switchgear

Abstract

A switchgear (100) comprises a pair of electrodes (1A, 1B) arranged with electrode surfaces (SA, SB) facing each other in a first direction and being mutually contactable and separable in the first direction. Each of the electrodes (1A, 1B) has an accommodation hole (HA, HB) recessed from the electrode surface (SA, SB). Magnets (10) are respectively accommodated in the accommodation holes (HA, HB) of the respective electrodes (1A, 1B) such that polarities which attract each other by magnetic force face each other between the electrodes (1A, 1B). On respective magnet surfaces (10S), which face each other between the electrodes (1A, 1B), of the magnets (10) respectively accommodated in the respective electrodes (1A, 1B), ferromagnetic bodies (20) covering the magnet surfaces (10S) are respectively disposed. Adjacent to magnet side surfaces of the magnets (10) along the first direction, first substances (21) each having a relative permeability lower than a relative permeability of the ferromagnetic body (20) are respectively disposed.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a switchgear.BACKGROUND ART

[0002] A switchgear, which is one of high-voltage power distribution facilities, is used for interrupting current at the time of a failure or an abnormal condition of the high-voltage power distribution facilities. Generally, a gas-insulated switchgear includes switching devices such as a circuit breaker, a disconnector, and an earthing switch, which are accommodated in a container filled with an insulating gas such as SF 6 gas (sulfur hexafluoride gas) or dry air, and which interrupt and connect current by contact and separation of a pair of electrodes arranged to face each other. At the time of opening, in which the pair of electrodes are separated, an arc, which is a discharge phenomenon, is generated between the electrodes. In each switching device, in order to ensure insulation, performance of quickly extinguishing the arc generated at the time of opening is required.

[0003] When the insulating gas inside the gas-insulated switchgear is SF 6 gas having high interrupting performance, the arc can be extinguished by a so-called "arc-stretching method" described later. However, when the insulating gas is dry air, of which the interrupting performance is about one one-hundredth that of SF 6 gas, it is known that extinguishing the arc is difficult. The arc-stretching method is a method in which current is interrupted by stretching the path of an arc current generated at the time of opening by means of a driving device. As techniques for improving current interrupting performance, an early-break method and a magnetic drive method are known. The early-break method is a method in which a quick-motion mechanism is provided on one side of an electrode, and the separating speed of the electrodes is increased, thereby extending the arc to a length necessary for arc extinction within a time in which damage to the electrode contact does not occur, and thereby obtaining interrupting performance. Further, the magnetic drive method is a method in which a magnet is provided in the switchgear to magnetically drive the arc, thereby obtaining interrupting performance. A switchgear having the following configuration with both the early-break method and the magnetic drive method is disclosed.

[0004] That is, in a conventional switchgear, a second electrode driven to be contactable with and separable from a first electrode is provided, and a configuration is provided in which conduction between the electrodes is maintained by an attractive force of magnets disposed inside the electrodes. Opening between a first terminal and a second terminal is performed by separation of the first electrode and the second electrode, and the first electrode is fastened to the first terminal by a spring. The opening between the first terminal and the second terminal utilizes the attractive force of the magnets between the second electrode driven in the opening direction while maintaining conduction and the first electrode, and restoring force of the spring fastening the first electrode. An arc generated by separation of the first electrode and the second electrode is rotated in a circumferential direction of the electrodes by a magnetic field generated by the magnets, is stretched, and is cooled, thereby being interrupted (see, for example, Patent Document 1).CITATION LISTPATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent No. 7162782SUMMARY OF THE INVENTIONPROBLEM TO BE SOLVED BY THE INVENTION

[0006] In the above conventional switchgear, an arc generated at the time of current interruption is extinguished by rotating the arc in a circumferential direction of the electrodes by means of a magnetic field generated by magnets, and by instantaneously stretching the path thereof by increasing the separating speed of the electrodes with restoring force of a spring fastening the first electrode. However, when magnetic adsorption force of the magnets respectively disposed inside the first electrode and the second electrode is weak, contact between the first electrode and the second electrode may be released before restoring force of the spring fastening the first electrode is accumulated, so that sufficient separating speed cannot be obtained, and as a result, interrupting performance of the arc may be reduced. When the magnets are enlarged in order to ensure sufficient magnetic force of the magnets, prices of the magnets increase, and at the same time, since weight of the electrodes increases, prices of peripheral equipment for driving the electrodes also increase. Therefore, a problem arises in that cost increases.

