JP2005353317A - Arc-extinguishing device of circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc-extinguishing device of a circuit breaker capable of increasing a rated voltage, a rated current and rated breaking capacity of the circuit breaker, without increasing the size of the container of the circuit breaker. <P>SOLUTION: This arc-extinguishing device 2 is provided with an arc-extinguishing gas generation plate 27 (arc-extinguishing gas generation member), arranged by being stacked in the thickness direction of an evacuation plate 26 (insulating member) for generating an arc-extinguishing gas by heat generated by an arc generated, when a moving contact 21b separates from a fixed contact 21a; and three grids 38 held to the evacuation plate 26 through the arc-extinguishing gas generating plate 27. Each grid 38 has a U-shaped form and has a recessed part 39 surrounding a passage of the fixed contact; and the connecting part (back face part) thereof for connecting both leg parts (both side surface parts) is exposed to the arc. A part of the arc-extinguishing gas generating plate 27 is interposed between the back face parts of the respective grids 38. The arc is divided and cooled, while being exposed to the back face parts of the respective grids 38, and extinguished by the arc-extinguishing gas generated from the arc-extinguishing gas generating plate 27. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an arc extinguishing device for a circuit breaker that extinguishes an arc generated between a fixed contact and a movable contact in the body of the circuit breaker.

  Conventionally, as a circuit breaker, there is known a circuit breaker in which an arc extinguishing device that extinguishes an arc generated when a contact portion composed of a fixed contact and a movable contact is opened (for example, Patent Document 1).

  The circuit breaker disclosed in Patent Document 1 is a three-pole circuit breaker, and as shown in FIG. 5, terminal blocks 16a are provided at both ends (left and right ends in FIG. 5) of the vessel body 10 ′. 16b is formed, and on the terminal block 16a at one end, three power supply side terminals (input terminals) 17 each having a terminal screw 19a with a washer are arranged side by side in a direction perpendicular to the plane of FIG. Three load-side terminals (output terminals) 18 having washer-attached terminal screws 19b are arranged in parallel in the direction perpendicular to the paper surface of FIG. Insulation walls 16c and 16d are formed on the terminal blocks 16a and 16b so as to insulate between the adjacent power supply side terminals 17 and between the load side terminals 18. Further, in the circuit breaker 1 ′ having the configuration shown in FIG. 5, the power supply side terminal 17 and the load side terminal 18 are associated with each other in a one-to-one relationship, and between the power supply side terminal 17 and the load side terminal 18. A contact portion 21 accommodated in the container 10 ′ is inserted in each electric path.

  Note that the body 10 'of the circuit breaker 1' can be synthesized as shown in FIGS. 5 and 6 if the front and back directions of FIG. A base 11 made of a resin molded product, a body 12 made of a synthetic resin molded product disposed on the front side of the base, and a box-shaped synthetic resin molded product with a front opening disposed on the front side of the body 12 It is formed by joining the cover 13. In addition, the body 12 is formed with an insulating wall 12a that divides the internal space of the body 12 for each pole, so that insulation between adjacent contact portions 21 can be achieved.

  The above-mentioned power supply side terminal 17 has a connecting piece 17b extending backward from a side edge (right side edge in FIG. 5) of a terminal plate 17a made of a metal plate, and from the rear end edge of the connecting piece 17b to the inner bottom surface of the body 12. A fixed contact holding piece 17c is extended in a direction toward the center of the body 12 along the above. The contact portion 21 is formed of a fixed contact 21a fixed to the fixed contact holding piece 17c and a conductive metal. The movable contact 22 is fixed to one end portion (tip portion) of the movable contact 22 and is made up of a movable contact 21b that contacts and leaves the fixed contact 21a. Each movable contact 22 is electrically connected to the load-side terminal 18 via a connection line 34 made of a braided wire and an abnormal current detection device 30.

  In addition, each contact portion 21 when an abnormal current flows in one of the trip mechanisms 40 and any of the three electric paths in which the contact portions 21 are inserted in the body 10 ′ of the circuit breaker 1 ′. The tripping mechanism 40 is operated so as to force the opening of the trip mechanism 40, and a single handle 45 exposing the three-pole contact portion 21 on the front surface of the body 10 'is accommodated. It can be opened and closed. The cover 13 is formed with a window hole 13a for exposing the operation portion of the handle 45.

