JP3086714B2 - Method and apparatus for detecting decomposed gas in gas-filled electric equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, partial discharge or local overheating of a gas-filled electric device in which an electric device main body is housed in a tank together with an insulating gas for insulation or cooling, such as a gas insulating transformer. The present invention relates to a detection method and a device for quickly and reliably detecting generated decomposition gas.

[0002]

2. Description of the Related Art Conventionally, in an electric device such as a transformer, an oil-filled transformer in which an insulating oil excellent in insulation and cooling performance is sealed in a tank accommodating the device main body has been the mainstream. However, if a failure due to abnormal overheating occurs in this oil-immersed transformer, there is a risk that the insulating oil may ignite or explode, causing a secondary disaster such as a fire in surrounding buildings.
In particular, with the increase in demand for electric power in recent years, electrical equipment is often installed in the basement of buildings near city centers due to the difficulty in securing the installation location. As a result, transformers are subject to fire due to changes in the installation environment. There is a social demand for a material that is safe and has no risk of generation and environmental destruction.

In recent years, however, a gas-insulated transformer has been adopted in place of the oil-immersed transformer, which has no risk of fire or the like, and which is smaller and lighter than the oil-immersed cooling system and which has excellent disaster prevention and reliability. It has become. This gas insulating transformer encloses an insulating gas such as SF ₆ gas (sulfur hexafluoride gas) as a cooling medium in place of the insulating oil in a tank accommodating the equipment main body, and provides the insulating and cooling of the equipment main body. Have been. Further, even if the temperature inside the tank becomes abnormally high due to a failure or the like, there is almost no risk of fire occurrence and there is little adverse effect on the surrounding environment.

On the other hand, electrical equipment such as a transformer must be shut down due to an accident from the viewpoint of stable power supply. However, in the case of the transformer, for example, an eddy current flows through a structural member constituting a tank or a device main body due to leakage magnetic flux, and abnormal overheating occurs locally, or heat generation due to incomplete contact of a conductor connection portion, and further, There are many causes of abnormalities such as insulation deterioration caused by partial discharge and heat generation due to aging deterioration of insulators, and when these abnormalities expand, as described above, it leads to a major accident and causes a power supply stop. Become.

[0005]

As described above, it is very important to detect or detect an internal abnormality of an electric device at an early stage in order to prevent a major accident of the electric device from occurring. This point, for example, the same in the gas insulated transformer using an insulating gas such as SF ₆ gas, or abnormality occurs in the apparatus body, constantly or periodically detecting insulating gas in order to determine whether Need to be analyzed. When an abnormality occurs in the device main body, for example, a winding conductor (CU) that is overheated due to the abnormality directly reacts with an insulating gas such as SF ₆ gas to generate a decomposition gas such as SF ₄ gas.
By examining the presence or absence of these decomposed gases, it is possible to easily know whether or not the device main body is abnormal. However, conventionally, when detecting the decomposition gas, for example, a gas is collected from the inside of the tank of the transformer, and the gas is contained in the collected gas by using a gas chromatograph or a mass analyzer. By analyzing whether or not there is an abnormality, the abnormality detection of the main body of the device was attempted, but there were the following problems.

[0006] (1) When checking the presence or absence of an abnormality in the main body of the apparatus, the gas in the tank is temporarily taken into a cylinder, and the gas is transported to a place where an analyzer such as a gas chromatograph is located to detect the presence or absence of a decomposition gas. Therefore, there is a problem that it takes time and effort to perform the detection, and if an abnormality of the device main body progresses during this time, it is not possible to predict and maintain a major accident of the device beforehand. (2) In addition, the above-mentioned gas sampling operation must be performed under the live condition of the transformer, which is extremely dangerous. Since the pressure drops, there is naturally a limit.As a result, when the magnitude of the abnormality is small or in the initial stage of the occurrence of the abnormality, the sensitivity is often lower than the detection sensitivity of the analyzer, and it is not possible to detect the abnormality early. There were also problems. (3) Furthermore, on the tank side, equipment for collecting decomposed gas, such as a gas sampling valve and a sampling pipe, must be separately installed in order to collect the internal gas. There was a problem that the structure became complicated. (4) Separately installed analyzers for decomposed gas such as small gas chromatographs in gas-insulated transformers, and always or regularly detect decomposed gases at the transformer installation site. However, since this requires an expensive analyzer to be installed in the transformer, there is a problem that the manufacturing cost of the gas-insulated transformer is necessarily increased.

