switchgear

Abstract

A switchgear (100) is provided with a pair of electrodes (1A, 1B) that are disposed so that electrode surfaces (SA, SB) are opposing in a first direction, and that can be brought close together and father apart to / from one another in the first direction. Accommodation holes (HA, HB) indented from the electrode surfaces (SA, SB) are formed in each of the electrodes (1A, 1B). Magnets (10) are respectively accommodated in the accommodation holes (HA, HB) of the electrodes (1A, 1B) so as to have opposing polarities magnetically attracted to one another between the electrodes (1A, 1B). Ferromagnets (20) for covering magnet surfaces (10S) are respectively disposed on the magnet surfaces (10S) that are part of the magnets (10) accommodated respectively in the electrodes (1A, 1B) and that are opposing between the electrodes (1A, 1B). First substances (21) having a lower relative magnetic permeability than that of the ferromagnets (20) are disposed in proximity to a magnet lateral surface of the magnets (10) that runs along the first direction.

Description

Switchgear

[0001] The present application relates to a switching device.

[0002] Switchgear, a type of high-voltage power distribution equipment, is used to interrupt current in the event of a breakdown or abnormality in the high-voltage power distribution equipment. Generally, gas-insulated switchgear contains switching devices such as circuit breakers, disconnectors, and earthing switches that interrupt current by contacting and separating a pair of opposing electrodes in a container filled with an insulating gas such as SF6 gas (sulfur hexafluoride gas) or dry air. When the pair of electrodes separate, an arc, a discharge phenomenon, occurs between the electrodes. To ensure insulation, each switching device is required to quickly extinguish the arc that occurs when the electrodes separate.

[0003] When the insulating gas inside a gas-insulated switchgear is SF6 gas, which has high interruption performance, arc extinguishing can be achieved using the standard-break method described below. However, it is known that extinguishing the arc is difficult when dry air, whose interruption performance is approximately 1 / 100 that of SF6 gas, is used. The standard-break method interrupts the current by using a drive device to extend the path of the arc current generated when the electrodes are opened. Known technologies for improving current interruption performance include the early-break method and the magnetic drive method. The early-break method is a method in which a quick-acting mechanism is provided on one side of the electrodes to increase the electrode opening speed, thereby extending the arc to the length required for arc extinguishing within a time period that does not damage the electrode contacts, thereby achieving interruption performance. The magnetic drive method is a method in which a magnet is installed inside the switchgear to magnetically drive the arc to achieve interruption performance. A switchgear having the following configuration, equipped with both the early-break method and the magnetic drive method, has been disclosed.

[0004] That is, a conventional switchgear is provided with a second electrode that can be driven to move toward or away from a first electrode, and electrical continuity between the electrodes is maintained by the attractive force of magnets disposed inside each electrode. The first and second terminals are opened by separating the first and second electrodes, and the first electrode is connected to the first terminal by a spring. This opening of the first and second terminals utilizes the attractive force of the magnets between the first electrode and the second electrode, which is driven in the opening direction while maintaining electrical continuity, and the restoring force of the spring connecting the first electrode. An arc generated by the separation of the first and second electrodes rotates circumferentially around the electrodes due to the magnetic field generated by the magnets, and is stretched and cooled, thereby being interrupted (see, for example, Patent Document 1).

[0005] Patent No. 7162782

[0006] In the conventional switchgear described above, an arc generated during current interruption is extinguished by rotating the electrodes circumferentially using the magnetic field generated by the magnets and by increasing the electrode opening speed using the restoring force of the spring that holds the first electrode, thereby instantly extending the arc path. However, if the magnetic attraction of the magnets disposed inside the first and second electrodes is weak, the first and second electrodes may break contact before the restoring force of the spring that holds the first electrode is charged, resulting in insufficient opening speed and reduced arc interruption performance. Increasing the size of the magnet to ensure sufficient magnetic force increases the cost of the magnet and the weight of the electrode, which in turn increases the cost of peripheral equipment that drives the electrode. This results in increased costs. The present application discloses a technology for solving the above-mentioned problems and aims to provide a low-cost switchgear that ensures arc interruption performance.

