JP6913639B2 - Gas circuit breaker - Google Patents

Description

The present invention relates to a gas circuit breaker.

A gas circuit breaker cuts off a large current such as a short circuit current. As an example of the configuration, there is a configuration in which a fixed contact that interrupts an electric current and a movable contact are arranged coaxially so as to be detachable and housed in a container filled with insulating gas.

In particular, when the fixed and movable contacts are opened, an arc is generated between them. In order to quickly blow out this arc, a tubular nozzle is provided to surround the space between the fixed contact and the movable contact, and compressed gas is guided into this nozzle to guide the fixed contact and the movable contact. There is known a puffer type gas circuit breaker that blows the arc to the contact / detachment portion to blow out the arc (for example, Patent Document 1).

Generally, a fluororesin having an insulating property is used as a material for a nozzle for blowing out an arc. However, the nozzle is exposed to an extremely hot (eg 20000K) arc. Therefore, the arc energy permeates into the fluororesin, and the fluororesin or the like is decomposed and gasified. As a result, voids may be generated on the surface (surface layer portion) or the inside (the inner portion, that is, most of the portion other than the surface layer portion of the nozzle) of the nozzle, or the surface or the inside of the nozzle may be carbonized. As a result, the inner wall surface of the nozzle is worn, the flow path area of the sprayed gas is increased, and the spraying effect may be reduced. Further, the surface and the inside of the nozzle are carbonized, and the insulation performance of the nozzle is deteriorated, so that the current cutoff performance of the gas circuit breaker may be deteriorated. The phenomenon in which the fluororesin or the like is decomposed and gasified as described above is called "ablation".

In order to solve such a problem, a technique of adding a filler to a resin material constituting a nozzle used for a gas circuit breaker has been conventionally proposed.

Patent Document 2 discloses an arc-resistant material in which a powder containing carbon, silicon carbide, or the like having high light absorption is added to a fluororesin, and the black density index has a predetermined range for light reflection thereof.

Further, in Patent Document 3, a nozzle that prevents internal deterioration and surface wear due to arc by adding boron nitride powder or the like having high light reflectivity as a filler to a fluorine resin such as tetrafluorinated ethylene resin is described. It is disclosed.

Patent Document 4 prevents the nozzle from being consumed due to the sublimation of the tetrafluorinated ethylene resin and the light energy radiated from the arc from entering the nozzle, and is caused by the difference in the thermal expansion rate for each nozzle portion. For the purpose of preventing mechanical damage, the filling amount of the inorganic filler in the vicinity of the throat portion of the nozzle is reduced, and the filling amount of the inorganic filler on the upstream side and the downstream side of the nozzle is increased, so that the throat portion is filled. Disclosed is a puffer-type gas circuit breaker in which a region in which the filling amount of the inorganic filler changes substantially linearly according to the axial distance of the nozzle is provided at the boundary between the upstream side and the downstream side, respectively. ing. Further, Patent Document 4 describes a configuration in which boron nitride is used for the upstream side and the downstream side of the nozzle as an inorganic filler, and aluminum oxide having a lower thermal conductivity than boron nitride is used for the throat portion. There is.

Jitsukosho 61-25148 Gazette Japanese Unexamined Patent Publication No. 60-107203 Special Fair 1-37822 Gazette Japanese Unexamined Patent Publication No. 7-296689

The gas generated by the ablation of the nozzle raises the pressure around the nozzle. As a result, a strong gas flow is generated, and the action of blowing out the arc is promoted. Therefore, it is considered that the gasification of the fluororesin contributes to the improvement of the blocking performance.

As in Patent Document 2, in a nozzle in which a light-absorbing filler is added to a portion exposed to an arc, the gas pressure rise due to the ablation of the nozzle increases by efficiently absorbing the arc energy, but on the other hand, the nozzle There is a problem that the wear of the inner wall surface becomes large.

On the other hand, as in Patent Document 3, in a nozzle to which a filler having high light reflection is added, ablation is suppressed along with wear due to the arc of the nozzle, so that there is a problem that an increase in gas pressure becomes small.

