A magnetic actuator for a medium-high voltage electrical switch based on a moving permanent magnet

Abstract

The application relates to a magnetic drive mechanism for a medium and high voltage electrical switch based on a moving permanent magnet, which comprises a moving permanent magnet assembly, a static iron assembly, a guide rod and an outer cover. The static iron assembly is fixedly installed on the inner wall of the upper end of the outer cover, and the moving permanent magnet assembly is slidably connected to the inner wall of the outer cover. The guide rod is fixedly connected to the moving permanent magnet assembly, and the guide rod is slidably connected to the static iron assembly and the outer cover. The static iron assembly comprises a single electromagnetic coil and a soft magnetic yoke. The beneficial effects are that the closing and opening efficiency is improved through the movement of the permanent magnet assembly towards the static iron assembly, the recessing of the high-coercivity permanent magnet in the soft magnetic shell, the recessing of the single electromagnetic coil in the annular outer groove, the surrounding of the single electromagnetic coil by the inner and outer soft magnetic yokes, the smaller outer diameter of the high-coercivity permanent magnet than the inner diameter of the outer ring end face and the axial distribution of the magnetic force lines of the high-coercivity permanent magnet and the soft magnetic yoke.

Description

Technical Field

[0001] This application relates to the field of magnetic actuators for electrical switches, and in particular to a magnetic actuator for medium and high voltage electrical switches based on a moving permanent magnet. Background Technology

[0002] The permanent magnet operating mechanism uses the interaction between the magnetic field generated by the permanent magnet and the magnetic field generated by the electromagnetic coil to realize the opening and closing operation. When the switch needs to be opened or closed, the polarity of the coil is changed to drive the opening or closing by using the principle of magnetic attraction or repulsion.

[0003] Existing circuit breaker operating mechanisms mainly include spring mechanisms, traditional permanent magnet mechanisms (FPMA), and magnetic control mechanisms. Spring mechanisms rely on mechanical latches and linkage transmission, resulting in complex structures, short lifespans, and slow response. Traditional permanent magnet mechanisms typically fix the permanent magnet to a stationary component, with the moving part being a soft magnetic moving iron. This requires dual coils to ensure sufficient magnetic force, leading to high costs and low closing efficiency.

[0004] In view of this, this application proposes a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet. Summary of the Invention

[0005] The purpose of this application is to address the technical problems pointed out in the background art by proposing a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet.

[0006] The technical solution of this application is: a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet, comprising: a moving permanent magnet assembly, a stationary iron assembly, a guide rod, and an outer cover; The static iron assembly is fixedly installed on the upper inner wall of the outer cover, and the moving permanent magnet assembly is slidably connected to the inner wall of the outer cover. The guide rod is fixedly connected to the moving permanent magnet assembly, and the guide rod is slidably connected to the stationary iron assembly and the outer cover; The static iron assembly includes a single set of electromagnetic coils and a soft magnetic yoke. The soft magnetic yoke has an annular outer groove at one end near the moving permanent magnet assembly to form an inner ring soft magnetic yoke and an outer ring soft magnetic yoke. The single set of electromagnetic coils is recessed in the annular outer groove. When the single electromagnetic coil is energized, the moving permanent magnet component moves toward or away from the stationary iron component. In an optional embodiment, the motion permanent magnet assembly includes a soft magnetic permeable shell and a high coercivity permanent magnet. The upper end of the soft magnetic permeable shell has a groove, and the high coercivity permanent magnet is recessed in the groove.

[0007] In an optional embodiment, the magnetic field lines of the high coercivity permanent magnet are axial magnetic field lines; the magnetic field lines of the soft magnetic yoke after magnetization are axial magnetic field lines.

[0008] In an optional embodiment, the inner ring end face of the inner ring soft magnetic yoke is disposed opposite to the upper end face of the high coercivity permanent magnet, and the outer ring end face of the outer ring soft magnetic yoke is disposed opposite to the upper end face of the magnetic shell ring. The outer diameter of the high coercivity permanent magnet is smaller than the inner diameter of the outer ring end face.

