Arc extinguishing plates and circuit breakers

Abstract

The arc extinguishing plate (10) is disposed between a fixed contact (21) and a movable contact (22) connected to a conductor (1, 2) through which a current flows, and extinguishes an arc that occurs when the fixed contact (21) and the movable contact (22) are separated during current interruption. The arc extinguishing plate (10) is configured by arranging a first arc extinguishing plate (11) made of ceramic having a thermal expansion coefficient of 5 ppm / K or less and not containing inorganic hydrates, and a second arc extinguishing plate (12) made of resin or ceramic containing inorganic hydrates adjacent to each other in the in-plane direction of the arc extinguishing plate (10).

Description

[Technical Field]

[0001] The present application relates to an arc extinguishing plate and a circuit breaker. [Background technology]

[0002] Circuit breakers, switches, and other devices used in power distribution facilities, vehicle equipment, and other applications interrupt current when an abnormality occurs by separating a pair of contacts to open the contacts. Arc extinguishing devices have traditionally been used to extinguish arcs that occur between the separated contacts when the contacts open. Arc extinguishing devices are equipped with an arc extinguishing plate to efficiently extinguish the arc, and a mechanism is provided to guide the arc generated between the contacts to the arc extinguishing plate using electromagnetic force applied to a coil or other device. The electromagnetic force extends the arc's current path, and the arc is cooled when it contacts the arc extinguishing plate. This increases the arc voltage above the power supply voltage, suppressing the arc current and resulting in extinguishing the arc. Poor arc extinguishing performance of the arc extinguishing plate can damage the circuit breaker due to the arc current, potentially causing serious malfunctions. Therefore, there is a need for arc extinguishing plates with excellent arc cooling and extinguishing properties.

[0003] For this reason, a method for manufacturing an arc-extinguishing plate has been disclosed (see, for example, Patent Document 1), which includes a step of preparing an inorganic hydrate paint by dispersing an inorganic hydrate in an inorganic adhesive, and a step of vacuum-impregnating the inorganic hydrate paint into the pores of a porous ceramic sintered body, in which the vacuum-impregnation step causes the pores to contain a paint portion and a void portion after shrinkage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6161371 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the above-mentioned conventional manufacturing method of the arc extinguishing plate, even when the arc has not yet been sufficiently extended immediately after the contacts are opened, the pressure of the large amount of water vapor that is generated can sometimes hinder the extension of the arc's electrical path, resulting in the problem that sufficient arc extinguishing performance cannot be obtained.

[0006] The present application discloses a technique for solving the above-mentioned problems, and aims to provide an arc-extinguishing plate that does not hinder arc extension and has excellent arc cooling performance, and a circuit breaker that has excellent arc-extinguishing performance. [Means for solving the problem]

[0007] The arc extinguishing plate disclosed in the present application comprises: In an arc extinguishing plate that extinguishes an arc that occurs between contacts, a first arc-extinguishing plate made of ceramic having a thermal expansion coefficient of 5 ppm / K or less and not containing inorganic hydrates; a second arc-extinguishing plate made of resin or ceramic containing an inorganic hydrate, and the second arc-extinguishing plate is disposed adjacent to the first arc-extinguishing plate in the in-plane direction. 、 The second arc-extinguishing plate is configured so that at least one of the amount of water vapor or the amount of pyrolysis gas generated when exposed to an arc at 1000°C is 1 x 10^-5 mol or more per 1 g of the arc-extinguishing plate. It is something. The circuit breaker disclosed in the present application further comprises: A circuit breaker comprising: a first contact and a second contact as the contacts that are connected to a conductor through which a current flows and that can be separated from each other; and a first arc runner and a second arc runner that extend so as to guide an arc generated between the first contact and the second contact in a direction away from the first contact and the second contact in a current interrupting path where the first contact and the second contact are separated, one end of the first arc runner is disposed on the first contact side, one end of the second arc runner is disposed on the second contact side, the first arc runner and the second arc runner are arranged such that a distance between the other ends thereof increases with increasing distance from the first contact point and the second contact point; The arc-extinguishing plate configured as described above is disposed such that the first arc-extinguishing plate side of the arc-extinguishing plate is located on the first contact point and the second contact point side, and the in-plane direction of the arc-extinguishing plate is aligned with the current path direction of the arc between the first arc runner and the second arc runner. It is something. [Effects of the Invention]

[0008] According to the arc-extinguishing plate disclosed in the present application, an arc-extinguishing plate that does not hinder the extension of the arc and has excellent arc cooling performance can be obtained. Furthermore, the circuit breaker disclosed in the present application has excellent arc-extinguishing performance. [Brief explanation of the drawings]