[0007] The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a switchgear which ensures interrupting performance of an arc while being low in cost.MEANS TO SOLVE THE PROBLEM

[0008] A switchgear according to the present disclosure includes a pair of electrodes arranged with respective electrode surfaces facing each other in a first direction and being mutually contactable and separable in the first direction, wherein each of the electrodes has an accommodation hole recessed from the electrode surface, magnets are respectively accommodated in the accommodation holes of the respective electrodes such that polarities which attract each other by magnetic force face each other between the electrodes, and on respective magnet surfaces, which face each other between the electrodes, of the magnets respectively accommodated in the respective electrodes, ferromagnetic bodies covering the magnet surfaces are respectively disposed, and adjacent to a magnet side surface of each of the magnets along the first direction, a first substance having a relative permeability lower than a relative permeability of the ferromagnetic body is respectively disposed. EFFECT OF THE INVENTION

[0009] The switchgear to the present disclosure makes it possible to provide a switchgear with low-cost while ensuring arc interrupting performance.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] [FIG. 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a switchgear according to Embodiment 1. [FIG. 2] FIG. 2 is a conceptual diagram for explaining magnetic characteristics in the switchgear according to Embodiment 1. [FIG. 3] FIG. 3 is a cross-sectional view showing another configuration of the switchgear according to Embodiment 1. [FIG. 4] FIG. 4 is a cross-sectional view showing a schematic configuration of a switchgear according to Embodiment 2. [FIG. 5] FIG. 5 is a cross-sectional view showing a schematic configuration of a switchgear according to Embodiment 3. [FIG. 6] FIG. 6 is a conceptual diagram showing a current path in the switchgear according to Embodiment 3. DESCRIPTION OF EMBODIMENTSEmbodiment 1

[0011] The switchgear of the present embodiment is provided in a gas-insulated switchgear used for power distribution facilities, vehicle equipment, and the like, and interrupts current at the time of occurrence of an abnormality.

[0012] FIG. 1 is a cross-sectional view showing a schematic configuration of a switchgear 100 according to Embodiment 1.

[0013] As shown in FIG. 1, the switchgear 100 includes a first electrode 1A and a second electrode 1B as a pair of electrodes that are mutually contactable and separable. The first electrode 1A and the second electrode 1B are cylindrical, and are respectively accommodated inside a hollow cylindrical first terminal 2A and second terminal 2B. In FIG. 1, an open state in which the first electrode 1A and the second electrode 1B are separated is shown.

[0014] In the figure, axial and radial directions of the cylindrical first electrode 1A and second electrode 1B are respectively shown as X and Y. In the following description, when the first electrode 1A and the second electrode 1B are not distinguished, they are simply referred to as the electrode 1.

[0015] The first electrode 1A and the second electrode 1B have accommodation holes HA and HB recessed in an axial direction X as the first direction, respectively on electrode surfaces SA and SB facing each other in the axial direction X. Cylindrical magnets 10 are respectively accommodated in the accommodation holes HA and HB.

[0016] A side cover 21 is attached to a magnet side surface of the magnet 10 along the axial direction X, and the magnet 10 is fixed to an inner peripheral surface of the accommodation holes HA and HB by the side cover 21.

[0017] Further, facing covers 20 covering magnet surfaces 10S of the magnet 10 of the first electrode 1A and the magnet 10 of the second electrode 1B, which magnet surfaces 10S face each other in the axial direction X, are respectively disposed.

[0018] Here, the magnets 10 respectively provided in the first electrode 1A and the second electrode 1B are arranged such that magnetic poles attracting each other by magnetic force face each other when the first electrode 1A and the second electrode 1B are brought close to each other. In this embodiment, an S-pole side is arranged on the electrode surface SA side of the first electrode 1A, and an N-pole side is arranged on the electrode surface SB side of the second electrode 1B.

[0019] The facing cover 20 is made of a ferromagnetic body such as iron or nickel. The side cover 21 is made of a first substance having a relative permeability lower than that of the ferromagnetic body such as iron or nickel. In the present embodiment, the first substance constituting the side cover 21 is a nonmagnetic body such as aluminum or stainless steel having a relative permeability of 10 or less.