Further, Patent Document 4 describes adjustment of the filling amount of the inorganic filler when boron nitride or the like having high light reflectivity is used as the inorganic filler, but when a filler having high light absorption is used in combination. It does not focus on the issues in.

An object of the present invention is to suppress wear of a nozzle used in a gas circuit breaker, maintain the shape of the nozzle, increase the efficiency of pressure increase due to nozzle ablation, and improve the durability and breaking performance of the gas circuit breaker. To improve.

The gas breaker of the present invention includes a fixed contact, a movable contact, and a nozzle, and has a function of extinguishing an arc generated between the fixed contact and the movable contact at the time of opening a pole. However, the nozzle includes a fluororesin, a filler that absorbs light, and a filler that reflects light.

According to the present invention, wear of the nozzle used in the gas circuit breaker is suppressed, the shape of the nozzle is maintained, the efficiency of pressure increase due to nozzle ablation is increased, and the durability and the circuit breaker performance of the gas circuit breaker are both improved. Can be improved.

It is a schematic cross-sectional view which shows the main part of the gas circuit breaker which concerns on one Embodiment of this invention. It is a schematic diagram which shows the component of the nozzle used in the gas circuit breaker which concerns on one Embodiment of this invention. It is a schematic diagram which shows the photodecomposition of polytetrafluoroethylene. It is a schematic diagram which shows the thermal decomposition of polytetrafluoroethylene. It is sectional drawing which shows the example of the internal structure of the nozzle of this invention. It is sectional drawing which shows another example of the internal structure of the nozzle of this invention. It is sectional drawing which shows another example of the internal structure of the nozzle of this invention.

The present invention relates to a gas circuit breaker, and more particularly to a material for an arc blowout nozzle that achieves both durability and improved circuit breaker performance.

Hereinafter, the gas circuit breaker of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a main part of a gas circuit breaker according to an embodiment of the present invention.

As shown in this figure, the ring-shaped movable contactor 2 is arranged at a position coaxially separated from the tip of the rod-shaped fixed contactor 1. The movable contact 2 is hollowly fixed to the tip of the operating rod 4. The movable contact 2 is driven forward and backward in the axial direction of the arrow 3 shown in the drawing.

A puffer cylinder 5 having a diameter larger than that of the operation rod 4 is coaxially provided on the outside of the operation rod 4. A puffer piston 6 is slidably inserted into the puffer cylinder 5. A wall portion 8 is provided at an end portion of the puffer cylinder 5 on the movable contact 2 side. The area surrounded by the outer peripheral surface of the operation rod 4, the inner wall surface of the puffer cylinder 5 including the wall portion 8, and the tip surface of the puffer piston 6 is the puffer chamber 7. The wall portion 8 is provided with a plurality of through holes 9. The tip of the fixed contact 1 and the movable contact 2 are surrounded by a cylindrical nozzle 10. One end of the nozzle 10 is fixed to the outer surface of the wall 8 via the nozzle retainer 11. A space is formed between the outer wall surface of the movable contact 2 and the inner wall surface of the nozzle 10. This space serves as a flow path when the gas in the puffer chamber 7 enters and exits through the through hole 9.

Further, a reduced diameter throat portion 12 is formed in the central portion of the inner wall surface of the nozzle 10. The minimum diameter of the throat portion 12 is formed so that the fixed contactor 1 can be inserted. Further, a cylindrical fixed contact 13 for energization is installed on the outside of the fixed contact 1. The energizing fixed contact 13 is arranged so as to surround the outer circumference of the nozzle 10.

These components are housed in a container (not shown), and an insulating gas (arc-extinguishing gas) is sealed in the container to form a gas circuit breaker. That is, the gas breaker surrounds the fixed contact 1 and the movable contact 2 arranged so as to be detachable in the container filled with the insulating gas, and the contact portion between the fixed contact 1 and the movable contact 2. A configuration including a tubular nozzle 10 provided in the nozzle 10 and a puffer cylinder 5 and a puffer piston 6 which are gas ejection mechanisms that compress insulating gas in conjunction with the movable contact 2 and eject the insulating gas into the nozzle 10. Have. Here, sulfur hexafluoride (SF ₆ ) is generally used as the insulating gas.