[0009] In an optional embodiment, When the single electromagnetic coil is energized with a positive current pulse, the magnetic pole direction of the inner ring end face is opposite to that of the upper end face of the permanent magnet, the magnetic pole direction of the outer ring end face is opposite to that of the upper end face of the magnetic shell ring, and the magnetic pole direction of the inner ring end face is opposite to that of the outer ring end face.

[0010] In an optional embodiment, when the single electromagnetic coil is energized with a reverse current pulse, the magnetic pole direction of the inner ring end face is the same as that of the upper end face of the permanent magnet, the magnetic pole direction of the outer ring end face is the same as that of the upper end face of the magnetic shell ring, and the magnetic pole direction of the inner ring end face is opposite to that of the outer ring end face.

[0011] In an optional embodiment, the soft magnetic yoke is fixedly installed on the upper inner wall of the outer cover, and the end of the single electromagnetic coil near the moving permanent magnet assembly is fixedly connected with epoxy resin b, which is recessed in the annular outer groove.

[0012] In an optional embodiment, a unipolar switching drive circuit is also included. The unipolar switching drive circuit is mounted on the outer casing and applies positive or reverse current pulses to the single set of electromagnetic coils.

[0013] In an optional embodiment, the soft magnetic conductive shell slides on the inner wall of the outer cover, the epoxy adhesive a is fixedly connected to the outer wall of the high coercivity permanent magnet, and the epoxy adhesive a is recessed in the groove.

[0014] In an optional embodiment, a concentric through groove is provided at the center of the outer cover, the stationary iron assembly, and the moving permanent magnet assembly, and the guide rod is connected through the concentric through groove; an inner groove is provided at the center of the end of the stationary iron assembly near the moving permanent magnet assembly. A gate-opening spring is sleeved on the guide rod, and the gate-opening spring is located between the moving permanent magnet assembly and the stationary iron assembly; one end of the gate-opening spring is fixedly connected to the inner wall of the inner groove, and the other end of the gate-opening spring is fixedly connected to the high coercivity permanent magnet. The upper end of the guide rod is connected to the switch spindle or the arc-extinguishing chamber pull rod.

[0015] Compared with the prior art, this application has the following beneficial technical effects: This application improves the efficiency of closing and opening circuits and reduces the number of coil bundles by using a permanent magnet assembly that moves toward a stationary iron assembly, a high-coercivity permanent magnet recessed in a soft magnetic shell, a single set of electromagnetic coils recessed in an annular outer groove, an inner ring soft magnetic yoke and an outer ring soft magnetic yoke surrounding the single set of electromagnetic coils, the inner ring end face of the inner ring soft magnetic yoke being opposite to the upper end face of the high-coercivity permanent magnet and the permanent magnet, the outer ring end face of the outer ring soft magnetic yoke being opposite to the annular upper end face of the magnetic shell, the outer diameter of the high-coercivity permanent magnet being smaller than the inner diameter of the outer ring end face, and the axial distribution of the magnetic lines of force of the high-coercivity permanent magnet and the soft magnetic yoke. Attached Figure Description

[0016] Figure 1 This is a schematic cross-sectional view of a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet in a static, unpowered state. Figure 2 This is a schematic cross-sectional view of the instantaneous energization state (including magnetic lines of force) of a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet; Figure 3 This is a schematic diagram of the closing state of a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet. Figure 4 This is a schematic cross-sectional view (including magnetic lines of force) of a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet in the closed state. Figure 5 This is a structural schematic diagram of the static iron assembly in this application; Figure 6 This is a schematic diagram of the moving permanent magnet component in this application.

