CN113035636A - Switchgear and distribution equipment - Google Patents

Abstract

The invention relates to a switchgear and a power distribution apparatus. The switching device includes: the first fixed contact is electrically connected with the bus; the first moving contact can move along a first direction to be separated from and far away from the first fixed contact and move along a second opposite direction to be close to and jointed with the first fixed contact; a vacuum arc extinguishing assembly comprising: a vacuum tube fixed relative to the first fixed contact; a second fixed contact of the bus is electrically connected in the vacuum tube; and a second movable contact in the vacuum tube; the connecting rod transmission mechanism is connected to the second moving contact; during the movement of the first moving contact along the first direction, the first moving contact is in driving connection with the connecting rod transmission mechanism, the connecting rod transmission mechanism drives the second moving contact to be separated from the second fixed contact, and before separation, the first moving contact is separated from the first fixed contact; during the first moving contact moves along the second direction, the first moving contact is in driving connection with the connecting rod transmission mechanism, the connecting rod transmission mechanism drives the second moving contact to be connected with the second fixed contact, and before connection, the first moving contact is connected with the first fixed contact.

Description

Switchgear and distribution equipment

Technical Field

The invention relates to the technical field of transmission and distribution electrical equipment, in particular to a switching device and distribution equipment.

Background

The existing distribution equipment, such as load switches used in ring main units, mainly includes two types, one is to use sulfur hexafluoride (SF6) as an insulating and breaking arc extinguishing medium, wherein sulfur hexafluoride gas is an important greenhouse gas and is also one of greenhouse gases definitely prohibited from being emitted by kyoto protocol. The other is a no-SF 6 load switch, and the more common scheme is that a vacuum arc-extinguishing chamber is connected with a three-position isolating switch in series, the main disadvantage of the scheme is that two mechanisms are required to respectively act on the vacuum arc-extinguishing chamber and the three-position isolating switch, at least two operations are required for opening and isolating, the process is complex and time-consuming, and in addition, the scheme has higher cost.

Therefore, there is a need in the industry for a switching device that can achieve opening and isolation with simplified operation and has a simple structure and easy operation.

Disclosure of Invention

The present invention aims to provide a switching device which solves at least some of the above-mentioned technical problems.

The present invention also aims to provide a power distribution apparatus employing the improved switchgear described above.

According to an aspect of the present invention, there is provided a switching apparatus comprising: a first stationary contact electrically connected to the bus bar; the first moving contact can move along a first direction to be separated from and far away from the first fixed contact, and can move along a second direction opposite to the first direction to be close to and jointed with the first fixed contact; a vacuum arc extinguishing assembly, comprising: a vacuum tube fixed relative to the first stationary contact; the second fixed contact is positioned in the vacuum tube and is electrically connected to the bus; the second moving contact is positioned in the vacuum tube; the connecting rod transmission mechanism is connected to the second moving contact; during the movement of the first movable contact along the first direction, the first movable contact is in driving engagement with the link transmission mechanism, the link transmission mechanism drives the second movable contact to be separated from the second fixed contact, and the first movable contact is separated from the first fixed contact before the second movable contact is separated from the second fixed contact; during the movement of the first movable contact along the second direction, the first movable contact is in driving engagement with the link transmission mechanism, the link transmission mechanism drives the second movable contact to be engaged with the second fixed contact, and the first movable contact is already engaged with the first fixed contact before the second movable contact is engaged with the second fixed contact.

According to the switching device provided by the embodiment, the vacuum arc extinguishing assembly can be synchronously switched on or off only by operating the first moving contact, and the requirement of the vacuum arc extinguishing assembly for safely breaking a circuit is met. Compared with the traditional three-position isolating switch series connection vacuum arc-extinguishing chamber, the operation can be completed in one step, the operation process is simplified on the premise of ensuring safety, and the time is saved. In addition, first moving contact moves and joint first moving contact along the second direction before, the second moving contact and the second static contact of vacuum arc extinguishing subassembly are in the state of separating each other all the time, do not worry when carrying out the combined floodgate operation to first moving contact, because this return circuit of vacuum arc extinguishing subassembly that first moving contact can lead to through the indirect contact vacuum arc extinguishing subassembly of connecting rod drive mechanism is switched on, satisfy the needs of circuit safety, and need not additionally to increase insulating material and keep apart first moving contact and vacuum arc extinguishing subassembly, the structure is simplified and good economic benefits has. The whole switch device has simple structure and convenient operation, and does not cause pollution to the environment.

