configuration of FIG.

In FIG. 5, the electromagnetic wave traveling in the waveguide 29 in the axial direction is limited to a specific frequency component by the branch pipe 30. The specific frequency depends on the depth D from the inlet of the branch pipe 30 to the terminal plate 31. FIG. 6 shows a branch pipe 3.
FIG. 6 is a characteristic diagram showing a relationship between a depth D of 0 and an attenuation amount of an electromagnetic wave propagating in the waveguide 29 in the axial direction (from Reference 1).

Reference 1 ... Udagawa, "New Edition, Radio Engineering I, Transmission Edition", published by Maruzen KK, 1964: The horizontal axis in FIG. 6 shows the branch pipe depth D, and the vertical axis shows the electromagnetic wave attenuation. λ represents the wavelength of the electromagnetic wave, and if the speed of light is C (= 3 × 10 ¹⁰ m / s), its frequency F is C / λ. Electromagnetic wave attenuation characteristics 3
5 is the smallest when the depth D is λ / 4, or λ / 4. That is, when D = λ / 4,

[0028]

## EQU1 ## Electromagnetic waves having only frequency components determined by F = C / λ = C / 4D propagate, and other frequency components are greatly attenuated. This is the waveguide 2
9 means that a bandpass filter is provided. Therefore, the cutoff frequency Fc of the waveguide 29 is not necessarily 0.7 GHz.
It is possible to pass only a specific frequency component of 0.8 GHz or higher by adjusting the depth D of the branch pipe 30 without detecting, and to detect only partial discharge in SF ₆ gas generated inside the tank 4. be able to. If the diameter d of the waveguide 29 is large and the desired cut-off frequency Fc is too low, the branch pipe 30 can be made to play its role.

Returning to FIG. 5, the depth D of the end plate 31 can be adjusted to a desired size by the driving unit 34. Although the end plate 31 should completely block the inner lumen of the branch pipe 30,
A slight gap 31A is provided between the outer peripheral surface of the end plate 31 and the inner peripheral surface of the branch pipe 30 so that the end plate 31 can slide.
Need to leave. As an L-shaped groove, A = B = λ /
By making the shape satisfying the relation of 4, the condition equivalently corresponds to the case where there is no gap 31A.

FIG. 7 is a cross-sectional view of essential parts showing the structure of an internal abnormality detecting device for a gas insulation device according to a further different embodiment of the present invention. In the middle of the waveguide 36, an expansion tube 37 having a diameter larger than that of the waveguide 36 and having an axial length L is interposed between the tank 4 and the electromagnetic wave sensor 23. Others are the same as the configuration of FIG. In FIG. 7, the waveguide 3
The electromagnetic wave traveling in the axial direction 6 is limited to a specific frequency component by the expansion tube 37. The specific frequency depends on the length L of the expansion tube.

FIG. 8 shows the length L of the expansion tube 37 and the waveguide 36.
FIG. 4 is a characteristic diagram showing the relationship with the attenuation amount of electromagnetic waves propagating in the axial direction (from the above-mentioned Document 1). The horizontal axis of FIG. 8 indicates the length L of the expansion tube, and the vertical axis indicates the amount of attenuation of electromagnetic waves. The electromagnetic wave attenuation characteristic 38 becomes minimum when the length L is λ / 2. That is, when L = λ / 2,

[0032]

## EQU00002 ## Electromagnetic waves having only frequency components determined by F = C / .lambda. = C / 2L propagate, and other frequency components are greatly attenuated. This is the waveguide 3
6 means that a bandpass filter is provided. Therefore, the cutoff frequency Fc of the waveguide 36 is not necessarily 0.7 GHz.
Even if it does not, by adjusting the length L of the expansion tube 37, it is possible to pass only a specific frequency component of 0.8 GHz or higher, and only the partial discharge in the SF ₆ gas generated inside the tank 4 is detected. be able to. If the diameter d of the waveguide 36 is large and the desired cut-off frequency Fc is too low, the expansion tube 37 can be made to do its job.

FIG. 9 is a cross-sectional view of the essential parts showing the structure of the internal abnormality detecting device for a gas-insulated equipment according to still another embodiment of the present invention. A flexible pipe 39 is interposed as an expansion pipe in the middle of the waveguide 40. Others are shown in FIG.
The configuration is the same as that of. The flexible pipe 39 can be easily changed in the axial direction, and even if the terminal side (right side) of the waveguide 40 is slightly displaced from the tank side (left side), it is absorbed, and the installation work of the waveguide 40 is performed. It becomes easier and the earthquake resistance is improved. By selecting a flexible pipe 39 having a lumen diameter larger than that of the waveguide 40,
It can have a function as an expansion tube.

