Arc-quenching insulating material molded body and circuit breaker

Abstract

Provided is an arc-quenching insulating material molded body (10) capable of achieving both: a shorter breaking time as compared to conventional products; and insulation performance after exposure to arc and impact resistance required for the arc-quenching insulating material molded body (10). An arc-quenching insulating material molded body (10) according to the present disclosure is formed of a resin composition containing a resin (11), an inorganic filler (12), and inorganic fibers (13). The proportion of the inorganic fibers (13) with respect to the entirety of the resin composition is 60-80 wt%. The proportion of the total of the inorganic filler (12) and the inorganic fibers (13) is 75-90 wt% with respect to the entirety of the resin composition.

Description

Arc-extinguishing insulating material compact and circuit breaker

[0001] The present disclosure relates to an arc-extinguishing insulating material compact that promotes the extinguishing of an arc that occurs between separated electrodes, and a circuit breaker including the same.

[0002] A circuit breaker is a device used to prevent damage to a load circuit and electric wires by opening an electric circuit and cutting off the power supply from the primary side when an abnormal current flows in a circuit including a load circuit and electric wires on the secondary side due to factors such as an overload or short circuit. For example, such circuit breakers are used in ordinary homes, factories, offices, etc.

[0003] Generally, a circuit breaker comprises an arc-extinguishing chamber, a moving contact, and a fixed contact. Each of these contacts has a contact and is housed in the arc-extinguishing chamber. When current is applied, the moving contact and the fixed contact are in contact. In such a circuit breaker, when an excessive current or a rated current is applied, the contact of the moving contact and the contact of the fixed contact are separated, forcibly interrupting the current. At this time, an arc is generated between the moving contact and the fixed contact. The generation of an arc is also called an arc. This occurs because the current continues to flow even when the moving contact and the fixed contact are separated.

[0004] Arcs impose thermal and electromagnetic stresses on the components of circuit breakers, so they must be extinguished quickly. To facilitate the extinguishing of arcs that occur during circuit breakers, arc-extinguishing devices containing arc-extinguishing insulating material compacts that contribute to arc extinguishing are arranged around the arc-generating area. When exposed to an arc, the material that constitutes the arc-extinguishing insulating material compacts decomposes to generate gas, which contributes to the rapid extinguishing of the arc by spraying the generated gas onto the arc, thereby cooling and extending the arc.

[0005] Patent Document 1 discloses an arc-extinguishing insulating material molded body used in conventional arc-extinguishing devices. The arc-extinguishing insulating material molded body described in Patent Document 1 is obtained by molding a resin composition containing an epoxy resin as a matrix resin, an inorganic filler such as glass fiber or metal hydroxide as an additive, and microcapsules encapsulating a core substance containing water. This arc-extinguishing insulating material molded body has excellent impact resistance and voltage resistance performance, and also has excellent arc current reduction effect, i.e., current limiting performance, because decomposition gases such as water vapor generated during arc exposure are effective in cooling the arc.

[0006] JP 2009-295419 A

[0007] However, the arc-extinguishing insulating material molded body having the material composition described in Patent Document 1 has the problem that the arc tends to remain near the contacts and restrike, increasing the interruption time (the time until the arc is extinguished) and the amount of wear on the components. This is presumably because high-temperature gases such as decomposition gases generated from the matrix resin and microcapsules of the arc-extinguishing insulating material molded body, and water vapor released from the microcapsules remain near the contacts, reducing the spatial insulation compared to the destination where the arc extends and moves, creating a situation where the arc is more likely to exist.

[0008] The present disclosure has been made in consideration of the above, and aims to obtain an arc-extinguishing insulating material molded body that can achieve both the impact resistance and insulating performance after arc exposure required of an arc-extinguishing insulating material molded body, as well as a shorter interruption time compared to conventional molded bodies.

[0009] In order to solve the above-mentioned problems and achieve the objectives, the arc-extinguishing insulating material molded body according to the present disclosure is a resin composition containing a resin, an inorganic filler, and inorganic fibers, in which the proportion of the inorganic fibers is 60% by weight or more and 80% by weight or less of the entire resin composition, and the total proportion of the inorganic filler and the inorganic fibers is 75% by weight or more and 90% by weight or less of the entire resin composition.

[0010] According to the present disclosure, it is possible to achieve both the impact resistance and insulating performance after arc exposure required for an arc-extinguishing insulating material molded article, and a shorter interruption time compared to conventional methods.