  Further, the arc extinguishing device 2 ′ in the circuit breaker 1 ′ described above has a U-shaped yoke 29 attached to the exhaust plate 26 in which the exhaust hole 26a is formed, and is fixed when a short-circuit current flows. The arc generated between both contacts 21a and 21b is extinguished by an electromagnetic force corresponding to the current flowing between the contact 21a and the movable contact 21b. Here, the exhaust plate 26 is formed of a melamine resin laminate or a polyester resin laminate.

  By the way, in the overload switching test of the circuit breaker specified in the JIS standard (JIS C8370), when the rated current In is 100 A or less, the test voltage is set to the rated voltage and the test current is set to 6In (for example, the rated current In is When the rated voltage is 100A and the rated voltage is 220V, the test voltage is set to 220V and the test current is set to 600A), the handle must be opened and closed to clear the number of times of opening and closing 50 times, and the rated current In exceeds 100A and is less than 225A In this case, the test voltage is set to the rated voltage and the test current is set to 6In (for example, when the rated current In is 150A and the rated voltage is 220V, the test voltage is set to 220V and the test current is set to 900A). You must clear the opening and closing times. Here, “must be cleared” means that there will be no electrical or mechanical problems before the specified number of opening / closing operations is completed. Specifically, the movable contact and the fixed contact are welded together. This means that the opening cannot be made impossible, and the inability to shut off due to re-ignition does not occur.

  Moreover, in the short circuit breaking test of the circuit breaker defined in the JIS standard, there are 1.0 kA, 2.5 kA,..., 200 kA as the short circuit breaking capacity, and the short circuit breaking capacity of the circuit breaker as the test current. Test whether the trip mechanism trips when current is passed.

  The circuit breaker 1 ′ disclosed in Patent Document 1 is used as a circuit breaker having a rated voltage of 220 V, a rated current of 100 A, and a rated breaking capacity of 5 kA based on an overload switching test and a short circuit breaking test. As a circuit breaker having a larger rating (eg, rated voltage of 460 V, rated current of 150 A) and rated breaking capacity (eg, 7.5 kA) without changing the outer dimensions of the vessel body 10 ′. It could not be used.

  On the other hand, as shown in FIG. 7, the vessel body 10 ″ is larger than the circuit breaker 1 ′ disclosed in the above-mentioned Patent Document 1, and is between the movable contact 21b and the fixed contact 21a in the open state. The gap between the contact portion 21 and the power supply side terminal 17 is widened, and a plurality of grids 38 'made of conductive plates are arranged in the front-rear direction (vertical direction in FIG. 7) at predetermined intervals. A circuit breaker 1 ″ in which an arc device 2 ″ is housed in a container 10 ″ is known (Patent Document 2). Here, in the circuit breaker 1 ″ having the configuration shown in FIG. 7, an exhaust plate 26 ′ is provided on the side surface of the container 10 ″ on the side of the arc extinguishing device 2 ″ to communicate the inside and outside of the container 10 ″. Yes.

  In the circuit breaker 1 ″ having the configuration shown in FIG. 7 disclosed in Patent Document 2, the rated voltage, the rated current, the rated breaking capacity, etc. can be increased as compared with the circuit breaker 1 ′ having the configuration shown in FIG. For example, the rated voltage can be set to 460 V, the rated current can be set to 150 A, or the rated breaking capacity can be increased to 25 kA with the same rated voltage 220 V and rated current 100 A as the circuit breaker 1 ′ having the configuration shown in FIG. For this reason, the circuit breaker 1 ″ having the configuration shown in FIG. 7 has been used as a circuit breaker having a rated voltage of 460 V and a rated current of 150 A.

In addition, regarding the external dimensions of the body 10 'of the circuit breaker 1' shown in FIG. 5, the length dimension in the left-right direction in FIG. 5 (the direction in which the power supply side terminal 17 and the load side terminal 18 are aligned). Is approximately 9.6 cm, the length dimension in the direction orthogonal to the paper surface (width direction) in the figure is approximately 7.5 cm, and the length dimension in the vertical direction in the figure is 6.4 cm, and the circuit shown in FIG. Regarding the external dimensions of the body 10 ″ of the circuit breaker 1 ″, the length dimension in the left-right direction in FIG. 7 (the direction in which the pair of the power supply side terminal 17 and the load side terminal 18 are arranged) is approximately 15.5 cm. The length dimension in the direction perpendicular to the paper surface (width direction) is approximately 9 cm, and the length dimension in the vertical direction in the figure is 7.2 cm.
JP 2000-76981 A (see [0018], [0019], FIG. 4 and FIG. 5) Japanese Examined Patent Publication No. 8-24026 (page 2, left column, lines 23 to 39, page 4, right column, lines 14 to 18; see FIG. 1)

  As described above, the circuit breaker 1 ″ including the arc extinguishing device 2 ″ disclosed in the above-mentioned Patent Document 2 is compared with the circuit breaker 1 ′ including the arc-extinguishing device 2 ′ disclosed in the above-mentioned Patent Document 1. Although the rated voltage, the rated current, the rated breaking capacity, and the like can be increased, the body 10 ″ becomes larger than the body 1 ′.