FIG. 10 is a cross-sectional view of essential parts showing the structure of an internal abnormality detecting device for a gas-insulated equipment according to a further different embodiment of the present invention. The solid insulator 42 is provided in the inner cavity of the waveguide 41.
To fill. Others are the same as the configuration of FIG. Figure 1
At 0, the lumen of the waveguide 41 is filled with a material having a relative dielectric constant ε larger than that of gas. In order for the waveguide 41 filled with the solid insulator 42 to have the same value as the cutoff frequency Fc of the gas-filled waveguide, the diameter of the gas-filled waveguide is divided by ε ^0.5. You can do this. Therefore, even if the cutoff frequency Fc does not necessarily match 0.7 GHz, the cutoff frequency Fc can be changed to 0.7 GHz by filling the solid insulator 42 having an appropriate value of ε. Further, the waveguide 41 can be made more compact by filling the solid insulator 42 having a large ε.

FIG. 11 is a cross-sectional view of the essential parts showing the structure of the internal abnormality detecting apparatus for a gas-insulated equipment according to still another embodiment of the present invention. A wire netting 44 is provided so as to close the inner cavity of the waveguide 43. FIG. 12 shows a diameter of 500 mm.
FIG. 3 is a frequency characteristic diagram of electromagnetic waves propagating in the cylindrical waveguide of FIG. The horizontal axis represents the frequency F, and the vertical axis represents the attenuation amount of the electromagnetic wave level per unit length. The characteristic 45 is the case where the wire net 44 is not provided in FIG. 11, and the characteristic 46 is the case where the wire net 44 is provided in FIG. Characteristic 4
Although the cut-off frequency Fc of 5 is 0.35 GHz, which is too low to remove noise, the low-frequency side can be cut like the characteristic 46 by installing the wire net 44. Since the frequency components of only the shaded area 47 are detected, the waveguide 43
Even if the cutoff frequency Fc is not appropriate, the partial discharge in the SF ₆ gas can be detected by installing the wire net 47.

In FIG. 12, the characteristic 46 changes depending on the mesh of the wire mesh, and the smaller the mesh, the higher the frequency shifts. Therefore, by selecting the kind of wire mesh, it is possible to detect a desired frequency component.

[0037]

As described above, the present invention provides the electromagnetic wave sensor in the waveguide provided with the waveguide communicating with the tank. As a result, an abnormality inside the tank can be reliably detected without using a filter circuit that is difficult to use, and the detection sensitivity is improved. In such a configuration, a branch pipe having a built-in end plate is provided in the middle of the waveguide. Thereby, only the specific frequency component of the electromagnetic wave can be detected, and even if the width or diameter of the waveguide is not appropriate, the abnormality inside the tank can be surely detected.

In this structure, the end plate in the branch pipe can be slid by the drive unit from the outside of the tank via the drive rod. As a result, the depth of the branch pipe can be adjusted from the outside, and even if ambient noise of a specific frequency component enters, the SF can be avoided by avoiding the specific frequency component.
Only partial discharge in ₆ gas can be detected reliably,
The detection sensitivity is improved.

Further, in such a structure, instead of the branch pipe, an expansion pipe is inserted in the middle of the waveguide. Also in this case,
It is possible to detect only the specific frequency component of the electromagnetic wave, and it is possible to reliably detect an abnormality inside the tank even if the width or diameter of the waveguide is not appropriate. In addition, in such a configuration, a flexible pipe is used as the expansion pipe.
As a result, the installation work of the device is facilitated and the earthquake resistance is improved. Further, in such a configuration, the solid insulator is filled in the lumen of the waveguide instead of the expansion tube. Thereby, even if the width or diameter of the waveguide is not appropriate, an abnormality inside the tank can be reliably detected and the waveguide can be made compact.

In such a structure, instead of filling the waveguide with the solid insulator, the wire mesh is provided so as to close the inner cavity. Thus, even if the cutoff frequency of the waveguide is too low for noise removal and is not appropriate, the wire mesh removes the noise component, so that an abnormality in the tank can be reliably detected.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing the configuration of an internal abnormality detection device for a gas insulation device according to an embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram of electromagnetic waves propagating in a waveguide.

FIG. 3 is a characteristic diagram showing a relationship between a lumen diameter d of a waveguide and a cutoff frequency Fc.

[Fig. 4] Frequency characteristic diagram of electromagnetic waves captured by an electromagnetic wave sensor

FIG. 5 is a partially cutaway side view showing the configuration of an internal abnormality detection device for a gas insulation device according to a different embodiment of the present invention.

FIG. 6 is a characteristic diagram showing the relationship between the depth D of the branch pipe and the amount of attenuation of electromagnetic waves propagating in the waveguide.

FIG. 7 is a cross-sectional view of essential parts showing the configuration of an internal abnormality detection device for a gas-insulated device according to still another embodiment of the present invention.

