JP2014154352A - Arc-extinguishing plate and air circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc-extinguishing plate having excellent arc-extinguishing performance and durability and also to provide an air circuit breaker equipped with the arc-extinguishing plate.SOLUTION: A ceramic arc-extinguishing plate 10 includes: low thermal expansion ceramics 30 having pores 30b on a surface 30a; a ceramic filling layer 20 which seals the pores 30b; and an arc cooling layer 11 which is formed on the surface 30a of the low thermal expansion ceramics 30 and discharges moisture by heating. By providing this configuration, the ceramic arc-extinguishing plate 10 has excellent arc-extinguishing performance and durability.

Description

  The present invention relates to an arc extinguishing plate and an air circuit breaker, and more particularly to an arc extinguishing plate excellent in arc extinguishing performance and durability, and an air circuit breaker including the arc extinguishing plate. .

  Circuit breakers used for vehicle equipment circuits and power transmission and substations cut off and turn on current by opening and closing contacts. Normally, when a contact is opened to interrupt current in a circuit breaker, arcing occurs between the contacts, which can damage the circuit breaker. Therefore, in order to quickly extinguish (extinguish) the generated arc discharge, an arc extinguishing chamber is usually incorporated in the circuit breaker. In particular, in an air circuit breaker that cuts off current in the atmosphere, an arc extinguishing plate is generally incorporated in the arc extinguishing chamber, and the arc generated by the arc extinguishing plate is extended while being cooled, and the arc resistance is reduced. A method of facilitating shut-off by increasing the value is adopted.

  Arc extinguishing plates are required to have characteristics such as electrical insulation, durability against pressure, temperature and vibration at the time of arc generation, arc extinguishing performance for cooling the arc, metal materials, ceramic materials or organic materials, etc. Is used as a constituent material. In particular, excellent heat resistance against arc discharge exceeding 1000 ° C. and heat shock resistance against temperature change in an extremely short time from generation of arc discharge to extinction are required.

  For example, in Japanese Examined Patent Publication No. 7-43975 (hereinafter referred to as Patent Document 1), 2.5% to 2.7% magnesium oxide is sintered to a powder obtained by mixing aluminum oxide and silica and pulverizing to a particle size of 10 μm or less. An arc extinguishing plate using ceramics added as an auxiliary agent and sintered at high pressure at a temperature of 1400 ° C. to 1600 ° C. is disclosed. In Japanese Patent Publication No. 61-41089 (hereinafter referred to as Patent Document 2), the binder integrally formed from the laminated inorganic base material and the adhesive contains boric acid, zinc oxide or calcium oxide. A featured arc extinguishing plate manufacturing method is disclosed.

Japanese Patent Publication No. 7-43975 Japanese Examined Patent Publication No. 61-41089

  In Patent Document 1, ceramics mainly composed of aluminum oxide (alumina) are used as a material for the arc extinguishing plate, so that the coefficient of thermal expansion of the arc extinguishing plate is increased. Therefore, there exists a problem that an arc extinguishing board is inferior to a thermal shock resistance, and there is a high possibility that it will be destroyed by repeated rapid heating by arc discharge and rapid cooling after arc extinction.

  Further, Patent Document 2 discloses an arc extinguishing plate in which an arc cooling effect is enhanced by incorporating a component that generates moisture or the like by thermal decomposition into the arc extinguishing plate, thereby improving arc extinguishing performance. However, in this case, although the arc extinguishing performance is excellent, the arc extinguishing plate does not have sufficient strength, so that there is a problem that it is difficult to apply to a circuit breaker to which vibration is applied. Thus, conventionally, it has been difficult to obtain an arc extinguishing plate that is excellent in both arc extinguishing performance and durability.

  The present invention has been made in view of the above problems, and an object thereof is to provide an arc extinguishing plate excellent in arc extinguishing performance and durability and an air circuit breaker including the arc extinguishing plate.