[0020] The first electrode 1A and the second electrode 1B are respectively supported so as to be movable in the axial direction X inside the hollow cylindrical first terminal 2A and second terminal 2B by guide components (not shown).

[0021] Further, the second electrode 1B is connected to a driving device (not shown) for driving the second electrode 1B in the axial direction X so as to be contactable with and separable from the first electrode 1A.

[0022] Further, a contact 5A is provided on an outer circumferential surface of the first electrode 1A, and a contact 5B is provided on an outer circumferential surface of the second electrode 1B. Through these contacts 5A and 5B, the first electrode 1A and the second electrode 1B are conducted to the first terminal 2A and the second terminal 2B provided outside in the radial direction Y.

[0023] When the first electrode 1A is moved to one side X1 in the axial direction, which is the direction D shown in FIG. 1, by the driving device and comes into contact with the second electrode 1B, a current path via the first terminal 2A and the second terminal 2B is formed, and power is transmitted.

[0024] Further, a movable stopper 7 is attached to the outer circumferential surface of the first electrode 1A. When the first electrode 1A moves in the axial direction X, an outer end surface 7OUT of the movable stopper 7 in the radial direction Y comes into sliding contact with an inner circumferential surface of the first terminal 2A.

[0025] Further, a fixed stopper 6 is attached to the inner circumferential surface of the first terminal 2A. When the first electrode 1A moves in the axial direction X, an inner end surface 6IN of the fixed stopper 6 in the radial direction Y comes into sliding contact with the outer circumferential surface of the first electrode 1A. Since the fixed stopper 6 is fixed to the first terminal 2A, even if the first electrode 1A moves in the axial direction X, its axial position does not change.

[0026] A spring 8 is provided between the movable stopper 7 and the fixed stopper 6, and the spring 8 is structured to expand and contract in accordance with movement of the first electrode 1A in the axial direction X.

[0027] Next, contact and separation operations of the first electrode 1A and the second electrode 1B in the switchgear 100 configured as described above will be described.

[0028] In order to close the electrodes by bringing the first electrode 1A and the second electrode 1B into contact, as described above, the second electrode 1B is moved to one side X1 in the axial direction, which is the direction D, by the driving device, and is brought into contact with the first electrode 1A to conduct. At this time, the contact between the first electrode 1A and the second electrode 1B is maintained by magnetic adsorption force between the magnets 10 respectively provided in the first electrode 1A and the second electrode 1B.

[0029] In order to separate the first electrode 1A and the second electrode 1B in contact with each other to open the electrodes, the second electrode 1B is moved to the other side X2 in the axial direction, which is the direction opposite to the arrow D, by the driving device. At this time, since the contact between the first electrode 1A and the second electrode 1B is maintained by the magnetic adsorption force of the magnets 10, the first electrode 1A moves to the other side X2 in the axial direction together with the second electrode 1B while maintaining the contact state with the second electrode 1B. When the first electrode 1A moves to the other side X2 in the axial direction, the movable stopper 7 fixed to the first electrode 1A also moves to the other side X2 in the axial direction, so that the spring 8 is compressed and restoring force thereof is accumulated.

[0030] When the second electrode 1B is further moved to the other side X2 in the axial direction by the driving device, when the restoring force of the spring 8 and magnetic force between the magnets 10 are balanced, magnetic adsorption between the first electrode 1A and the second electrode 1B is released, and the first electrode 1A vigorously moves to one side X1 in the axial direction in accordance with restoring of the spring 8 and is opened. By using restoring force of the spring 8 thus accumulated for opening of the electrode 1, separating speed of the first electrode 1A and the second electrode 1B increases, so that a current path can be stretched to a length necessary for arc extinction within a time in which damage to the electrode 1 does not occur, and high interrupting performance of an arc current can be obtained.

[0031] Here, analysis results of magnetic characteristics of the switchgear 100 of the present embodiment will be described with reference to a figure.

[0032] FIG. 2 is a conceptual diagram for explaining magnetic characteristics at the time of closing of the electrodes 1 in the switchgear 100 according to Embodiment 1.

[0033] The switchgear 100 of the present embodiment is configured such that facing covers 20 made of ferromagnetic bodies are respectively disposed on the magnet surfaces 10S of the magnets 10 facing each other between the electrodes 1 as described above. Further, side covers 21 made of aluminum, stainless steel, or the like as the first substance having a relative permeability lower than that of the facing covers 20 are disposed adjacent to the magnet side surfaces of the magnets 10.