[0011] 3 is a cross-sectional view showing an example of the configuration of the arc-extinguishing insulating material molded body according to the first embodiment; FIG. 4 is a front view showing an example of the state of the arc-extinguishing device in the circuit breaker according to the second embodiment when the arc-extinguishing device is in an interrupted state; FIG. 5 is a cross-sectional view showing an example of the state of the arc-extinguishing device in the circuit breaker according to the second embodiment when the arc-extinguishing device is in an interrupted state, the cross-sectional view being taken along III-III in FIG. 2; FIG. 6 is a diagram showing an example of the arc-extinguishing operation of the arc-extinguishing device in the circuit breaker according to the second embodiment;

[0012] An arc-extinguishing insulating material molded body and a circuit breaker according to an embodiment of the present disclosure will be described in detail below with reference to the drawings. Note that in the drawings shown below, the scale of each part may differ from the actual scale for ease of understanding. This also applies to the differences between the drawings.

[0013] Embodiment 1 In Embodiment 1, an arc-extinguishing insulating material molded body will be described. The arc-extinguishing insulating material molded body is used in a circuit breaker. The arrangement of the arc-extinguishing insulating material molded body within the circuit breaker will be described in detail in Embodiment 2.

[0014] 1 is a cross-sectional view schematically showing an example of the configuration of an arc-extinguishing insulating material molded body according to Embodiment 1. Arc-extinguishing insulating material molded body 10 according to Embodiment 1 is a resin composition containing resin 11, inorganic filler 12, and inorganic fibers 13, characterized in that the proportion of inorganic fibers 13 is 60% by weight or more and 80% by weight or less of the entire resin composition, and the total proportion of inorganic filler 12 and inorganic fibers 13 is 75% by weight or more and 90% by weight or less of the entire resin composition.

[0015] In one example, the inorganic fibers 13 have a structure in which a plurality of inorganic fibers 13 form a group, and the groups of inorganic fibers 13 are stacked. Resin 11 is present so as to fill the entire group of stacked inorganic fibers 13. In addition, inorganic filler 12 is dispersed in the resin 11. Figure 1 shows an example in which groups of inorganic fibers 13 extending in multiple directions are stacked.

[0016] It is preferable to use at least one resin selected from the group consisting of polyamide resin, melamine resin, modified melamine resin, epoxy resin, and unsaturated polyester resin as resin 11. This is because these resins 11 generate pyrolysis gases when exposed to an arc and exhibit a current-limiting effect when blown onto the arc. Furthermore, these resins 11 are characterized by being less susceptible to carbonization due to the arc and easily maintaining the insulating properties of the surface of arc-extinguishing insulating material molded body 10 after arc exposure by blowing off the surface. Resin 11 functions as a matrix resin.

[0017] The inorganic filler 12 is preferably at least one material selected from the group consisting of metal hydroxides, clay minerals, metal oxides, and solidified acids, from the viewpoint of improving the arc-extinguishing performance and insulating performance of the arc-extinguishing insulating material compact 10. These inorganic fillers 12 are materials that exhibit the effect of enhancing current-limiting performance by releasing gases such as water vapor during arc exposure, and the effect of enhancing the pressure resistance performance of the surface of the arc-extinguishing insulating material compact 10 by maintaining the insulating properties of the particles even after arc exposure.

[0018] Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, zinc hydroxide, and calcium hydroxide. From the viewpoints of the amount of water released in a high-temperature environment during arc exposure and the stability and insulating properties of the metal oxide after dehydration, it is preferable to use aluminum hydroxide or magnesium hydroxide as the metal hydroxide. These metal hydroxides may be used alone or in combination of two or more.

[0019] Examples of clay minerals include kaolinite, bentonite, montmorillonite, zeolite, etc. These clay minerals may be used alone or in combination of two or more.

[0020] Examples of metal oxides include aluminum oxide, zinc oxide, titanium oxide, zirconium oxide, etc. These metal oxides may be used alone or in combination of two or more.

[0021] Examples of solidified acids include silicon dioxide (SiO), aluminum oxide, etc. impregnated with an acid such as sulfuric acid, phosphoric acid, or acetic acid, and silicon dioxide, aluminum oxide, etc., washed with an acid such as sulfuric acid, phosphoric acid, or acetic acid to modify the surface.

[0022] From the viewpoint of improving the impact resistance and heat resistance of the arc-extinguishing insulating material compact 10 and the surface insulation properties of the arc-extinguishing insulating material compact 10 after arc exposure, the inorganic fibers 13 are preferably fibers primarily composed of silicon dioxide or alumina. The inorganic fibers 13 envisioned here refer to materials having a diameter of 30 μm or less and an aspect ratio of 3 or more. Here, the aspect ratio refers to the ratio of the fiber length to the fiber diameter. These inorganic fibers 13 have excellent heat resistance and are therefore less susceptible to thermal decomposition even under rapid heating conditions such as arc exposure, leading to reduced wear. Furthermore, the impact resistance and surface insulation properties of the arc-extinguishing insulating material compact 10 after arc exposure can be maintained.