Next, the operation of the gas circuit breaker having such a configuration will be described.

FIG. 1 shows a state in which the fixed contact 1 and the movable contact 2 are opened.

The energization of the gas circuit breaker is performed by driving the operating rod 4 to the right of the arrow 3 in the drawing and bringing the movable contact 2 into contact with the tip of the fixed contact 1 to close the pole. At this time, the nozzle retainer 11 and the fixed contactor 13 for energization also come into contact with each other and are also electrically connected. When a shutoff command is input to the gas circuit breaker for some reason, the operation rod 4 is instantaneously driven to the left of the arrow 3 shown in the figure. As a result, the tip of the fixed contact 1 and the movable contact 2 are separated from each other, and an arc 14 is formed between them.

At this time, the insulating gas in the puffer chamber 7 is compressed by the puffer piston 6, and the compressed insulating gas is blown out into the nozzle 10 from the through hole 9. The blown gas is guided to the throat portion 12 located at the separated portion between the fixed contact 1 and the movable contact 2, and blows out the arc 14 to shut it off.

In this blocking process, the inner wall surface of the nozzle 10 is exposed to an ultra-high temperature arc 14 as high as 20000K. Due to this arc energy, the fluororesin constituting the nozzle 10 evaporates, and ablation gas is generated. Therefore, the gas pressure rises in the vicinity of the throat portion 12. Due to this pressure increase, the arc 14 is quickly extinguished and the breaking performance is improved.

The present invention is not limited to the configuration shown in this figure, and can be applied to, for example, a gas circuit breaker that does not have a puffer chamber 7.

FIG. 2 shows the components of the nozzle used in the gas circuit breaker of the present embodiment.

Examples of the fluororesin used for the nozzle material include polytetrafluoroethylene (PTFE). Usually, a polytetrafluoroethylene molding material is produced by a compression powder molding method using the powder as a raw material.

On the left side of this figure are polytetrafluoroethylene particles 21, molybdenum disulfide particles 22 (MoS ₂ ) which are light-absorbing fillers (light-absorbing particles), and light-reflecting fillers (light-reflecting particles). ) Is shown before the compression molding step in which the boron nitride particles 23 (BN) are mixed. On the other hand, the right side of this figure shows the state after the compression molding process. The molding material produced by the compression molding step contains polytetrafluoroethylene 25 as a matrix resin, and molybdenum disulfide particles 22 and boron nitride particles 23 dispersed in the polytetrafluoroethylene 25. Here, it is polytetrafluoroethylene 25, which is a relatively soft resin, that is greatly deformed. The molybdenum disulfide particles 22 and the boron nitride particles 23 are hard substances and hardly deform.

Polytetrafluoroethylene, which constitutes a molding material, has a high light reflectance from the ultraviolet region to the infrared region, but is not 100%, and a certain amount of light is transmitted. For this reason, when the filler is not included, as described above, in the polytetrafluoroethylene constituting the nozzle, the strong arc light generated when the current is cut off is transmitted to the inner part thereof, so that the surface layer portion of the nozzle and the surface layer portion of the nozzle are used. Voids may occur in the back or may be partially carbonized.

As shown on the right side of this figure, a part of the light incident from below the molding material is absorbed by the molybdenum disulfide particles 22 and converted into heat energy. Further, a part of the light hits the boron nitride particles 23 and is reflected. As a result, less light passes through the surface layer of the molding material and reaches the inner part of the molding material. Therefore, among the incident light, the absorbed light is converted into heat at the surface layer portion of the molding material, and the polytetrafluoroethylene 25 at the surface layer portion is decomposed by this heat. Alternatively, the polytetrafluoroethylene 25 on the surface layer is decomposed by the heat of the sulfur hexafluoride gas that has become hot due to the energy of the arc light. These are pyrolysis. On the other hand, in the surface layer portion, there is also polytetrafluoroethylene 25 which is directly decomposed by the energy of incident light. This is photolysis.