FIG. 8 is a characteristic diagram showing the relationship between the length L of the expansion tube and the attenuation of electromagnetic waves propagating in the waveguide.

FIG. 9 is a cross-sectional view of essential parts showing the configuration of an internal abnormality detection device for a gas-insulated device according to still another embodiment of the present invention.

FIG. 10 is a cross-sectional view of an essential part showing the configuration of an internal abnormality detection device for a gas-insulated device according to still another embodiment of the present invention.

FIG. 11 is a cross-sectional view of essential parts showing the configuration of an internal abnormality detection device for gas-insulated equipment according to still another embodiment of the present invention.

FIG. 12 is a frequency characteristic diagram of electromagnetic waves propagating in a cylindrical waveguide having a diameter of 500 mm.

FIG. 13 is a partially cutaway side view showing a configuration of a conventional internal abnormality detection device for gas-insulated equipment.

14 is a frequency characteristic diagram of electromagnetic waves captured by the electromagnetic wave sensor 6 in FIG.

[Explanation of symbols]

 1 Gas Insulation Equipment 2 Bushing 3 Circuit Breaker 4 Tank 4A Manhole Section 8 Signal Processing Section 9 Display Section 22, 29, 36, 40, 41, 43 Waveguide 23 Electromagnetic Wave Sensor 30 Branch Pipe 31 End Plate 31A Gap 32 L-shaped Groove 33 drive rod 34 drive part 37 expansion tube 39 flexible pipe 42 solid insulator 44 wire mesh

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshitake Nakagami 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. (72) Inventor, Tomoyuki Hosoi Nitta Tanabe, Kawasaki-ku, Kawasaki-shi, Kanagawa No. 1 in Fuji Electric Co., Ltd. (72) Inventor Satoshi Matsuura 5-14-24 Hiyoshidai, Takatsuki-shi, Osaka (72) Inventor Zenichiro Kawasaki 2-1023 Nishi, Toshima-cho, Moriguchi-shi, Osaka

Claims (8)

[Claims] 1. A method for detecting an internal abnormality of a gas-insulated device in which an electric device is housed in a tank filled with SF ₆ gas, the method comprising: a conductor tube having an axial length longer than a width or a diameter of a lumen. The formed waveguide is attached to the tank wall with one end in the axial direction communicating with the inside of the tank, and the electromagnetic wave sensor provided inside the waveguide transmits the electromagnetic wave propagating inside the waveguide to an electric signal. A method for detecting an internal abnormality of a gas-insulated device, which comprises converting the electric signal into a signal and processing the electric signal by a signal processing unit to notify that an abnormality has occurred inside the tank. 2. An apparatus for carrying out the method according to claim 1, which is formed of a conductor tube having an axial length longer than a width or a diameter of the lumen, and one axial end of which is communicated with the inside of the tank. In this state, the waveguide is attached to the tank wall and the other end in the axial direction is gas-sealed, and an electromagnetic wave is provided inside the waveguide to detect electromagnetic waves and output an electric signal to the outside of the waveguide. An internal abnormality detection device for a gas-insulated device, comprising an electromagnetic wave sensor and a signal processing unit that processes an output signal of the electromagnetic wave sensor and notifies that an abnormality has occurred inside the tank. 3. The branch pipe according to claim 2, wherein a branch pipe is provided in communication with the waveguide between the tank-side opening of the waveguide and the electromagnetic wave sensor, and a gas pipe is provided on the side opposite to the branch pipe. An internal abnormality detection device for a gas-insulated device, which is provided with a conductive terminal plate that is sealed and that closes the inner lumen inside the branch pipe. 4. The drive rod according to claim 3, wherein the end plate is slidably arranged in the axial direction of the branch pipe lumen, one end of which is attached to the end plate and the other end of which is drawn out of the branch pipe. An internal abnormality detection device for a gas-insulated device, comprising: a drive unit that grips the drive rod outside the branch pipe and slides an end plate in the axial direction of the branch pipe. 5. The expansion tube according to claim 2, wherein an expansion tube having a partially increased width or diameter of the inner cavity is interposed between the tank-side opening of the waveguide and the electromagnetic wave sensor. An internal abnormality detection device for gas-insulated equipment. 6. The apparatus for detecting an internal abnormality in a gas insulation device according to claim 5, wherein the expansion tube is a flexible pipe whose axial direction can be changed. 7. The apparatus for detecting an internal abnormality in a gas-insulated device according to claim 2, wherein the lumen of the waveguide is filled with a solid insulator. 8. The gas-insulated device according to claim 2, further comprising: a wire mesh that closes an inner cavity of the waveguide between the tank-side opening of the waveguide and the electromagnetic wave sensor. Internal abnormality detection device.