Air circuit breaker

Abstract

An air circuit breaker (100) according to the present disclosure includes: a breaker unit (30) that interrupts a current by opening contacts between a stator (2) and a mover (4); a plurality of arc-extinguishing plates (50) which are provided above the breaker unit and which are formed by stacking a plurality of conductive plate-like grids (12) and insulating plates (13) in a stacking direction; a fastening member including nuts (20) and bolts (21) that secure the plurality of arc-extinguishing plates and a loosening prevention member (26) that prevents loosening of the nuts, the nuts and bolts being provided at mutually different ends of the plurality of arc-extinguishing plates in the stacking direction; and an elastic body (22) provided between the fastening member and the arc-extinguishing plate provided at an end in the stacking direction.

Description

Air Circuit Breaker

[0001] The present disclosure relates to an air circuit breaker used as a protective breaker for an electric power system, etc.

[0002] When a fault occurs in a power system and a fault current flows through the system, a discharge phenomenon called an arc occurs at the fault location. A circuit breaker can interrupt the current by extinguishing this arc, thereby protecting the power system. An air circuit breaker is a circuit breaker that interrupts current in air. It consists of a stator with fixed contacts, a moving contact with a moving contact that can be freely separated from the fixed contacts, an arc runner that transfers the arc generated between the contacts from the contacts, an arc extinguishing chamber that extinguishes the arc, and a molded frame made of insulating material that supports them. When an air circuit breaker is used to interrupt a fault current in a power system, an arc is generated between the fixed and moving contacts when the moving contact separates from the stator. The generated arc is transferred to the arc runners located above the stator and moving contact and moves along the arc runner. The arc that has moved along the arc runner then moves to the arc extinguishing chamber, where an arc voltage greater than the power supply voltage is generated, resulting in current-limiting interruption and extinguishing the arc.

[0003] The arc extinguishing chamber for extinguishing the arc is constructed by stacking a plurality of arc extinguishing plates, each of which includes a conductive plate-shaped grid and an insulating plate. Patent Document 1 discloses a technique in which fastening members such as screws are used to fix the plurality of arc extinguishing plates in the arc extinguishing chamber.

[0004] International Publication No. 2020 / 241397

[0005] However, when multiple arc-extinguishing plates are fastened with fastening members such as screws or bolts, plastic deformation known as settling occurs, particularly at the contact surfaces between the arc-extinguishing plates and the fastening members, due to the tightening force applied when fastening. The fastening force of the fastening members decreases in proportion to this settling. When multiple arc-extinguishing plates are fastened together, there are multiple contact surfaces, so the increased settling significantly reduces the fastening force, causing the plates to loosen.

[0006] Furthermore, because the arc-extinguishing plate contains an insulator, it undergoes linear expansion and creep deformation due to temperature changes. This causes not only a decrease in fastening force due to settling, but also dimensional changes. If the dimensional change exceeds the amount of elastic deformation at the time of fastening, a gap will appear between the fastening member and the arc-extinguishing plate. This gap, along with the vibrations and rattles caused by the operating environment during operation of the air circuit breaker, causes wear of the arc-extinguishing plate. This wear powder generated by the arc-extinguishing plate can cause malfunctions of the air circuit breaker and damage to the arc-extinguishing chamber, which is an issue.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an air circuit breaker that can reduce wear caused by fastening members and suppress rattle and wear of the arc-extinguishing plate due to vibration.

[0008] The air circuit breaker according to the present disclosure includes an interrupting section that interrupts current by opening the contacts between the stator and the movable element, a plurality of arc-extinguishing plates provided on top of the interrupting section and consisting of a plurality of conductive plate-shaped grids and insulating plates stacked in the stacking direction, nuts and bolts that secure the plurality of arc-extinguishing plates, and anti-loosening members that prevent the nuts from loosening, and is also provided with fastening members with nuts and bolts provided at ends of the plurality of arc-extinguishing plates in different stacking directions, and an elastic body provided between the fastening members and the arc-extinguishing plates provided at the ends in the stacking direction.

[0009] The air circuit breaker according to the present disclosure reduces wear by reducing the contact area between the fastening member and the arc extinguishing plate, and prevents loosening of the fastening member by suppressing a decrease in fastening force due to wear, while also suppressing rattling and wear of the arc extinguishing plate due to vibration.