  The present invention has been made in view of the above reasons, and its purpose is to increase the rated voltage, rated current, rated breaking capacity, etc. of the circuit breaker without increasing the size of the circuit breaker body. An object of the present invention is to provide an arc extinguishing device for a circuit breaker capable of performing the above-described operation.

  The invention of claim 1 is an arc extinguishing device for a circuit breaker that extinguishes an arc generated when the movable contact provided at the tip of the movable contact in the body of the circuit breaker leaves the fixed contact. A plurality of conductive plates made of a back surface portion exposed to an arc and both side surface portions extending from both end portions of the back surface portion so as to form a recess surrounding the passage path of the movable contact and spaced apart in the direction in which the movable contact contacts and separates. And an arc-extinguishing gas generating member that is disposed so as to be interposed between the back surfaces of each grid and that generates arc-extinguishing gas by the heat generated by the arc.

  According to the present invention, the arc generated when the movable contact leaves the fixed contact is separated and cooled while being exposed to the back surface of each grid, and the arc is interposed between the back surfaces of the grid by the heat generated by the arc. Since the arc extinguishing gas is generated from the reactive gas generating member, the area occupied by the arc extinguishing device in the body is widened compared to the arc extinguishing device having a configuration in which a U-shaped yoke is attached to the conventional exhaust plate. It is possible to improve arc extinguishing performance without arcing, and increase the rated voltage, rated current, rated breaking capacity, etc. of the circuit breaker without increasing the size of the circuit breaker body.

  The invention of claim 2 is the invention of claim 1, wherein the arc extinguishing gas generating member is formed of a material having higher mechanical strength and electrical insulation than the arc extinguishing gas generating member, and the arc extinguishing property on the back side of each grid. An insulating member is provided so as to overlap the gas generating member and hold the grids.

  According to this invention, each said grid can be hold | maintained firmly with an insulating member.

  According to a third aspect of the present invention, in the second aspect of the invention, the insulating member is disposed on the one surface side of the fixed contact holding piece provided with the fixed contact protruding from the one surface in the container. An arc gas generating member is formed such that a part thereof is interposed between the insulating member and the one surface of the fixed contact holding piece.

  According to this invention, since a part of the arc extinguishing gas generating member is interposed between the insulating member and the fixed contact holding piece, the insulating member is directly placed on the fixed contact holding piece. In comparison, the insulating member is less likely to deteriorate due to arcing, and arc extinguishing properties are further improved.

  The invention according to claim 4 is the invention according to claim 3, wherein the arc-extinguishing gas generating member is interposed between the grids, and the arc-extinguishing gas generating part for generating the arc-extinguishing gas is provided in parallel with each grid. A commutation preventing portion that is in contact with both end faces of each grid orthogonal to the direction and prevents arc commutation from each grid to another grid is integrally formed of the same material.

  According to this invention, it becomes difficult for an arc to commutate from the both end surface sides of each grid to another grid, and the arc extinguishing performance is further improved.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the shortest distance between the grid farthest from the fixed contact and the movable contact in an open state among the plurality of grids is A, When the shortest distance between the grid second away from the fixed contact and the movable contact in the open state is C, the relationship of A <C is satisfied.

  According to the present invention, an arc generated when the movable contact leaves the fixed contact flows in the order of the grid farthest from the fixed contact and the grid second most distant from the fixed contact. As a result, the arc can be sufficiently stretched and extinguished.

  The invention of claim 6 is the invention of claim 1 to claim 5, wherein the number of the grids is at least three, and the distance between each pair of grids adjacent in the direction in which the movable contact contacts and separates is It is characterized in that the grid pair closer to the fixed contact is wider.

  According to this invention, when the movable contact moves away from the fixed contact, an arc that causes thermal damage in the vicinity of the fixed contact can be quickly extended to the grid, and the electric field strength between the fixed contact and the grid can be increased. By lowering, it is possible to prevent interruption due to reignition and improve arc extinguishing performance.