[0007] The opening and closing device disclosed in the present application is a opening and closing device comprising a pair of electrodes arranged with their electrode surfaces facing each other in a first direction and capable of moving toward and away from each other in the first direction, wherein each of the electrodes has a housing hole recessed from the electrode surface, a magnet is housed in the housing hole of each of the electrodes so that the polarities attracting each other by magnetic force are opposite between the electrodes, a ferromagnetic body covering the magnet surface of each of the magnets housed in each of the electrodes facing each other between the electrodes, and a first substance having a relative permeability lower than that of the ferromagnetic body is disposed adjacent to the magnet side of each of the magnets along the first direction.

[0008] According to the switchgear disclosed in the present application, a low-cost switchgear can be obtained while ensuring arc interruption performance.

[0009] Fig. 1 is a cross-sectional view showing a schematic configuration of a switchgear according to embodiment 1. Fig. 2 is a conceptual diagram for explaining magnetic characteristics in the switchgear according to embodiment 1. Fig. 3 is a cross-sectional view showing another configuration of the switchgear according to embodiment 1. Fig. 4 is a cross-sectional view showing a schematic configuration of a switchgear according to embodiment 2. Fig. 5 is a cross-sectional view showing a schematic configuration of a switchgear according to embodiment 3. Fig. 6 is a conceptual diagram showing a current path in the switchgear according to embodiment 3.

[0010] Embodiment 1. A switchgear according to this embodiment is provided in a gas-insulated switchgear used in power distribution facilities, vehicle equipment, etc., and interrupts current when an abnormality occurs. Fig. 1 is a cross-sectional view showing a schematic configuration of a switchgear 100 according to Embodiment 1. As shown in Fig. 1, the switchgear 100 includes a pair of electrodes, a first electrode 1A and a second electrode 1B, which are capable of being brought into and out of contact with each other. The first electrode 1A and the second electrode 1B are cylindrical and are housed inside hollow cylindrical first terminals 2A and second terminals 2B, respectively. Fig. 1 shows an open state in which the first electrode 1A and the second electrode 1B are separated from each other.

[0011] In the figure, the axial direction and radial direction of the cylindrical first electrode 1A and second electrode 1B are indicated as X and Y, respectively. In the following description, when there is no need to distinguish between the first electrode 1A and the second electrode 1B, they will simply be referred to as electrode 1.

[0012] The first electrode 1A and the second electrode 1B have respective electrode surfaces SA and SB facing each other in the axial direction X, which is a first direction, on which are formed accommodation holes HA and HB recessed in the axial direction X. Cylindrical magnets 10 are accommodated in these accommodation holes HA and HB. Side covers 21 are attached to the magnet side surfaces along the axial direction X of the magnet 10, and the magnet 10 is fixed to the inner circumferential surfaces of the accommodation holes HA and HB by these side covers 21. Furthermore, facing covers 20 are disposed on the magnet surfaces 10S of the magnet 10 of the first electrode 1A and the magnet surfaces 10S of the magnet 10 of the second electrode 1B, which face each other in the axial direction X, respectively, to cover these magnet surfaces 10S.

[0013] The magnets 10 provided on the first electrode 1A and the second electrode 1B are arranged so that when the first electrode 1A and the second electrode 1B are brought close to each other, their magnetic poles, which attract each other by magnetic force, face each other. In this embodiment, the south pole is arranged on the electrode surface SA side of the first electrode 1A, and the north pole is arranged on the electrode surface SB side of the second electrode 1B.

[0014] The material of the facing cover 20 is a ferromagnetic material such as iron, nickel, etc. The material of the side cover 21 is a first material having a lower relative magnetic permeability than the ferromagnetic material such as iron, nickel, etc. In this embodiment, the first material constituting the side cover 21 is a non-magnetic material such as aluminum or stainless steel having a relative magnetic permeability of 10 or less.

[0015] The first electrode 1A and the second electrode 1B are supported by guide components (not shown) inside the hollow cylindrical first terminal 2A and second terminal 2B so as to be movable in the axial direction X. Furthermore, the second electrode 1B is connected to a drive device (not shown) that drives the second electrode 1B in the axial direction X so as to be able to contact and separate from the first electrode 1A.