In one embodiment, the link transmission mechanism is provided with a return spring, the return spring applies a force to the link transmission mechanism to move at least one part of the link transmission mechanism to a direction close to the second fixed contact, and the at least one part of the link transmission mechanism is connected to the second movable contact; during the movement of the first movable contact along the first direction and after the second movable contact is separated from the second fixed contact, the link transmission mechanism is kept static under the action of the return spring, and after the first movable contact moves along the second direction and is jointed with the first fixed contact, the link transmission mechanism drives the second movable contact to be jointed with the second fixed contact under the action of the return spring.

According to the embodiment, the driving action of the connecting rod transmission mechanism on the second moving contact of the vacuum arc extinguishing assembly is controllable by designing the driving and restricting relationship between the reset spring and the connecting rod transmission mechanism. When the first moving contact moves along the first direction and drives the connecting rod transmission mechanism to move, at least one part of the connecting rod transmission mechanism is kept at the position of the tail end of the movement due to the force of the reset spring, so that the second moving contact is limited to be connected with the second fixed contact under the action of the reset spring force and the self closing force of the vacuum arc extinguish chamber. And the second movable contact is allowed to be connected with the second fixed contact under the action of the reset spring force and the self closing force of the vacuum arc-extinguishing chamber. The motion process generated by the matching of the connecting rod transmission mechanism and the return spring can be realized only by reasonably designing the configuration of the connecting rod transmission mechanism, and the whole process only needs the motion of the first moving contact without additional operation or device.

In some embodiments, the link transmission mechanism has a first engagement end and a second engagement end; during movement of the first movable contact in the first direction, the first movable contact is in driving engagement with the first engagement end; the first movable contact is in driving engagement with the second engagement end during movement of the first movable contact in the second direction.

In some embodiments, the link transmission mechanism includes: a first rod rotatable about a first axis fixed in position relative to the first stationary contact and connected to the second movable contact, the return spring being coupled to the first rod and applying a force to the first rod to move an end of the first rod away from the first axis in a direction closer to the second stationary contact; a second rod hinged to the first rod; a third bar hinged to said second bar and rotatable about a second axis fixed in position with respect to said first stationary contact, said first movable contact drivingly engaging said third bar during movement in either said first direction or said second direction.

According to the embodiment, the link transmission mechanism is constructed in a four-bar mechanism mode, the motion of the first moving contact is effectively transmitted to the second moving contact of the vacuum arc extinguishing assembly, and the vacuum arc extinguishing assembly is simple in structure and reliable in action.

In some embodiments, during the movement of the first movable contact in the first direction, the third rod, during the rotation driven by the first movable contact about the second axis, has a rotation end at which the third rod is kept stationary under the action of the return spring; during the movement of the first movable contact along the second direction, the third rod rotates around the second axis under the driving of the first movable contact and is separated from the rotating end, allowing the return spring to drive the first rod to drive the second movable contact to be connected with the second fixed contact.

In some embodiments, the second movable contact is connected to a movable conductive rod extending out of the vacuum tube and movably connected to the first rod.

In some embodiments, the movable conducting rod is formed with a sliding groove at a section extending out of the vacuum tube, and the first rod is provided with a shaft rod which is arranged in the sliding groove in a penetrating way and can move along the sliding groove.

In some embodiments, the first stationary contact is provided with a bracket, and the first shaft and the second shaft are respectively provided on the bracket.

In some embodiments, a static conductive rod is connected to the second stationary contact, and the static conductive rod extends out of the vacuum tube and is connected to the first stationary contact.

According to another aspect of the invention, there is provided a power distribution apparatus comprising the aforementioned switchgear.

Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following, or may be learned from the practice of the invention.

Drawings

Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:

fig. 1 is a schematic diagram of a switching apparatus according to an embodiment of the present invention;

fig. 2a to 2h are schematic diagrams of a switching-on and switching-off process of the switching device according to the embodiment of the invention.

Description of reference numerals:

1. a first fixed contact; 2. a first moving contact; 21. a pivotal shaft; 3. a vacuum arc extinguishing assembly; 31. a vacuum tube; 32. a second fixed contact; 33. a second moving contact; 34. a static conductive rod; 35. a movable conductive rod; 351. a shaft lever; 352. a chute; 4. a link transmission mechanism; 41. a first lever; 412. a first shaft; 42. a second lever; 423. a first hinge shaft; 424. a second hinge shaft; 43. a third lever; 431. a second shaft; 432. a first pole segment; 433. a second pole segment; 434. a third pole segment; 435. a first engagement end; 436. a second engagement end; 5. a support; 51. a support plate; 52. a support plate; 53. a connecting plate; 9. switching device

Detailed Description

Referring now to the drawings, illustrative aspects of the disclosed switchgear and distribution equipment will be described in detail. Although the drawings are provided to present some embodiments of the invention, the drawings are not necessarily to scale of particular embodiments, and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. The position of some components in the drawings can be adjusted according to actual requirements on the premise of not influencing the technical effect. The appearances of the phrase "in the drawings" or similar language in the specification are not necessarily referring to all drawings or examples.

Certain directional terms used hereinafter to describe the drawings, such as "inner", "outer", "above", "below", and other directional terms, will be understood to have their normal meaning and refer to those directions as they normally relate to when viewing the drawings. Unless otherwise indicated, the directional terms described herein are generally in accordance with conventional directions as understood by those skilled in the art.

The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

The invention provides a switch device which can be applied to power distribution equipment, such as a ring main unit. Fig. 1 shows an embodiment of a switching device. As shown in the figure, the switching device 9 includes a first fixed contact 1, a first movable contact 2, a vacuum arc extinguishing assembly 3 and a link transmission mechanism 4. One end of the first fixed contact 1 is electrically connected to the bus, and the other end extends out in the direction far away from the bus. A pivot shaft 21 which is static relative to the first fixed contact 1 is arranged at a position which is at a certain distance from the first fixed contact 1, and the first movable contact 2 is arranged on the pivot shaft 21 and can rotate around the pivot shaft 21. As shown in fig. 2b to 2f, the first movable contact 2 can move along the first direction a around the pivot 21 to be separated from the first stationary contact 1 and gradually move away from the first stationary contact 1. As shown in fig. 2g to 2h, the first movable contact 2 is also movable about the pivot axis 21 in a second direction b opposite to the first direction a to gradually approach the first stationary contact 1 and engage with the first stationary contact 1. The pivot shaft 21 can be mounted, for example, at the end of another stationary contact joined to the cable. The first stationary contact 1 and the first movable contact 2 form an isolating switch. The vacuum arc extinguishing assembly 3 is arranged in parallel with the isolating switch. Besides rotating around a pivot shaft, in other alternative embodiments, the motion form of the first movable contact can be a linear motion or a curvilinear motion.

As shown in fig. 1, the vacuum arc extinguishing assembly 3 includes a vacuum tube 31, and a second stationary contact 32 and a second movable contact 33 disposed in the vacuum tube 31. The second fixed contact 32 is fixed relative to the first fixed contact 1, and the second movable contact 33 is movable relative to the second fixed contact 32 to engage with the second fixed contact 32 or separate from the second fixed contact 32. In the embodiment shown, the second stationary contact 32 is connected to one end of a stationary conducting rod 34, while the other end of the stationary conducting rod 34 extends out of the vacuum tube 31 and is fixedly connected to the first stationary contact 1. In other embodiments not shown, the static conductive bar 34 may also be directly joined to the bus bar. The vacuum tube 31 is mounted on the static conductive rod 34 and is thereby fixed relative to the first stationary contact 1. The second movable contact 33 is connected to one end of a movable conductive rod 35, and the other end of the movable conductive rod 35 extends out of the vacuum tube 31 and is movably connected with the link transmission mechanism 4. The vacuum tube 31 of the vacuum arc extinguishing assembly 3 of the present embodiment may be provided with a sealing structure to isolate the vacuum environment in the tube from the external atmospheric environment, and the vacuum tube 31 may further be provided with a shielding structure, a guiding structure, a bellows and other components, and the specific structure and arrangement of these components may refer to the existing vacuum arc extinguishing chamber and will not be described herein again.