  According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the arc extinguishing gas generating member comprises a thermoplastic resin, an inorganic compound that undergoes a dehydration reaction at 200 ° C. or higher, and an alkali metal or alkaline earth. It contains a metal-based metal oxide and a reinforcing material.

  According to this invention, the arc-extinguishing gas generating member generates an arc-extinguishing gas from an inorganic compound that undergoes a dehydration reaction at 200 ° C. or higher, and is included in an alkali metal or alkaline earth metal oxide. Oxygen reacts with the carbon in the carbon layer formed on the surface by the heat generated by the arc to form carbon dioxide, thereby removing the carbon layer, thereby preventing insulation deterioration of the arc extinguishing gas generating member. It is possible to prevent the arc extinguishing performance from being lowered. Here, in terms of a material having a high arc extinguishing property, an inorganic compound that undergoes a dehydration reaction at 200 ° C. or higher is superior to a metal oxide of an alkali metal or alkaline earth metal, but has a low vapor pressure. In terms of materials, alkali metal or alkaline earth metal oxides are superior to inorganic compounds that undergo a dehydration reaction at 200 ° C. or higher. Also, in terms of a material having high heat resistance (durability), an alkali metal or alkaline earth metal oxide is superior to an inorganic compound that undergoes a dehydration reaction at 200 ° C. or higher.

  The invention according to claim 8 is the invention according to claim 7, wherein the arc extinguishing gas generating member uses nylon 6 as the thermoplastic resin, magnesium hydroxide as the inorganic compound, and magnesium oxide as the metal oxide. It is characterized by that. Here, magnesium oxide has a higher melting point than magnesium hydroxide and a low vapor pressure at the same temperature. The melting point of magnesium oxide is 2800 ° C., and the melting point of magnesium hydroxide is 350 ° C.

  According to this invention, since the arc-extinguishing gas generating member contains magnesium oxide, the arc-extinguishing gas generating member has higher heat resistance (durability) than when no magnesium oxide is contained. As a result, it is possible to suppress an increase in pressure in the container due to the heat generated by the arc, and to prevent damage to the container.

  In the case where magnesium oxide as the metal oxide is not contained in the arc extinguishing gas generating member, nylon 6 is used in order to enhance arc extinguishing properties and suppress an increase in pressure in the vessel due to heat generated by the arc. It is conceivable that the content of magnesium hydroxide is decreased to decrease the content of magnesium hydroxide, but the thermal conductivity of nylon 6 is lower than that of magnesium oxide (the thermal conductivity of magnesium oxide is 42 W / at 273K). Since the thermal conductivity of m · K and nylon 6 is 0.3 W / m · K), it is difficult to release the heat of each grid when the contact part consisting of the fixed contact and the movable contact is opened and closed or when a short circuit is interrupted. The temperature of each of the grids is likely to increase and re-ignition is likely to occur. In short, when the arc-extinguishing gas generating member does not contain magnesium oxide, if the magnesium hydroxide content is increased by that amount, the pressure inside the vessel will increase when the arc is generated and the vessel will be damaged. There is a fear, and if nylon 6 is increased, there is a risk of reignition (cannot be shut off). On the other hand, in the invention of claim 8, the arc-extinguishing property can be obtained by containing magnesium oxide in the arc-extinguishing gas generating member as described above, compared with a case where magnesium oxide is not contained. While improving the heat resistance (durability) of the gas generating member, it is possible to suppress an increase in pressure in the container due to the heat generated by the arc, and to prevent damage to the container.

  According to the first aspect of the present invention, compared with a conventional arc extinguishing apparatus having a U-shaped yoke attached to an exhaust plate, the arc extinguishing performance against an arc without increasing the area occupied by the arc extinguishing apparatus in the body. As a result, the rated voltage, rated current, rated breaking capacity, etc. of the circuit breaker can be increased without increasing the size of the circuit breaker body.

  Hereinafter, an arc extinguishing device for a circuit breaker according to the present embodiment will be described with reference to FIGS. 1 to 4. With respect to the circuit breaker 1, the same components as the conventional configuration shown in FIGS. The description will be omitted as appropriate. In addition, the same code | symbol is attached | subjected about the component similar to a conventional structure regarding the part which the circuit breaker 1 illustrated.