[0009] [Figure 1] 2 is a schematic diagram of an arc-extinguishing plate according to the first embodiment. FIG. [Figure 2] 1 is a cross-sectional schematic view of an air circuit breaker according to a first embodiment. [Figure 3] 2 is a schematic diagram of an arc-extinguishing plate according to the first embodiment. FIG. [Figure 4] 2 is a schematic diagram of an arc-extinguishing plate according to the first embodiment. FIG. [Figure 5] 2 is a schematic diagram of an arc-extinguishing plate according to the first embodiment. FIG. [Figure 6] 2 is a cross-sectional schematic view of an arc-extinguishing plate according to the first embodiment. FIG. [Figure 7] FIG. 3 is a diagram for explaining details of an evaluation experiment according to the first embodiment. [Figure 8] FIG. 3 is a diagram for explaining details of an evaluation experiment according to the first embodiment. [Figure 9] FIG. 3 is a diagram for explaining details of an evaluation experiment according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiment 1 FIG. 1 is a schematic diagram of an arc-extinguishing plate 10 according to the first embodiment. FIG. 2 is a cross-sectional schematic view of an air circuit breaker 100 equipped with an arc-extinguishing plate 10 according to the first embodiment. FIG. 3 is a schematic diagram showing another example of the configuration of the arc-extinguishing plate 10 according to the first embodiment. FIG. 4 is a schematic diagram showing another example of the configuration of the arc-extinguishing plate 10 according to the first embodiment. FIG. 5 is a schematic diagram showing another example of the configuration of the arc-extinguishing plate 10 according to the first embodiment. FIG. 6 is a cross-sectional schematic view showing another example of the configuration of the arc-extinguishing plate 10 according to the first embodiment. In the drawing, the left-right direction, the up-down direction, and the depth direction of the arc-extinguishing plate 10 are indicated as X, Y, and Z, respectively. An air circuit breaker 100 as a circuit breaker according to this embodiment is used in power distribution facilities and the like, and protects the facilities by interrupting current when an abnormality occurs.

[0011] First, the arc extinguishing plate 10 used in the air circuit breaker 100 will be described. As shown in Figure 1, the arc-extinguishing plate 10 according to the first embodiment is configured by arranging and connecting a first arc-extinguishing plate 11 made of a ceramic plate having a thermal expansion coefficient of 5 ppm / K or less and not containing inorganic hydrates, and a second arc-extinguishing plate 12 made of a resin plate or ceramic plate containing inorganic hydrates, adjacent to each other in the in-plane direction of the arc-extinguishing plate 10.

[0012] Next, the air circuit breaker 100 according to the first embodiment will be described. The air circuit breaker 100 of this embodiment 2 comprises a contact section 20 that interrupts current by making and breaking electrical contacts, an operating mechanism section 30 that performs the opening operation of this contact section 20, and an arc extinguishing chamber 50 that extinguishes an arc generated between the contacts.

[0013] The contact portion 20 includes a fixed contact 21 as a first contact and a movable contact 22 as a second contact, which can be separated from each other. When there is no need to distinguish between the fixed contact 21 and the movable contact 22, they are simply referred to as contacts. The fixed contact 21 is fixed by brazing to a fixed contactor 23 connected to an upper conductor 1 as a main circuit through which current flows, and the movable contact 22 is fixed by brazing to a movable contactor 24 connected to a lower conductor 2 as a main circuit through which current flows.

[0014] The operating mechanism unit 30 includes an overcurrent detector 31 that is arranged on the lower conductor 2 and detects overcurrent flowing through the lower conductor 2, a latch 32 that holds the movable contactor 24, and a rotating shaft 33 that holds the movable contactor 24 rotatably. The movable contact 22 and the fixed contact 21 come into contact or separate when the movable contactor 24 rotates around the rotation axis 33. When the contacts come into contact with each other, power is supplied from the power source through the lower conductor 2 connected to the movable contactor 24 and the upper conductor 1 connected to the fixed contactor 23. To ensure reliable conduction, the movable contact 22 is pressed against the fixed contact 21 with a specified contact pressure.

[0015] The arc extinguishing chamber 50 has the fixed contact 21 and the movable contact 22 of the contact unit 20 installed therein. Also provided are a fixed contact side arc runner 51 as a first arc runner that commutates an arc generated between the fixed contact 21 and the movable contact 22, and a movable contact side arc runner 52 as a second arc runner.

[0016] The fixed contact side arc runner 51 has one end disposed on the fixed contact 21 side and the other end disposed on the upper Y side of the arc extinguishing chamber 50 . Moreover, one end of the movable contact side arc runner 52 is disposed on the movable contact 22 side, and the other end is disposed on the upper Y side of the arc extinguishing chamber 50 . As shown in the figure, the distance in the left-right direction X between the other ends of the fixed contact side arc runner 51 and the movable contact side arc runner 52 is arranged to increase toward the upper direction Y of the arc-extinguishing chamber 50. In this way, the fixed contact side arc runner 51 and the movable contact side arc runner 52 are formed to extend toward the upper direction Y of the arc-extinguishing chamber 50 so as to extend the arc generated between the fixed contact 21 and the movable contact 22 as it moves away from the fixed contact 21 and the movable contact 22. In the following description, when there is no need to distinguish between the fixed contact side arc runner 51 and the movable contact side arc runner 52, they will simply be referred to as arc runners.

[0017] In addition, within the arc extinguishing chamber 50, an arc extinguishing plate 10 is positioned with the first arc extinguishing plate 11 side of the arc extinguishing plate 10 on the contact side, and further, is arranged so that its in-plane direction is along the electrical path direction of the arcs A1 and A2 generated between the fixed contact side arc runner 51 and the movable contact side arc runner 52.