According to the invention, the engagement and disengagement of the second movable contact 33 with and from the second stationary contact 32 is controlled by means of the movement of the first movable contact 2. For this purpose, the second movable contact 33 is connected to a link gear 4. The first movable contact 2 controls the connection or separation of the second movable contact 33 and the second fixed contact 32 by driving and connecting the connecting rod transmission mechanism 4 during the movement and driving the second movable contact 33 to move by means of the connecting rod transmission mechanism 4. In the embodiment shown in fig. 1, the first stationary contact 1 is provided with a holder 5, which holder 5 comprises two support plates 51, 52 on opposite sides of the vacuum tube 31, and a connecting plate 53 connected between the two support plates 51, 52. The link transmission mechanism 4 is installed on the support 5 and movably connected with the second movable contact 33. In one embodiment, the bracket 5 may be integrally formed. In another embodiment, the two plates 51, 52 and the connecting plate 53 can be separately machined and assembled together by bonding, welding, snapping, interference fit, etc. to form the bracket 5. In other embodiments, the holder 5 may be disposed on another mounting base fixed with respect to the first stationary contact 1.

As shown in fig. 1, the link transmission mechanism 4 includes a first lever 41, a second lever 42, and a third lever 43 connected in sequence. The first end of the first lever 41 is hinged to a first shaft 412 mounted on the fulcrum 51, so that the first lever 41 can rotate about this first shaft 412. The first shaft 412 is rotatable on the stay 51 about its central axis. The second end of the first lever 41 is hinged to the first end of the second lever 42 through a first hinge shaft 423. The movable conductive rod 35 is movably connected to the first rod 41 between the first shaft 412 and the first hinge shaft 423 through a shaft 351. In one embodiment, the section of the electrically conductive rod 35 extending out of the vacuum tube 31 has a sliding slot 352 extending along its length, and the shaft 351 is disposed on the first rod 41 and passes through the sliding slot 352, such that the shaft 351 can move along the sliding slot 352. The movable connection between the movable conducting rod 35 and the first rod 41 via the sliding slot 353 and the shaft 351 can ensure that the second movable contact 33 is separated from the second fixed contact 32 later than the first movable contact 2 is separated from the first fixed contact 1. The second end of the second lever 42 is hinged to the third lever 43 through a second hinge shaft 424. The third lever 43 is also hinged to a second shaft 431 mounted on the fulcrum 52 so as to be rotatable about this second shaft 431. The second shaft 431 is located closer to the first stationary contact 1 with respect to the first shaft 412. In the illustrated embodiment, the third rod 43 is configured to include a first rod segment 432, a second rod segment 433, and a third rod segment 434 that are angularly connected to one another. In the illustrated embodiment, the second axis 431 is located approximately where the second pole segment 433 intersects the third pole segment 434, and the intersection of the first pole segment 432 and the second pole segment 433 forms an end for articulating the second pole 42. The first pole segment 432 has a first engagement end 435 and the third pole segment 434 has a second engagement end 436. A space for the movement of the first movable contact 2 is formed between the first engagement end 435 and the second engagement end 436. The first and second engaging ends 435 and 436 can be respectively engaged with the first movable contact 2, so that the link transmission mechanism 4 drives the second movable contact 33 to move relative to the second fixed contact 32 under the driving of the first movable contact 2.