[0023] The inorganic fibers 13 are contained in a proportion of 60% by weight to 80% by weight of the entire resin composition. By achieving a composition within this range, the arc-extinguishing insulating material molded body 10 has excellent impact resistance and insulation properties and can appropriately suppress the amount of pyrolysis gas generated during arc exposure. In particular, by appropriately suppressing the amount of pyrolysis gas generated during arc exposure, pyrolysis gas retention near the contacts is suppressed, thereby suppressing arc retention and restrike near the contacts compared to conventional methods. Furthermore, suppressing arc retention and restrike reduces interruption time compared to conventional methods and reduces the amount of wear on peripheral components. Note that if the inorganic fiber 13 content is greater than 80% by weight, the amount of pyrolysis gas generated from the arc-extinguishing insulating material molded body 10 during arc exposure is insufficient, resulting in reduced current-limiting performance. On the other hand, if the inorganic fiber 13 content is less than 60% by weight, impact resistance and insulation properties after arc exposure are reduced. Therefore, the content of the inorganic fibers 13 is preferably 60% by weight or more and 80% by weight or less of the entire resin composition.

[0024] The total amount of inorganic filler 12 and inorganic fiber 13 is 75% by weight or more and 90% by weight or less of the total weight of arc-extinguishing insulating material molded body 10. If the total amount of inorganic filler 12 and inorganic fiber 13 is more than 90% by weight, the amount of pyrolysis gas generated during arc exposure is insufficient, resulting in reduced current-limiting performance. If the total amount of inorganic filler 12 and inorganic fiber 13 is less than 75% by weight, the amount of pyrolysis gas generated during arc exposure increases, increasing the risk of arc retention and restrike due to the pyrolysis gas.

[0025] As described above, the inorganic fibers 13 may have an aspect ratio of 3 or more, and preferably 50 or more. The use of such inorganic fibers 13 results in an arc-extinguishing insulating material molded body 10 with excellent impact resistance. In addition, a large amount of the inorganic fibers 13 of the insulator remains on the surface of the arc-extinguishing insulating material molded body 10 after arc exposure, thereby enhancing the effect of suppressing deterioration of insulating performance. In other words, making the aspect ratio of the inorganic fibers 13 50 or more is effective in shortening the arc interruption time while simultaneously achieving impact resistance and insulating performance.

[0026] Furthermore, the inorganic fibers 13 are preferably fibers having an aspect ratio of 50 or more processed into a cross or sheet shape. By using such a processed product, the variation in the composition of the resin 11, inorganic filler 12, and inorganic fibers 13 on the surface of the arc-extinguishing insulating material molded body 10 is reduced, and various performances such as impact resistance, current-limiting performance, interrupting performance, and voltage resistance performance are stabilized. Furthermore, an arc-extinguishing insulating material molded body 10 with particularly excellent impact resistance is obtained. As described above, processing the inorganic fibers 13 into a cross or sheet shape is effective in achieving both a shortened arc interruption time and impact resistance and insulating performance.

[0027] Furthermore, it is preferable that the inorganic fibers 13 be made of a material with excellent heat resistance. In one example, the inorganic fibers 13 contain silicon dioxide, calcium oxide (CaO), and magnesium oxide (MgO) as constituent components, and the total amount of the constituent silicon dioxide, calcium oxide, and magnesium oxide is 90 parts by weight or more, based on 100 parts by weight of all constituent components. The silicon dioxide component is 40 parts by weight or more and 80 parts by weight or less, the calcium oxide component is 2 parts by weight or more and 30 parts by weight or less, and the magnesium oxide component is 2 parts by weight or more and 30 parts by weight or less, and the softening point is preferably 1000°C or more. Inorganic fibers 13 with such a composition have better heat resistance than general glass fibers and are less susceptible to thermal decomposition and melting during arc exposure, which allows them to remain on the surface of the arc-extinguishing insulating material molded product 10 and reduces the amount of soot adhesion. This effect results in an arc-extinguishing insulating material molded product 10 with particularly excellent insulating performance after arc exposure.