[0018] In addition, the boundary E between the first arc extinguishing plate 11 and the second arc extinguishing plate 12 in the arc extinguishing plate 10 is located within a first range P between one end and the other end on the contact side of the fixed contact side arc runner 51 and the movable contact side arc runner 52.

[0019] The operation of the air circuit breaker 100 configured as above will now be described. When a short circuit or other problem occurs and a large overcurrent flows in the circuit, overcurrent detector 31 disposed in lower conductor 2 detects the overcurrent. When an overcurrent is detected, latch 32, which held movable contactor 24 when current was flowing, is released, causing movable contactor 24 to rotate clockwise around rotation axis 33, separating movable contact 22 and fixed contact 21. An arc generated between the contacts when movable contact 22 and fixed contact 21 are separated is commutated to fixed contact side arc runner 51 and movable contact side arc runner 52, respectively. The arc commutated to fixed contact side arc runner 51 and movable contact side arc runner 52 rises upward in the Y direction and is stretched in the left-right direction X, as shown by arcs A1 and A2 in Figure 2, causing the arc voltage to rise and the arc to be extinguished.

[0020] Here, the arc extinguishing action of the arc extinguishing plate 10 in extinguishing the arc commutated to the arc runner, which is a main part of this embodiment, will be described. Generally, in air arc extinction, it is important to increase the arc voltage through two mechanisms: arc extension and arc cooling. As described above, the arc is extended by commutating and ascending the arc to the arc runner, which is provided to extend in the upward direction Y within the arc-extinguishing chamber 50. At this time, when the arc current is large, the arc's ascending force is also large, and it is relatively easy to sufficiently extend the arc. However, in areas where the arc current is small, the arc's ascending force is small, and therefore, if an external factor occurs that inhibits the arc's ascending, the arc may not be sufficiently extended.

[0021] Therefore, in order to minimize factors that inhibit the rise of the arc, the arc extinguishing plate 10 of this embodiment uses a first arc extinguishing plate 11 made of a ceramic plate with a thermal expansion coefficient of 5 ppm / K or less and containing no inorganic hydrates at the location where the arc A1 contacts immediately after the contacts are opened. As a result, while the arc is in contact with the first arc extinguishing plate 11, no water vapor gas that would inhibit the rise of the arc is generated, and the arc voltage increases due to the cooling effect of the heat conduction of the first arc extinguishing plate 11 and the effect of extending the arc. The arc A1 thus generated is cooled and stretched while in contact with the first arc-extinguishing plate 11, which is arranged so that its surface follows the electric path of the arc A1.

[0022] Next, the arc A2 is sufficiently stretched and reaches the end of the arc runner in the upward direction Y. When the arc A2 comes into contact with the second arc-extinguishing plate 12, which is made of a resin plate or ceramic plate containing inorganic hydrate, it is cooled by the generated water vapor or pyrolysis gas, and the arc voltage further increases, causing the arc to be extinguished.

[0023] As described above, arc-extinguishing plate 10 of the present embodiment has a structure in which first arc-extinguishing plate 11 and second arc-extinguishing plate 12 are connected adjacently in the in-plane direction. Furthermore, first arc-extinguishing plate 11 is disposed closer to the contact point than second arc-extinguishing plate 12. In this way, immediately after an arc is generated, the arc contacts first arc-extinguishing plate 11, which does not generate water vapor or pyrolysis gas that would inhibit arc extension, and after the arc has been sufficiently extended, the arc contacts second arc-extinguishing plate 12, allowing the arc to be cooled by water vapor or pyrolysis gas. Therefore, the arc-extinguishing plate 10 of the first embodiment does not hinder the extension of the arc due to the commutation from the contact to the arc runner, and is excellent in the arc cooling performance due to the generated gas.

[0024] It is important that the first arc-extinguishing plate 11 constituting the arc-extinguishing plate of this embodiment cools the arc by heat conduction when it contacts the arc without impeding arc extension. Therefore, it is preferable that the first arc-extinguishing plate 11 be made of a material that does not contain inorganic hydrates that generate water vapor or organic substances that generate thermal decomposition gases. Furthermore, the amount of water vapor or decomposition gas generated from the first arc-extinguishing plate 11 is preferably so small that it does not impede arc extension. More preferably, the amount of water vapor or decomposition gas generated when the first arc-extinguishing plate 11 is exposed to 1000°C is 1 × 10 mol or less per gram of the arc-extinguishing plate. As such a material, a sintered ceramic with a low thermal expansion coefficient is preferable.

[0025] The small thermal expansion coefficient prevents breakage, cracks, etc. from occurring due to the thermal shock when the arc contacts the arc, making the arc extinguishing plate durable for repeated use. When the arc extinguishing plate contacts the arc, high temperatures of several thousand degrees are applied to the arc extinguishing plate, albeit for an extremely short time of less than a few milliseconds. Therefore, if the thermal expansion coefficient of the ceramic sintered body exceeds 5 ppm / K, the arc extinguishing plate will break, crack, etc. due to the thermal shock when the arc contacts the arc, and the arc extinguishing plate will be damaged. Therefore, the ceramic sintered body used for the arc extinguishing plate is preferably an insulating ceramic material with a low thermal expansion coefficient of 5 ppm / K or less.