One configuration of the third lever 43 is shown in fig. 1 by way of example only, and it will be understood by those skilled in the art that the configuration of the third lever 43 is not limited thereto, and that there may be variations, for example, in one embodiment not shown, three lever segments may be angularly joined to one and mounted to the bracket at that point by a second shaft so that the third lever may rotate about the second shaft, the second lever may be hinged to the end of one of the three lever segments of the third lever by a second hinge shaft, and the ends of the other two lever segments may be respectively a first joint end and a second joint end.

In the embodiment shown in fig. 1, the first lever 41 is also engaged with a return spring (not shown in the drawings). The return spring applies a force to the first rod 41 to enable the second end of the first rod 41 to move in a direction approaching the second fixed contact 32, so that the first rod 41 can push the second movable contact 33 to move in a direction engaging with the second fixed contact 32. In the embodiment shown in fig. 1, the first lever 41 is movable in a counterclockwise direction about the first shaft 412 under the influence of a return spring. The return spring may be a torsion spring that is fitted over the first shaft 412 and abuts against the first lever 41, or a compression spring or a tension spring that is coupled to the first lever 41.

The first lever 41, the second lever 42 and the third lever 43 are configured, arranged and connected in such a manner that the link transmission mechanism 4 is integrally formed as a four-bar linkage. Wherein the connecting rod transmission mechanism 4 is designed to meet the following motion conditions between the connecting rod transmission mechanism and the return spring: the first movable contact 2, during the movement in the first direction, drives the third lever 43 in rotation until the third lever 42 reaches its end position of rotation, in which the third lever 42 remains stationary under the action of the return spring force, which can also be understood as being blocked in the dead-centre position by the return spring, so that the entire link gear 4 cannot move. Thereby, the second movable contact 33 is maintained in a state of being separated from the second stationary contact 32. During the movement of the first movable contact 2 in the second direction, the third rod 43 is driven by the first movable contact 2 to pass through the rotation end position (dead point position) and thus to be out of the state of being clamped by the return spring, the whole link transmission mechanism 4 is moved, and the second movable contact 33 is allowed to approach and be jointed with the second fixed contact 32 under the action of the return spring force and the closing force of the vacuum interrupter itself (the force which is borne by the second movable contact and points to the second fixed contact based on the difference between the internal pressure and the external pressure of the vacuum interrupter assembly).

The operation of the switching device 9 according to the invention is explained in detail below with reference to fig. 2a to 2 h.

As shown in fig. 2a, in a closing state of the switching device 9, the first movable contact 2 is stationary relative to the first stationary contact 1 and is connected to the first stationary contact 1, the second movable contact 33 of the vacuum arc-extinguishing component 3 is connected to the second stationary contact 32, and the first movable contact 2 is not connected to the link transmission mechanism 4, so that the circuit of the vacuum arc-extinguishing component 3 is not conducted.

As shown in fig. 2b, the switching device 9 starts to open, and the first movable contact 2 starts to rotate around the pivot shaft 21 in the first direction indicated by the arrow a to prepare to be disengaged from the first stationary contact 1. During this time, the first movable contact 2 shown in fig. 2b is engaged with the first stationary contact 1 and also engaged with the first engaging end 435 of the link transmission mechanism 4. In this state, the first movable contact 2 and the first fixed contact 1 are kept in conduction, and meanwhile, since the second movable contact 33 and the second fixed contact 32 of the vacuum arc-extinguishing component 3 are still in a joint state, the circuit of the vacuum arc-extinguishing component 3 is also conducted, and the vacuum arc-extinguishing component 3 starts shunting. In the illustrated embodiment, the first movable contact 2 is drivingly engaged with the side of the first engagement end 435 facing the second engagement end 436 and pushes the third rod 43 to rotate around the second axis 431, so as to drive the entire linkage mechanism 4 to move. But at this stage the second movable contact 33 does not move.

As shown in fig. 2c, the first movable contact 2 of the switch device 9 continues to rotate in the first direction indicated by the arrow a to disengage from the first stationary contact 1, while the first movable contact 2 remains engaged with the first engaging end 435 of the link transmission mechanism 4. In this way, when the first movable contact 2 is disconnected from the first stationary contact 1, the vacuum arc extinguishing assembly 3 is kept in a conductive loop. Because the separation of the second movable contact 33 and the second fixed contact 32 of the vacuum arc-extinguishing component 3 is delayed compared with the separation of the first movable contact 2 and the first fixed contact 1, the vacuum arc-extinguishing component 3 is ensured to complete the safe breaking of the current.