[0028] The arc-extinguishing insulating material compact 10 has a specific gravity of 2.0 g / cm 3 It is preferable that the specific gravity is 2.0 g / cm or more. By using the arc-extinguishing insulating material molded body 10 having such a composition, it is possible to suppress the excessive generation of pyrolysis gas that causes arc retention and restriking. In other words, it is possible to obtain the arc-extinguishing insulating material molded body 10 that can suppress arc retention and restriking and is particularly effective in shortening the interruption time. 3 If the temperature is less than 1000 K, the amount of pyrolysis gas increases, which is undesirable because it increases the possibility of restriking and the like.

[0029] The arc-extinguishing insulating material molding 10 according to embodiment 1 can be added with known additives such as flame retardants, flame retardant assistants, antioxidants, stabilizers, colorants, etc., within a range that does not impair the effects of embodiment 1.

[0030] The method for manufacturing the arc-extinguishing insulating material molded body 10 according to embodiment 1 is not particularly limited, and methods known in the art, such as injection molding, reaction injection molding, casting, compression molding, and transfer molding, can be used.

[0031] The arc-extinguishing insulating material molded body 10 according to the first embodiment is a resin composition containing a resin 11, an inorganic filler 12, and inorganic fibers 13. The inorganic fibers 13 account for 60% to 80% by weight of the entire resin composition, and the combined weight of the inorganic filler 12 and the inorganic fibers 13 is 75% to 90% by weight of the entire resin composition. This suppresses degradation of spatial insulation due to decomposition gases released from the arc-extinguishing insulating material molded body 10, thereby reducing the frequency of arc retention and restrike. Furthermore, when the arc-extinguishing insulating material molded body 10 is placed near a contact point of an arc-extinguishing chamber, it can shorten the arc interruption time and reduce the amount of wear on surrounding components compared to conventional arc-extinguishing insulating material molded bodies 10. In this way, the arc-extinguishing insulating material molded body 10 can achieve both the impact resistance and insulating performance after arc exposure required of the arc-extinguishing insulating material molded body 10, as well as the effect of shortening the interruption time.

[0032] Embodiment 2 In Embodiment 2, a circuit breaker using the arc-extinguishing insulating material molded body 10 will be described. FIG. 2 is a front view schematically showing an example of the state of an arc-extinguishing device in a circuit breaker according to Embodiment 2 when the circuit is interrupted. FIG. 3 is a cross-sectional view, taken along III-III in FIG. 2, schematically showing an example of the state of an arc-extinguishing device in a circuit breaker according to Embodiment 2 when the circuit is interrupted. In FIGS. 2 and 3, within a plane in which the fixed contacts 21 are arranged, the extension direction of the fixed contacts 21 is defined as the X-axis direction, and the direction perpendicular to the X-axis direction is defined as the Y-axis direction. Furthermore, the direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction.

[0033] The circuit breaker 20 includes a fixed contactor 21 extending in the X-axis direction, a movable contactor 23 movable in the ZX-plane direction, and an arc-extinguishing insulating material molding 10. The fixed contactor 21 has a fixed contact 22 at one end in the extension direction of the fixed contactor 21 on a surface facing the movable contactor 23. The movable contactor 23 has a movable contact 24. The movable contact 24 is provided at a position corresponding to the fixed contact 22 on the surface facing the fixed contactor 21. When the movable contact 24 is in contact with the fixed contact 22, the movable contactor 23 has a shape extending in the X-axis direction. In one example, the movable contactor 23 is supported rotatably in the ZX-plane direction at an end of the movable contactor 23 opposite to the end where the movable contact 24 is provided.

[0034] Arc-extinguishing insulating material molded body 10 is disposed so as to surround movable contact 24 and fixed contact 22. That is, arc-extinguishing insulating material molded body 10 is disposed at a position where it is exposed to an arc generated between movable contact 24 and fixed contact 22 when movable contact 24 and fixed contact 22 separate. In the example of FIGS. 2 and 3 , arc-extinguishing insulating material molded body 10 is disposed on both sides of fixed contact 21 and movable contact 23 in the Y-axis direction. This arc-extinguishing insulating material molded body 10 is the same as that described in the first embodiment, and is formed from a resin composition containing resin 11, inorganic filler 12, and inorganic fibers 13, in which the proportion of inorganic fibers 13 is 60% by weight or more and 80% by weight or less of the entire resin composition, and the combined proportion of inorganic filler 12 and inorganic fibers 13 is 75% by weight or more and 90% by weight or less of the entire resin composition.