[0010] FIG. 1 is a cross-sectional view showing the configuration of an air circuit breaker according to a first embodiment of the present disclosure. FIG. 1 is a cross-sectional view showing movement of an arc when an arc is extinguished in the air circuit breaker according to the first embodiment of the present disclosure. FIG. 2 is a cross-sectional view showing the fastening structure of an arc-extinguishing plate of the air circuit breaker according to the first embodiment of the present disclosure. FIG. 3 is a perspective view showing the configuration of an arc-extinguishing chamber of a comparative example. FIG. 4 is a cross-sectional view showing the fastening structure of an arc-extinguishing plate of a comparative example. FIG. 5 is a graph showing changes in fastening force in the fastening structure of a comparative example. FIG. 6 is a graph showing changes in fastening force in the fastening structure of an arc-extinguishing plate of the air circuit breaker according to the first embodiment of the present disclosure. FIG. 7 is a cross-sectional view showing the fastening structure of an arc-extinguishing chamber of an air circuit breaker according to a second embodiment of the present disclosure. FIG. 8 is a perspective view showing the fastening structure of an arc-extinguishing plate of an air circuit breaker according to a third embodiment of the present disclosure. FIG. 9 is a cross-sectional view showing the configuration of an outer case-retained type circuit breaker in a comparative example. FIG. 10 is a cross-sectional view showing the configuration of an air circuit breaker according to a fourth embodiment of the present disclosure.

[0011] Hereinafter, the configuration of the air circuit breaker according to the first embodiment of the present disclosure will be described with reference to the drawings.

[0012] Embodiment 1. Fig. 1 is a cross-sectional view showing the configuration of an air circuit breaker according to embodiment 1 of the present disclosure. As shown in Fig. 1, the air circuit breaker 100 includes a stator 2 having a fixed contact 1, a mover 4 having a movable contact 3 that can be separated from the stator 2, a closing actuator 5 that moves the mover 4 to contact the stator 2, an upper conductor 6 and a lower conductor 7, a detector 8 that detects a fault current, a latch 9 that holds the mover 4, arc runners 10 and 11 that transfer an arc generated between the fixed contact 1 and the movable contact 3 from the contacts 1 and 3, an arc-extinguishing chamber 14 that extinguishes the arc, a conductive plate-like grid 12, and an insulating plate 13. A molded frame 15 is made of an insulator and supports the arc runners 10 and 11, the arc-extinguishing chamber 14, the grid 12, and the insulating plate 13. The grid 12 and the insulating plate 13 form an arc-extinguishing plate 50, and a plurality of arc-extinguishing plates 50 are stacked. The air circuit breaker according to the first embodiment of the present disclosure extinguishes the arc using the plurality of arc-extinguishing plates 50. Here, the arc-extinguishing chamber 14 is a space in which the plurality of arc-extinguishing plates 50 are provided. In the present disclosure, the interrupting unit includes at least the stator 2 and the movable member 4, and interrupts the current by opening the contact between the stator 2 and the movable member 4 (i.e., the contact between the fixed contact member 1 and the movable contact member 3). The arc-extinguishing chamber 14 is configured by laminating a conductive plate-shaped grid 12 and an insulating plate 13 for supporting and insulating it. Each component constituting the air circuit breaker 100 is supported by a molded frame 15.

[0013] The following describes the case where an accident occurs in the power system. In normal operation of the air circuit breaker 100, the fixed contact 1 of the stator 2 and the movable contact 3 of the movable element 4 are held in contact with each other by the closing actuator 5. This electrically connects the upper conductor 6 and the lower conductor 7.

[0014] 2 is a cross-sectional view showing the movement of an arc during arc extinguishing in the air circuit breaker according to the first embodiment of the present disclosure. When an accident occurs in the power system and a fault current flows, a detector 8 disposed on the lower conductor 7 detects the fault current and releases the latch 9 holding the moving member 4. The moving contact 3 of the moving member 4 separates from the fixed contact 1 of the stator 2, performing an opening operation. When the opening operation is performed during current interruption, an arc 16 is generated between the fixed contact 1 and the moving contact 3. The arc 16 generated between the contacts is commutated to the arc runner 11 on the moving member side disposed near the upper part of the fixed contact 1, and becomes an arc 17. The arc 17 then travels on each arc runner 10 or 11, away from the contacts, due to the electromagnetic force generated by the current flowing through the arc runner 11 and the highly conductive hot gas generated by the arc. The arc 17 then moves into the arc extinguishing chamber 14 and becomes an arc 18. The arc 18 that has moved into the arc extinguishing chamber 14 generates an electromagnetic force due to the biased magnetic flux of the grid 12, and the generated electromagnetic force moves the arc 18 toward the grid 12. The arc 19 that has entered the grid 12 is divided by the grid 12, and as this state is maintained, the arc voltage rises. When this arc voltage exceeds the power supply voltage of the circuit, current-limiting interruption occurs.