[0034] The inventors of the present disclosure have discovered, as a result of repeated analysis of magnetic characteristics of the switchgear 100 having such a configuration, that magnetic adsorption force of the magnets 10 between the electrodes 1 becomes large. This is considered to be because, in the switchgear 100 of the present embodiment, as shown in FIG. 2, a magnetic circuit by magnetic flux M2 passing inside the side cover 21 of the magnet 10 is not formed, and thereby magnetic flux density of magnetic flux M1 having a component parallel to the axial direction X between the electrodes 1 increases.

[0035] Further, an arc current flowing between the electrodes 1 flows so as to swell outward in the radial direction Y. That is, the arc current flows at an angle not less than a certain angle with respect to the magnetic flux M1 having a component in the axial direction X. Therefore, when the magnetic flux density of the magnetic flux M1 having the component in the axial direction X between the electrodes 1 is increased in this way, Lorentz force in the radial direction and the circumferential direction acting on the arc current also increases. The inventors of the present disclosure have discovered that, thereby, an arc generated between the electrodes 1 can be quickly rotated on the outer circumference of the electrodes 1 on the outside in the radial direction Y and extinguished. Thus, the switchgear 100 of the present embodiment has a configuration capable of supplying, simultaneously with separation of the pair of electrodes 1, a strong magnetic field necessary for extinguishing the arc.

[0036] Furthermore, the inventors have discovered that adhesion of foreign matter of magnetic material generated by the arc to the facing cover 20 is suppressed. This is considered to be because, as described above, Lorentz force toward the outside in the radial direction Y increases, and the arc current quickly moves from the facing cover 20 to the outer circumference of the electrode 1 on the outside in the radial direction Y. Thus, adhesion of irregularities due to foreign matter on the surface of the electrode 1 is suppressed, so that a reliable close contact state between the electrodes 1 can be ensured, and demagnetization and damage of the magnets 10 by the arc can be suppressed.

[0037] Furthermore, as a result of diligent studies by the inventors, it has been discovered that, when the switchgear 100 is configured as follows, magnetic flux density of the magnetic flux M1 having a component parallel to the X-axis between the electrodes 1 can be further increased.

[0038] FIG. 3 is a partially enlarged cross-sectional view showing another configuration example of the switchgear 100 according to Embodiment 1.

[0039] As shown in FIG. 3, a length W1 of the facing cover 20 in the radial direction Y, which is a direction perpendicular to the axial direction X, is set smaller, by a set dimension, than a length W2 of the magnet 10 in the radial direction Y. In the present embodiment, the length W1 of the facing cover 20 in the radial direction Y is set about 5% to 12% smaller than the length W2 of the magnet 10 in the radial direction Y. By setting such a dimensional relationship, magnetic flux density of the magnetic flux M1 having a component parallel to the X-axis between the electrodes 1 can be further increased.

[0040] Furthermore, as a result of diligent studies by the inventors, it has been discovered that magnetic flux density of the magnetic flux M1 having a component parallel to the axial direction X between the electrodes 1 can be further increased by setting a length W1 of the facing cover 20 in the radial direction Y, which is a direction perpendicular to the axial direction X, larger than a length W3, that is, a thickness of the facing cover 20 in the axial direction X.

[0041] In the above, aluminum, stainless steel, and the like have been exemplified as the first substance constituting the side cover 21 disposed on the side surface of the magnet 10, but it is not limited thereto. The first substance disposed on the side surface of the magnet 10 may be any substance having a relative permeability lower than that of the facing cover 20 made of a ferromagnetic body, and may be, for example, a gas or an insulator.

[0042] When a gas is disposed as the first substance on the side surface side of the magnet 10, it suffices that a gap is provided between the magnet 10 and the inner peripheral surface of the accommodation holes HA and HB. In this case, for example, a configuration in which the magnet 10 is fixed on a bottom surface of the accommodation holes HA and HB by means of an adhesive or the like can be considered.

[0043] Further, when relative permeability of a material constituting the electrode 1 is lower than relative permeability of the facing cover 20 made of a ferromagnetic body, the side cover 21 may not be provided. In this case, the electrode 1 itself becomes the first substance disposed on the side surface of the magnet 10.