  An arc-extinguishing plate according to the present invention includes a ceramic body having holes on the surface, a sealing layer that seals the holes, and a cooling layer that is formed on the surface of the ceramic body and releases moisture by heating. And.

  The air circuit breaker according to the present invention includes the arc extinguishing plate according to the present invention.

  According to the arc extinguishing plate according to the present invention, the arc extinguishing plate having the arc extinguishing performance and durability is provided by including the cooling layer that releases moisture by heating and the sealing layer that seals the hole of the ceramic body. An arc plate can be provided. Moreover, according to the air circuit breaker according to the present invention, by providing the arc extinguishing plate according to the present invention, which is excellent in arc extinguishing performance and durability, the air is excellent in arc extinguishing performance and highly reliable. A circuit breaker can be provided.

It is sectional drawing which shows schematically the structure of the air circuit breaker which concerns on this Embodiment. It is sectional drawing which shows schematically the structure of the ceramic arc-extinguishing board which concerns on this Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

  First, the schematic structure and operation of the air circuit breaker 1 according to an embodiment of the present invention will be described. With reference to FIG. 1, the air circuit breaker 1 mainly includes a base housing 2, a fixed conductor 3, a mover 4, a terminal conductor 5, and an arc extinguishing device 6.

  The fixed conductor 3 is fixed to the base casing 2. A fixed contact 3a is fixed to one end of the fixed conductor 3, and the other end is disposed outside the base casing 2 to constitute a power supply side terminal 3b. A movable contact 4a is fixed to a part of the movable element 4, and the movable contact 4a faces the fixed contact 3a. The terminal conductor 5 is fixed to the base housing 2 similarly to the fixed conductor 3. One end portion of the terminal conductor is disposed outside the base housing 2 to constitute the load side terminal 5a. The terminal conductor 5 is connected to the mover 4 by a flexible conductor (not shown).

  The arc extinguishing device 6 is for cooling an arc generated between both contacts when the current between the fixed contact 3a and the movable contact 4a is interrupted, and is configured by arranging a plurality of ceramic arc extinguishing plates 10 side by side. ing. Here, the ceramic arc extinguishing plate 10 is an arc extinguishing plate according to the present embodiment that is excellent in arc extinguishing performance and durability. Therefore, the air circuit breaker 1 including the ceramic arc extinguishing plate 10 has excellent arc extinguishing performance and high reliability. The detailed structure of the ceramic arc extinguishing plate 10 will be described later.

  In the air circuit breaker 1, when an excessive current is detected, an open / close mechanism (not shown) is operated to rotate the mover 4 in the arrow direction in FIG. As a result, the fixed contact 3a and the movable contact 4a are separated from each other, and the current flowing between the two contacts is interrupted. And after an electric current is interrupted | blocked, an arc generate | occur | produces between both contacts, the said arc is attracted to the arc-extinguishing apparatus 6, and is extinguished. In this way, the air circuit breaker 1 operates.

  Next, the structure of the ceramic arc extinguishing plate 10 according to the present embodiment will be described. Referring to FIG. 2, the ceramic arc extinguishing plate 10 is mainly composed of an arc cooling layer 11, a ceramic sealing layer 20, and a low thermal expansion ceramic (ceramic body) 30.

  The arc cooling layer 11 is formed on the surface 30 a of the low thermal expansion ceramic 30 so that the ceramic sealing layer 20 is sandwiched between the arc cooling layer 11 and the low thermal expansion ceramic 30. The arc cooling layer 11 includes a base material 12 and a low thermal expansion filler 13. The base material 12 and the low thermal expansion filler 13 constituting the arc cooling layer 11 are preferably made of an inorganic material having excellent heat resistance and durability, whereby the ceramic arc extinguishing plate 10 is exposed to a high temperature due to arc discharge. Even in this case, the arc cooling function can be exhibited stably over a long period of time.

