JP6989449B2 - 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 and disengages a current and a movable contact are arranged coaxially so as to be connectable and detachable, and stored 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 cylindrical nozzle is provided surrounding 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 an arc to a contact / detachment portion to blow out an 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 part, 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 charred. As a result, the inner wall surface of the nozzle may be worn, the flow path area of the sprayed gas may increase, and the spraying effect may decrease. Further, the surface and the inside of the nozzle are charred, 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, Patent Document 3 discloses a PTFE (polytetrafluoroethylene) nozzle material to which molybdenum disulfide, which is a black powder, is added as a filler.

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 and downstream sides of the nozzle is increased to increase the filling amount of the throat portion. Disclosed is a puffer-type gas breaker in which a region is provided at the boundary between the upstream side and the downstream side, respectively, in which the filling amount of the inorganic filler changes substantially linearly according to the distance in the axial direction of the nozzle. 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 Japanese Unexamined Patent Publication No. 2001-189118 Japanese Unexamined Patent Publication No. 7-296689

The gas generated by the ablation of the nozzle increases the pressure around the nozzle. As a result, a strong gas flow is generated, which promotes the action of blowing out the arc. 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 powder containing carbon, silicon carbide, etc. with high light absorption is added as a filler to a portion exposed to an arc, the arc energy is efficiently absorbed and the nozzle is ablated. While the increase in gas pressure increases, there is a problem that the insulating performance of the nozzle is deteriorated by filling the filler with conductive carbon or semi-conductive silicon carbide.

Nozzle arc with a nozzle to which a light-absorbing filler is added as in Patent Document 2 and Patent Document 3, and a nozzle to which boron nitride or aluminum oxide having high light reflectivity is added as a filler as in Patent Document 4. Although the wear due to the nozzle is suppressed, there is a problem that the filler added together with the fluororesin constituting the nozzle is also exposed to the arc energy and is worn.

An object of the present invention is to improve both the durability and the breaking performance of a gas circuit breaker.

To show one of the representatives of the present invention, a gas circuit breaker is provided with a first contact that interrupts and disengages a current, and a second contact that is arranged so as to be separably opposed to the first contact. A gas circuit breaker comprising a tubular nozzle surrounding the contact / detachment portion between the child and the first and second contacts, wherein the first gas circuit breaker is open when the gas circuit breaker is opened. has the function of extinguishing the arc generated between the contacts and the second contacts, said nozzle is constituted by a molding material tungsten disulfide (WS ₂₎ is dispersed as a filler in the matrix resin To be done.

According to the present invention, both the durability and the breaking performance of the gas circuit breaker can be improved.

It is a schematic sectional drawing 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.

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 improvement in 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 distant position on the same axis so as to face the tip end portion of the rod-shaped fixed contactor 1. The movable contact 2 is hollowly fixed to the tip of the operation rod 4. The movable contact 2 is driven forward and backward in the axial direction of the arrow 3 shown in the figure.

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 contactor 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 periphery 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 circuit 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. The structure is provided with a cylindrical nozzle 10 provided therein, 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 operation rod 4 to the right of the arrow 3 in the figure 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 20000 K. 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 having no 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, the polytetrafluoroethylene molding material is produced by a compression powder molding method using the powder as a raw material.

The left side of this figure shows the state before the compression molding step in which the _{polytetrafluoroethylene particles 21 and the tungsten disulfide particles 22 (WS 2} ) which are the fillers (light-absorbing particles) that absorb light 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 tungsten disulfide particles 22 dispersed in the polytetrafluoroethylene 25. Here, it is polytetrafluoroethylene 25, which is a relatively soft resin, that is greatly deformed. The tungsten disulfide particles 22 are hard substances and hardly deform.