As shown in fig. 2d, after the first movable contact 2 is separated from the first fixed contact 1, it continues to rotate around the pivot shaft 21 in the first direction indicated by the arrow a and still drives the first engagement end 435 of the connecting-rod transmission mechanism 4, further driving the third rod 43 to rotate. The link transmission mechanism 4 continues to move, so that the second movable contact 33 of the vacuum arc extinguishing assembly 3 is separated from the second fixed contact 32, the vacuum arc extinguishing assembly 3 starts to break the current, an electric arc is generated between the second movable contact 33 and the second fixed contact 32, and the electric arc is extinguished until the current naturally crosses zero, thereby realizing the safe brake separation of the whole switching device 9.

As shown in fig. 2e, the first movable contact 2 continues to rotate around the pivot shaft 21 in the first direction indicated by the arrow a and continues to push the first engagement end 435 of the link transmission mechanism 4 until the first movable contact 2 is separated from the first engagement end 435. As shown in fig. 2f, during the movement of the first movable contact 2 in the first direction to disengage from the first engagement end 435, the third lever 43 is driven to its dead-center position. As mentioned above, in this dead point position, the third rod 43 is dead-ended, and the entire link transmission mechanism 4 cannot move, so that the second movable contact of the vacuum arc-extinguishing assembly is kept separated from the second stationary contact.

As shown in fig. 2g, the switching device 9 starts to close, and the first movable contact 2 starts to rotate around the pivot shaft 21 in the second direction indicated by the arrow b to approach the first stationary contact 1, during which the first movable contact 2 first engages the second engaging end 436 of the link transmission mechanism 4.

As shown in fig. 2h, the first movable contact 2 rotates in the second direction to re-engage with the first stationary contact 1, and pushes the third rod 43 of the link transmission mechanism 4 to rotate around the second shaft 431 beyond the dead point position, allowing the second movable contact 33 to approach and engage with the second stationary contact 32 under the action of the reset spring force and the closing force of the vacuum arc extinguishing assembly itself. Since the speed of the second movable contact 33 approaching and joining the second fixed contact 32 is slower than the speed of the first movable contact 2 approaching and joining the first fixed contact 1, the second movable contact 33 and the second fixed contact 32 are joined later than the first movable contact 2 and the first fixed contact 1.

According to the switching device, the vacuum arc extinguishing assembly is connected with the isolating switch in parallel, and the first moving contact of the isolating switch drives the vacuum arc extinguishing assembly to be switched on and off through the connecting rod transmission mechanism in the four-connecting-rod form. The vacuum arc-extinguishing assembly only works in the opening stage of the switching device and needs to bear Transient Recovery Voltage (TRV) when the current is opened or closed but does not need to have short-circuit closing capability, short-time current tolerance capability and continuous current tolerance capability. The first moving contact is used for ensuring the short circuit of the vacuum arc extinguishing assembly. In the closing stage of the first moving contact, the current cannot pass through the vacuum arc extinguishing assembly, and in the opening stage, the time for the current to pass through the vacuum arc extinguishing assembly is only a few milliseconds or a dozen milliseconds. Therefore, the technical scheme of the invention can reduce the cost and the size of the vacuum arc extinguishing assembly.

It should be understood that although the description is in terms of various embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein may be combined as suitable to form other embodiments, as will be appreciated by those skilled in the art.

The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.