[0015] FIG. 3 is a cross-sectional view showing a fastening structure of arc-extinguishing plates in an air circuit breaker according to a first embodiment of the present disclosure. As shown in FIG. 3 , the air circuit breaker 100 of the present disclosure includes a plurality of arc-extinguishing plates 50, a fastening member, and an elastic body 22. The plurality of arc-extinguishing plates 50 are provided at the upper portion of the interrupter and are formed by stacking a plurality of conductive plate-like grids 12 and insulating plates 13 in the stacking direction. Here, the "upper portion" may refer, for example, to a position where an arc generated at a contact point during opening is guided. The fastening member includes nuts 20 and bolts 21 that secure the plurality of arc-extinguishing plates 50, and a loosening prevention member that prevents the nuts 20 from loosening. The nuts 20 and bolts 21 are provided at ends of the plurality of arc-extinguishing plates 50 that are different from each other in the stacking direction. In FIG. 3 , the bolts 21 penetrate the arc-extinguishing plates 50. The elastic body 22 is provided between the fastening member and the arc-extinguishing plates 50 provided at the ends in the stacking direction.

[0016] 3 shows a case where the loosening prevention member is another nut (nut 26) placed on top of nut 20. This method of fastening nuts by stacking them is called double nuts, and by fastening two nuts together, friction is generated between the upper and lower nuts, enhancing the effectiveness of loosening prevention. The loosening prevention member is not limited to double nuts, and can be any other configuration that prevents the end nuts from turning, such as by attaching taps to the nuts to fix them or by applying adhesive to the nuts to fix them.

[0017] The double nut method, in which nuts 20 and 26 are fastened together by overlapping them, is a fastening method in which the upper nut 26 does not come into contact with the object being fastened, the arc-extinguishing plate 50. There are two main types of double nut fastening methods: the forward rotation method, in which the lower nut 20 is tightened first, then the upper nut 26, and then the upper nut 26 is tightened, and the reverse rotation method, in which the lower nut 20 is tightened in the reverse direction. By arranging nuts 20 and 26 in this way, the force applied to the arc-extinguishing plate 50 can be reduced, thereby suppressing settling.

[0018] 3 , the air circuit breaker 100 according to the first embodiment of the present disclosure has an elastic body 22 provided between the lower nut 20 and the arc-extinguishing plate 50. By providing the elastic body 22 in this manner, it is possible to reduce rattle and wear of the arc-extinguishing plate 50 due to vibration. While FIG. 3 shows an example in which the elastic body 22 is provided between the arc-extinguishing plate 50 and the nut 20, the elastic body 22 may be provided between the arc-extinguishing plate 50 and the bolt 21 in consideration of the work process, or may be provided both between the arc-extinguishing plate 50 and the bolt 21 and between the arc-extinguishing plate 50 and the lower nut 20. In this way, the air circuit breaker 100 according to the present disclosure uses the fastening member provided with the loosening prevention member and the elastic body 22 to reduce settling and prevent loosening, thereby suppressing rattle and wear of the arc-extinguishing plate 50 due to vibration.

[0019] Fig. 4 is a perspective view showing the configuration of an arc-extinguishing chamber of a comparative example. As shown in Figs. 2 and 4, the arc-extinguishing chamber 14 is provided with an arc-extinguishing plate 50 composed of a conductive, plate-shaped grid 12 and an insulating plate 13. This arc-extinguishing plate 50 is fastened with fastening members such as metal bolts 21 and nuts 20 through holes formed in the insulating plate 13. Note that in the air circuit breaker 100 of the present disclosure, the arc-extinguishing plate 50 is also composed of the grid 12 and the insulating plate 13, as in Fig. 4, and the arc is extinguished in the arc-extinguishing chamber 14.