[0026] Preferred ceramic materials with low thermal expansion and insulation include cordierite, zircon, zircon cordierite, β-spodumene, and aluminum titanate. Furthermore, in order to cool the arc when contacting it, it is preferable for the material to have high thermal conductivity in the temperature range of several thousand degrees Celsius when contacting the arc. In such a high-temperature range, air has a higher thermal conductivity than ceramic materials.

[0027] Therefore, it is more preferable that the first arc extinguishing plate 11 of this embodiment contains a large number of voids B in the ceramic sintered body, like the arc extinguishing plate 10 shown in Figure 3, and more specifically, it is more preferable that the porosity, which is the porosity relative to the entire volume of the first arc extinguishing plate 11, is 20% or more and 50% or less. A porosity of 20% or more improves the thermal conductivity of the arc extinguishing plate in high temperature ranges, and is expected to further improve the arc cooling performance. On the other hand, if the porosity exceeds 50%, the thermal conductivity will be improved further, but the mechanical strength of the arc extinguishing plate will be significantly reduced, and if used as an arc extinguishing plate, there is a risk that the arc extinguishing plate will be damaged by the mechanical shock when the circuit breaker contacts open.

[0028] Furthermore, the second arc-extinguishing plate 12 constituting the arc-extinguishing plate of this embodiment generates water vapor, pyrolysis gas, etc. when it comes into contact with the arc, thereby cooling the arc. Therefore, the second arc-extinguishing plate 12 is preferably made of a resin plate or a ceramic plate containing an inorganic hydrate. Furthermore, when not only arc-extinguishing performance but also heat resistance and durability for repeated use are required, the second arc-extinguishing plate 12 is more preferably a ceramic plate. To obtain a sufficient arc-cooling effect, the amount of water vapor or pyrolysis gas generated from the second arc-extinguishing plate 12 when exposed to 1000°C is preferably 1 × 10 mol or more per gram of the arc-extinguishing plate.

[0029] The resin plate can be, for example, a composite resin plate made by mixing an inorganic filler into a resin matrix. Examples of the resin matrix include epoxy resin, polyimide resin, and silicone resin. Examples of the inorganic filler include crystalline silica, alumina, magnesium hydroxide, titanium oxide, zirconium oxide, zinc oxide, and glass, as well as inorganic hydrates such as hydroxides of Group 2A elements, Group 3B elements, and Group 4B elements, transition metal elements, and rare earth elements. Specifically, boric acid, magnesium hydroxide, tin hydroxide, zinc hydroxide, lanthanum hydroxide, aluminum hydroxide, calcium hydroxide, barium hydroxide, iron hydroxide, nickel hydroxide, gallium hydroxide, and strontium hydroxide can be used alone or in combination with the inorganic fillers listed above. Furthermore, the resin plate can be a resin plate made by mixing the inorganic fillers listed above with a GFRP-based laminate consisting of glass cloth and a resin matrix.

[0030] Furthermore, the ceramic plate is preferably a ceramic plate in which inorganic filler and inorganic hydrate are bound with an inorganic binder. Arc-extinguishing plates are required to have two properties: arc resistance (durability) and arc-extinguishing properties (cooling properties), and these two properties depend on the composition of the ceramic plate. For example, when arc resistance is emphasized, durability is improved by increasing the blending ratio of inorganic filler. Conversely, when arc-extinguishing properties are emphasized, arc-cooling performance is improved by increasing the blending amount of inorganic hydrate. Here, when arc-extinguishing properties are emphasized, the content of inorganic hydrate in the second arc-extinguishing plate 12 is preferably 40% or more and 60% or less by weight of the total weight of the second arc-extinguishing plate 12.

[0031] The inorganic filler may be any insulating ceramic particle, such as crystalline silica, alumina, magnesium oxide, titanium oxide, zirconium oxide, zinc oxide, mica, or glass, which may be used alone or in combination. The inorganic hydrate may be any inorganic substance that adsorbs or chemically bonds with water at room temperature and releases water vapor when in contact with an arc, such as hydroxides of Group 2A elements, Group 3B elements, Group 4B elements, transition metal elements, and rare earth elements. Specifically, any one or a combination of boric acid, magnesium hydroxide, tin hydroxide, zinc hydroxide, lanthanum hydroxide, aluminum hydroxide, calcium hydroxide, barium hydroxide, iron hydroxide, nickel hydroxide, gallium hydroxide, and strontium hydroxide may be used.

[0032] Furthermore, mineral-based hydrous silicate minerals can be used alone or in combination with the above-mentioned inorganic fillers. The use of hydrous silicate minerals is particularly preferred from the standpoints of availability and cost. The hydrous silicate minerals are not particularly limited, but include hydrous phyllosilicates, hydrous aluminum silicates, hydrous magnesium silicates, hydrous kaolin minerals, mica clay minerals, sepiolite, smectite, vermiculite, saponite, montmorillonite, hectorite, sauconite, stevensite, swinholdite, beidellite, nontronite, and volkonscoite. As inorganic binders, inorganic substances with relatively low melting points are preferably used. For example, inorganic binders such as boric acid, boric anhydride, phosphoric acid, and metaphosphates can be used alone or in combination. Phosphoric acid is liquid at room temperature, but when used in combination with other transition metal oxides, it undergoes a chemical reaction during heat treatment to produce compounds such as metaphosphates. This allows it to function as a binder. As the metaphosphate, zinc metaphosphate, aluminum metaphosphate, etc. can be used alone or in combination.