[0035] Next, the operation of the circuit breaker 20 will be described. In Figures 2 and 3, the switching mechanism shown in Figure 5 (described later) operates to rotate the movable contactor 23, thereby bringing the movable contact 24 and the fixed contact 22 into contact with or separating from each other. In other words, the switching mechanism operates the movable contactor 23 so that the movable contact 24 comes into contact with or separates from the fixed contact 22. By bringing the contacts into contact with each other, power is supplied from the power source to the load. To ensure reliable conduction, the movable contact 24 is pressed against the fixed contact 22 with a specified contact pressure.

[0036] When a short circuit or other accident occurs and a large overcurrent flows in the circuit, the electromagnetic repulsive force at the contact surface between the movable contact 24 and the fixed contact 22 becomes very strong. When the electromagnetic repulsive force overcomes the contact pressure applied to the movable contact 24, the movable contactor 23 rotates, and the movable contact 24 and the fixed contact 22 are separated. Furthermore, as the separation distance between the fixed contact 22 and the movable contact 24 increases due to the operation of the switching mechanism and the tripping device (not shown), the arc resistance increases. The increased arc resistance causes the arc voltage to rise.

[0037] During such an interruption operation, a large amount of energy is generated by the arc between the movable contact 24 and the fixed contact 22 within a short period of several milliseconds. At this time, the arc-extinguishing insulating material compact 10 provided on the side of the arc-extinguishing device is exposed to the arc, generating decomposition gas. The generated decomposition gas has the effect of cooling and stretching the arc, causing the arc voltage to rise.

[0038] FIG. 4 is a diagram schematically illustrating an example of the arc-extinguishing operation of the arc-extinguishing device in the circuit breaker according to the second embodiment. FIG. 4 illustrates the circuit breaker 20 in an off-state during interruption. The arc-extinguishing device 30 includes a plurality of arc-extinguishing plates 31 each having a U-shaped or V-shaped notch 31 a made of metal. The plurality of arc-extinguishing plates 31 are stacked and arranged at regular intervals. In this circuit breaker 20, an arc 100 generated between the movable contact 24 and the fixed contact 22 is attracted toward the arc-extinguishing plates 31 by a magnetic force and extends, further increasing the arc voltage. Furthermore, the arc 100 is captured by the arc-extinguishing plates 31 of the arc-extinguishing device 30, thereby limiting the overcurrent, extinguishing the arc 100, and breaking the circuit.

[0039] The circuit breaker 20 will now be described in more detail. Fig. 5 is a cross-sectional view schematically showing an example of a circuit breaker according to a second embodiment. Fig. 5 shows the circuit breaker 20 in contact, i.e., in an on state. Fig. 6 is a partial cross-sectional view schematically showing an example of a circuit breaker according to the second embodiment. Fig. 6 is a partial view of the circuit breaker 20 shown in Fig. 5 in a disconnected state, i.e., in an off state.

[0040] The circuit breaker 20 includes a movable contactor 23 made of a conductor such as copper, a movable contact 24 fixed to one end of the movable contactor 23, a fixed contact 22 that moves in and out of contact with the movable contact 24, a fixed contactor 21 made of a conductor such as copper to which the fixed contact 22 is fixed, a power supply side terminal 41 formed at the other end of the fixed contactor 21, and a load side terminal 42. Wiring from an external power supply is connected to the terminal 41. Wiring from the load is connected to the terminal 42.

[0041] The circuit breaker 20 includes an opening / closing mechanism 60 that rotates the movable contact 23 to open and close the circuit breaker, a handle 61 for manually operating the opening / closing mechanism 60 , and a tripping device 70 .

[0042] The circuit breaker 20 includes a cover 51 and a base 52 that house or secure the above-mentioned components and form part of a housing 50. The circuit breaker 20 also includes an end plate 53 that isolates the terminal portion 41 from the inside of the housing 50. The end plate 53 is inserted into a guide groove 51a provided in the base 52 and attached to the base 52. The end plate 53 has an exhaust hole 53a that exhausts hot gas generated by the arc 100.

[0043] The circuit breaker 20 includes an arc-extinguishing device 30. The arc-extinguishing device 30 includes a plurality of arc-extinguishing plates 31 called grids made of magnetic metal that cool and extinguish an arc 100 generated between the movable contact 24 and the fixed contact 22, arc-extinguishing side plates 32 that hold the plurality of arc-extinguishing plates 31 on both sides, and an arc-extinguishing insulating material molding 10. The plurality of arc-extinguishing plates 31 are stacked with gaps between them. In the example of FIGS. 5 and 6, only one side of the arc-extinguishing side plate 32 is shown. The arc-extinguishing insulating material molding 10 and the arc-extinguishing side plate 32 are made of insulating material, and the arc-extinguishing insulating material molding 10 includes the material described in the first embodiment.