  The circuit breaker 1 in this embodiment is a three-pole circuit breaker in which the outer dimensions of the body 10 are set to the same dimensions as those of the conventional configuration shown in FIGS. Every time, the arc extinguishing device 2 is provided in the vicinity of the power supply side terminal 17 in the container 10. Here, the power supply side terminal 17 has a connecting piece 17b extending backward from the side edge of the terminal plate 17a made of a metal plate (the right side edge in FIG. 1A), and the body 12 extends from the rear end edge of the connecting piece 17b. A fixed contact holding piece 17c is extended in the direction toward the center of the body 12 along the inner bottom surface of the body, and the contact portion 21 is fixed to the fixed contact holding piece 17c and is one surface of the fixed contact holding piece 17 (FIG. 1). The fixed contact 21a protrudes toward the upper surface) in (a) and the movable contact 21b fixed to one end (tip) of the movable contact 22 made of a conductive metal and contacting and leaving the fixed contact 21a. (Here, the contact direction of the movable contact 21b with respect to the fixed contact 21a is the vertical direction in FIG. 1A). Although not shown, each movable contact 22 is electrically connected to a load side terminal via a connection line made of a braided wire and an abnormal current detection device. Further, in the case 10 of the circuit breaker 1, each contact point when an abnormal current flows through one trip mechanism (not shown) and one of the three electric paths through which the contact portions 21 are respectively inserted. A tripping device (not shown) for operating the trip mechanism to force open the portion 21 is housed, and a single contact portion 21 with three poles exposed on the front surface of the body 10 is stored. The handle 45 can be opened and closed. Therefore, when an abnormal current flows when the handle 45 is in a position where the contact portion 21 is in a closed state or when the handle 45 is operated, the movable contact 21b is separated from the fixed contact 21a and is opened.

  The arc-extinguishing device 2 is arranged so as to overlap the exhaust plate 26 made of an electrically insulating material in the thickness direction of the exhaust plate 26, and generates arc-extinguishing gas by heat generated by the arc generated when the movable contact 21b is separated from the fixed contact 21a. An arc extinguishing gas generating plate 27 that is generated and a plurality (three in this embodiment) of grids 38 that are held on the exhaust plate 26 through the arc extinguishing gas generating plate 27 are provided, and arc gas that accompanies arc generation. Is discharged out of the body 10 through the exhaust plate 26, and the arc is divided by three grids 38 and cooled. In the present embodiment, the power supply side terminal 17 constitutes a terminal, the arc extinguishing gas generating plate 27 constitutes an arc extinguishing gas generating member, and the exhaust plate 26 is more mechanical than the arc extinguishing gas generating member. The insulating member is formed of a material having high strength and electrical insulation. The materials of the arc extinguishing gas generating plate 27 and the exhaust plate 26 will be described later.

  The outer peripheral shape of the exhaust plate 26 is a rectangular shape. If the vertical direction of FIG. 1A is the vertical direction of the exhaust plate 26, a plurality ( In the present embodiment, four) exhaust holes 26a are provided in the thickness direction, and rectangular assembly holes 26b (see FIG. 3) for attaching the grid 38 are vertically arranged on both sides of the lower part of the exhaust plate 26. They are spaced apart in the direction. Each grid 38 is formed in a U shape by providing a conductive plate (iron plate) with a recess 39 surrounding the passage of the movable contact 21b, and is arranged so that the inner bottom surface of the recess 39 is exposed to an arc. The Here, each grid 38 has an assembly projection 38c (see FIG. 5) that fits into the assembly hole 26b of the exhaust plate 26 on the surface facing the exhaust plate 26 in the connecting portion 38a that connects the legs 38b, 38b continuously and integrally. 3) is provided so as to protrude in the longitudinal direction of the connecting portion 38a. Therefore, each pair of assembly protrusions 38c of each grid 38 is fitted in each pair of assembly holes 26b of the exhaust plate 26, whereby each grid 38 is fixedly held on the exhaust plate 26 and exhausted at the connecting portion 38a. The surface opposite to the surface facing the plate 26 is the inner bottom surface of the recess 39 (that is, the connecting portion 38a is exposed to the arc). In the present embodiment, in each grid 38, the connecting portion 38a constitutes a back surface portion exposed to the arc, and both leg portions 38b, 38b constitute both side surface portions extending from both ends of the back surface portion, A recess 39 surrounding the passage route of the movable contact 21b is formed by the back surface portion and both side surface portions. Further, the exhaust plate 26 serving as the insulating member is disposed on the back side of each grid 38 so as to overlap the arc extinguishing gas generation plate 27 and holds each grid 38.