[0020] Fig. 5 is a cross-sectional view showing a fastening structure of arc-extinguishing plates according to a comparative example. As shown in Fig. 5, a plurality of arc-extinguishing plates 50 are stacked inside the arc-extinguishing chamber 14 and fastened together via fastening members. At this time, plastic deformation called "sag" occurs at the contact surfaces of the plurality of arc-extinguishing plates 50 due to the tightening force of the fastening members. Since the sag increases with the number of contact surfaces, the number of sag locations also increases with the number of arc-extinguishing plates 50.

[0021] FIG. 6 is a graph showing changes in fastening force in the fastening structure of the comparative example. In FIG. 6 , the vertical axis represents the tightening force applied to the arc-extinguishing plate 50. The horizontal axis represents the deformation of the fastening member (labeled "bolt side" in the figure) on the left side of the center, and the deformation of the arc-extinguishing plate 50 (labeled "fastened side" in the figure) on the right side. As shown in FIG. 6 , when the arc-extinguishing plate 50 is fastened using the fastening member of the comparative example, the fastening force F1 at the time of fastening decreases to F2 due to settling L of the insulating plate 13, which is the fastened object. Furthermore, settling occurs in the insulating plate 13 due to linear expansion and deformation called creep caused by temperature changes. When settling occurs, the fastening force of the arc-extinguishing plate 50 decreases from F2 to F3. Insulators generally deform more greatly during linear expansion and creep deformation than metals, and therefore there are many factors that contribute to a decrease in fastening force, such as settling and deformation. The fastening structure shown in the comparative example has a large decrease in fastening force and has many factors that cause the fastening force to decrease, so there tends to be a large variation in fastening force and a high risk of the screws loosening.

[0022] FIG. 7 is a graph showing changes in the fastening force in the fastening structure of the arc-extinguishing plate of the air circuit breaker according to the first embodiment of the present disclosure. As shown in FIG. 7 , the fastening force F1 during fastening decreases to F2b due to settling Lb of the contact surfaces between the nuts 20 and 26. Comparing FIG. 3 with FIG. 5 , the decrease in fastening force is suppressed because the number of contact surfaces between the fastening member and the arc-extinguishing plate 50 is reduced. Furthermore, the bolt 21 and the nut 20 also undergo linear expansion and creep deformation due to temperature changes, so the fastening force decreases to F3b. Because metallic materials have smaller linear expansion and creep deformation than insulating materials, the decrease in fastening force is also very small compared to FIG. 5 . Therefore, the air circuit breaker 100 according to the first embodiment of the present disclosure can reduce the risk of loosening by reducing factors that reduce fastening force, and can also ensure high reliability when fastening the arc-extinguishing plate 50.

[0023] As described above, the air circuit breaker 100 according to the first embodiment of the present disclosure includes an interrupting section that interrupts current by opening the contact points between the stator 2 and the movable member 4, a plurality of arc-extinguishing plates 50 that are provided above the interrupting section and are each formed by stacking a plurality of conductive plate-like grids 12 and insulating plates 13 in the stacking direction, nuts 20 and bolts 21 that secure the plurality of arc-extinguishing plates 50, and anti-loosening members that prevent the nuts 20 from loosening, and includes fastening members in which the nuts 20 and bolts 21 are provided at ends of the plurality of arc-extinguishing plates 50 that are in different stacking directions, and an elastic body 22 that is provided between the fastening member and the arc-extinguishing plates 50 that are provided at the ends in the stacking direction.

[0024] With this configuration, the air circuit breaker 100 according to the present disclosure can reduce wear by using the anti-loosening member to reduce the contact surface between the fastening member and the arc extinguishing plate 50, and can prevent loosening of the fastening member by suppressing the reduction in fastening force due to wear.

[0025] Furthermore, even if the fastening portion of the arc-extinguishing plate is prevented from loosening, vibrations applied to the air circuit breaker may cause rattle or wear on the arc-extinguishing plate 50. Even in such a case, the air circuit breaker 100 according to the present disclosure is provided with the elastic body 22 between the fastening member and the arc-extinguishing plate 50, thereby making it possible to suppress rattle and wear caused by vibration.

[0026] Embodiment 2 In embodiment 2, the same components as those in embodiment 1 of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts will be omitted. Hereinafter, an air circuit breaker according to embodiment 2 will be described with reference to the drawings.

[0027] 8 is a cross-sectional view showing the fastening structure of the arc extinguishing chamber of the air circuit breaker according to the second embodiment of the present disclosure. In the first embodiment, the loosening prevention member is a double nut in which a nut 26 is placed on a nut 20, whereas the loosening prevention member of the air circuit breaker according to the second embodiment is a strut 25 having an internal thread 24 at one end and an external thread 23 at the other end.