In any case, the decomposition of the polytetrafluoroethylene 25 occurs mostly at the surface layer of the molding material. Therefore, in the molding material containing the molybdenum disulfide particles 22 and the boron nitride particles 23 as the filler, the light reaches the deep part and voids and carbonization are less likely to occur.

In addition, as the fluororesin, polyvinylidene fluoride (PVDF), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), or the like can be used. From the viewpoint of long-term reliability of the gas circuit breaker, it is preferable that chlorine, oxygen and the like are not contained as elements constituting the fluororesin.

FIG. 3A is a schematic diagram for explaining the photodecomposition of polytetrafluoroethylene.

In this figure, a part of the molecule of polytetrafluoroethylene is shown.

It is known that polytetrafluoroethylene is hardly deteriorated by ultraviolet rays having a wavelength of about 300 nm contained in sunlight, but chemical bonds are broken and deteriorated by ultraviolet rays having a shorter wavelength of about 300 nm or less and having high energy. Therefore, in order to prevent deterioration due to light inside the nozzle, it is necessary to prevent the invasion of ultraviolet rays in a short wavelength region of about 300 nm or less. Further, since the chemical bond of the portion exposed to light is cleaved, it is considered that the bond of the polytetrafluoroethylene molecule is cleaved at random.

FIG. 3B shows the thermal decomposition reaction of polytetrafluoroethylene.

In this figure, the thermal decomposition process of polytetrafluoroethylene molecules is shown by a chemical reaction formula. This reaction can be considered in two stages. In the first step, the polymer is broken down into monomers. This reaction is considered to occur at about 500 to 600 ° C.

The monomer produced in the first stage is considered to be decomposed into atoms in the high temperature state due to the arc (second stage). This reaction is believed to occur at temperatures above 3000 ° C.

It is considered that the polytetrafluoroethylene constituting the nozzle is thermally decomposed by converting the light energy of the arc into heat after being absorbed by the components of the nozzle.

In general, in a chain polymer obtained by polymerizing a monomer, the main chain is cleaved and the monomer unit of the raw material is sequentially desorbed from the end by thermal decomposition, which causes depolymerization. In the case of polytetrafluoroethylene, it is known that tetrafluoroethylene, which is a raw material monomer, is mainly produced, and the monomer recovery rate is very high.

Therefore, in the case of thermal decomposition, the reaction proceeds more rapidly until decomposition into the atomic state by passing through the tetrafluoroethylene monomer, as compared with the case of photodecomposition in which the bond is randomly cleaved as described above, and due to ablation. While the contribution to the increase in gas pressure is large, it is considered that the wear of the nozzle is also large.

A nozzle in which light-absorbing particles and light-reflecting particles are appropriately dispersed in polytetrafluoroethylene, which is a matrix resin, can absorb and reflect arc light on its surface layer. As a result, it is possible to prevent the arc light from entering the inner part of the nozzle, convert the light absorbed on the nozzle surface into heat, and efficiently thermally decompose only the surface layer portion. This promotes an increase in gas pressure due to ablation. Further, it is possible to minimize the wear of the nozzle, increase the efficiency of the pressure increase due to the ablation of the nozzle, and achieve both the durability of the nozzle and the improvement of the breaking performance of the circuit breaker.

As the light-absorbing filler, it is desirable to add at least one of a black pigment, a colored pigment, and an ultraviolet-absorbing pigment. A black pigment that absorbs light in a wide wavelength range from the ultraviolet region to the infrared region can be preferably used. For example, by adding a black pigment such as molybdenum disulfide, it is possible to absorb an ultraviolet component of arc light, particularly about 300 nm or less. As a result, it is possible to prevent the penetration into the inside of the nozzle and suppress the decomposition of the fluororesin by ultraviolet light. At the same time, by converting the light in a wide wavelength range absorbed by the surface layer portion of the nozzle into heat, only the surface layer portion of the nozzle can be efficiently thermally decomposed, and the contribution to the increase in gas pressure due to ablation can be enhanced. Although carbon is well known as a black pigment, an insulating filler can be more preferably used because a nozzle is required to have high insulating performance.