[0033] The boundary E of the connection between the first arc-extinguishing plate 11 and the second arc-extinguishing plate 12 may be a straight line as shown in Fig. 1 or a non-linear line as shown in Fig. 4. The in-plane arrangement of the first arc-extinguishing plate 11 and the second arc-extinguishing plate 12 may be any arrangement that does not hinder the extension of the arc. For example, as in the arc-extinguishing plate 10 shown in Fig. 5, the second arc-extinguishing plate 12 may be arranged not only on the upward direction Y side of the first arc-extinguishing plate 11 but also on both ends in the left-right direction X. That is, in the arc-extinguishing plate 10, the first arc-extinguishing plate 11 may be arranged closer to the contact point than the second arc-extinguishing plate 12. Furthermore, to supplement the mechanical strength of the arc-extinguishing plate 10, a reinforcing plate 13 may be provided on the surface of the arc-extinguishing plate 10 opposite the surface that comes into contact with the arc, as in the arc-extinguishing plate 10 shown in FIG.

[0034] Next, a method for manufacturing the arc-extinguishing plate 10 of this embodiment will be described. First, the first arc-extinguishing plate 11 is manufactured. A raw ceramic powder to be used for the first arc-extinguishing plate 11, a resin binder, a dispersant, and water are mixed together to prepare a slurry. The dispersant is not particularly limited as long as it can be used in aqueous slurries, and those known in the art can be used. Examples of dispersants include anionic surfactants such as alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate ester salts, alkylbenzene sulfonates, reactive surfactants, fatty acid salts, and naphthalene sulfonate-formaldehyde condensates; cationic surfactants such as alkylamine salts, quaternary ammonium salts, and amphoteric surfactants such as alkylbetaine and alkylamine oxide; and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene derivatives, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene fatty acid castor oil, polyoxyethylene alkylamines, and alkylalkanolamides. These can be used alone or in combination of two or more.

[0035] The binder is not particularly limited, and binders known in the art can be used. Examples of binders include acrylic, cellulose, polyvinyl alcohol, polyvinyl acetal, urethane, and vinyl acetate resins. These can be used alone or in combination of two or more. The water is not particularly limited, and pure water, RO water, deionized water, etc. can be used. The mixing method for preparing the slurry is not particularly limited and can be performed using a method known in the art, such as a kneader, a ball mill, a planetary ball mill, a kneading mixer, or a bead mill.

[0036] Next, the slurry is granulated to prepare a granulated powder. The granulation method is not particularly limited and can be carried out in accordance with a method known in the art. For example, granulated powder can be obtained by spray drying using a spray dryer or the like. The conditions for spray drying can be appropriately adjusted depending on the equipment used and are not particularly limited. Next, the produced granules are press-molded using a mold of a desired shape to produce a molded body. Next, the molded body is sintered in an electric furnace at a desired sintering temperature to produce the first arc-extinguishing plate 11. If necessary, the shape can be processed after sintering.

[0037] Next, the second arc-extinguishing plate 12 is fabricated. An inorganic filler, an inorganic hydrate, and an inorganic binder are blended in a desired ratio to prepare a mixture. The mixing method is not particularly limited, and methods known in the art can be used, such as a kneader, a ball mill, a planetary ball mill, a kneading mixer, or a grinding machine. The mixture is then heated and press-molded using a mold to prepare the second arc-extinguishing plate 12. The heating temperature is sufficient as long as it melts the inorganic binder and can be adjusted appropriately depending on the type of inorganic binder selected. Specifically, the heating temperature is preferably in the range of 200°C to 400°C. Depending on the composition of the selected inorganic binder, the second arc-extinguishing plate 12 may be heat-treated in an electric furnace after press-molding, if necessary, to complete the reaction of the inorganic binder. The heat treatment temperature is preferably in the range of 300°C to 500°C. Furthermore, if necessary, shape processing can be performed after molding or heat treatment.

[0038] Next, the prepared first arc-extinguishing plate 11 and second arc-extinguishing plate 12 are connected. The connection method is not particularly limited, and methods such as bonding with an adhesive or screw fastening can be used. Furthermore, even if the first arc-extinguishing plate 11 and the second arc-extinguishing plate 12 are not connected to each other as individual arc-extinguishing plates, when the arc-extinguishing plates are attached to the arc-extinguishing chamber of the circuit breaker, the first arc-extinguishing plate 11 and the second arc-extinguishing plate 12 can be attached to the members constituting the arc-extinguishing chamber 50 so that the first arc-extinguishing plate 11 and the second arc-extinguishing plate 12 are adjacent to each other in the in-plane direction.