[0017] Reference numerals: 1. Moving permanent magnet assembly; 11. Soft magnetic conductive shell; 111. Annular upper end face of the magnetic shell; 12. High coercivity permanent magnet; 121. Upper end face of the permanent magnet; 13. Epoxy resin a; 2. Static iron assembly; 21. Single set of electromagnetic coils; 22. Soft magnetic yoke; 221. Annular outer groove; 222. Outer ring end face; 223. Inner ring end face; 224. Inner groove; 23. Epoxy resin b; 3. Guide rod; 4. Opening spring; 5. Outer cover. Detailed Implementation

[0018] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application.

[0020] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] like Figures 1-6 As shown, this application proposes a magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet, including a moving permanent magnet assembly 1, a stationary iron assembly 2, a guide rod 3, and an outer cover 5. The stationary iron assembly 2 is fixedly installed on the upper inner wall of the outer cover 5, and the moving permanent magnet assembly 1 is slidably connected to the inner wall of the outer cover 5. The guide rod 3 is fixedly connected to the moving permanent magnet assembly 1, and is slidably connected to the stationary iron assembly 2 and the outer cover 5. The stationary iron assembly 2 includes a single set of electromagnetic coils 21 and a soft magnetic yoke 22. The soft magnetic yoke 22 has an annular outer groove 221 at one end near the moving permanent magnet assembly 1 to form an inner ring soft magnetic yoke and an outer ring soft magnetic yoke. The single set of electromagnetic coils 21 is recessed in the annular outer groove 221. When the single set of electromagnetic coils 21 is energized, the moving permanent magnet assembly 1 moves toward or away from the stationary iron assembly 2. See appendix Figure 1In this embodiment, during the closing process, the permanent magnet assembly 1 moves toward the stationary iron assembly 2. Since the mass of the permanent magnet assembly 1 is less than the mass of the soft magnetic yoke 22, when the same current is applied to magnetize the soft magnetic yoke 22 in the stationary iron assembly 2 with the coil parameters unchanged, the magnetic force generated by the soft magnetic yoke 22 and the attraction between it and the permanent magnet assembly 1 remain unchanged. This results in the permanent magnet assembly 1 moving toward the soft magnetic yoke 22 at a speed greater than the soft magnetic yoke 22 moving toward the permanent magnet assembly 1 under the same conditions. Moreover, to maintain magnetic field stability, the soft magnetic yoke 22 also needs to carry a single set of electromagnetic coils 21 along with it, further increasing the mass of the moving parts and causing the closing efficiency to decrease further. If the magnetic field is unstable, the closing efficiency will continue to decrease. Therefore, this embodiment proposes a closing scheme in which the permanent magnet assembly 1 moves toward the stationary iron assembly 2 to improve the closing efficiency. If the positions of the permanent magnet component 1 and the stationary iron component 2 in this embodiment are interchanged, that is, the soft magnetic yoke 22 moves toward the permanent magnet component 1, not only will the aforementioned reduction in closing efficiency occur, but also, due to the use of a single coil, the attraction force will be insufficient, and the soft magnetic yoke 22 will not be able to move toward the permanent magnet component 1. The use of the permanent magnet component 1 moving toward the stationary iron component 2 is also one of the core contributions of this application. In the prior art, the volume of the soft magnetic yoke 22 is generally reduced, or the mass (volume) of the assisting permanent magnet or the fixed permanent magnet is increased simultaneously to ensure sufficient attraction force to drive the soft magnetic yoke core, such as in Chinese Patent CN108257800A.

[0024] By using the closing method where the permanent magnet component 1 moves toward the soft magnetic yoke 22, the attraction between the permanent magnet component 1 and the soft magnetic yoke 22 can be relatively reduced, which can reduce the number of coil turns, thereby enabling the use of a single set of electromagnetic coils 21 as the drive. The single set of electromagnetic coils 21 has 250 turns, a wire diameter of Φ1.1 mm, and a DC resistance of 1.85 Ω.

