JPH06201647A - Gas-leakage detector - Google Patents

Abstract

PURPOSE:To obtain an SF6 gas-filled electric apparatus wherein it stabilizes the operation of an oxygen sensor which detects the concentration of oxygen inside a hermetically sealed SF6 container and which judges the leakage of a gas and it is provided with a gas monitoring device which outputs an accurate concentration. CONSTITUTION:An electrolytic solution 22 as the constituent member of an oxygen sensor 21 used as a gas-leakage detection part is used after it has removed dissolved oxygen. Consequently, since the dissolved oxygen as a factor to drop the output of an oxygen sensor is removed, the output which is stable and whose accuracy is good can be obtained for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leak detection device for SF ₆ gas filled equipment.

[0002]

2. Description of the Related Art FIG. 7 is a schematic structural sectional view of a gas leakage detecting portion of a conventional gas-filled device disclosed in Japanese Utility Model Publication No. 58-33624. In the figure, 1 is a sealed container, 1
3 is SF ₆ gas, 53 is bellows, 54 is pressure plate, 55
Is a coil spring, 56 is a pressure receiving rod, 57 is a stopper, 51
Is a bellows storage part.

Next, the operation will be described. When the SF ₆ gas is sealed at a predetermined pressure, for example, 0.05 MPa at 20 ° C., the pressure applied to the pressure receiving plate 54 is reduced by the coil spring 55.
The bellows 53 is compressed to move the pressure receiving rod 56 in order to overcome the extension force of the pressure. Therefore, the stopper 57 comes into contact with the wall of the bellows storage portion. The pressure receiving rod 56 is finally connected to the movable electrode via the connecting block 58 and thereafter. If the SF ₆ gas pressure remains the filled gas pressure, the pressure receiving plate 54 remains pressed, but if the SF ₆ gas leaks, the pressing force of the pressure receiving plate 54 decreases. Therefore, the extension force of the coil spring 55 is increased, the bellows 53 extends, and the pressure receiving rod 56 moves. For this reason, this change is transmitted to the connection block 58 and thereafter, and finally is transmitted to the movable electrode and comes into contact with the fixed electrode to be in the conductive / closed state and locked.

[0004]

Since the conventional gas leak detection device is constructed as described above, there is a problem that a mechanism for compensating pressure change due to temperature is required when the filling pressure is low. It was

The present invention has been made in view of the above problems, and gas leakage using a galvanic battery type oxygen sensor focused on the increase in oxygen concentration in the phenomenon of air mixing that occurs in response to SF ₆ gas leakage. The purpose is to obtain a detection device, and in particular to make this oxygen sensor a stable and long-life sensor.

[0006]

A gas leak detection device according to the present invention comprises a galvanic battery type oxygen sensor,
₍₆₎ Detects the amount of oxygen in the air that enters in response to gas leakage.It removes dissolved oxygen in the electrolytic solution and prevents contact between the bubbles and the positive electrode to absorb the volume change of the electrolytic solution. is there. Further, a high boiling point liquid is filled in a gap between the oxygen sensor and the oxygen sensor storage container, and the oxygen sensor storage container is covered with a member having low heat conductivity.

[0007]

The gas leakage detection device according to the present invention outputs the accurate oxygen concentration of the atmosphere by removing the dissolved oxygen in the electrolytic solution and prevents the bubble for absorbing the change in the electrolytic solution volume from contacting the cathode. The stable output is achieved by filling the gap between the oxygen sensor and the oxygen sensor storage container with a high boiling point liquid or by covering the oxygen sensor storage container with a low thermal conductive member, thereby suppressing the evaporation (depletion) of the electrolytic solution.

[0008]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an electric device filled with SF ₆ gas. In the figure, 1 is a sealed container, 2 is a movable electrode, 3 is a movable side terminal, 4 and 7 are bushings, 5 is a fixed side electrode, and 6 is a fixed electrode. A side terminal, 8 is a drive shaft, 9 is a drive lever, 10 is a lock mechanism device, 11 is a gas leak monitoring device, 12 is an alarm display device, and 13 is SF ₆ gas. FIG. 2 is a sectional view of a sensor portion of a gas leakage monitoring device using a galvanic battery type oxygen sensor. In the figure, 21 is an oxygen sensor body, 22 is an electrolytic solution, 23 is a negative electrode material, 24 is a positive electrode material, and 25 is a positive electrode material.
Is a lead wire, 26 is a diaphragm, 27 is a buffer sheet, 28 is a test gas inlet, 29 is a seal ring, 30 is a bubble, 3
Reference numeral 1 is an oxygen sensor storage container, and 32 is an output terminal.