[0044] In the above, the length in the axial direction X of the side cover 21 has been described as a length covering the entire side surface of the magnet 10, but it is not limited thereto. Even when the side cover 21 is shorter than the length of the magnet 10 in the axial direction X, if at least a part on the electrode surface SA, SB side of the side surface of the magnet 10 is covered, the above-described effects can be obtained.

[0045] Further, the side cover 21 does not need to be attached over the entire circumference of the side surface of the magnet 10, and the same effects can be obtained by attaching it to a part of the circumferential surface of the side surface of the magnet 10.

[0046] The switchgear of the present embodiment configured as described above is a switchgear comprising a pair of electrodes arranged with respective electrode surfaces facing each other in a first direction and being mutually contactable and separable in the first direction, wherein each of the electrodes has an accommodation hole recessed from the electrode surface, magnets are respectively accommodated in the accommodation holes of the respective electrodes such that polarities attracting each other by magnetic force face each other between the electrodes, and on respective magnet surfaces, which face each other between the electrodes, of the magnets respectively accommodated in the respective electrodes, ferromagnetic bodies covering the magnet surfaces are respectively disposed, and adjacent to magnet side surfaces of the magnets along the first direction, first substances each having a relative permeability lower than a relative permeability of the ferromagnetic body are respectively disposed.

[0047] Thus, ferromagnetic bodies are respectively disposed on the magnet surfaces of the magnets provided in the respective electrodes, and first substances having a relative permeability lower than that of the ferromagnetic body are disposed on the magnet side surfaces. Thereby, since magnetic adsorption force becomes larger than that of a single magnet, the magnets can be downsized, and weight reduction and cost reduction are possible.

[0048] Further, since magnetic flux density of magnetic flux having a component in the axial direction X between the electrodes increases, an arc generated can be quickly extinguished. As a result, a decrease in magnetic force of the magnets due to the arc can be suppressed, and stable magnetic adsorption force can be ensured, and stabilization of current interrupting performance can be achieved. Further, effects of relaxing electric field and protecting the electrodes from damage due to the arc are also obtained.

[0049] Further, in the switchgear of the present embodiment configured as described above, a length of the ferromagnetic body in a direction perpendicular to the first direction is configured to be smaller, by a set dimension, than a length of the magnet in the direction perpendicular to the first direction.

[0050] Further, in the switchgear of the present embodiment configured as described above, a length of the ferromagnetic body in the direction perpendicular to the first direction is configured to be larger than a length of the ferromagnetic body in the first direction.

[0051] By setting such a dimensional relationship, magnetic flux density of magnetic flux having a component parallel to the X-axis between the electrodes can be further increased.Embodiment 2.

[0052] Hereinafter, Embodiment 2 of the present disclosure will be described mainly focusing on portions different from Embodiment 1 described above, with reference to figures. Parts similar to those in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted. FIG. 4 is a cross-sectional view showing a schematic configuration of a switchgear 200 according to Embodiment 2. As shown in FIG. 4, recesses 20G recessed in the axial direction X are formed in the facing covers 20 provided on the respective electrodes 1. By providing such recesses 20G, since contact area between the facing covers 20 is reduced at the time of closing of the electrodes 1, magnetic flux density passing through the facing covers 20 can be increased, and magnetic adsorption force of the magnets 10 between the electrodes 1 can be increased. Thus, the magnets can be downsized.

[0053] The recess 20G may be provided in at least one of the two facing covers 20 facing each other, so that the contact area between the facing covers 20 can be reduced. Further, the contact area between the facing covers 20 is adjusted in consideration of magnetic saturation.

[0054] Further, the inventors of the present disclosure have discovered, as a result of repeated magnetic analysis, that magnetic adsorption force, which is a force attracting the magnets 10 between the electrodes 1, increases by configuring the switchgear 200 as follows.

[0055] That is, a depth W4 of the recess 20G of the facing cover 20 in the axial direction X is set smaller than a length W1 of the facing cover 20 in the radial direction Y, which is a direction perpendicular to the X-axis.

[0056] In the switchgear of the present embodiment configured as described above, at least one of the ferromagnetic bodies respectively disposed on the electrodes has a recess recessed from each surface thereof facing each other between the electrodes.

[0057] Further, in the switchgear of the present embodiment configured as described above, a depth of the recess of the ferromagnetic body in the first direction is configured to be smaller than a length of the ferromagnetic body in a direction perpendicular to the first direction. As a result, magnetic adsorption force of the magnets can be further increased, so that the magnets can be downsized, and weight reduction and cost reduction are possible.Embodiment 3.