[0044] FIG. 7 is a side view showing an example of the arrangement between a contact pair consisting of a fixed contact and a movable contact and an arc-extinguishing insulating material molding according to the second embodiment, and FIG. 8 is a top view showing an example of the arrangement between the contact pair and the arc-extinguishing insulating material molding according to the second embodiment. The arc-extinguishing insulating material molding 10 is disposed between the movable contact 24 and the fixed contact 22 in the state shown in FIG. 6. In FIGS. 7 and 8, the arc-extinguishing insulating material molding 10 is disposed near the contact pair. Also, as shown in FIG. 8, when viewed from above, the arc-extinguishing insulating material molding 10 is disposed so as to expose the fixed contact 22 and cover most of the remaining portion of the fixed contact 21 exposed to the arc 100. The arc-extinguishing insulating material molding 10 also functions as an insulating member to prevent the arc 100 from moving to portions of the fixed contact 21 other than the fixed contact 22.

[0045] Arc-extinguishing insulating material molded body 10 is installed for the purposes of cooling arc 100 by spraying decomposition gas, guiding arc 100 to arc-extinguishing plate 31 by the gas flow of decomposition gas, and providing insulating shielding within arc-extinguishing device 30. In embodiment 2, arc-extinguishing insulating material molded body 10 is formed from a resin composition containing resin 11, inorganic filler 12, and inorganic fiber 13, in which the proportion of inorganic fiber 13 is 60% by weight or more and 80% by weight or less of the entire resin composition, and the total proportion of inorganic filler 12 and inorganic fiber 13 is 75% by weight or more and 90% by weight or less of the entire resin composition. This makes it possible to adjust the amount of decomposition gas that has high arc-extinguishing performance when exposed to arc 100, and to shorten the time it takes for arc 100 to move to arc-extinguishing plate 31 while maintaining the cooling effect and insulating shielding effect of arc 100. This effect contributes to shortening the interruption time of the arc 100, as well as reducing the amount of wear on the arc-extinguishing insulating material compact 10 and the contact material, and improving the insulating performance, thereby contributing to safe and rapid arc extinguishing during repeated use.

[0046] The shape and arrangement of the arc-extinguishing insulating material compact 10 in the circuit breaker 20 according to the second embodiment are not limited to those described above. That is, it is sufficient that the arc-extinguishing insulating material compact 10 is arranged in the circuit breaker 20 in a position near the location where the arc 100 occurs, where a sufficient amount of pyrolysis gas can be generated, and where the movement of the arc 100 is prevented. In one example, the arc-extinguishing insulating material compact 10 may be arranged around or near a magnet installed inside the circuit breaker 20 for the purpose of attracting and extending the arc 100 by the action of a magnetic field.

[0047] In the second embodiment, the circuit breaker 20 includes a fixed contactor 21 having a fixed contact 22, a movable contactor 23 having a movable contact 24, an opening / closing mechanism 60 that operates the movable contactor 23 so that the movable contact 24 comes into contact with or separates from the fixed contact 22, and the arc-extinguishing insulating material molded body 10 described in the first embodiment that is disposed in a position exposed to the arc 100 that is generated when the fixed contact 22 and the movable contact 24 separate. This configuration has the effect of suppressing retention of the arc 100 that is generated at the contacts of the circuit breaker 20 when a fault current occurs, shortening the interruption time, and thereby improving the interruption performance.

[0048] Examples of the arc-extinguishing insulating material molded body 10 according to the first embodiment will be described below, but the contents of the present disclosure are not limited to these examples.

[0049] Table 1 shows the material compositions and the results of the characteristic evaluation of the arc-extinguishing insulating material compacts of Examples 1 to 6 and Comparative Examples 1 to 5.

[0050]

[0051] (Material Composition) All of the arc-extinguishing insulating material molded bodies 10 of Examples 1 to 6 and Comparative Examples 1 to 5 were made using epoxy resin as the resin 11, aluminum hydroxide as the inorganic filler 12, and glass fiber as the inorganic fiber 13. The material compositions of Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1.

[0052] Here, the following specific materials are used. Epoxy resin: 100 parts by weight of epoxy compound (jER828, Mitsubishi Chemical Corporation), 130 parts by weight of acid anhydride curing agent (HN-2200, Resonaq Corporation), and 1 part by weight of curing accelerator (Curesol (registered trademark) 2E4MZ, Shikoku Chemical Industries Co., Ltd.) are added and stirred. Aluminum hydroxide (C-305, Sumitomo Chemical Co., Ltd.) Glass fiber (CS 13 C-897, Nitto Boseki Co., Ltd.)