Here, ABS resin is used as a constituent member of the oxygen sensor body 21, and acetic acid-potassium acetate-is used as the electrolytic solution 22.
An aqueous solution of lead acetate is used as the negative electrode material 23, and lead is used as the positive electrode material 24.
As the diaphragm 26, a porous carbon is used, and as the diaphragm 26, a tetrafluoroethylene-hexafluoropropylene copolymer film is used.
A PET membrane having good gas permeability is used as 7.

Next, the operation will be described. Galvanic battery type oxygen sensor built into SF ₆ gas filled equipment 1
1, in the state in which SF ₆ gas leakage does not occur, the oxygen in the residual air at the time of SF ₆ gas sealed via the septum 26 positive 24
And a current corresponding to the amount of oxygen is generated, but the amount is minute. On the other hand, SF ₆ gas leakage occurred and the sealed container 1
When air is mixed within, it will be also oxygen which is part of the air mixed in the positive electrode _{O 2 + 2H 2 O + 4e} → 4OH - a negative electrode ^{2Pb + 4OH - → 2PbO + 2H} 2 O
A + 4e 2 reaction occurs, and a current corresponding to the amount of oxygen is generated. The voltage at the resistance end provided between both poles is a predetermined voltage (for example, O
₂ 10%; voltage equivalent to 50% of air inclusion), the drive shaft 8 is operated by the signal transmitted from the signal processing unit (omitted) to make the movable electrode 2 and the fixed electrode 5 contact or remain in contact with each other. In this state, the lock mechanism 10 locks and the alarm display device displays. As described above, the galvanic battery type oxygen sensor detects gas leakage regardless of pressure fluctuation. The electrolytic solution 22 used in this oxygen sensor is an aqueous solution in which a predetermined amount of acetic acid, potassium acetate, and lead acetate is dissolved, but the SF ₆ gas atmosphere should maintain a low water content in order to ensure insulation. Since a desiccant is provided, the evaporation of the electrolytic solution is more likely to proceed than when it is used in a normal atmosphere. For this reason, a synthetic resin container (for example, A
In order to prevent water or acetic acid from decreasing due to permeation of the BS resin), a gas impermeable oxygen sensor storage container 3
It is stored in 1.

Oxygen dissolved in the electrolytic solution is stored in the positive electrode 24.
Since a part of the electrolytic solution 22 that is in contact with is also similarly contained, the fact that the amount of dissolved oxygen is large means that the test gas inlet port 28,
This means that the amount of oxygen that permeates through the buffer sheet 27 and the diaphragm 26 is apparently reduced, which is inappropriate for more accurate gas leak detection, and an electrolytic solution from which dissolved oxygen has been removed is used. Is appropriate. In order to remove dissolved oxygen, a gas that does not contain oxygen is removed by bubbling, but in order to suppress the composition change of the electrolytic solution, the evaporation of low boiling point components is suppressed and SF ₆ gas is removed. While circulating, it is appropriate to intermittently renew with fresh SF ₆ gas. FIG. 3 shows a method for diffusing the electrolytic solution. 41 is an electrolytic solution diffusing container, 42 is a diffusing port, 43 is a diffusing gas (SF ₆
Gas) flow path, 44 is an on-off valve, 45 is an SF ₆ gas storage tank, 4
6 is a pump, 47 is an oxygen removal tank, 48 is an oxygen concentration meter, 4
9 is a cooling unit. With this method, about 1
The liter can be removed to about 1/10 of the equilibrium in the atmosphere in 2 hours, and the effect of dissolved oxygen becomes a negligible level. Further, the oxygen sensor storage container 3 for incorporating the oxygen sensor assembly using the thus obtained electrolyte solution in which the dissolved oxygen is suppressed to a low level into an SF ₆ gas filled electric device is used.
When the work of housing the oxygen sensor in 1 or both of them is performed in a glove box in an SF ₆ gas atmosphere, it becomes possible to install the oxygen sensor in an SF ₆ gas-filled electric device without additional operation.