  Here, the arc extinguishing gas generating plate 27 has a width dimension substantially equal to the width dimension of the lower portion of the exhaust plate 26, and two insertion holes 27a through which the second and third grids 38 are inserted, respectively. And a notch 27b that passes through the first-stage grid 38 is formed. Accordingly, the arc extinguishing gas generating plate 27 is orthogonal to the arc extinguishing gas generating portion 27c formed by the portion interposed between the grids 38 and the parallel arrangement direction of the grids 38 (vertical direction in FIG. 1A). A commutation preventing portion 27d that is in contact with both end faces of the grid 38 and prevents arc commutation from each grid 38 to the other grid 38 is integrally formed of the same material, and is formed in a ladder shape as a whole. Has been. Therefore, it becomes difficult for the arc to commutate from the both end surfaces of each grid 38 to the other grid 38, and arc extinguishing performance is further improved. In the present embodiment, the thickness dimension of the two grids 38 (the second-stage grid 38 and the third-stage grid 38) on the side close to the fixed contact 21 a among the three grids 38 is set to 2.6 mm. Although the thickness of the grid 38 farthest from the contact 21a (the first-stage grid 38) is 2 mm, these numerical values are not particularly limited.

  As can be seen from the above description, the arc extinguishing device 2 has a plurality of grids 38 that are spaced apart from each other in the direction in which the movable contact 21b contacts and separates, and each grid 38 has a recess that surrounds the passage path of the movable contact 21b. 39 is formed, and the inner bottom surface of each recess 39 is exposed to an arc. In addition, the shape of the inner peripheral surface of the recessed part 39 is not specifically limited, For example, it may be U-shaped not only in U shape.

  4A shows the relative positional relationship between the main part of the arc extinguishing device 2 and the movable contact 21b when the movable contact 21b is in contact with the fixed contact 21a (closed state). 4 (b) shows the relative positional relationship between the main part of the arc extinguishing device 2 and the movable contact 21b when the movable contact 21b is separated from the fixed contact 21a (opened state). The shortest distance between the grid 38 farthest from the fixed contact 21a and the movable contact 21b in the open state is A (see FIG. 4B), and the grid 38 and the second openest state from the fixed contact 21a are in the open state. The dimension of the grid 38 is designed to satisfy the relationship of A <C, where C is the shortest distance between the movable contact 21b and the movable contact 21b (see FIG. 4B). Therefore, an arc generated when the movable contact 21b is separated from the fixed contact 21a flows in the order of the grid 38 farthest from the fixed contact 21a and the grid 38 second from the fixed contact 21a. The arc can be sufficiently stretched and extinguished.

  Further, in the arc extinguishing device 2, the distance between each pair of adjacent grids 38 in the direction in which the movable contact 21b is contacted and separated is wider as the pair of grids 38 is closer to the fixed contact 21a, and the fixed contact 21a to the movable contact 21b. The arc that causes thermal damage to the vicinity of the fixed contact 21a when the distance between the fixed contact 21a can be quickly extended to the grid 38, and the electric field strength between the fixed contact 21a and the grid 38 is reduced, thereby interrupting the occurrence of re-ignition. Impedance can be prevented and arc extinguishing performance can be improved.

  A protective piece 27e that covers the lower end edge of the exhaust plate 26 extends from the lower end edge of the arc extinguishing gas generating plate 27, and the lower end edge of the arc extinguishing gas generating plate 27 is on the one surface of the fixed contact holding piece 17c. The protective piece 27e is interposed between the lower end edge of the exhaust plate 26 and the one surface of the fixed contact holding piece 17c. Therefore, as compared with the case where the exhaust plate 26 is directly placed on the fixed contact holding piece 17c, the exhaust plate 26 is less likely to be insulated and deteriorated by the arc, and the arc extinguishing property is further improved.

  Further, the arc extinguishing device 2 is configured such that a flexible thin plate-like valve plate 28 is arranged on the opposite side of the exhaust plate 26 from the surface facing the arc-extinguishing gas generating plate 27 and exhausted from the valve plate 28. The lower portions of the plate 26 are fixed to each other, and the lower portion of the valve plate 28 is disposed so as to face the connecting piece 17b. Therefore, in a state where the contact portion 21 is closed, the exhaust hole 26a is closed by the valve body 28, so that foreign matters such as dust enter the device body 10 from the outside of the device body 10 through the exhaust hole 26a. Can be prevented.