[0016] A contactor 5A is provided on the outer peripheral surface of the first electrode 1A, and a contactor 5B is provided on the outer peripheral surface of the second electrode 1B. The first electrode 1A and the second electrode 1B are electrically connected to a first terminal 2A and a second terminal 2B disposed on the outer side in the radial direction Y via these contactors 5A and 5B. When the drive device moves the first electrode 1A toward one axial direction X1, which is the direction of arrow D shown in FIG. 1 , and the first electrode 1A comes into contact with the second electrode 1B, a current path is formed via the first terminal 2A and the second terminal 2B, and power is transmitted.

[0017] A movable stopper 7 is attached to the outer peripheral surface of the first electrode 1A. When the first electrode 1A moves in the axial direction X, an outer end face 7OUT of the movable stopper 7 in the radial direction Y slides against the inner peripheral surface of the first terminal 2A. A fixed stopper 6 is attached to the inner peripheral surface of the first terminal 2A. When the first electrode 1A moves in the axial direction X, an inner end face 6IN of the fixed stopper 6 in the radial direction Y slides against the outer peripheral surface of the first electrode 1A. Because the fixed stopper 6 is fixed to the first terminal 2A, its position in the axial direction X does not change even when the first electrode 1A moves in the axial direction X. A spring 8 is installed between the movable stopper 7 and the fixed stopper 6, and the spring 8 expands and contracts in response to movement of the first electrode 1A in the axial direction X.

[0018] The contact and separation operation between the first electrode 1A and the second electrode 1B in the opening and closing device 100 configured as described above will be described. To bring the first electrode 1A and the second electrode 1B into contact with each other to close the contact, as described above, the drive device moves the second electrode 1B toward one axial direction X1, which is the direction of arrow D, so that the second electrode 1B comes into contact with the first electrode 1A and establishes electrical continuity. At this time, the contact between the first electrode 1A and the second electrode 1B is maintained by the magnetic attraction force between the magnets 10 provided on the first electrode 1A and the second electrode 1B.

[0019] To separate the first electrode 1A and second electrode 1B from their contact state, the drive device moves the second electrode 1B toward the other axial direction X2, which is the direction opposite to the arrow D. At this time, the first electrode 1A is maintained in contact with the second electrode 1B by the magnetic attraction force of the magnet 10, so the first electrode 1A moves toward the other axial direction X2 together with the second electrode 1B while maintaining its contact state with the second electrode 1B. When the first electrode 1A moves toward the other axial direction X2, the movement stopper 7 fixed to the first electrode 1A also moves toward the other axial direction X2, compressing the spring 8 and storing its restoring force.

[0020] When the drive device moves the second electrode 1B further toward the other axial direction X2, the attraction between the first electrode 1A and the second electrode 1B due to the magnetic force is released when the restoring force of the spring 8 and the magnetic force between the magnets 10 are balanced, and the first electrode 1A moves vigorously toward the one axial direction X1 in response to the restoration of the spring 8, causing the electrodes 1 to separate. By using the restoring force of the spring 8 thus stored to separate the electrodes 1, the separation speed between the first electrode 1A and the second electrode 1B increases, and the current path can be extended to the length required for arc extinguishing within a time period that does not cause damage to the electrode 1, thereby achieving high arc current interruption performance.

[0021] Here, the analysis results of the magnetic characteristics of the switchgear 100 of this embodiment will be explained using the figures. Fig. 2 is a conceptual diagram for explaining the magnetic characteristics when the electrode 1 is closed in the switchgear 100 according to embodiment 1. In the switchgear 100 of this embodiment, facing covers 20 made of a ferromagnetic material are disposed on each of the magnet surfaces 10S facing each other between the electrodes 1 as described above. Furthermore, side covers 21 made of aluminum, stainless steel, or the like as a first material having a lower relative magnetic permeability than the facing covers 20 are disposed adjacent to the magnet side surfaces of the magnets 10.