[0053] (Manufacturing Method) Arc-extinguishing insulating material molded body 10 is manufactured using the blending ratio shown in the material composition in Table 1. Resin 11, inorganic filler 12, and inorganic fiber 13 can be compounded by a conventionally known method. The resulting compound is poured into a mold and subjected to a heat-curing treatment to obtain arc-extinguishing insulating material molded body 10 having a length of 40 mm, a width of 60 mm, and a thickness of 2 mm. The heat-curing treatment involves pre-curing the arc-extinguishing insulating material molded body 10 at 120°C for two hours, and post-curing the arc-extinguishing insulating material molded body 10 at 160°C for four hours.

[0054] (Evaluation of Characteristics of Arc-Extinguishing Insulating Material Molded Article 10) An arc exposure test was conducted to evaluate the arc-extinguishing and insulating performance of the obtained arc-extinguishing insulating material molded article 10. FIG. 9 is a cross-sectional view showing an example of the configuration of an apparatus used for testing insulating properties and arc-extinguishing performance, and FIG. 10 is a side view showing an example of the configuration of an apparatus used for testing insulating properties and arc-extinguishing performance. The test apparatus 80 shown in FIGS. 9 and 10 includes a test vessel 81, a sample stage 82 supporting samples 85 within the test vessel 81, and a counter electrode 83 in which a pair of electrodes 83a, 83b are disposed facing each other at a predetermined distance between the pair of samples 85. The pair of samples 85 are disposed on the sample stage 82 so as to cover the side of the counter electrode 83, including the gap between the electrodes 83a, 83b. The samples 85 are arc-extinguishing insulating material molded articles 10 having the material compositions of Examples 1 to 6 and Comparative Examples 1 to 5 shown in Table 1, and manufactured by the manufacturing method described above. The samples 85 are arranged at predetermined intervals by supports 84. The counter electrode 83 comprises a copper conductor cylinder and an electrode contact.

[0055] The test was conducted in an electric circuit with a 300V, 20kA overcurrent. The electrode contacts were made of a material with a composition of 60wt% Ag (silver), 36wt% tungsten carbide (WC), and 4wt% graphite. This measurement simulated the phenomenon in which an arc 100 occurs when an overcurrent flows through an electric circuit, resulting in the thermal decomposition of the arc-extinguishing insulating material compact 10 shown in Figures 2, 3, 5, and 8. The current flowing through the circuit during arc generation was measured with an oscilloscope, and the arc-extinguishing performance was evaluated as the current-limiting value, which was calculated by subtracting the measured current value from 20kA. In Table 1, a cross indicates a current-limiting value less than 8kA, a circle indicates a current-limiting value between 8kA and 9kA, and a double circle indicates a current-limiting value of 9kA or greater. The measured current waveform was also used to check for the presence or absence of arc 100 retention, which is a phenomenon in which the current value does not increase from a constant value, and restrike, which is a phenomenon in which the current value drops instantaneously. Furthermore, the arc-extinguishing insulating material compact 10, i.e., sample 85, was recovered after arc exposure, and its surface resistance was measured over a 1 cm width using a megger. This value was used to evaluate the insulating properties of the arc-extinguishing insulating material compact 10. In Table 1, a cross is indicated if the surface resistance is less than 100 MΩ, and a circle is indicated if the surface resistance is 100 MΩ or greater. The results of these characteristic evaluations are shown in Table 1.

[0056] As shown in Fig. 1, in the arc-extinguishing insulating material molded body 10 according to Examples 1 to 6, the resin 11 and inorganic filler 12 are present so as to fill the spaces between the inorganic fibers 13. By adjusting the amount of resin 11 present on the surface exposed to the arc 100, it is possible to supply an appropriate amount of pyrolysis gas that prevents the retention of the arc 100 and the occurrence of restrike. Furthermore, although the residue of the resin 11 after the arc exposure remains on the surface in a carbonized state, by adopting the structure shown in Fig. 1, the inorganic filler 12 and inorganic fibers 13 inhibit the formation of a conductive path, thereby maintaining the insulation of the surface.

[0057] On the other hand, the basic structure of the arc-extinguishing insulating material molded body 10 according to comparative examples 1 to 5 is the same as that shown in Figure 1, but the content of each constituent component is outside the specified range for the arc-extinguishing insulating material molded body 10 according to embodiment 1.