[0028] As shown in Figure 8, in the air circuit breaker, the support 25 is provided so as to penetrate the arc-extinguishing plate 50 and is fastened by fastening members consisting of bolts 27 and nuts 20. A fastening method using a plurality of arc-extinguishing plates 50 carries a high risk of a decrease in fastening force due to settling or dimensional changes. By fastening both ends of the support 25, which is longer than the length of the stacked arc-extinguishing plates 50, with bolts 27 and nuts 20 and disposing an elastic body 22 between the arc-extinguishing plate 50, no arc-extinguishing plate 50 is interposed between the nut 20 and the seating surface of the support 25, it is possible to obtain the same effect as in embodiment 1.

[0029] Furthermore, there are two types of double nut fastening methods: the forward rotation method of the upper nut and the reverse rotation method of the lower nut. However, both require a lot of work, and incorrect procedures and tightening torque values ​​can lead to loosening. In the second embodiment, a support 25 is used instead of a double nut, so it is only necessary to tighten the nut 20 and bolt 27. This reduces the number of work steps and improves the reliability of the work.

[0030] As described above, in the air circuit breaker according to the second embodiment of the present disclosure, the loosening prevention member is a strut 25 having an internal thread 24 at one end and an external thread 23 at the other end, which penetrates the plurality of arc-extinguishing plates 50. Both ends of the strut 25, which is longer than the length of the plurality of arc-extinguishing plates 50 stacked together, are fastened together with bolts 27 and nuts 20, and an elastic body 22 is disposed between the strut 25 and the arc-extinguishing plates 50, resulting in a structure in which no arc-extinguishing plates 50 are interposed between the nuts 20 and the bearing surfaces of the struts 25. Therefore, while loosening is prevented by a fastening member provided with a loosening prevention member as in the first embodiment, the elastic body 22 reduces the contact area between the fastening member and the arc-extinguishing plates 50, thereby reducing sagging and suppressing rattle and wear of the arc-extinguishing plates 50 due to vibration.

[0031] Furthermore, in the air circuit breaker according to the second embodiment of the present disclosure, by using the support 25, it is only necessary to tighten the nut 20 instead of a double nut, which reduces the number of work steps and improves the reliability of the work.

[0032] Embodiment 3 In embodiment 3, the same components as those in embodiment 1 of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts will be omitted. Hereinafter, an air circuit breaker according to embodiment 3 will be described with reference to the drawings.

[0033] FIG. 9 is a perspective view showing the fastening structure of an arc-extinguishing plate in an air circuit breaker according to a third embodiment of the present disclosure. As shown in FIG. 9 , the loosening prevention member in the air circuit breaker according to the third embodiment of the present disclosure differs from the first embodiment in that, in addition to a double-nut structure in which another nut (nut 26) is provided overlapping a nut 20 serving as a fastening member, the loosening prevention member includes a strut 25 having an internal thread 24 at one end and an external thread 23 at the other end, penetrating the arc-extinguishing plate 50. The loosening prevention member according to the third embodiment of the present disclosure includes the strut 25 described in the second embodiment in addition to the double nuts described in the first embodiment. This further improves the reliability of the work process and the effectiveness of loosening prevention. Note that, because FIG. 9 is a perspective view, the strut 25 penetrating the arc-extinguishing plate 50 and the internal thread 24 provided at the end on the bottom side are not shown in FIG. 9 .

[0034] 9, in the arc-extinguishing plate 50, on a surface intersecting the stacking direction (corresponding to the surface on which the nuts 20 and bolts 27 are provided in the figure), nuts 20 and bolts 27 (shown in FIG. 8) with supports 25 are arranged at the longitudinal end of the surface. Furthermore, a nut 26 is arranged on top of the nut 20 in the longitudinal center of the surface. With this configuration, compared to when all of the points fixed with nuts 20 and bolts 27 have a double-nut structure, it is possible to reduce the number of double nuts, thereby reducing some of the work hours, and also to reduce loosening due to vibration.

[0035] In the air circuit breaker according to the third embodiment of the present disclosure, an example has been shown in which, in a plane intersecting the stacking direction, nuts 20 and bolts 27 (not shown in FIG. 9 ) with supports 25 attached to their longitudinal ends are arranged, and nut 26 is arranged in the center, overlapping nut 20, but any arrangement may be used as long as loosening due to vibration can be reduced. Also, in FIG. 9 , arc-extinguishing plate 50 is fastened at six locations, but the number of fastening locations may be less than six or more than six as long as loosening can be reduced.