[0058] Hereinafter, Embodiment 3 of the present disclosure will be described mainly focusing on portions different from Embodiment 1 described above, with reference to figures. Parts similar to those in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.

[0059] FIG. 5 is a cross-sectional view showing a schematic configuration of a switchgear 300 according to Embodiment 3.

[0060] FIG. 6 is a conceptual diagram showing a current path in the switchgear 300 according to Embodiment 3.

[0061] In the switchgear 300 of the present embodiment, an insulating tape 22 as an insulator is disposed between a side surface of the magnet 10 and an inner wall of the accommodation holes HA and HB.

[0062] When the electrode 1 is opened, if an arc ignition point is not between the electrode surfaces SA and SB of the electrode 1, but between the side covers 21, current may flow through a path of the magnet 10 → the facing cover 20 → the electrode 1. In this case, the magnet 10 is demagnetized by the current, and magnetic adsorption force decreases. However, by providing an insulating layer of the insulating tape 22 around the magnet 10 in this way, as shown in FIG. 6, current i flows along a path avoiding the magnet 10.

[0063] The insulating tape 22 may be provided between the magnet 10 and the side cover 21, or may be provided between an outer side of the side cover 21 and an inner wall of the accommodation holes HA and HB.

[0064] Even when the insulating tape 22 is provided between the outer side of the side cover 21 and the inner wall of the accommodation holes HA and HB, since it is possible to prevent current from flowing from the electrode 1 side to the magnet 10 side, an effect of preventing demagnetization of the magnet 10 can be obtained.

[0065] In the switchgear of the present embodiment configured as described above, an insulator is disposed between the magnet and an inner wall of the accommodation hole. Accordingly, since it is possible to suppress demagnetization of the magnet due to current and decrease of magnetic adsorption force, stable magnetic adsorption force between the electrodes can be ensured.

[0066] Although the disclosure is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects, and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations to one or more of the embodiments of the disclosure.

[0067] It is therefore understood that numerous modifications which have not been exemplified can be devised without departing from the scope of the present disclosure. For example, at least one of the constituent components may be modified, added, or eliminated. At least one of the constituent components mentioned in at least one of the preferred embodiments may be selected and combined with the constituent components mentioned in another preferred embodiment.DESCRIPTION OF THE REFERENCE CHARACTERS

[0068] 1A first electrode 1B second electrode 10 magnet 10S magnet surface 20 facing cover (ferromagnetic body) 20G recess 21 side cover (first substance) 22 insulating tape (insulator) 100, 200, 300 switchgear HA, HB accommodation hole SA, SB electrode surface

Claims

1. A switchgear comprising a pair of electrodes arranged with respective electrode surfaces facing each other in a first direction and being mutually contactable and separable in the first direction, wherein each of the electrodes has an accommodation hole recessed from the electrode surface, magnets are respectively accommodated in the accommodation holes of the respective electrodes such that polarities which attract each other by magnetic force face each other between the electrodes, and on respective magnet surfaces, which face each other between the electrodes, of the magnets respectively accommodated in the respective electrodes, ferromagnetic bodies covering the magnet surfaces are respectively disposed, and adjacent to a magnet side surface of each of the magnets along the first direction, a first substance having a relative permeability lower than a relative permeability of the ferromagnetic body is respectively disposed.

2. The switchgear according to claim 1, wherein at least one of the ferromagnetic bodies respectively disposed on the electrodes has a recess recessed from each surface thereof facing each other between the electrodes.

3. The switchgear according to claim 1 or 2, wherein an insulator is disposed between the magnet and an inner wall of the accommodation hole.

4. The switchgear according to any one of claims 1 to 3, wherein a length of the ferromagnetic body in a direction perpendicular to the first direction is configured to be smaller, by a set dimension, than a length of the magnet in the direction perpendicular to the first direction.

5. The switchgear according to any one of claims 1 to 4, wherein the length of the ferromagnetic body in the direction perpendicular to the first direction is configured to be greater than a length of the ferromagnetic body in the first direction.

6. The switchgear according to claim 2, wherein a depth of the recess of the ferromagnetic body in the first direction is configured to be smaller than the length of the ferromagnetic body in the direction perpendicular to the first direction.

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