  The base material 12 is made of a material that releases moisture by heating, such as a material obtained by hardening water glass (sodium silicate) as a main raw material. Thus, moisture can be released when the base material 12 is heated at high temperature by arc discharge. Moreover, the water of crystallization contained in the water glass foams by heating and can evaporate to evaporate. For example, a fire glass made by enclosing and laminating a water glass layer is widely used as one that actively uses such a phenomenon. With such a cooling function of the arc cooling layer 11, the generated arc discharge can be efficiently cooled and extinguished.

  The low thermal expansion filler 13 is arranged in a dispersed manner in the base material 12, and the content thereof is 30 volume (vol)% or more and 70 volume% or less. The low thermal expansion filler 13 is preferably made of a material that has heat resistance to a high temperature caused by arc discharge and has a smaller thermal expansion coefficient than water glass, and is made of, for example, zirconium phosphate. As the filler material, there is manganese nitride or the like, but it is difficult to use for the ceramic arc extinguishing plate 10 because it is oxidized at a temperature of 300 ° C. or higher in the atmosphere and its performance is lowered. Thus, the arc cooling layer 11 composed of the base material 12 made of hardened water glass and the low thermal expansion filler 13 has an excellent arc extinguishing function and is excellent in heat resistance and durability. Yes.

  From the viewpoint of improving the thermal shock resistance of the arc extinguishing plate, the low thermal expansion ceramic 30 is preferably made of a ceramic material having a small thermal expansion coefficient and excellent thermal shock resistance. More specifically, the low thermal expansion ceramic 30 includes cordierite (thermal expansion coefficient: 2 ppm / ° C.), β-spodumene (thermal expansion coefficient: 1 ppm / ° C.), aluminum titanate (thermal expansion coefficient: 1 ppm / ° C.) and It is preferably made of one material selected from the group consisting of zircon (thermal expansion coefficient: 3 ppm / ° C.). Moreover, the additive may be further added to the said material from a viewpoint of making a thermal expansion coefficient smaller. As a result, the shape can be maintained without being damaged even by a rapid temperature change at the time of occurrence of arc discharge or after completion of arc extinction.

  In general, a ceramic material having a small coefficient of thermal expansion and excellent thermal shock resistance is a porous material having a high porosity. Therefore, as shown in FIG. 2, the low thermal expansion ceramic 30 has pores 30b (holes) on the surface 30a. A ceramic filler layer 20 is formed on the surface 30a of the low thermal expansion ceramic 30 so as to seal the pore 30b. The ceramic sealing layer 20 is made of a material having a smaller coefficient of thermal expansion than the low thermal expansion ceramic 30 such as quartz glass, and has a function of sealing the pores 30b.

  Here, when the arc cooling layer 11 is formed directly on the low thermal expansion ceramic 30 without forming the ceramic sealing layer 20, the components of the arc cooling layer 11 penetrate into the low thermal expansion ceramic 30 through the pores 30b. To do. As described above, since the arc cooling layer 11 includes the base material 12 made of water glass, when the arc cooling layer 11 is heated to a high temperature by arc discharge, the water glass that has entered the inside of the low thermal expansion ceramic 30. The components abruptly foam and expand in volume, and as a result, stress is generated inside the low thermal expansion ceramic 30 and cracks are generated. Then, when arc discharge is repeatedly applied to the ceramic arc extinguishing plate 10, cracks generated in the low thermal expansion ceramic 30 gradually progress, and as a result, the ceramic arc extinguishing plate 10 is destroyed and its function is lost. .

  On the other hand, in the ceramic arc extinguishing plate 10, the pores 30 b of the low thermal expansion ceramic 30 are preliminarily sealed by the ceramic sealing layer 20. Thereby, the component of the arc cooling layer 11 can be prevented from entering the low thermal expansion ceramic 30 through the pore 30b. As a result, when the ceramic arc extinguishing plate 10 is heated by arc discharge, generation of stress in the low thermal expansion ceramic 30 is suppressed, and destruction of the low thermal expansion ceramic 30 due to the generation of the stress is prevented. Can do. Thus, the ceramic arc extinguishing plate 10 according to the present embodiment has an arc extinguishing performance superior to the arc cooling layer 11, and the ceramic sealing layer 20 prevents the arc extinguishing plate from being broken as described above. The arc extinguishing plate has durability against repeated interruption of current.