[0036] As described above, the air circuit breaker according to the third embodiment of the present disclosure is characterized in that, in addition to the configuration of the first embodiment, the loosening prevention member is another nut provided on top of the nut 20 which is the fastening member, and the strut 25 which has an internal thread 24 at one end and an external thread 23 at the other end and which penetrates the arc-extinguishing plate 50. Therefore, while loosening is prevented by the fastening member provided with the loosening prevention member as in the first embodiment, the elastic body 22 reduces the contact area between the fastening member and the arc-extinguishing plate 50, thereby reducing sag and suppressing rattle and wear of the arc-extinguishing plate 50 due to vibration.

[0037] Furthermore, in the air circuit breaker according to the third embodiment of the present disclosure, the loosening prevention member is a nut 26 provided on top of the nut 20, and a support 25 having an internal thread 24 at one end and an external thread 23 at the other end. With this configuration, it is also possible to reduce the number of double nuts and thereby reduce some of the work man-hours.

[0038] Fourth Embodiment In a fourth embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts will be omitted. Hereinafter, an air circuit breaker 101 according to the fourth embodiment will be described with reference to the drawings.

[0039] Before describing the configuration of the air circuit breaker 101 according to the fourth embodiment of the present disclosure, the configuration of a case-enclosed circuit breaker will be described. A case-enclosed circuit breaker is a circuit breaker that is mainly installed outdoors and is housed in an outer case to prevent the intrusion of rain and foreign objects.

[0040] Fig. 10 is a cross-sectional view showing the configuration of a comparative example of a case-enclosed circuit breaker. As shown in Fig. 10, the case of the comparative example of a case-enclosed circuit breaker is composed of an upper case 28 that houses the arc-extinguishing plate 50, a lower case 29 that houses the circuit breaker 30, and an intermediate plate 31 that is placed between the two and protects the circuit breaker 30 from hot gas during circuit breaking. In this case, the upper case 28, the lower case 29, and the intermediate plate 31 are made of insulating material.

[0041] In a case-enclosed circuit breaker as shown in FIG. 10 , the intermediate plate 31 and the arc-extinguishing plate 50 are integrated. In this case, the arc-extinguishing plate 50 is supported at both ends of the intermediate plate 31, so there are two support points for the arc-extinguishing plate 50. If the arc-extinguishing plate 50 is supported at both ends of the intermediate plate 31, the distance from the center of gravity of the arc-extinguishing plate 50 to the intermediate plate 31 becomes the distance from the center of gravity to the support point. As the distance from the center of gravity to the support point increases, the moment generated by vibrations and the like increases. Therefore, in the case of a case-enclosed circuit breaker as in the comparative example, measures such as thickening the intermediate plate 31 were necessary to withstand this. On the other hand, as will be described in detail later with reference to FIG. 11 , the circuit breaker according to this embodiment does not require such measures.

[0042] Fig. 11 is a cross-sectional view showing the configuration of an air circuit breaker according to a fourth embodiment of the present disclosure. In an air circuit breaker 101 according to the fourth embodiment of the present disclosure, the loosening prevention member is a strut 25 having an internal thread 24 at one end and an external thread 23 at the other end, and penetrating an arc-extinguishing plate 50. As shown in Fig. 11 , the air circuit breaker 101 according to the fourth embodiment of the present disclosure includes an upper outer casing 28 that stores a plurality of arc-extinguishing plates 50, a lower outer casing 29 that stores the circuit-breaking unit 30, and an intermediate plate 31 that is provided below the upper outer casing 28 and protects the circuit-breaking unit 30 from gas generated in the upper outer casing 28. The air circuit breaker 101 differs from the other embodiments in that the upper outer casing 28, the arc-extinguishing plate 50, and the intermediate plate 31 are integrated together by the fastening members, the internal threads 24, and the external threads 23. Here, the upper outer casing 28 and the lower outer casing 29 include insulators.