[0025] Furthermore, the moving permanent magnet assembly 1 includes a soft magnetic permeable shell 11 and a high coercivity permanent magnet 12. A groove is formed at the upper end of the soft magnetic permeable shell 11, and the high coercivity permanent magnet 12 is recessed in the groove. The soft magnetic permeable shell 11 can not only be magnetized, fully utilizing the magnetic lines of force around the high coercivity permanent magnet 12, but also cover the high coercivity permanent magnet 12, reducing magnetic leakage. It should be noted that the soft magnetic permeable shell 11 slides on the inner wall of the outer cover 5, and epoxy resin a13 is fixedly connected to the outer wall of the high coercivity permanent magnet 12, with the epoxy resin a13 recessed in the groove. The high coercivity permanent magnet 12 is also recessed in the groove (the height of the upper end face 121 of the high coercivity permanent magnet 12 is lower than the annular upper end face 111 of the magnetic shell), further reducing magnetic leakage and ensuring the magnetic stability of the high coercivity permanent magnet 12.

[0026] In this embodiment, the magnetic field lines of the high coercivity permanent magnet 12 are axial magnetic field lines; the magnetic field lines of the magnetized soft magnetic yoke 22 are also axial magnetic field lines. The magnetic field lines of both the high coercivity permanent magnet 12 and the soft magnetic yoke 22 are axial, which can maximize the attraction and repulsion between the two (permanent magnet assembly 1 and static iron assembly 2), compared with other magnetic field line arrangements.

[0027] Specifically, the soft magnetic yoke 22 is fixedly installed on the upper inner wall of the outer casing 5, and an epoxy resin b23 is fixedly connected to one end of the single electromagnetic coil 21 near the moving permanent magnet assembly 1. The epoxy resin b23 is recessed in the annular outer groove 221. That is to say, the single electromagnetic coil 21 is recessed in the annular outer groove 221, so that the inner and outer ring soft magnetic yokes of the soft magnetic yoke 22, which are attracted or repelled by the high coercivity permanent magnet 12, surround the single electromagnetic coil 21, so that the magnetic lines of force of the single electromagnetic coil 21 are fully utilized, ensuring the magnetization effect of the inner and outer ring soft magnetic yokes, and further improving the closing efficiency.

[0028] It should also be noted that the inner ring end face 223 of the inner ring soft magnetic yoke is positioned opposite to the upper end face 121 of the high coercivity permanent magnet 12, and the outer ring end face 222 of the outer ring soft magnetic yoke is positioned opposite to the upper end face 111 of the magnetic shell ring. The outer diameter of the high coercivity permanent magnet 12 is smaller than the inner diameter of the outer ring end face 222. This minimizes mutual interference when the inner ring end face 223 and the outer ring end face 222 interact with the upper end face 121 of the permanent magnet and the upper end face 111 of the magnetic shell ring, further improving the closing efficiency. Combined with the axial magnetic lines of force of both, interference can be further reduced and the closing efficiency improved.