  As described above, the ceramic arc extinguishing plate 10 according to the present embodiment includes the low thermal expansion ceramic 30 having the pore 30b on the surface 30a, the ceramic sealing layer 20 that seals the pore 30b, and the low thermal expansion ceramic 30. The arc cooling layer 11 is formed on the surface 30a and releases moisture by heating.

  Since the ceramic arc extinguishing plate 10 according to the present embodiment includes the arc cooling layer 11 that releases moisture by heat generation (heating) due to arc discharge or the like, the arc extinguishing performance is high and the arc can be efficiently cooled. it can. Further, as described above, by forming the ceramic sealing layer 20, the components of the arc cooling layer 11 enter the inside of the low thermal expansion ceramic 30 through the pores 30b, and are expanded due to the expansion inside the ceramic. The destruction of 30 is suppressed. Thus, the ceramic arc extinguishing plate 10 according to the present embodiment is an arc extinguishing plate excellent in arc extinguishing performance and durability.

  In the ceramic arc extinguishing plate 10 according to the present embodiment, the low thermal expansion ceramic 30 is made of one material selected from the group consisting of cordierite, β-spodumene, aluminum titanate, and zircon as described above. It may be. As a result, it is possible to obtain the ceramic arc extinguishing plate 10 that has sufficient mechanical strength and is excellent in thermal shock resistance that is not easily damaged by heating by arc discharge and rapid quenching after arc extinction.

  In the ceramic arc extinguishing plate 10 according to the present embodiment, the arc cooling layer 11 includes a base material 12 made of water glass cured as described above, and a low thermal expansion filler 13 having a smaller thermal expansion coefficient than water glass. And may be included. Thus, the generated arc can be effectively cooled by including water glass that releases moisture by heating. Further, by including the low thermal expansion filler 13, it is possible to suppress breakage and dropout (peeling) of the arc cooling layer 11 due to repeated expansion and contraction resulting from heating at the time of arc discharge and cooling after extinguishing.

  In the ceramic arc extinguishing plate 10 according to the present embodiment, the content of the low thermal expansion filler 13 in the arc cooling layer 11 is preferably 30% by volume or more and 70% by volume or less as described above. When the said content rate is less than 30 volume% or exceeds 70 volume%, there exists a problem that peeling of the arc cooling layer 11 arises. For these reasons, the content is preferably 30% by volume or more and 70% by volume or less.

  First, low thermal expansion ceramics composed of sintered bodies of cordierite, β-spodumene, aluminum titanate and zircon were prepared. Next, in order to form a ceramic sealing layer, the sintered body was immersed in a glass paint (manufactured by Liquid Glass Turtle yk). And after taking out the said sintered compact, it was left to stand at room temperature for about 2 days, and was hardened. Thereby, quartz glass permeates into pores (pores) formed on the surface of the sintered body, and a ceramic sealing layer is formed. Note that quartz glass that has penetrated into the pore has a very low coefficient of thermal expansion (0.5 ppm / ° C.), so even if it penetrates into the low thermal expansion ceramic, it can be observed without impairing its function. .

  Next, a low thermal expansion filler made of zirconium phosphate (Kyoritsu Material Co., Ltd., ZP-F30) was added at a content of 30% by volume to 70% by volume with respect to the water glass, and was sufficiently stirred and mixed. And the said water glass was apply | coated on the low thermal expansion ceramic in which the ceramic sealing layer was formed, and it was hardened by heating at 200 degreeC for 2 hours. In this way, an arc cooling layer was formed on the ceramic filler layer. As described above, ceramic arc extinguishing plates of Examples 1 to 12 and Comparative Examples 3 to 10 having different materials for the low thermal expansion ceramic and different contents of the low thermal expansion filler were produced (see Table 1). Moreover, the ceramic arc-extinguishing board which does not have an arc cooling layer was also produced as comparative examples 1 and 2 (refer Table 1).