Example 2. In the above examples, the case of using an electrolytic solution in which oxygen dissolved in the electrolytic solution is removed is described, but it is also possible to maintain a stable contact state between the positive electrode and the electrolytic solution in order to obtain a reproducible output. Needed for. In the method of positively providing the bubbles 30 in order to absorb the change in volume of the electrolytic solution with respect to the change in temperature, the bubbles may be transported in a state of being overturned in a packed / transported state. Even in such a case, in order to keep the positive electrode and the electrolytic solution in contact with each other in a stable manner, the bubbles 30 need not be in contact with the positive electrode 24. The volume expansion of the electrolytic solution under the use environment is 10% or less as compared with the room temperature, and the volume of the bubbles at the room temperature may be 10% of the amount of the electrolytic solution. FIG. 4 is made in view of these points, and the positive electrode and the bubbles do not come into contact with each other even when the guide plate 33 rolls over and when vibration is further applied. The material of the guide plate 33 is preferably the same ABS resin as the main body. This guide plate 3
Reference numeral 3 is circular and does not contact the entire surface of the negative electrode 23 or the thermistor portion (no number).
The method for preventing contact between the positive electrode and the bubbles is not necessarily limited to the above method, and it is also possible to widen the shape of the container or change the shape such as providing a recess.

Embodiment 3. FIG. 5 shows a high-boiling-point liquid 34 filled in the gap between the oxygen sensor body and the oxygen sensor housing, and is a non-hydrophilic liquid that does not interact with the oxygen sensor body (ABS resin), such as transformer oil or fluorocarbon liquid ( FC-70, boiling point 215 ° C) may be filled. Since these liquids are less likely to dissolve the electrolyte component, liquid exhaustion can be suppressed and the life of the sensor can be extended.

Example 4. Further, as a method of suppressing the liquid depletion, it is possible to suppress the temperature rise of the electrolytic solution. That is, as shown in FIG. 6, the heat insulating member 35 can be realized by using a member such as foamed rubber.

[0015]

As described above, according to the present invention, the dissolved oxygen in the electrolytic solution, which is the main constituent member of the galvanic battery type oxygen sensor, is removed, and the sensor is assembled in the SF ₆ gas atmosphere to remove the positive electrode and the electrolytic solution. Always keep constant contact, fill the gap between the oxygen sensor main body and the oxygen sensor storage container with a non-hydrophilic high boiling point liquid, or suppress the heat transfer from the outside to the oxygen sensor storage container, so it is accurate with good reproducibility. Not only the output is obtained, but also stable operation can be performed over a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an SF ₆ gas filled electric device.

FIG. 2 is a sectional view showing the configuration of an oxygen sensor unit according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a dissolved oxygen removing device.

FIG. 4 is a sectional view showing the configuration of an oxygen sensor unit according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a configuration of an oxygen sensor unit according to another embodiment of the present invention.

FIG. 6 is a sectional view showing the configuration of an oxygen sensor unit according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an SF ₆ gas filled electric device including a conventional gas leak detection device.

[Explanation of symbols]

 21 Oxygen Sensor Main Body 22 Electrolyte Solution 23 Negative Electrode Material 24 Positive Electrode Material 25 Lead Wire 26 Diaphragm 27 Buffer Sheet 28 Test Gas Introducing Port 29 Seal Ring 30 Bubbles 31 Oxygen Sensor Storage Container 32 Output Terminal 33 Guide Plate 34 High Boiling Liquid 35 Heat insulating material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location 7235-2J G01N 27/46 321 (72) Inventor Shiro Yamauchi 8-1-1 Tsukaguchihonmachi, Amagasaki Mitsubishi Electric Corporation Itami Works

Claims (3)

[Claims] 1. An SF ₆ gas leak detection device, which is installed in an SF ₆ gas-filled electric device sealed at a low pressure close to atmospheric pressure and uses a galvanic battery oxygen sensor as a sensor for detecting the purity of the sealed gas, wherein A gas leakage detection device, characterized in that an electrolytic solution from which dissolved oxygen has been removed in advance is used as the electrolytic solution. 2. The structure according to claim 1, wherein the bubble for absorbing pressure change provided in the electrolytic solution storage portion of the galvanic battery type oxygen sensor does not come into contact with the positive electrode when the sensor falls. Gas leak detection device. 3. The galvanic battery type oxygen sensor is housed in a housing container made of a gas impermeable member,
The gas leak detection device according to claim 1 or 2, wherein a high-boiling-point liquid is filled in most of the gap between the container and the sensor.