[0022] The inventors of the present application have repeatedly analyzed the magnetic characteristics of the switching device 100 configured as described above, and as a result have discovered that the magnetic attraction force of the magnet 10 between the electrodes 1 is large. This is thought to be because, in the switching device 100 of this embodiment, a magnetic circuit is not formed by the magnetic flux M2 that passes through the inside of the side cover 21 of the magnet 10, as shown in Figure 2, and as a result, the magnetic flux density of the magnetic flux M1 that has a component parallel to the axial direction X between the electrodes 1 is large.

[0023] Furthermore, the arc current flowing between the electrodes 1 flows so as to bulge outward in the radial direction Y. That is, the arc current flows at an angle equal to or greater 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 manner, the Lorentz forces acting on the arc current in the radial and circumferential directions also increase. The inventors of the present application discovered that this allows the arc generated between the electrodes 1 to be quickly rotated on the outer periphery of the electrodes 1 in the radial direction Y, thereby extinguishing the arc. In this way, the switchgear 100 of this embodiment has a configuration that can supply a strong magnetic field required for extinguishing the arc to the pair of electrodes 1 as soon as they separate.

[0024] Furthermore, the inventors discovered that the adhesion of magnetic foreign matter generated by the arc to the facing cover 20 is suppressed. This is thought to be because, as described above, the Lorentz force outward in the radial direction Y increases, causing the arc current to quickly move from above the facing cover 20 to the outer periphery of the electrode 1 outside in the radial direction Y. In this way, irregularities caused by foreign matter are prevented from adhering to the surface of the electrode 1, ensuring a reliable state of contact between the electrodes 1 and suppressing demagnetization and damage to the magnet 10 due to the arc.

[0025] Furthermore, as a result of diligent efforts, the inventors discovered that the magnetic flux density of the magnetic flux M1 having a component parallel to the X-axis between the electrodes 1 can be increased when the switching device 100 is configured as follows. FIG. 3 is a partially enlarged cross-sectional view showing another configuration example of the switching device 100 according to embodiment 1. As shown in FIG. 3 , the length W1 of the facing cover 20 in the radial direction Y, which is a direction perpendicular to the axial direction X, is configured to be smaller by a set dimension than the length W2 of the magnet 10 in the radial direction Y. In this embodiment, the length W1 of the facing cover 20 in the radial direction Y is configured to be approximately 5% to 12% smaller than the length W2 of the magnet 10 in the radial direction Y. By achieving this dimensional relationship, the magnetic flux density of the magnetic flux M1 having a component parallel to the X-axis between the electrodes 1 can be increased.

[0026] Furthermore, as a result of the inventors' diligent efforts, they discovered that by configuring the length W1 in the radial direction Y, which is the direction perpendicular to the axial direction X of the facing cover 20, to be greater than the length W3 in the axial direction X of the facing cover 20, i.e., its thickness, it is possible to further increase the magnetic flux density of the magnetic flux M1 between the electrodes 1, which has a component parallel to the axial direction X.

[0027] In the above, aluminum, stainless steel, etc. are shown as the first material constituting the side cover 21 disposed on the side of magnet 10, but this is not limited to these. The first material disposed on the side of magnet 10 may be any material with a lower relative magnetic permeability than the facing cover 20, which is made of a ferromagnetic material, and may be, for example, a gas or an insulator. When a gas is disposed on the side of magnet 10 as the first material, it is sufficient to configure the magnet 10 so that a gap is provided between the magnet 10 and the inner surfaces of the receiving holes HA and HB. In this case, for example, a configuration is conceivable in which magnet 10 is fixed to the bottom surfaces of the receiving holes HA and HB with an adhesive or the like.

[0028] Furthermore, if the relative permeability of the material constituting electrode 1 is lower than that of facing cover 20 made of a ferromagnetic material, side cover 21 may not be provided. In this case, electrode 1 itself becomes the first material disposed on the side surface of magnet 10.

[0029] Furthermore, while the length of side cover 21 in the axial direction X is shown above as a length that covers the entire side surface of magnet 10, this is not limited to this. Even if side cover 21 is shorter than the length of magnet 10 in the axial direction X, the above-mentioned effect can be achieved as long as it covers at least a portion of the electrode surface SA, SB side of magnet 10. Furthermore, side cover 21 does not need to be attached around the entire circumference of the side surface of magnet 10; the same effect can be achieved by attaching it to a portion of the circumferential surface of the side surface of magnet 10.