[0007] In view of the above problems, an insulating property such as SF ₆ gas, without giving any way affect the performance of cooling performance such as an insulating gas itself is originally provided, including partial discharge or local heating or the like It is an object of the present invention to provide a method and an apparatus for detecting a decomposed gas in a gas-filled electric device which enables a small abnormality such as an abnormal state of a small scale or an initial stage of occurrence of an abnormality to be detected early and easily. I do.

[0008]

According to the present invention, in order to achieve the above object, a decomposed gas detection device is installed in a gas flow pipe between a tank containing an apparatus main body and a cooler. internal this decomposition gas detection apparatus, a detection sealed containers heat medium such as antifreeze can withstand high and low temperature, the gas flow pipe and openably connecting stub of <br/> is in the detection container A detection tube filled with an adsorbent is housed in a liquid-tight manner, and the detection tube is connected to the pressure detection device via an opening / closing means.
And a vacuum pump for keeping the inside of the detection tube at a required degree of vacuum, and a cooling / heating device for lowering and increasing the temperature of the heating medium to a required temperature in the detection vessel in which the heating medium is sealed. It is characterized by having been configured to.

[0009]

When detecting a decomposition gas in the present invention, the valve for communicating the detection pipe with the gas flow pipe is closed to temporarily stop the flow between the detection pipe and the gas flow pipe.
The cooling / heating device is operated to cool the heat medium to a required temperature, and the decomposition gas contained in the insulating gas such as SF ₆ gas is physically adsorbed (captured) by the adsorbent at the low temperature.
Then, the gas remaining in the granular space of the adsorbent is evacuated while depressurizing the inside of the detection tube to a required degree of vacuum, and then the temperature of the heat medium is raised by the cooling / heating device so that the inside of the detection tube is removed. While the adsorbent is heated to a predetermined temperature, the decomposition gas physically adsorbed to the adsorbent is released. That is, the decomposition gas is released from the adsorbent by heating the adsorbent, and the pressure change in the detection tube caused by the release is detected by the pressure detection device.

When the detected value is compared with a set value set in advance when the insulating gas such as SF ₆ gas is not decomposed or within an allowable decomposition range, the detected value is determined. If it is within the range of the set value, it is normal, and if it is out of the range, the display device is activated to notify occurrence of abnormality. Thereby, the detection operation of the decomposition gas generated by the thermal decomposition or partial discharge of the insulating gas can be quickly and reliably performed at the installation location of the transformer, and the on-site operation of the transformer according to the degree of generation of the decomposition gas can be performed. Maintenance and inspection work can be performed at an early stage, and a serious accident of the gas insulated transformer can be avoided. Also, when detecting the decomposition gas, it is easy to detect whether or not the decomposition gas of the insulating gas such as SF ₆ gas remains by simply detecting the pressure change in the detection tube caused by cooling and heating the adsorbent. Therefore, there is an advantage that the decomposition gas can be reliably detected even in the initial stage where the abnormal scale of the device main body is small. Furthermore, when detecting the decomposed gas, the decomposed gas adsorbed on the adsorbent can be detected only by detecting the pressure change caused by heating the adsorbent without using an expensive detection device or analyzer. It is possible to easily determine whether or not to generate a decomposition gas.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention applied to a gas-insulated transformer will be described below with reference to FIGS.
In FIG. 1, reference numeral 1 denotes a tank of a gas-insulated transformer, which internally includes an iron core 2, a winding 3 wound around the iron core 2, and clamping clamps 4, 5 for tightening the upper and lower parts of the iron core 2. The configured transformer main body 6 is accommodated and installed. In addition to the transformer main body 6, an inert gas having excellent inertness and noncombustibility such as SF ₆ gas for insulation and cooling is sealed in the tank 1 at a predetermined pressure. Reference numeral 7 denotes a cooling device for insulating gas which is communicated with the inside of the tank 1 and inserted and installed between gas flow pipes 8 and 9 mounted above and below the side wall of the tank 1.
The insulating gas heated in the tank 1 is guided by the gas blower 10 from the upper portion of the tank 1 to the cooling device 7 through the upper gas flow pipe 8, cooled therein, and then passed through the lower gas flow pipe 9. 1 circulates through the transformer body 6
Cooling. Numerals 11 and 12 are bushings mounted on the upper surface of the tank 1 for drawing out the lead wires from the windings 3 to the outside.