A combination of an ultraviolet absorbing pigment that absorbs short-wavelength ultraviolet rays that are thought to contribute to the photolysis of fluororesin and a colored pigment that absorbs light from the ultraviolet region to the visible region and infrared region that does not contribute to photodecomposition of the fluororesin. It is also possible to use it. By combining a plurality of pigments, it is possible to efficiently absorb light in the entire wavelength region. The ultraviolet absorbing pigment absorbs ultraviolet rays on the surface to suppress photodecomposition inside the nozzle, and the colored pigment absorbs light of wavelengths including the visible region and the infrared region to efficiently heat only the surface. Can be disassembled. As the ultraviolet absorbing pigment, for example, an _{inorganic pigment such as titanium oxide (TiO 2} ) and zinc oxide (ZnO), as well as an organic ultraviolet absorbing material can be used. Further, as the colored pigment, in addition to inorganic pigments such as ultramarine blue and cobalt blue, organic pigments such as phthalocyanine pigments can be used.

At the same time, it is desirable to add a white pigment as a filler that reflects light. A white pigment that reflects light in a wide wavelength range from the ultraviolet region to the infrared region can be preferably used. For example, by adding a white pigment such as boron nitride (BN), ultraviolet rays can be reflected. This makes it possible to prevent deterioration due to light inside the nozzle. In addition, alumina (Al ₂ O ₃ ), titanium oxide (TIO ₂ ), zinc oxide (Zn O) and the like can be preferably used.

The filler is preferably an insulating material.

The particle size of the filler that absorbs light is preferably sufficiently larger than the wavelength of light, and those having an average particle size of 1 to 30 μm can be preferably used. The particle size of the filler that reflects light is preferably sufficiently larger than the wavelength of light, and those having an average particle size of 1 to 30 μm can be preferably used. The particle size was measured by a laser diffraction method. For the average particle size, a median diameter D _{50 based} on the number was adopted.

If the amount of the filler that absorbs light is too large, the light absorbed on the surface is converted into heat, which promotes thermal decomposition, increases the contribution to the increase in gas pressure due to ablation, and increases the amount of wear. The filling amount of the filler that absorbs light (the ratio of the filler to the total components of the nozzle, that is, the content) is preferably 0.05% by mass or more and less than 0.4% by mass. On the other hand, it is known that the larger the amount of the filler that reflects light, the higher the reflectance, but at the same time, the mechanical strength of the nozzle tends to decrease. Therefore, the filling amount of the filler that reflects light is preferably 0.05% by mass or more and less than 1.0% by mass.

In addition, the internal structure can be devised as shown below.

FIG. 4 is a cross-sectional view showing an example of the internal structure of the nozzle of the present invention.

In this figure, the nozzle 10 is composed of a light absorbing portion 51, which is a region having a relatively large content of light absorbing particles, and a light reflecting portion 52, which is a region having a relatively large content of light reflecting particles. It is configured.

The light reflecting portion 52 constitutes a surface layer portion of the throat portion of the nozzle 10. The light absorbing portion 51 is configured to be exposed on the surfaces of the upstream portion and the downstream portion of the nozzle 10 other than the throat portion. Therefore, a light reflecting portion 52 is provided in a portion where the shape should be maintained as a throat portion, and a light absorbing portion 51 is provided in a portion where a slight change in shape is allowed. In this example, most of the nozzle 10 is formed by the light absorbing portion 51, and only the necessary portion is formed by the light reflecting portion 52.

As a result, ablation is likely to occur in the upstream and downstream portions of the nozzle 10, and the shape of the throat portion can be maintained.

Examples of such a method for manufacturing the nozzle 10 are as follows.