  By the way, in determining the material of the arc extinguishing gas generating plate 27, the inventors of the present invention are concerned with the arc extinguishing property, the vapor pressure of the gas generated along with the arc generation, and the heat resistance of the arc extinguishing gas generating plate 27. When various materials were examined by paying attention, the arc extinguishing gas generating plate 27 was obtained by using a thermoplastic resin, an inorganic compound that undergoes a dehydration reaction at 200 ° C. or higher, and an alkali metal or alkaline earth metal oxide. As a result, a circuit breaker with improved rated voltage, rated current, rated breaking capacity, and the like can be realized by forming the material and a reinforcing material (reinforcing material). Here, as each constituent material of the arc extinguishing gas generating plate 27, for example, nylon 6 as a thermoplastic resin, magnesium hydroxide as the inorganic compound (magnesium hydroxide dehydrates at 288 ° C.), the above metal Magnesium oxide may be used as the oxide, and glass fiber may be used as the reinforcing material. As an example of the mixing ratio (mass percentage) in this case, the example shown in Table 1 below may be adopted.

  In this embodiment, an inorganic laminated plate is used as the exhaust plate 26 serving as an insulating member. However, the insulating laminated plate is not limited to the inorganic laminated plate, and has a mechanical strength higher than that of the arc extinguishing gas generating plate 27 and is electrically insulated. For example, a melamine resin laminate and a silicon resin laminate may be used.

  As for the circuit breaker 1 of the present embodiment, a test voltage was set to 460 V, a test current was set to 900 A, and a power factor was set to 0.47 with respect to an overload switching test based on the above-described JIS standard. Since it was possible to clear the double opening / closing frequency 50 times, it can be used as a circuit breaker having a rated voltage of 460 V and a rated current of 150 A. Further, as a result of an overload switching test under the same conditions for the circuit breaker 1 adopting a structure in which the lower end edge of the exhaust plate 26 is in contact with the fixed contact holding piece 17c without the protective piece 27e, 25 switching operations are performed. Even when such a structure is adopted, it can be used as a circuit breaker with a rated voltage of 460 V and a rated current of 150 A, but it is protected from the viewpoint of the number of switching operations in the overload switching test. The structure provided with the piece 27e is more preferable. In the conventional configuration shown in FIG. 5, the number of opening / closing operations of 25 times could not be cleared in the overload switching test under the same conditions. In the conventional configuration shown in FIG. 5, the rated breaking capacity is up to 5 kA at a rated voltage of 220 V and a rated current of 100 A. However, in the circuit breaker 1 of this embodiment, the rated voltage is 220 V and the rated current of 100 A is 25 kA. Can be used up to the rated breaking capacity.

  In the arc extinguishing device 2 of the present embodiment described above, the arc generated when the movable contact 21b is separated from the fixed contact 21a is separated and cooled while being exposed to the connecting portion 38a which is the back surface of each grid 38, and the arc Since the arc extinguishing gas is generated from the arc extinguishing gas generating plate 27 in which a part (the arc extinguishing gas generating unit 27c) is interposed between the connecting portions 38a of the grid 38 due to the generated heat, Compared to the arc extinguishing device 2 ′ having a configuration in which the letter-shaped yoke 29 is attached, the arc extinguishing performance against the arc can be improved without increasing the occupation area of the arc extinguishing device 2 in the body 10, It becomes possible to increase the rated voltage, rated current, rated breaking capacity, etc. of the circuit breaker 1 without increasing the size of the body 10 of the circuit breaker 1.

  The numerical values in the above-described Table 1 regarding the mixing ratio of the materials of the arc extinguishing gas generating plate 27 are merely examples, and may be set within the range of the following Table 2.

  In the present embodiment, the U-shaped guard plate 23a and the fixed contact holding piece 17c which are disposed so as to surround the fixed contact 21a on the one surface side of the fixed contact holding piece 17c and protect the fixed contact 21a. The contact guard plate 23 having a guard plate 23b that protrudes toward the one surface side and prevents the arc from being re-ignited to the other end side of the movable contact 22 and the movable contact 22 faces the fixed contact 21a. Since the contact guard member 25 which is attached to the lower surface side and prevents the arc from re-igniting to the lower surface side of the movable contact 22 is also formed of the same material as the arc extinguishing gas generating plate 27, The performance can be further enhanced.

  Further, regarding the material of the arc extinguishing gas generating plate 27, the thermoplastic resin is not limited to nylon 6, and for example, polybutylene terephthalate, nylon 66, or the like may be used. Moreover, as said inorganic compound, you may use not only magnesium hydroxide but aluminum hydroxide, calcium hydroxide, etc., for example. Further, the metal oxide is not limited to magnesium oxide (alkaline earth metal oxide), for example, sodium oxide (alkali metal oxide), calcium oxide (alkaline earth metal oxide). Etc. may be used.