[0039] The arc-extinguishing effect of the arc-extinguishing plate will be described below based on evaluation experiments using the first arc-extinguishing plate of the example and comparative example. Note that the configuration of the arc-extinguishing plate used in the following experiments is a reference example for explaining the arc-extinguishing effect, and does not limit the configuration of the arc-extinguishing plate 10 of this embodiment.

[0040] FIG. 7 is a diagram showing the types and characteristics of the ceramic sintered bodies of the first arc-extinguishing plates used in the evaluation experiments. In FIG. 7, Nos. A to G are ceramic sintered bodies adjusted so that the porosity measured by the mercury intrusion porosimeter is 14% to 65%, and the thermal expansion coefficient is 4.5 to 9 ppm / K.

[0041] FIG. 8 is a diagram showing various raw materials used for the ceramic plates of the arc-extinguishing plates in the examples. FIG. 9 is a diagram showing various raw materials used for the ceramic plates of the arc-extinguishing plates in the comparative example. Hydrous magnesium silicate was used as the inorganic hydrate, crystalline silica, alumina, and zinc oxide were used as the inorganic filler, and boric acid and phosphoric acid were used as the inorganic binder.

[0042] [Example 1] Ceramic sintered body No. C was used as the first arc-extinguishing plate. Test specimens for mechanical strength evaluation and test samples for interrupting performance evaluation were fabricated, each shaped to match the shape of the arc-extinguishing chamber near the contacts of the air circuit breaker under evaluation. Next, the raw materials for the second arc-extinguishing plate, 50 parts by mass of hydrous magnesium silicate, 2 parts by mass of crystalline silica, 27 parts by mass of alumina, 3 parts by mass of zinc oxide, 3 parts by mass of boric acid, and 15 parts by mass of phosphoric acid, were blended and mixed using a mortar and pestle. The resulting mixture was then press-molded in a mold while heated to 400°C to obtain the second arc-extinguishing plate. The shape of the second arc-extinguishing plate was tailored to match the shape of the arc-extinguishing chamber far from the contacts of the air circuit breaker under evaluation.

[0043] [Example 2] The same procedure as in Example 1 was carried out except that the ceramic sintered body No. A was used as the first arc-extinguishing plate. [Example 3] The same procedure as in Example 1 was carried out except that ceramic sintered body No. B was used as the first arc-extinguishing plate. [Example 4] The same procedure as in Example 1 was carried out except that the ceramic sintered body No. D was used as the first arc-extinguishing plate. [Example 5] The same procedure as in Example 1 was carried out except that ceramic sintered body No. E was used as the first arc-extinguishing plate. [Example 6] The same procedure as in Example 1 was carried out except that ceramic sintered body No. F was used as the first arc-extinguishing plate. [Example 7] The second arc-extinguishing plate was prepared in the same manner as in Example 1, except that the raw materials for the second arc-extinguishing plate were 35 parts by mass of hydrous magnesium silicate, 5 parts by mass of crystalline silica, 35 parts by mass of alumina, and 7 parts by mass of zinc oxide. [Example 8] The second arc-extinguishing plate was prepared in the same manner as in Example 1, except that the raw materials for the second arc-extinguishing plate were 20 parts by mass of hydrous magnesium silicate, 8 parts by mass of crystalline silica, 35 parts by mass of alumina, and 9 parts by mass of zinc oxide.

[0044] [Comparative Example 1] A test sample for evaluating the interrupting performance was prepared using only the first arc-extinguishing plate 11 using the ceramic sintered body No. C. Comparative Example 2 A test sample for evaluating the interrupting performance was prepared using only a second arc-extinguishing plate having the same composition as the second arc-extinguishing plate of Example 1. Comparative Example 3 The first arc-extinguishing plate 11 was the same as in Example 1, except that the ceramic sintered body No. G was used. Comparative Example 4 The same procedure as in Example 1 was performed except that a test sample was prepared using the second arc extinguishing plate 12 to match the shape of the side of the arc extinguishing chamber of the evaluation air circuit breaker that was closer to the contacts, and a test sample was prepared using the first arc extinguishing plate 11 to match the shape of the side of the arc extinguishing chamber of the evaluation air circuit breaker that was farther from the contacts.

[0045] The arc-extinguishing plates obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were evaluated for breaking time as breaking performance. Each arc-extinguishing plate was placed in the arc-extinguishing chamber of an air circuit breaker, and the breaking time was measured when the contacts were opened from a current flowing state of 50 A. The breaking time results are shown in Figures 8 and 9 as relative values ​​of the breaking time obtained with the arc-extinguishing plate of each Example or Comparative Example, with the breaking time obtained with the arc-extinguishing plate of Example 1 as the reference (value of [breaking time obtained with the arc-extinguishing plate of each Example or Comparative Example] / [breaking time obtained with the arc-extinguishing plate of Example 1]).

[0046] The three-point bending strength of the first arc-extinguishing plate was measured using an autograph at a support distance of 40 mm. The three-point bending strength results are shown in Figs. 8 and 9 as relative values ​​of the three-point bending strengths obtained for the arc-extinguishing plates of each Example or Comparative Example, with the three-point bending strength obtained for the arc-extinguishing plate of Example 1 as the reference (value of [three-point bending strength obtained for the arc-extinguishing plate of each Example or Comparative Example] / [three-point bending strength obtained for the arc-extinguishing plate of Example 1]).