[0058] Examples 1 to 6 exhibit good performance in terms of current limiting performance, prevention of arc 100 retention and restriking, and surface insulation of the arc-extinguishing insulating material compact 10 after arc exposure. The main factors contributing to the current limiting performance and prevention of arc 100 retention and restriking are thought to be the control of the amount of pyrolysis gas generated from the arc-extinguishing insulating material compact 10, which reduces the difference in composition between the gas components near the contact point and the gas components to which the arc 100 is extended a certain time after the arc 100 is generated. The main factors contributing to the surface insulation of the arc-extinguishing insulating material compact 10 are thought to be the inorganic fibers 13 and the like of the insulator, which prevent conductive paths formed by metal and carbides scattered from the contact point.

[0059] In Comparative Example 1, the content of inorganic fiber 13 is lower than in Examples 1 to 6, making it difficult to prevent a decrease in the insulation properties of the surface of arc-extinguishing insulating material molded body 10 after exposure to an arc. In Comparative Example 2, the content of inorganic fiber 13 is higher than in Examples 1 to 6, and in Comparative Example 3, the content of resin 11 is lower than in Examples 1 to 6, making it difficult to prevent a decrease in the insulation properties of the surface of arc-extinguishing insulating material molded body 10 after exposure to an arc. In Comparative Example 4 and Comparative Example 5, the content of resin 11 is higher than in Examples 1 to 6, making it possible to obtain arc-extinguishing insulating material molded body 10 with excellent current-limiting performance. However, it is difficult to prevent retention and restrike of arc 100, increasing the risk that it will take a long time to extinguish arc 100.

[0060] As can be seen from the above results, according to Examples 1 to 6, the degradation of spatial insulation due to decomposition gases released from the arc-extinguishing insulating material compact 10 is suppressed, the frequency of retention and restrike of the arc 100 is reduced, and it is possible to achieve a reduction in the interruption time and the amount of wear on peripheral components. Furthermore, it is possible to achieve both the impact resistance and insulating performance after arc exposure required of the arc-extinguishing insulating material compact 10 and the effect of reducing the interruption time.

[0061] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0062] 10 Arc-extinguishing insulating material molded body, 11 Resin, 12 Inorganic filler, 13 Inorganic fiber, 20 Circuit breaker, 21 Fixed contact, 22 Fixed contact, 23 Movable contact, 24 Movable contact, 30 Arc-extinguishing device, 31 Arc-extinguishing plate, 31a Notch, 32 Arc-extinguishing side plate, 41, 42 Terminal portion, 50 Housing, 51 Cover, 51a Guide groove, 52 Base, 53 End plate, 53a Exhaust hole, 60 Opening / closing mechanism portion, 61 Handle, 70 Tripping device portion, 80 Testing device, 81 Test container, 82 Sample stand, 83 Counter electrode, 83a, 83b Electrode, 84 Support, 85 Sample, 100 Arc.

Claims

1. A molded arc-extinguishing insulating material comprising a resin composition containing a resin, an inorganic filler, and inorganic fibers, wherein the proportion of the inorganic fibers is 60% by weight or more and 80% by weight or less of the entire resin composition, and the total proportion of the inorganic filler and the inorganic fibers is 75% by weight or more and 90% by weight or less of the entire resin composition.

2. The arc-extinguishing insulating material compact according to claim 1, characterized in that the inorganic fibers have an aspect ratio of 50 or more.

3. The arc-extinguishing insulating material compact according to claim 2, characterized in that the inorganic fibers are processed into a cloth or sheet shape.

4. The arc-extinguishing insulating material compact according to any one of claims 1 to 3, characterized in that the inorganic fibers contain silicon dioxide (SiO2), calcium oxide (CaO) and magnesium oxide (MgO) as constituent components, the total of the constituent components of the silicon dioxide, calcium oxide and magnesium oxide being 90 parts by weight or more when the total of all constituent components is 100 parts by weight, the silicon dioxide is 40 parts by weight or more and 80 parts by weight or less, the calcium oxide is 2 parts by weight or more and 30 parts by weight or less, and the magnesium oxide is 2 parts by weight or more and 30 parts by weight or less, and the softening point is 1000°C or more.

5. The specific gravity of the resin composition is 2.0 g / cm 3 5. The arc-extinguishing insulating material molded article according to claim 1, wherein the arc-extinguishing insulating material molded article is a molded article of arc-extinguishing insulating material.

6. A circuit breaker comprising: a fixed contactor having a fixed contact; a movable contactor having a movable contact; an opening / closing mechanism that operates the movable contactor so that the movable contact makes contact with or separates from the fixed contact; and an arc-extinguishing insulating material molded article according to any one of claims 1 to 5, which is arranged in a position where it is exposed to an arc that occurs when the fixed contact and the movable contact separate.

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