  If only the opening / closing performance is to be improved, a structure in which each grid 38 is directly held by the arc extinguishing gas generating plate 27 may be employed. However, the arc extinguishing gas generating plate 27 has a relatively low mechanical strength. . However, since the arc extinguishing device 2 is disposed in the vicinity of the power supply side terminal 17 and a force for connecting a conductor (for example, an external electric wire) as an external wiring acts on the power supply side terminal 17, it is mechanical. It is preferable to increase the strength. On the other hand, since it is preferable to use the above-mentioned materials for the material of the arc extinguishing gas generating plate 27, in this embodiment, each grid in the exhaust plate 26 having higher mechanical strength than the arc extinguishing gas generating plate 27. 38 is held. Therefore, it is possible to prevent the arc extinguishing gas generating plate 27 from being damaged by a force when connecting a conductor as an external wiring to the power supply side terminal 17.

Embodiment is shown, (a) is principal part sectional drawing of the circuit breaker which accommodated the arc-extinguishing apparatus, (b) is perspective views, such as an arc-extinguishing apparatus. It is a principal part perspective view of the arc-extinguishing apparatus in the same as the above. It is a principal part disassembled perspective view of the arc-extinguishing apparatus in the same as the above. It is explanatory drawing of the relative positional relationship of the arc-extinguishing apparatus and movable contact in the same as the above. It is sectional drawing of the circuit breaker which shows a prior art example It is a disassembled perspective view of the container in a circuit breaker same as the above. It is sectional drawing of the circuit breaker which shows another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circuit breaker 2 Arc-extinguishing device 10 Body 17 Power supply side terminal 17c Fixed contact holding piece 21 Contact part 21a Fixed contact 21b Movable contact 22 Movable contact 26 Exhaust plate 27 Arc-extinguishing gas generating plate 38 Grid 39 Concave part

Claims (8)

  An arc extinguishing device for a circuit breaker that extinguishes an arc generated when a movable contact provided at a tip of a movable contact in the body of a circuit breaker leaves a fixed contact, comprising: a back surface exposed to the arc; A plurality of grids made of conductive plates that are formed in both sides of the back surface so as to surround the passage path of the movable contact and that are spaced apart in the direction in which the movable contact contacts and separates, An arc extinguishing device for a circuit breaker, comprising: an arc extinguishing gas generating member that is arranged in a form interposed between back portions and generates arc extinguishing gas by heat generated by the arc.   It is formed of a material having higher mechanical strength and electrical insulation than the arc-extinguishing gas generating member, and arranged on the back side of each grid so as to overlap the arc-extinguishing gas generating member to hold each grid. 2. An arc extinguishing device for a circuit breaker according to claim 1, wherein an insulating member is provided.   The insulating member is disposed on the one surface side of the fixed contact holding piece provided so that the fixed contact protrudes from one surface in the container, and the arc extinguishing gas generating member is partly connected to the insulating member. 3. An arc extinguishing device for a circuit breaker according to claim 2, wherein the arc breaker is formed so as to be interposed between the fixed contact holding piece and the one surface.   The arc-extinguishing gas generating member includes an arc-extinguishing gas generator that is interposed between the grids and generates the arc-extinguishing gas, and is in contact with both end faces of the grids orthogonal to the parallel arrangement direction of the grids. An arc extinguishing device for a circuit breaker according to claim 3, wherein a commutation preventing portion for preventing commutation of arc from one grid to another is integrally formed of the same material.   A shortest distance between the grid farthest from the fixed contact among the plurality of grids and the movable contact in the open state is A, and the grid farthest away from the fixed contact and the movable contact in the open state The arc extinguishing device for a circuit breaker according to any one of claims 1 to 4, wherein a relationship of A <C is satisfied, where C is a shortest distance between the circuit breakers.   The number of the grids is at least three, and an interval between each pair of adjacent grids in a direction in which the movable contact contacts and separates is wider as a pair of grids closer to the fixed contact. An arc extinguishing device for a circuit breaker according to any one of claims 1 to 5.   The arc-extinguishing gas generating member contains a thermoplastic resin, an inorganic compound that undergoes a dehydration reaction at 200 ° C. or higher, an alkali metal or alkaline earth metal oxide, and a reinforcing material. An arc extinguishing device for a circuit breaker according to any one of claims 1 to 6.   8. The circuit breaker according to claim 7, wherein the arc extinguishing gas generating member is made of nylon 6 as the thermoplastic resin, magnesium hydroxide as the inorganic compound, and magnesium oxide as the metal oxide. Arc extinguishing device.

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