[0030] The opening and closing device of this embodiment configured as described above is a opening and closing device having a pair of electrodes arranged with their electrode surfaces facing each other in a first direction and which can be moved toward and away from each other in the first direction, wherein each of the electrodes has a storage hole formed therein that is recessed from the electrode surface, a magnet is stored in the storage hole of each of the electrodes so that the polarities that attract each other by magnetic force between the electrodes are opposite, a ferromagnetic body covering the magnet surface of each of the magnets stored in each of the electrodes that face each other between the electrodes, and a first substance having a relative permeability lower than that of the ferromagnetic body is disposed adjacent to the magnet side of each of the magnets along the first direction.

[0031] In this way, a ferromagnetic material is disposed on the magnet surface of each magnet provided in each electrode, and a first material with a lower relative magnetic permeability than the ferromagnetic material is disposed on the side of the magnet. This increases the magnetic attraction force compared to the magnet alone, allowing for the magnet to be made smaller, lighter, and less expensive. Furthermore, the magnetic flux density with a component in the axial direction X between the electrodes is increased, allowing any arc that occurs to be quickly extinguished. This prevents the magnetic force of the magnet from decreasing due to the arc, ensuring a stable magnetic attraction force and stabilizing current interruption performance. It also has the effect of mitigating the electric field and protecting the electrodes from damage caused by the arc.

[0032] In the opening / closing device of the present embodiment configured as described above, the length of the ferromagnetic body in the direction perpendicular to the first direction is configured to be smaller by a set dimension than the length of the magnet in the direction perpendicular to the first direction. In the opening / closing device of the present embodiment configured as described above, the length of the ferromagnetic body in the direction perpendicular to the first direction is configured to be larger than the length of the ferromagnetic body in the first direction.

[0033] By adopting such a dimensional relationship, it is possible to further increase the magnetic flux density of the magnetic flux having a component parallel to the X-axis between the electrodes.

[0034] Embodiment 2. Hereinafter, Embodiment 2 of the present application will be described with reference to the drawings, focusing on the differences from Embodiment 1 above. The same parts as in Embodiment 1 above will be assigned the same reference numerals and will not be described again. FIG. 4 is a cross-sectional view showing the schematic configuration of a switching device 200 according to Embodiment 2. As shown in FIG. 4, the facing covers 20 provided on each electrode 1 are each formed with a recess 20G recessed in the axial direction X. By providing such recess 20G, the contact area between the facing covers 20 is reduced when the electrode 1 is closed, thereby increasing the magnetic flux density passing through the facing covers 20 and increasing the magnetic attraction force of the magnet 10 between the electrodes 1. This makes it possible to miniaturize the magnet.

[0035] Incidentally, if the recess 20G is provided on at least one of the two opposing facing covers 20, it is possible to reduce the contact area between the facing covers 20. Furthermore, the contact area between the facing covers 20 is adjusted in consideration of magnetic saturation.

[0036] Furthermore, as a result of repeated magnetic analysis, the inventors of the present application discovered that the magnetic attraction force, which is the force by which the magnets 10 attract each other between the electrodes 1, can be increased by configuring the opening and closing device 200 as follows: That is, the depth W4 in the axial direction X of the recess 20G of the facing cover 20 is configured to be smaller than the length W1 in the radial direction Y, which is the direction perpendicular to the X axis of the facing cover 20.

[0037] In the switchgear of the present embodiment configured as described above, at least one of the ferromagnetic bodies disposed on each of the electrodes has a recess formed therein that is recessed from the surface facing the electrodes. Furthermore, in the switchgear of the present embodiment configured as described above, the depth of the recess in the ferromagnetic body in the first direction is configured to be smaller than the length of the ferromagnetic body in a direction perpendicular to the first direction. This further increases the magnetic attraction force of the magnet, thereby enabling the magnet to be made smaller, lighter, and less expensive.

