JPS60169752A - Gas sensor for detecting sulfur hexafluoride decomposition gas - Google Patents

Abstract

PURPOSE:To stably detect decomposition gas with good sensitivity, by using an acetylene polymer as a responsive film for detecting sulfur hexafluoride decomposition gas. CONSTITUTION:Both surfaces of a film 3 comprising an acetylene polymer (-CH=CH-)n are held between electrodes 2, 2' each formed in a comb-shape by the vapor deposition of silver to a support 1 as a responsive film to constitute a sensor for detecting sulfur hexafluoride decomposition gas. This sensor is provided in a sulfur hexafluoride gas insulating apparatus of a breaker or a switch. Sulfur hexafluoride is decomposed into sulfuryl fluoride or thionyl fluoride in the apparatus by arc discharge to dope the acetylene polymer film 3. Because of this, the conductivity of the film 3 changes and the specific resistance between both electrodes 2, 2' changes to detect decomposition gas. By using the acetylene polymer as the responsive film as mentioned above, even a minute amount of decomposition gas can be detected with good sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas sensor for detecting sulfur hexafluoride decomposition gas.

In recent years, hexafluoride has been used inside circuit breakers, switchgears, etc. for safety reasons, and has features such as being extremely stable both thermally and chemically, heat resistant, non-flammable, and non-corrosive. Sulfur gas is used as a filler gas for electrical insulation. However, due to repeated use of the switch, etc., the sulfur hexafluoride gas decomposes due to partial discharge that occurs at its internal contacts, and as a result, decomposed gases such as thionyl fluoride are generated, resulting in so-called gas deterioration. The downside was that it happened.

For this reason, sulfur hexafluoride gas analysis has been adopted for preventive maintenance of sulfur hexafluoride gas insulated equipment, but according to this analysis method, after sampling the gas, it is passed to another analytical device and the sealed gas is It was extremely time-consuming to investigate the deterioration of

On the other hand, attempts have been made to use polymer compounds as sensors for detecting various gases. For example, the NASA report (NATIONAL AERONAUTIC8AN
D 5PA (J ADMINISTRATION CR
134885), polyimidazole/thiophene-based, polyimidazole/ferrocene-based, polyester/iron phthalocyanine-based, polysic base-based, etc. have been studied as polymeric compounds sensitive to SO□, NOx, HCN, and NH3 gases. However, all of them yielded unsatisfactory results in terms of sensitivity, stability, etc.

Furthermore, the EPRI report (EPRI gl, -22
49゜Re5earch Project 1360-
According to 2), polyphenylene oxide, polyferrocene imidazole, polyvinyl carbazole, polyaminophenyl acetylene, polynitrophenylacetylene, and polystyrene derivatives are used as preventive maintenance for sulfur hexafluoride gas insulated equipment and as gas sensors for detecting sulfur hexafluoride decomposed gas. , polydimethylvinylpyridinium chloride, etc. have been studied, but all of them have low sensitivity and are insufficient, so they have not been put into practical use.

This invention was made in view of the above situation,
The object of the present invention is to obtain a gas sensor for detecting sulfur hexafluoride decomposition gas (hereinafter referred to as a gas sensor) with excellent sensitivity and stability.

Thus, according to the present invention, there is provided a gas sensor for detecting sulfur hexafluoride decomposition gas, which is formed by forming an acetylene polymer film as a gas-sensitive film between a pair of electrodes.

The acetylene polymer in this invention is a high polymer obtained from so-called acetylene, and has the general formula: +CH=CH
+n structure, this acetylene polymer company,
For example, the method of Hakushu et al. (J.

Polym-Sci-PolY-Chern-Ed
-, 12, 11 (1974)-), acetylene can be produced using a Ziegler type catalyst.

A preferred example of the gas sensor of the present invention is shown in FIG. As shown in the figure, the gas sensor of the present invention has a support (
1) An acetylene polymer sensitive film (3) is formed as a gas sensitive film between a pair of comb-shaped electrodes (2) and (2') produced by depositing or coating silver 19 thereon. Note that since no support is particularly required, the pair of electrodes may be directly formed on the acetylene polymer membrane itself, or the acetylene polymer may be interposed between at least one pair of electrodes.

When using a support, for example, glass, alumina,
Epoxy resin, Teflon, etc. can be used, and in this case, an acetylene polymer sensitive film formed in advance may be bonded to the element with electrodes formed on the support, or an acetylene polymer sensitive film may be formed on the spot. The above gas sensor can be obtained.

The gas sensor of Jin's invention is normally installed and used inside a sulfur hexafluoride gas insulation device such as a circuit breaker or a switch. When these devices are used, decomposed gases such as sulfuryl fluoride and thionyl fluoride generated by arc discharge at contacts inside the devices diffuse into the acetylene polymer sensitive membrane, resulting in When the sensitive film is doped with decomposition gas, so-called electrical changes such as υ conductivity occur. Deterioration of the sulfur hexafluoride insulating gas can be investigated by measuring such electrical changes with a resistance meter or the like connected to a lead wire drawn from the electrode to the outside of the device.

Hereinafter, the invention will be described in detail by showing examples of the invention, but the invention is not limited thereto.

Example In nitrogen gas, tetrabutoxytitanium (Ti) was cooled with liquid nitrogen, solidified, degassed the nitrogen gas, returned to room temperature, degassed the dissolved nitrogen gas, cooled with dry ice-methanol, and removed acetylene gas. Immediately after introduction, polymerization occurred on the surface of the catalyst solution, producing a film-like acetylene polymer.

The produced acetylene polymer was washed with toluene and dried in vacuum. The thickness of this acetylene polymer film was 120.
μm, and the specific resistance was 109 Ωm. A gas sensor of the present invention was obtained by forming stain electrodes with silver paint on both sides of the acetylene polymer film thus obtained. This gas sensor was sealed in a sulfur hexafluoride gas breaker at 2 atm, and the arc voltage was 400 V and the arc current was 11 KA.
An arc was generated under the new conditions and the resistivity of the element was measured.

The specific resistance before arcing was 3×10 9 Ωα, whereas the specific resistance after arcing was I×10′ Ω.

Further, when an arc was generated continuously, the resistivity of the element decreased to 6×10 3 Ω scratches.

In order to investigate the decomposed gas components of sulfur hexafluoride in this state, the sealed gas was sampled and examined using a gas quadrature graph, and it was found that the main component of the decomposed gas was sulfuryl fluoride (SO□F2). capacity percentage,
Thionyl fluoride (5OF2) was 0.4 volume percent.

Here, as the decomposition gas diffuses into the acetylene polymer film, the conductivity changes, and there was almost no difference in conductivity between immediately after the decomposition gas diffused and after some time had elapsed.

As is clear from the examples, it can be seen that the gas sensor of the present invention has such high sensitivity that the specific resistance of the gas sensor changes by several orders of magnitude if even a small amount of decomposed gas is generated. Furthermore, since the insulation diagnosis of the device can be performed immediately inside the sulfur hexafluoride gas insulated device, it is extremely effective in terms of safety inspections, etc.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view showing an example of a gas sensor for detecting sulfur hexafluoride decomposition gas of the present invention. (1)......Support, (2) and (2.)
・・・・・・・・・Comb electric power, (3)・・・・・・
...Acetylene polymer sensitive membrane.

Claims (1)

[Claims] l A gas sensor for detecting sulfur hexafluoride decomposition gas, which is formed by forming an acetylene polymer film as a gas-sensitive film between a pair of electrodes.