[0047] 8, the arc-extinguishing plates of Examples 1 to 8 use a ceramic plate with a thermal expansion coefficient of 5 ppm / K or less and containing no inorganic hydrate for the first arc-extinguishing plate 11, and a ceramic plate containing an inorganic hydrate for the second arc-extinguishing plate, which results in short interruption times and good interruption performance.On the other hand, Comparative Example 1, which uses only the first arc-extinguishing plate, and Comparative Example 2, which uses only the second arc-extinguishing plate, are found to have poor interruption performance.

[0048] Furthermore, it can be seen that comparative example 4, in which the joining structure of first arc-extinguishing plate 11 and second arc-extinguishing plate 12 was reversed from that of the embodiment, with second arc-extinguishing plate 12 arranged closer to the contact and first arc-extinguishing plate 11 arranged farther from the contact, also had poor arc-extinguishing performance. On the other hand, in comparative example 3, in which alumina, which has a large thermal expansion coefficient, was used for first arc-extinguishing plate 11, the first arc-extinguishing plate 11 was destroyed by thermal shock during interruption, and interruption failed.

[0049] Furthermore, it can be seen that Examples 1 and 3 to 6, which use a ceramic plate with a porosity of 20% or more for the first arc extinguishing plate 11, have particularly short interruption times and are more excellent in interruption performance. However, it can be seen that Examples 5 and 6, which use a ceramic plate with a porosity of more than 50%, have extremely reduced mechanical strength. Therefore, in terms of the balance between mechanical strength and interruption performance, it can be said that it is more preferable for the ceramic plate used for the first arc extinguishing plate 11 to have a porosity of 20% or more and 50% or less. Furthermore, when attention is paid to the content of inorganic hydrates in the second arc extinguishing plate 12, it can be seen that Examples 1 to 6, which have a high content of inorganic hydrates, have better interruption performance than Examples 7 and 8, which have a low content of inorganic hydrates.

[0050] As can be seen from the above results, the inventors, after extensive research into arc-extinguishing plates with excellent arc-extinguishing performance, have discovered that arc-extinguishing performance can be improved by contacting the arc immediately after contact opening with an arc-extinguishing plate with a thermal expansion coefficient of 5 ppm / K or less and containing no inorganic hydrates, thereby sufficiently elongating the arc while cooling it, and then contacting the elongated arc with an arc-extinguishing plate containing inorganic hydrates, thereby further cooling the arc with the generated water vapor gas. They also found that applying this arc-extinguishing plate to an air circuit breaker improves arc-extinguishing performance.

[0051] The circuit breaker of this embodiment configured as described above has the following features: The arc extinguishing plate is based on the above experimental results. A circuit breaker comprising: a first contact and a second contact as the contacts that are connected to a conductor through which a current flows and that can be separated from each other; and a first arc runner and a second arc runner that extend so as to guide an arc generated between the first contact and the second contact in a direction away from the first contact and the second contact in a current interrupting path where the first contact and the second contact are separated, one end of the first arc runner is disposed on the first contact side, one end of the second arc runner is disposed on the second contact side, the first arc runner and the second arc runner are arranged such that a distance between the other ends thereof increases with increasing distance from the first contact point and the second contact point; The arc-extinguishing plate configured as described above is disposed such that the first arc-extinguishing plate side of the arc-extinguishing plate is located on the first contact point and the second contact point side, and the in-plane direction of the arc-extinguishing plate is aligned with the current path direction of the arc between the first arc runner and the second arc runner. It is something.

[0052] In this way, the pair of arc runners are arranged so that the distance between the other ends thereof increases with increasing distance from the contact point, thereby extending the arc. The arc extinguishing plate is arranged so that its first arc extinguishing plate side is located on the contact side, and its in-plane direction is arranged along the direction of the arc's electrical path between the arc runners arranged to extend the arc, and is not arranged so as to interrupt the arc's electrical path. Thus, the arc extinguishing plate and circuit breaker of this embodiment, which are made of ceramics with a thermal expansion coefficient of 5 ppm / K or less and which do not contain inorganic hydrates, have excellent arc extinguishing performance because they do not inhibit the extension of the arc due to commutation from the contact to the arc runner by generating water vapor gas and have excellent cooling function.In addition, they are resistant to thermal shock when contacting an arc, making them highly reliable arc extinguishing plates that can withstand repeated use. A second arc-extinguishing plate made of resin or ceramic containing inorganic hydrate is disposed adjacent to the first arc-extinguishing plate, whereby the arc cooled by the first arc-extinguishing plate and extended by the arc runner contacts the second arc-extinguishing plate 12, where it is further cooled by the water vapor or pyrolysis gas generated from the second arc-extinguishing plate, increasing the arc voltage and further improving the arc-extinguishing performance of the arc-extinguishing plate.

[0053] In addition, in the circuit breaker of this embodiment configured as described above, A boundary between the first arc-extinguishing plate and the second arc-extinguishing plate in the arc-extinguishing plate is provided within a first range between one end and the other end of the first arc runner and the second arc runner. It is something.