[0043] In FIG. 11 , male threads 23 provided on support posts 25 are fitted with female threads 32 fixed by insert nuts or the like provided on the ceiling of an upper outer casing 28. In an air circuit breaker 101 according to a fourth embodiment of the present disclosure, the female threads 32 fixed to the upper outer casing 28 are fitted with support posts 25, thereby integrating the upper outer casing 28, arc-extinguishing plates 50, and intermediate plates 31. As shown in FIG. 11 , by integrating the arc-extinguishing plates 50 and intermediate plates 31 with support posts 25 fixed to the ceiling of the upper outer casing 28, the positions where bolts 27 are provided become support points. As a result, the arc-extinguishing plates 50 have four support points. Comparing FIG. 10 with FIG. 11 , two more support points are added between the support points at both ends of the intermediate plate 31, allowing the arc-extinguishing plates 50 to be fixed at a position closer to the center of gravity of the arc-extinguishing plates 50 than in the comparative example of FIG. 10 . By fixing the arc-extinguishing plate 50 at a position close to the center of gravity in addition to both ends of the intermediate plate 31, the distance from the center of gravity of the arc-extinguishing plate 50 to the support point becomes shorter when the arc-extinguishing plate 50 sways due to vibration, thereby reducing the moment generated by vibration.

[0044] In addition, for an outer-casing-type circuit breaker, there is a method of drilling a through-hole in the top of the upper outer casing 28 and attaching the support 25 from outside the upper outer casing 28. However, with this attachment method, rainwater enters through the through-hole because the support 25 is fastened outside the upper outer casing 28. Therefore, waterproofing treatment such as sealing is required for the through-hole, which increases the number of parts and labor required. The air circuit breaker 101 according to the fourth embodiment of the present disclosure is effective in addressing this issue. By providing a female thread 32 on the inside of the upper outer casing 28 as shown in FIG. 11 , the support 25 can be attached without providing a through-hole on the outside of the upper outer casing 28. In this case, the female thread 32 is attached using an insert that is embedded inside the upper outer casing 28 during resin molding of the upper outer casing 28, an outsert that is embedded inside the upper outer casing 28 after resin molding of the upper outer casing 28, or the like. By providing the female thread 32 on the inside of the upper outer box 28 in this manner, the air circuit breaker 101 according to the fourth embodiment of the present disclosure can improve waterproof performance while reducing the number of parts and labor required.

[0045] According to the air circuit breaker 101 according to the fourth embodiment of the present disclosure, the weight of the arc-extinguishing plate 50 is supported not only by the intermediate plate 31 but also by the upper outer casing 28. This increases the number of locations throughout the outer casing that mechanically support the weight of the arc-extinguishing plate 50, improving the balance of load sharing. Furthermore, since the upper outer casing 28, the arc-extinguishing plate 50, and the intermediate plate 31 can be integrated, this provides the effects of improving resistance to vibration and allowing the intermediate plate 31 to be made thinner. Furthermore, by integrating the arc-extinguishing plate 50 and the intermediate plate 31 using the support posts 25 fixed to the ceiling of the upper outer casing 28 as guides, the air circuit breaker 101 according to the fourth embodiment of the present disclosure provides the effect of being easy to assemble.

[0046] As described above, the air circuit breaker 101 according to the fourth embodiment of the present disclosure is characterized in that, in addition to the configuration of the first embodiment, it includes an upper outer casing 28 that stores the arc-extinguishing plate 50, a lower outer casing 29 that stores the circuit-breaking unit 30, and an intermediate plate 31 that is provided below the upper outer casing 28 and protects the circuit-breaking unit 30 from gas generated in the upper outer casing 28, and the upper outer casing 28, the arc-extinguishing plate 50, and the intermediate plate 31 are integrated together by the fastening members, the female threads 24, and the male threads 23.

[0047] In the first to fourth embodiments, the elastic body 22 may be at least one of a compression coil spring, a disc spring, a disc spring washer, a leaf spring, rubber, and silicone rubber.

[0048] In the first to fourth embodiments, the insulating plate 13 constituting the arc-extinguishing plate 50 is made of, for example, a resin material.