[0029] Finally, due to all the structural arrangements described above in this embodiment, when a single electromagnetic coil 21 is energized with a positive current pulse, the magnetic pole direction of the inner ring end face 223 is opposite to that of the upper end face 121 of the permanent magnet, and the magnetic pole direction of the outer ring end face 222 is opposite to that of the upper end face 111 of the magnetic shell ring. Furthermore, the magnetic pole directions of the inner ring end face 223 and the outer ring end face 222 are opposite, as shown in the attached diagram. Figure 2 , 4The diagram shows the closed state. When a reverse current pulse is applied to a single electromagnetic coil 21, the magnetic pole direction of the inner ring end face 223 is the same as that of the upper end face 121 of the permanent magnet, and the magnetic pole direction of the outer ring end face 222 is the same as that of the upper end face 111 of the magnetic shell. The magnetic pole directions of the inner ring end face 223 and the outer ring end face 222 are opposite, i.e., the circuit is open. The efficient closing and opening of the circuit is due to the efficient arrangement of the single coil 21 within the annular outer groove 221 and surrounded by the soft magnetic yoke 22, the high coercivity permanent magnet 12 being recessed within the groove, the inner ring end face 223 of the inner soft magnetic yoke being opposite to the high coercivity permanent magnet 12 and the upper end face 121 of the permanent magnet, and the outer ring end face 222 of the outer soft magnetic yoke being opposite to the upper end face 111 of the magnetic shell. The outer diameter of the high coercivity permanent magnet 12 is small. The inner diameter of the outer ring end face 222; the above structures work together to achieve the above-mentioned efficient closing and opening process, so that the magnetic lines of force generated by the single coil 21 and the magnetic lines of force of the high coercivity permanent magnet 12 are not only fully utilized to magnetize the soft magnetic yoke 22 (outer ring end face 222) and the soft magnetic permeable shell 11 respectively, but also their (attraction and repulsion of the outer ring end face 222 and the annular upper end face 111 of the magnetic shell) are applied to the closing process, further improving the closing efficiency.

[0030] The opening process is the reverse of the closing process described above, and will not be repeated here. This magnetic structure also includes a unipolar switching drive circuit, which is mounted on the outer casing 5. The unipolar switching drive circuit applies forward or reverse current pulses to a single set of electromagnetic coils 21. A concentric slot is formed at the center of the outer casing 5, the stationary iron assembly 2, and the moving permanent magnet assembly 1. A guide rod 3 passes through and is connected within the concentric slot. An inner groove 224 is formed at the center of the stationary iron assembly 2 near the moving permanent magnet assembly 1. A closing spring 4 is fitted onto the guide rod 3, located between the moving permanent magnet assembly 1 and the stationary iron assembly 2. One end of the closing spring 4 is fixedly connected to the inner wall of the inner groove 224, and the other end is fixedly connected to the high coercivity permanent magnet 12. The upper end of the guide rod 3 is connected to the switch spindle or the arc-extinguishing chamber pull rod.

[0031] The following is a brief summary of the working process of this application: When the circuit is closed, the single electromagnetic coil 21 carries current to attract the lower polarity of the moving permanent magnet component 1, and overcomes the resistance of the opening spring 4 and the contact pressure spring to complete the closing action of the switch.

[0032] When the closed state is maintained: the moving permanent magnet component 1 and the stationary iron component 2 share the magnetic circuit and maintain the closed state. When the circuit is opened, a reverse current is applied to the single electromagnetic coil 21. Since it shares a magnetic circuit with the moving permanent magnet component 1, the resulting magnetomotive force breaks the holding of the high coercivity permanent magnet 12 and separates under the combined action of the opening spring 4 and the contact spring, thus achieving the opening.

[0033] When the circuit breaker is in the open position, the upward attraction of the moving permanent magnet component 1 is less than the preload of the opening spring 4, thus maintaining balance and stabilizing in the open position.

[0034] The above specific embodiments are merely preferred embodiments of this application. Based on the technical solutions of this application and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments. The above specific embodiments are merely explanations of this application and are not limitations on this application.

Claims

1. A magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet, characterized in that, include: Motion permanent magnet assembly (1), static iron assembly (2), guide rod (3) and outer cover (5); The static iron assembly (2) is fixedly installed on the upper inner wall of the outer cover (5), and the moving permanent magnet assembly (1) is slidably connected to the inner wall of the outer cover (5). The guide rod (3) is fixedly connected to the moving permanent magnet assembly (1), and the guide rod (3) is slidably connected to the static iron assembly (2) and the outer cover (5); The static iron assembly (2) includes a single set of electromagnetic coils (21) and a soft magnetic yoke (22). The soft magnetic yoke (22) has an annular outer groove (221) at one end near the moving permanent magnet assembly (1) to form an inner ring soft magnetic yoke and an outer ring soft magnetic yoke. The single set of electromagnetic coils (21) is recessed in the annular outer groove (221). When the single electromagnetic coil (21) is energized, the moving permanent magnet component (1) moves toward or away from the stationary iron component (2).