Reference numeral 13 denotes a cracked gas detection device inserted in the lower gas flow pipe 9 in the middle of the pipe, for example, between the tank 1 and the gas blower 10, and its detailed structure will be described with reference to FIG.
2, 14 is mounted can communicate with lower gas flow pipe 9 through the valve A, for example, in the detection pipe of the decomposition gas form tracks in a U-shape, the SF ₆ gas such as an insulating gas in the interior A granular adsorbent 15 capable of satisfactorily physically adsorbing various decomposed gas molecules generated upon thermal decomposition is packed therein. In this embodiment, for example, Tosoh Corporation (trade name: Zeoram A) The adsorbent of -5) is used. Reference numeral 16 denotes a detection container that accommodates the detection tube 14 in a state including a lower curved portion to a center portion thereof. The detection container 16 contains an antifreeze or silicone oil for cooling or heating the adsorbent to a predetermined temperature. Heat medium 17 is sealed.
18 is attached to the detection container 16 to cool the heat medium.
The device for heating includes, for example, a combination of a refrigerator and a heater, a heat pump, and the like. Reference numeral 19 denotes a small-diameter conduit which is connected to the detection tube 14 in the detection container 16 so as to be able to communicate with the detection tube 16. A pressure detection device 20 for detecting the pressure in the detection tube 14 via B is attached. And, the pressure detecting device 20 includes:
For example, a pressure sensor capable of detecting even a weak pressure generated in the detection tube 14 as a pressure signal, amplification calculation means for amplifying and calculating the detection signal, and setting of the amplified signal in advance. Comparing means for outputting a comparison signal when the comparison value exceeds the set value by comparing with a value, and signal conversion means for converting the signal output from the comparison means into an analog or digital signal and outputting the signal to the display device 21 It is comprised including. When the pressure in the detection tube 14 exceeds a preset value, the display device 21 activates a buzzer or a lamp (flashing of a light emitting diode, etc.) so as to notify an inspector of the device. Accordingly, it is possible to immediately know that the decomposition gas is generated in the tank 1 at a set value or more.
22 is connected to the detection tube 16 in communication with the detection tube 14 in the same manner as the conduit 19, and the other is liquid-tightly connected to the detection container 1.
6 protrude outside, and the vacuum pump 2
When detecting the decomposition gas, the exhaust pipe connected to the exhaust pipe 14
The inside is sucked by a vacuum pump 23 to maintain a predetermined degree of vacuum. The conduit 19 and the detection pipe 14 of the exhaust pipe 22
In a portion that is communicably connected to the sensor, there is provided an anti-dissipation means 24 such as a wire mesh in order to prevent the adsorbent 15 from escaping out of the detection tube 14 when detecting the decomposition gas.

Next, detection of a decomposition gas will be described with reference to a flow sheet shown in FIG. With the operation of the gas insulated transformer, for example, the insulating coating of the silicon steel strip constituting the iron core is damaged by vibration during transportation, causing local abnormal overheating of the iron core or incomplete contact of the conductor connection part When the temperature of the local abnormal overheating or the like generated from the inside of the tank 1 or the transformer body 6 such as heat generation or insulation deterioration caused by partial discharge reaches the temperature at which the insulating gas such as SF ₆ gas is thermally decomposed, that is, for example, , Superheated conductor (Cu) and SF
Decomposition gases such as SF ₄ and SO ₂ are generated as shown in the following Chemical Formula 1 (reaction formula) by directly reacting with an insulating gas such as ₆ gases.

[0014]

Embedded image

As described above, the decomposed gas generated by thermally decomposing the insulating gas due to local overheating or the like is supplied from the upper gas flow pipe 8 to the cooling device 7 to the lower gas flow from the tank 1 as shown in FIG. In the process of circulating from the pipe 9 to the tank 1, the gas sequentially flows into the detection pipe 14 of the cracked gas detection device 13 and is adsorbed by the adsorbent 15 filled in the detection pipe 14. As described above, the decomposed gas is sequentially adsorbed on the pores (not shown) of the adsorbent 15 in the above-described order, and the concentration of the decomposed gas in the detection tube 14 becomes higher sequentially.