[0049] Furthermore, according to the air circuit breakers of the first to fourth embodiments of the present disclosure, the fastening member provided with the loosening prevention member reduces sag, and the elastic body 22 suppresses rattle and wear of the arc-extinguishing plate 50 due to vibration. Therefore, the air circuit breaker may be installed, for example, in an electric railway vehicle, which is subject to severe external vibration. Even in such a vibration environment, the air circuit breaker of the present disclosure reduces sag with the loosening prevention member and suppresses rattle and wear of the arc-extinguishing plate 50 due to vibration with the elastic body 22. Furthermore, in the vibration environment when mounted on an electric railway vehicle, the arc-extinguishing plate 50 may be damaged by rattle and wear, and foreign matter may enter the interrupter part 30 (e.g., between the stator 2 and the mover 4), potentially degrading the functionality of the air circuit breaker. The air circuit breaker according to the present disclosure is effective against such failures, and the air circuit breaker according to the present disclosure can prevent loosening of the arc-extinguishing plate 50, thereby preventing degradation of the functionality of the air circuit breaker and, therefore, the degradation of the functionality of the electric railway.

[0050] Furthermore, a method of extinguishing an arc by extending the arc and causing the extended arc to penetrate a plurality of grids 12, as in the air circuit breaker of the present disclosure, is called a de-ionization method. In the de-ionization method, it is possible to generate the reverse voltage required for current-limiting interruption in the arc extinguishing chamber 14 by the electrode drop voltage due to the grids 12 and the arc voltage due to the arc extension. Since the air circuit breaker of the present disclosure extinguishes the arc by extending the arc and using the grids 12, it is possible to reduce the space required for the arc extinguishing chamber 14 compared to air circuit breakers that extinguish the arc only by extending the arc. Therefore, the air circuit breaker of the present disclosure can also reduce the space required for installation in places where space is limited, such as electric railway cars.

[0051] The air circuit breaker of the present disclosure may also be used as a breaker in a power system that handles DC voltages of 0 to 3600V.

[0052] The configurations described in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known technologies. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure.

[0053] REFERENCE SIGNS LIST 1 Fixed contact, 2 Stator, 3 Moving contact, 4 Moving contact, 5 Closing actuator, 6 Upper conductor, 7 Lower conductor, 8 Detector, 9 Latch, 10 Fixed side arc runner, 11 Moving side arc runner, 12 Grid, 13 Insulating plate, 14 Arc extinguishing chamber, 15 Mold frame, 16 17 18 19 Arc, 20 26 Nut, 21 27 Bolt, 22 Elastic body, 23 Male thread, 24 32 Female thread, 25 Support, 28 Upper outer casing, 29 Lower outer casing, 30 Breaking section, 31 Intermediate plate, 50 Arc extinguishing plate, 100 101 Air circuit breaker

Claims

1. A circuit breaker that opens the contact between the stator and the movable part to interrupt the current, A plurality of arc extinguishing plates are provided on the upper part of the aforementioned blocking section, and each plate is made up of multiple conductive plate-shaped grids and insulating plates stacked in the stacking direction, A fastening member having nuts and bolts for fixing a plurality of arc extinguishing plates and a loosening prevention member for preventing the nuts from loosening, wherein the nuts and bolts are provided at the ends of the plurality of arc extinguishing plates in different stacking directions, An air-insulated circuit breaker comprising an arc-extinguishing plate provided at the end in the stacking direction and an elastic body provided between the fastening member.

2. The air circuit breaker according to claim 1, characterized in that the anti-loosening member is another nut provided on top of the nut which is the fastening member.

3. The air circuit breaker according to claim 1, characterized in that the anti-loosening member has a female thread at one end and a male thread at the other end, and is a support column that penetrates a plurality of arc-extinguishing plates.

4. The aforementioned loosening prevention member is Another nut is provided on top of the nut which is the fastening member, The air circuit breaker according to claim 1, characterized in that it is a support column having a female thread at one end and a male thread at the other end, and passing through a plurality of arc extinguishing plates.

5. An upper outer box for housing multiple arc extinguishing plates, A lower outer box housing the aforementioned blocking unit, The upper outer box is provided at the lower part and includes an intermediate plate that protects the shut-off part from gas generated in the upper outer box, The air circuit breaker according to claim 3 or 4, characterized in that the upper outer casing, the plurality of arc extinguishing plates, and the intermediate plate are integrated by the fastening member, the female thread, and the male thread.

6. The air circuit breaker according to claim 5, characterized in that the female thread is provided inside the upper outer casing.

7. The air circuit breaker according to claim 1, characterized in that the elastic body is at least one of a compression coil spring, a disc spring, a disc spring washer, a leaf spring, rubber, or silicone rubber.

8. The air circuit breaker according to claim 1, characterized in that the insulating plate is made of a resin material.

9. The air circuit breaker according to claim 1, characterized in that it is installed in an electric railway vehicle.