A raw material for the light absorption unit 51 and a raw material for the light reflection unit 52, which are obtained by mixing a filler with a polytetrafluoroethylene powder so as to exhibit predetermined light absorption characteristics and light reflection characteristics, are prepared and have a shape shown in FIG. It can be produced by the compressed powder molding method by putting it in a mold as described above. After producing a cylindrical molded product using the raw material of the light absorbing portion 51 and the raw material of the light reflecting portion 52, it may be processed into the shape shown in FIG.

The method for manufacturing the nozzle 10 according to the present invention is not limited to the above example.

FIG. 5 is a cross-sectional view showing another example of the internal structure of the nozzle of the present invention.

In this figure, the light reflecting portion 52 constituting the throat portion of the nozzle 10 is provided integrally not only in the vicinity of the surface receiving the arc light but also in the outer peripheral portion of the nozzle 10. The upstream portion and the downstream portion of the nozzle 10 are each composed of a light absorbing portion 51.

When this is manufactured, the compressed powder molding method may be used as in the case of FIG. 4, or a columnar molded product may be manufactured and then processed into the shape of FIG. The light absorbing portion 51 and the light reflecting portion 52 may be formed by molding and joined to each other.

FIG. 6 is a cross-sectional view showing another example of the internal structure of the nozzle of the present invention.

In this figure, the nozzle 10 includes a base material 53 which constitutes most of the nozzle 10, a light absorbing portion 51 which constitutes a surface layer portion of an upstream portion and a downstream portion, and a light reflecting portion 52 which constitutes a surface layer portion of a throat portion. , Is equipped. It is not necessary to add the light absorbing particles and the light reflecting particles to the base material 53. The light absorbing portion 51 and the light reflecting portion 52 can be formed by the same molding method as the above-mentioned method.

The present invention is not limited to those illustrated in the above embodiments, and includes various modifications. For example, the above example has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the configurations described. Further, it is possible to replace a part of the configuration of the above example with the configuration of another example, and it is also possible to add the configuration of another example to the configuration of the above example. In addition, it is possible to add / delete / replace some of the configurations shown in each example.

1: Fixed contact, 2: Movable contact, 4: Operation rod, 5: Puffer cylinder, 6: Puffer piston, 7: Puffer chamber, 9: Through hole, 10: Nozzle, 11: Movable contact for energization, 12 : Throat part, 13: Fixed contact for energization.

Claims (8)

With fixed contacts,
Movable contacts and
With a nozzle,
It has a function of extinguishing an arc generated between the fixed contact and the movable contact at the time of opening the pole.
The nozzle is viewed contains a fluororesin, a filler that absorbs light, and filler for reflecting light, a
The filler that absorbs light has a filling amount of 0.05% by mass or more and less than 0.4% by mass.
The filler that reflects light is a gas circuit breaker having a filling amount of 0.05% by mass or more and less than 1.0% by mass. The light-absorbing filler is an insulator and contains at least one selected from the group consisting of black pigments, colored pigments and ultraviolet absorbing pigments.
The gas circuit breaker according to claim 1, wherein the filler that reflects light is an insulating material and contains a white pigment. The gas circuit breaker according to claim 1, wherein the filler that absorbs light contains molybdenum disulfide. The gas circuit breaker according to claim 1, wherein the light-absorbing filler contains at least one selected from the group consisting of ultramarine blue, cobalt blue and phthalocyanine pigments. The gas breaker according to claim 1, wherein the light-absorbing filler contains at least one selected from the group consisting of titanium oxide, zinc oxide, and an organic ultraviolet absorber. The gas breaker according to claim 1, wherein the light-reflecting filler contains at least one selected from the group consisting of boron nitride, titanium oxide, zinc oxide and alumina. The light-absorbing filler has an average particle size of 1 to 30 μm and has an average particle size of 1 to 30 μm .
Filler for reflecting said light has an average particle size of Ru 1~30μm der, gas circuit breaker according to any one of請Motomeko 1-6. The nozzle has a throat portion and an upstream portion and a downstream portion thereof.
A surface portion of said throat portion, compared with the surface portion of the upstream portion and the downstream portion of the nozzle, the filler for reflecting the light is contained rather large, any one of claims 1 to 7 The gas circuit breaker described in.

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