Claims (10)

1. A switching device, comprising:

a first stationary contact (1) electrically connected to the bus bar;

a first movable contact (1) capable of moving in a first direction to disengage from and move away from the first stationary contact (1), and capable of moving in a second direction opposite to the first direction to approach and engage with the first stationary contact (1);

a vacuum arc extinguishing assembly (3) comprising:

a vacuum tube (31) fixed with respect to the first stationary contact (1);

a second stationary contact (32) located inside the vacuum tube (31) and electrically connected to the busbar;

a second movable contact (33) positioned in the vacuum tube (31);

a link transmission mechanism (4) connected to the second movable contact (33);

wherein, during the movement of the first movable contact (2) along the first direction, the first movable contact (2) is in driving engagement with the link transmission mechanism (4), the link transmission mechanism (4) drives the second movable contact (33) to separate from the second fixed contact (32), and the first movable contact (2) is already separated from the first fixed contact (1) before the second movable contact (33) is separated from the second fixed contact (32); during the movement of the first movable contact (2) along the second direction, the first movable contact (2) is in driving engagement with the link transmission mechanism (4), the link transmission mechanism (4) drives the second movable contact (33) to be engaged with the second fixed contact (32), and the first movable contact (2) is already engaged with the first fixed contact (1) before the second movable contact (33) is engaged with the second fixed contact (32).

2. A switching device according to claim 1, wherein the link actuator (4) is provided with a return spring which applies a force to the link actuator (4) to move at least a part of the link actuator (4) in a direction close to the second stationary contact (32), said at least a part of the link actuator (4) being connected to the second movable contact (33);

during the movement of the first movable contact (2) along the first direction and after the separation of the second movable contact (33) from the second fixed contact (32), the link transmission mechanism (4) remains stationary under the action of the return spring, and after the movement of the first movable contact (2) along the second direction and the engagement of the first fixed contact (1), the link transmission mechanism (4) urges the second movable contact (33) into engagement with the second fixed contact (32) under the action of the return spring.

3. A switching device according to claim 2, wherein the link gear (4) has a first engagement end (435) and a second engagement end (436);

during the movement of the first movable contact (2) along the first direction, the first movable contact (2) is in driving engagement with the first engagement end (435);

during the movement of the first movable contact (2) along the second direction, the first movable contact (2) is in driving engagement with the second engagement end (436).

4. Switching device according to claim 2, characterized in that the link transmission (4) comprises:

a first lever (41) rotatable about a first axis (412) fixed in position with respect to the first fixed contact (1) and connected to the second movable contact (33), the return spring being coupled to the first lever (41) and exerting a force on the first lever (41) moving its end remote from the first axis (412) towards the second fixed contact (32);

a second lever (42) hinged to the first lever (41);

-a third lever (43) hinged to said second lever (42) and rotatable about a second axis (431) fixed in position with respect to said first fixed contact (1), said first movable contact (2) being in driving engagement with said third lever (43) during movement in said first direction or in said second direction.

5. A switching device according to claim 4, characterized in that during the movement of said first movable contact (2) in said first direction, said third rod (43), during the rotation around said second axis (431) driven by said first movable contact (2), has a rotation end at which said third rod (43) remains stationary under the action of said return spring;

during the movement of the first movable contact (2) along the second direction, the third rod (43) rotates around the second shaft (431) under the driving of the first movable contact (2) and is separated from the rotating end, allowing the return spring to drive the first rod (41) to drive the second movable contact (33) to be connected with the second fixed contact (32).

6. The switching device according to claim 4, characterized in that said second movable contact (33) is connected to a movable conducting rod (35), said movable conducting rod (35) extending outside said vacuum tube (31) and being movably connected to said first rod (41).

7. The switching device according to claim 6, characterized in that the moving conductor rod (35) is formed with a sliding groove (352) at a section extending out of the vacuum tube (31), the first rod (41) being provided with a shaft (351), the shaft (351) being arranged through the sliding groove (352) and being movable along the sliding groove (352).

8. The switching device according to claim 4, characterized in that the first stationary contact (1) is provided with a bracket (5), the first shaft (412) and the second shaft (431) being respectively provided on the bracket (5).

9. The switching device according to any one of claims 1 to 8, wherein a static conducting rod (34) is connected to the second stationary contact (32), said static conducting rod (34) extending out of the vacuum tube (31) and being connected to the first stationary contact (1).

10. An electrical distribution apparatus, characterized in that it comprises a switching device (9) according to any one of claims 1 to 9.

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