Polytetrafluoroethylene constituting the 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. Therefore, when the filler is not included, as described above, in the polytetrafluoroethylene constituting the nozzle, the strong arc light generated at the time of current interruption 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 not included. Voids may occur in the interior 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 tungsten disulfide particles 22 and converted into heat energy. As a result, less light passes through the surface layer of the molded material and reaches the inner part of the molded material. Therefore, among the incident light, the absorbed light is converted into heat at the surface layer portion of the molding material, and this heat decomposes the polytetrafluoroethylene 25 at the surface layer portion. Alternatively, the polytetrafluoroethylene 25 on the surface layer is decomposed by the heat of sulfur hexafluoride gas, which has become hot due to the energy of arc light. These are pyrolysis. On the other hand, in the surface layer portion, there is also polytetrafluoroethylene 25 that is directly decomposed by the energy of incident light. This is photolysis.

In any case, the decomposition of the polytetrafluoroethylene 25 occurs mostly in the surface layer portion of the molding material. Therefore, in the molding material containing the tungsten disulfide particles 22 as the filler, the light reaches the deep part and the 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.

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 ablation of the nozzle is increased, and the durability and the circuit breaker performance of the gas circuit breaker are both improved. Can be improved. Along with this, it is possible to provide a high quality gas circuit breaker.

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 intrusion 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.

A nozzle in which light-absorbing particles are appropriately dispersed in polytetrafluoroethylene, which is a matrix resin, can absorb arc light at its surface layer portion. This prevents arc light from entering the interior of the nozzle, converts the light absorbed on the nozzle surface into heat, and efficiently pyrolyzes only the surface layer, promoting an increase in gas pressure due to ablation. ..

By adding a black pigment such as molybdenum disulfide as a light-absorbing filler, 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 invasion 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.

_{The present invention is characterized in that tungsten disulfide (WS 2} ) is dispersed as a light-absorbing filler. Tungsten disulfide is known to have higher heat resistance than molybdenum disulfide. In addition, tungsten disulfide has a larger molecular weight and lower volatility than molybdenum disulfide. Therefore, the wear of the filler when exposed to the high temperature arc is also reduced, and the durability of the nozzle is further improved.

Although only tungsten disulfide can be used as the filler, it can be used for photodecomposition of molybdenum disulfide, other black pigments, UV-absorbing pigments that absorb short-wavelength ultraviolet rays that are thought to contribute to the photo-decomposition of fluororesins, and fluororesins. It can also be used in combination with a colored pigment that absorbs light from the ultraviolet region to the visible region and the infrared region, which do not contribute. 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 an inorganic pigment such as ultramarine blue and cobalt blue, an organic pigment such as a phthalocyanine pigment can be used. Although carbon is well known as a black pigment, an insulating filler can be more preferably used because the nozzle is required to have high insulating performance.

At the same time, it can also be used in combination with 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.

By selecting a light-absorbing filler combined with tungsten disulfide or a light-reflecting filler having high heat resistance, the heat resistance and durability of the nozzle can be further improved.

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.

The present invention is not limited to those exemplified in the above embodiments, and includes various modifications. For example, the above examples have been described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. 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 with other configurations. Although not described in this embodiment, the present invention can also be applied to a twin-drive type gas circuit breaker in which both the stator and the contact are driven.

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 (7)

With the first contact that interrupts the current,
A second contact that is arranged so as to be separably opposed to the first contact,
A gas circuit breaker comprising a cylindrical nozzle that surrounds the contact / detachment portions with the first and second contacts.
The gas circuit breaker has a function of extinguishing an arc generated between the first contactor and the second contactor when the pole is opened.
The nozzle is tungsten disulfide to the matrix resin (WS ₂₎ is a gas circuit breaker is configured in a distributed profiled as a filler. The gas circuit breaker according to claim 1.
A gas circuit breaker characterized in that the matrix resin is composed of an insulating material. The gas circuit breaker according to claim 1 or 2.
A gas circuit breaker characterized in that the matrix resin is made of a fluororesin. The gas circuit breaker according to claim 3.
A gas circuit breaker characterized in that the fluororesin is polytetrafluoroethylene (PTFE). The gas circuit breaker according to any one of claims 1 to 4.
A gas circuit breaker characterized by adding a black pigment as the filler. The gas circuit breaker according to any one of claims 1 to 4.
A gas circuit breaker characterized by adding an ultraviolet absorber as the filler. The gas circuit breaker according to any one of claims 1 to 6.
A gas circuit breaker characterized in that the average particle size of the filler is 1 to 30 μm.

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