[0038] Embodiment 3. Hereinafter, embodiment 3 of the present invention will be described with reference to the drawings, focusing on the differences from embodiment 1 above. The same parts as embodiment 1 above will be assigned the same reference numerals and description thereof will be omitted. Figure 5 is a cross-sectional view showing a schematic configuration of a switching device 300 according to embodiment 3. Figure 6 is a conceptual diagram showing a current path in switching device 300 according to embodiment 3.

[0039] In the switchgear 300 of this embodiment, insulating tape 22 is disposed as an insulator between the side surface of the magnet 10 and the inner walls of the accommodation holes HA and HB. When the electrode 1 is opened, if the arc ignition point is between the side cover 21 and not between the electrode surfaces SA and SB of the electrode 1, current may flow along the path of the magnet 10 → facing cover 20 → electrode 1. In this case, the magnet 10 is demagnetized by the current, and the magnetic attraction force decreases. However, by providing an insulating layer of insulating tape 22 around the magnet 10 in this way, the current i flows along a path that avoids the magnet 10, as shown in FIG. 6 .

[0040] The insulating tape 22 may be provided between the magnet 10 and the side cover 21, or may be provided between the outside of the side cover 21 and the inner walls of the accommodating holes HA, HB. Even when the insulating tape 22 is provided between the outside of the side cover 21 and the inner walls of the accommodating holes HA, HB, it is possible to prevent current from flowing from the electrode 1 side to the magnet 10 side, thereby achieving the effect of preventing demagnetization of the magnet.

[0041] In the switchgear of the present embodiment configured as described above, an insulator is disposed between the magnet and the inner wall of the accommodating hole, which prevents the magnet from being demagnetized by a current and a decrease in magnetic attraction force, thereby ensuring a stable magnetic attraction force between the electrodes.

[0042] Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are contemplated within the scope of the technology disclosed in this application. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0043] 1A First electrode, 1B Second electrode, 10 Magnet, 10S Magnet surface, 20 Facing cover (ferromagnetic material), 20G Recess, 21 Side cover (first material), 22 Insulating tape (insulator), 100, 200, 300 Switchgear, HA, HB Receiving hole, SA, SB Electrode surface.

Claims

1. An opening / closing device provided with a pair of electrodes arranged with their electrode surfaces facing each other in a first direction and capable of approaching and separating from each other in the first direction, each of the electrodes having a receiving hole recessed from the electrode surface, magnets being respectively received in the receiving holes of the electrodes such that polarities attracting each other by magnetic force face each other between the electrodes, a ferromagnetic material covering each of the magnet surfaces facing each other between the electrodes being respectively disposed on each of the magnet surfaces of the magnets respectively received in the electrodes, and a first material having a relative permeability lower than that of the ferromagnetic material being respectively disposed adjacent to the magnet side surfaces of the magnets along the first direction, the opening / closing device.

2. At least one of the ferromagnetic materials respectively disposed on the electrodes has a recess formed by being recessed from each of the surfaces facing each other between the electrodes, The opening / closing device according to Claim 1.

3. An insulator is disposed between the magnet and the inner wall of the receiving hole, The opening / closing device according to Claim 1.

4. An insulator is disposed between the magnet and the inner wall of the receiving hole, The opening / closing device according to Claim 2.

5. The length of the ferromagnetic material in a direction perpendicular to the first direction is configured to be smaller by a set dimension than the length of the magnet in a direction perpendicular to the first direction, The opening / closing device according to Claim 1.

6. The length of the ferromagnetic material in a direction perpendicular to the first direction is configured to be smaller by a set dimension than the length of the magnet in a direction perpendicular to the first direction, The opening / closing device according to Claim 2.

7. The length of the ferromagnetic material in a direction perpendicular to the first direction is configured to be smaller by a set dimension than the length of the magnet in a direction perpendicular to the first direction, The opening / closing device according to Claim 3.

8. The length of the ferromagnetic material in a direction perpendicular to the first direction is configured to be larger than the length of the ferromagnetic material in the first direction, The opening / closing device according to any one of Claims 1 to 7.

9. The depth of the recess of the ferromagnetic material in the first direction is configured to be smaller than the length of the ferromagnetic material in a direction perpendicular to the first direction, The opening / closing device according to Claim 2.