  And the exposure test in arc discharge was done with respect to each produced ceramic arc-extinguishing board. The arc generation conditions were a voltage (AC) value of 600 V, a maximum current value of 10 kA, and energization of 0.5 cycles. The arc voltage was defined by the extrapolation of the point at which the current value becomes 0 from the energized waveform of 0.5 cycles during the exposure test. Table 1 shows the material of the low thermal expansion ceramic (ceramic material), the presence or absence of the arc cooling layer, and the content of the low thermal expansion filler in the water glass for the 22 types of ceramic arc extinguishing plates produced. The arc voltage of a board and the state of the arc-extinguishing board after a test are shown.

  As is clear from Table 1, the arc voltage is clearly increased in the ceramic arc extinguishing plate having the arc cooling layer (Example) as compared with the ceramic arc extinguishing plates having no arc cooling layer (Comparative Examples 1 and 2). As a result, it was found that the voltage for maintaining the arc increased with respect to the generated arc, and the arc extinguishing performance was improved. This is considered to be because water vapor was generated from the arc cooling layer due to heat at the time of arc generation, and the arc was cooled. Further, as shown in the result of Comparative Example 2, when the low thermal expansion ceramic was made of zirconia (thermal expansion coefficient: 11 ppm / ° C.) and no arc cooling layer was formed, the arc extinguishing plate was broken after the exposure test.

  Moreover, in the ceramic arc extinguishing plates of Comparative Examples 3 to 10, since the content of the low thermal expansion filler contained in the arc cooling layer is outside the range of 30% by volume to 70% by volume, the arc extinguishing performance is improved. It was found that peeling of the arc cooling layer occurred after the exposure test. This peeling of the arc cooling layer is considered to be because the low thermal expansion filler did not function sufficiently. Further, when the ceramic sealing layer was omitted, cracks were confirmed near the surface of the low thermal expansion ceramic. From the above, by providing a low thermal expansion ceramic, a ceramic sealing layer introduced on the surface of the low thermal expansion ceramic, and an arc cooling layer containing a low thermal expansion filler in a content of 30% by volume to 70% by volume, It was found that ceramic arc extinguishing plates with excellent arc performance and durability can be obtained.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The arc extinguishing plate and the air circuit breaker of the present invention can be applied particularly advantageously in an arc extinguishing plate that is required to have excellent arc extinguishing performance and durability and an air circuit breaker including the arc extinguishing plate.

  DESCRIPTION OF SYMBOLS 1 Air circuit breaker, 2 Base housing, 3 Fixed conductor, 3a Fixed contact, 3b Power supply side terminal, 4 Movable element, 4a Moving contact, 5 Terminal conductor, 5a Load side terminal, 6 Arc extinguishing device, 10 Ceramic arc extinguishing Plate, 11 Arc cooling layer, 12 base material, 13 low thermal expansion filler, 20 ceramic sealing layer, 30 low thermal expansion ceramic, 30a surface, 30b pore.

Claims (5)

A ceramic body having holes on the surface;
A sealing layer for sealing the hole,
An arc extinguishing plate comprising a cooling layer formed on the surface of the ceramic body and releasing moisture upon heating.   The arc-extinguishing plate according to claim 1, wherein the ceramic body is made of one material selected from the group consisting of cordierite, β-spodumene, aluminum titanate, and zircon.   The arc-quenching plate according to claim 1 or 2, wherein the cooling layer includes a hardened water glass and a filler having a smaller thermal expansion coefficient than the water glass.   The arc-extinguishing plate according to claim 3, wherein a content of the filler in the cooling layer is 30% by volume or more and 70% by volume or less.   An air circuit breaker comprising the arc extinguishing plate according to any one of claims 1 to 4.

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