Next, a case where the transformer main body 6 is checked for any abnormality will be described. In this case, by detecting the concentration of the decomposed gas staying in the decomposed gas detector 13 periodically, the local overheating or partial discharge generated in the tank 1 can be replaced by a minor failure before the serious accident occurs. It is possible to detect or predict at a stage, and therefore, it is confirmed that the decomposition gas is mixed in the insulating gas of the tank 1 by the following detecting means. That is, when detecting the decomposed gas, as shown in the flow sheet diagram of FIG. 4, first, at step 101, the valve A of the decomposed gas detection device 13 is closed and the insulating gas in the tank 1 is discharged.
3 (the valves B and C are closed beforehand). Subsequently, the cooling / heating device 18 is started in step 102, and in this state, step 103
Then, the heat medium 17 sealed in the detection container 16 is cooled to indirectly cool the adsorbent 15 in the detection tube 14 to a predetermined temperature. When the adsorbent 15 is cooled to a predetermined temperature, the operation of the cooling / heating device 18 is temporarily stopped in step 104. Due to the cooling action of the adsorbent 15, the energy of the molecules of the decomposed gas adsorbed in the pores of the granules of the adsorbent 15 is deprived, the activity is stagnated, and good physical adsorption is performed in the pores. Then, the process proceeds to steps 105 to 107, and after opening the valve C, the vacuum pump 23 is started,
The pressure inside the detection tube 14 is reduced to a predetermined degree of vacuum, and the adsorbent 15
Is not adsorbed in the pores and floats in the granular space.
The molecules of the F ₆ gas and the decomposition gas (the molecules indicate a size that cannot fit in the pores) are forcibly exhausted from the exhaust pipe 22 to the outside. After a lapse of a predetermined time, the operation of the vacuum pump 23 is stopped in step 108, and the valve C is closed in step 109 while keeping the inside of the detection tube 14 in a reduced pressure state.

Next, when extracting the decomposed gas adsorbed in the fine pores of the adsorbent 15, steps 110 and 111
The cooling / heating device 18 is re-driven at the same time as the valve B
And the heating medium 17 is heated in the opposite direction to
4 is heated to a predetermined temperature (step 1).
12). As a result, the decomposed gas adsorbed in the pores of the adsorbent 15 is sequentially detected by the detection tube 1 as the temperature of the adsorbent 15 rises.
4 is released. As a result, if the decomposed gas is generated and adsorbed by the adsorbent, the amount of gas released from the adsorbent 15 increases, and the pressure rise value in the detection tube 14 also inevitably increases. Therefore, it is possible to easily know how much the decomposition gas is generated by comparing the pressure in the detection tube 14 between the case where the decomposition gas is not present and the case where the decomposition gas is present. For this reason, the present inventors set in advance how much the pressure in the detection tube 14 when the decomposition gas does not exist during the temperature rise process, and decompose the pressure change due to the temperature rise. A set value (reference value, graph indicated by a solid line in FIG. 3) generated when no gas is generated is set as X. Next, when a decomposition gas is generated, the amount of gas released from the adsorbent 15 is inevitable. It was confirmed by experiments that the pressure rise value increased in proportion to the temperature rise of the adsorbent 15 (see the graph of the detection value Y of the cracked gas shown by the dotted line in FIG. 3). The reason why the pressure of the decomposition gas increases due to the temperature rise is that when heat is applied to the adsorbent 15 from the outside, the thermal decomposition of the molecules of the decomposition gas adsorbed in the pores of the granules of the adsorbent 15 occurs. Molecular motion is activated as the temperature of the adsorbent 15 rises,
Accordingly, it is estimated that the pressure rise occurs due to the molecules of the decomposed gas jumping out of the granular pores of the adsorbent 15 (into the detection tube 14) (see steps 113 and 114).

As described above, the pressure increase value in the detection tube 14 is directly detected by the pressure sensor (not shown) in the pressure detection device 20 in step 113, and this detection signal is, for example, arithmetically amplified, and in step 114, The pressure is compared with a preset value X by a comparing means (not shown) of the pressure detecting device 20. And the detection value Y of the decomposition gas is
If the value is larger than the preset value X, FIG.
As shown by, the detection value Y indicating the pressure of the decomposition gas increases as the heating temperature of the adsorbent 15 increases. This detected value Y is converted into a predetermined signal (analog or digital) and displayed on the display device 21. The display means in this case is
Depending on how much the detection value Y differs from the set value X, the difference is displayed in characters or the like, or
An alarm may be set arbitrarily. In the present embodiment, for example, the difference in pressure between the set value X and the detected value Y is as follows.
Is exceeded by about 5%, which is a normal judgment criterion, the detected value Y is displayed on the display device 21 or an alarm is issued (see steps 115 and 117). In addition,
The display of the detection value Y is not limited to 5%, but may be changed arbitrarily depending on the degree of thermal decomposition of the insulating gas and the state of the abnormal state of the transformer body 6.