2. The magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 1, characterized in that, The motion permanent magnet assembly (1) includes a soft magnetic permeable shell (11) and a high coercivity permanent magnet (12). The upper end of the soft magnetic permeable shell (11) is provided with a groove, and the high coercivity permanent magnet (12) is recessed in the groove.

3. The magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet according to claim 2, characterized in that, The magnetic field lines of the high coercivity permanent magnet (12) are axial magnetic field lines; the magnetic field lines of the magnetized soft magnetic yoke (22) are axial magnetic field lines.

4. The magnetic mechanism for medium and high voltage electrical switches based on a moving permanent magnet according to claim 3, characterized in that, The inner ring end face (223) of the inner ring soft magnetic yoke is disposed opposite to the upper end face (121) of the high coercivity permanent magnet (12), and the outer ring end face (222) of the outer ring soft magnetic yoke is disposed opposite to the upper end face (111) of the magnetic shell ring. The outer diameter of the high coercivity permanent magnet (12) is smaller than the inner diameter of the outer ring end face (222).

5. A magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 4, characterized in that, When the single electromagnetic coil (21) is energized with a positive current pulse, the magnetic pole direction of the inner ring end face (223) is opposite to that of the upper end face (121) of the permanent magnet, the magnetic pole direction of the outer ring end face (222) is opposite to that of the upper end face (111) of the magnetic shell ring, and the magnetic pole direction of the inner ring end face (223) is opposite to that of the outer ring end face (222).

6. The magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 5, characterized in that, When the single electromagnetic coil (21) is subjected to a reverse current pulse, the magnetic pole direction of the inner ring end face (223) is the same as that of the upper end face (121) of the permanent magnet, the magnetic pole direction of the outer ring end face (222) is the same as that of the upper end face (111) of the magnetic shell ring, and the magnetic pole direction of the inner ring end face (223) is opposite to that of the outer ring end face (222).

7. A magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 6, characterized in that, The soft magnetic yoke (22) is fixedly installed on the upper inner wall of the outer cover (5), and the single electromagnetic coil (21) is fixedly connected to an epoxy resin b (23) at one end near the moving permanent magnet assembly (1), and the epoxy resin b (23) is recessed in the annular outer groove (221).

8. A magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 7, characterized in that, It also includes a unipolar switching drive circuit, which is mounted on the outer casing (5) and applies positive or reverse current pulses to the single set of electromagnetic coils (21) through the unipolar switching drive circuit.

9. A magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 2, characterized in that, The soft magnetic shell (11) slides on the inner wall of the outer cover (5), the epoxy adhesive a (13) is fixedly connected to the outer wall of the high coercivity permanent magnet (12), and the epoxy adhesive a (13) is recessed in the groove.

10. A magnetic actuator for medium- and high-voltage electrical switches based on a moving permanent magnet according to claim 4, characterized in that, The outer cover (5), the stationary iron assembly (2) and the moving permanent magnet assembly (1) are provided with a concentric through groove at their center, and the guide rod (3) is connected through the concentric through groove; the stationary iron assembly (2) is provided with an inner groove (224) at the center of one end near the moving permanent magnet assembly (1). A gate-opening spring (4) is sleeved on the guide rod (3). The gate-opening spring (4) is located between the moving permanent magnet assembly (1) and the stationary iron assembly (2). One end of the gate-opening spring (4) is fixedly connected to the inner wall of the inner groove (224), and the other end of the gate-opening spring (4) is fixedly connected to the high coercivity permanent magnet (12). The upper end of the guide rod (3) is connected to the switch spindle or the arc-extinguishing chamber pull rod.

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