[0054] That is, by positioning the boundary between the first arc-extinguishing plate and the second arc-extinguishing plate along the horizontal direction X within the first range, which is the region where the arc is cooled and extended, the arc that has been guided to the other end of the arc runner and extended can be reliably connected to the second arc-extinguishing plate made of resin or ceramic containing inorganic hydrate. In this way, a circuit breaker with excellent arc cooling performance due to the gas generated by the second arc-extinguishing plate can be provided.

[0055] In addition, in the circuit breaker of this embodiment configured as described above, The position of the boundary between the first arc-extinguishing plate and the second arc-extinguishing plate is adjusted within the first range based on the arc voltage of the arc generated between the first arc runner and the second arc runner. It is something.

[0056] In this way, by adjusting in advance the vertical position Y of the boundary between the first arc-extinguishing plate and the second arc-extinguishing plate along the horizontal direction X within the first range, which is the region where the arc is cooled and stretched, for example, based on the predicted arc voltage, reliable arc extinguishing according to the load is possible.

[0057] Although exemplary embodiments are described herein, the various features, aspects, and functions described in the embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this application, including, for example, modifying, adding, or omitting at least one component. [Explanation of symbols]

[0058] 10 arc extinguishing plate, 11 first arc extinguishing plate, 12 second arc extinguishing plate, 21 fixed contact (first contact, contact), 22 moving contact (second contact, contact), 51 fixed contact side arc runner (first arc runner), 52 moving contact side arc runner (second arc runner), 100 air circuit breaker (circuit breaker).

Claims

1. In an arc extinguishing plate that extinguishes an arc generated between contacts, A first arc-extinguishing plate made of a ceramic having a thermal expansion coefficient of 5 ppm / K or less and containing no inorganic hydrate; a second arc-extinguishing plate made of resin or ceramic containing an inorganic hydrate, the second arc-extinguishing plate being disposed adjacent to the first arc-extinguishing plate in an in-plane direction; The second arc-extinguishing plate is configured so that at least one of the amount of water vapor generated or the amount of pyrolysis gas generated when exposed to an arc at 1000°C is 1 x 10^-5 mol or more per 1 g of the arc-extinguishing plate. Arc extinguishing plate.

2. In the arc-extinguishing plate, the first arc-extinguishing plate is disposed closer to the contact point than the second arc-extinguishing plate. The arc extinguishing plate according to claim 1 .

3. The porosity of the first arc-extinguishing plate with respect to the entire volume of the first arc-extinguishing plate is 20% or more and 50% or less. The arc extinguishing plate according to claim 1 .

4. The porosity of the first arc-extinguishing plate with respect to the entire volume of the first arc-extinguishing plate is 20% or more and 50% or less. The arc extinguishing plate according to claim 2 .

5. The first arc-extinguishing plate is configured so that at least one of the amount of water vapor generated or the amount of pyrolysis gas generated when exposed to an arc at 1000°C is 1 x 10^-7 mol or less per 1 g of the arc-extinguishing plate. The arc extinguishing plate according to claim 1 .

6. The first arc-extinguishing plate is configured so that at least one of the amount of water vapor generated or the amount of pyrolysis gas generated when exposed to an arc at 1000°C is 1 x 10^-7 mol or less per 1 g of the arc-extinguishing plate. The arc extinguishing plate according to claim 2 .

7. The first arc-extinguishing plate is configured so that at least one of the amount of water vapor generated or the amount of pyrolysis gas generated when exposed to an arc at 1000°C is 1 x 10^-7 mol or less per 1 g of the arc-extinguishing plate. The arc extinguishing plate according to claim 3.

8. The first arc-extinguishing plate is configured so that at least one of the amount of water vapor generated or the amount of pyrolysis gas generated when exposed to an arc at 1000°C is 1 x 10^-7 mol or less per 1 g of the arc-extinguishing plate. The arc extinguishing plate according to claim 4.

9. A circuit breaker including: a first contact and a second contact as the contacts that are separable from each other and are connected to a conductor through which a current flows; and a first arc runner and a second arc runner that extend so as to guide an arc generated between the first contact and the second contact in a direction away from the first contact and the second contact in a current interruption path in which the first contact and the second contact are separated, The first arc runner has one end disposed on the first contact side, The second arc runner has one end disposed on the second contact side, the first arc runner and the second arc runner are arranged such that a distance between the other ends of the first arc runner and the second arc runner increases with increasing distance from the first contact point and the second contact point; The arc-extinguishing plate according to any one of claims 1 to 8 is disposed such that the first arc-extinguishing plate side of the arc-extinguishing plate is located on the first contact and the second contact side, and the in-plane direction of the arc-extinguishing plate is aligned along the electric path direction of the arc between the first arc runner and the second arc runner. Circuit breaker.

10. A boundary between the first arc-extinguishing plate and the second arc-extinguishing plate in the arc-extinguishing plate is provided within a first range between one end and the other end of the first arc runner and the second arc runner. The circuit breaker of claim 9.

11. The position of the boundary between the first arc-extinguishing plate and the second arc-extinguishing plate is adjusted within the first range based on an arc voltage of an arc generated between the first arc runner and the second arc runner. The circuit breaker of claim 10.

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