When the detected value Y of the decomposition gas is displayed on the display device 21, it is determined that some abnormal state has occurred in the tank 1, and the cause of the abnormality is investigated, and measures such as operation switching are performed. To prevent an accident from occurring (see step 118). On the other hand, if the detected value Y is not displayed, that is, if the difference from the set value X is 5% or less, it is determined that there is an error, and the process directly proceeds to step 116 to complete the operation of detecting and inspecting the insulating gas. As described above, according to the present invention, during the operation of the gas-insulated transformer, even if the degree of decomposition of the insulating gas differs depending on the content of the abnormal state (local overheating, partial discharge, etc.) of the transformer body 6, When gas is generated, a pressure change always occurs in the detection operation, and this pressure change can be accurately detected.
It is possible to detect an abnormal state in the equipment at the minor failure sign stage before the occurrence of the accident, thereby predicting the abnormal state of electrical equipment filled with insulating gas such as SF ₆ gas.
Maintenance can be performed quickly and reliably. In the present invention, it is not necessary to use a special adsorbent 15;
Needless to say, any material that can adsorb the decomposition gas can be used. In addition, the pressure detector 20 and the vacuum pump 23 are not installed in the conduit 19 and the exhaust pipe 22 from the beginning, but are provided in the conduit 19 and the exhaust pipe 22 so as to be detachable when inspecting the decomposed gas to detect the decomposed gas. Further, when detecting the pressure, the process from the opening and closing of the valves A to C to the display may be made remotely controllable, so that a plurality of gas-filled electric devices may be centrally managed. In addition, adsorbent 15
Of course, by using the cooling / heating device 18 and the vacuum pump 23 together, it is possible to heat to a temperature at which the decomposed gas can be completely removed and to reuse the adsorbent 15 without replenishing the adsorbent 15. .

[0020]

As described above, in the present invention, the decomposition gas generated when the insulating gas is decomposed is
The presence / absence of presence can be determined based on the minute pressure that changes depending on the amount of the generated gas, so the insulating gas in the tank is once collected in a cylinder or the like when the decomposition gas is detected, as in the past. Since it is not necessary to carry out the analysis, the detection operation of the decomposed gas can be performed quickly and easily at the installation site of the gas-filled electric equipment. In addition, when detecting the decomposed gas, the adsorbent that has adsorbed the decomposed gas is cooled and heated, and gas unnecessary for the detection is forcibly removed to the outside during the cooling and heating. Since only the required decomposition gas can be reliably contained and detected in the detection tube, the detection accuracy of the decomposition gas can be significantly increased, and the abnormality of the gas-filled electrical equipment can be accurately predicted and maintained in a minority. Therefore, occurrence of an accident of this kind of electrical equipment can be avoided. Further, as the detection means used in the detection process of the cracked gas, a commercially available product which can usually be purchased economically can be used, and the cracked gas detection device can be detachably installed as needed, so that the gas Since it is not necessary to install each of the sealed electric devices, the gas-sealed electric device can be economically manufactured with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a gas-filled electric device provided with an abnormality detection device according to the present invention, which is cut longitudinally.

FIG. 2 is an enlarged longitudinal sectional view showing a main part of the abnormality detection device of the present invention.

FIG. 3 is a temperature-pressure characteristic diagram of a decomposition gas.

FIG. 4 is a flow sheet diagram schematically showing an operation state of the abnormality detection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 6 Transformer main body 8 Gas flow pipe 9 Gas flow pipe 13 Decomposed gas detection device 14 Detection tube 15 Adsorbent 16 Detection container 17 Heat medium 18 Cooling / heating device 19 Conduit 20 Pressure detection device 21 Display device A Opening / closing means B Open / close Means C Opening / closing means

Continuation of the front page (72) Inventor Sumio Gota 2-14 Sakae-cho, Toyota-shi, Aichi Pref. National College of Technology Staff Dormitory 2 Examiner Shoko Yamamura (56) References JP-A-53-117728 (JP, A) JP-A-2-183159 ( JP, A) JP-A-1-278223 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 30/00 G01N 30/96

Claims (2)

(57) [Claims] A step of adsorbing a decomposition gas generated by thermal decomposition of an insulating gas to an adsorbent filled in a detection tube; a step of cooling the adsorbent by a cooling means to firmly adsorb and hold the adsorbent; Exhausting the pipe by exhaust means to forcibly remove decomposed gas not adsorbed by the adsorbent; heating the adsorbent by heating means to release the decomposed gas adsorbed by the adsorbent from the adsorbent; and ,
Detecting a change in pressure in the detection tube caused by the release of the decomposed gas. 2. A decomposed gas detection device is installed in the middle of a pipe in a gas flow passage through which an insulating gas flows. The decomposed gas detection device includes a detection container in which a heating medium is sealed, and a gas filled by adsorbent inside. a detection tube is immersed in a liquid-tight manner to the detection container is openably connected communication with the flow pipe, opened and closed manually in the sensing tube
An apparatus for detecting a decomposed gas in a gas-filled electric device, comprising: an exhaust pump and a pressure detecting device connected via a stage; and means for cooling and heating the heat medium to a predetermined temperature.