High-low voltage isolation structure of a direct current contactor

Abstract

The application discloses a high-low voltage isolation structure of a direct-current contactor and particularly relates to the technical field of high-voltage electrical equipment. The structure comprises a shell, a center movable contact rod, a partition type insulation baffle, a high-low voltage isolation assembly and an airflow guiding assembly. The partition type insulation baffle divides the shell into a high-voltage arc-extinguishing chamber in the upper part and a low-voltage control chamber in the lower part, thereby realizing physical space isolation. The high-voltage arc-extinguishing chamber is provided with an electric resistance assembly composed of an electromagnetic arc-extinguishing ring and a stepped labyrinth insulation sealing sleeve, and the electric resistance assembly effectively prevents high-voltage arc from flashover to the low-voltage side by prolonging and zigzagging the creepage path. The airflow guiding assembly comprises an airflow guiding baffle arranged at the top of the partition type insulation baffle and capable of guiding the high-temperature and high-pressure gas generated in arc extinguishing to be discharged upwards, thereby avoiding the direct impact of the high-temperature and high-pressure gas on the electromagnetic drive coil in the low-voltage chamber and avoiding the pollution of the electromagnetic drive coil. The application further provides a detachable self-cleaning scraping type insulation ring which can automatically scrape off the carbide on the surface of the center movable contact rod when the center movable contact rod moves up and down, thereby improving long-term insulation reliability.

Description

Technical Field

[0001] This invention relates to the field of high-voltage electrical equipment technology, specifically to a high-low voltage isolation structure for a DC contactor. Background Technology

[0002] A DC contactor is a control device used to connect and disconnect DC main circuits, widely used in photovoltaic energy storage, electric vehicles, rail transportation, DC power distribution, and other fields. When disconnecting high-current DC loads, a strong electric arc is generated between the contacts. Unlike AC arcs, which have a natural zero-crossing point, DC arcs are more stable and difficult to extinguish, placing extremely high demands on the contactor's arc-extinguishing capability and insulation structure. Especially in high-voltage DC applications (such as 750V, 1000V and above), the arc energy is enormous, generating high-temperature, high-pressure ionized gases and metal vapors. If these high-temperature gases and metal particles are not controlled, they can diffuse into the low-voltage control section of the contactor, contaminating the electromagnetic drive coil, reducing its insulation performance, and even causing electrical short circuits or creepage, leading to equipment failure and posing serious safety hazards.

[0003] Traditional DC contactors often use simple insulating baffles or increased air gaps to isolate the high and low voltage areas. This method has significant shortcomings: firstly, simple physical separation is insufficient to effectively prevent the spread of arc plasma and the migration of metal dust; secondly, if the hot airflow generated during arc extinguishing directly impacts the lower low-voltage chamber, it will accelerate the aging of the insulating material and adversely affect the reliability of the low-voltage control components. Therefore, we propose a high-low voltage isolation structure for DC contactors to address these problems. Summary of the Invention

[0004] The purpose of this invention is to provide a high-low voltage isolation structure for a DC contactor to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A high-low voltage isolation structure for a DC contactor includes a housing and a central moving contact rod. A top terminal is fixedly connected to the top of the housing, and a low-voltage control terminal base is fixedly connected to the bottom of the housing. The interior of the housing is fixedly connected to a partitioned insulating baffle, which divides the interior of the housing into a low-pressure chamber at the bottom and a high-pressure arc-extinguishing chamber at the top. An electromagnetic drive coil is installed inside the low-pressure chamber; a stationary contact and a moving contact are provided inside the high-pressure arc-extinguishing chamber, and the stationary contact is electrically connected to the top terminal; a through hole is opened in the center of the partitioned insulating baffle, and the central moving contact rod passes through the through hole vertically and is slidably installed, with the lower end of the central moving contact rod extending into the low-pressure chamber and the upper end extending into the high-pressure arc-extinguishing chamber and fixedly connected to the moving contact; a current-blocking component is provided inside the high-pressure arc-extinguishing chamber to extend the creepage distance from high pressure to low pressure; an airflow guide baffle is fixedly connected to the top of the partitioned insulating baffle to change the flow direction of the arc-extinguishing gas and prevent it from directly impacting the low-pressure chamber.

[0006] Preferably, the resistive component includes an electromagnetic arc-quenching coil and a stepped labyrinth insulating sealing sleeve; The stepped labyrinth insulating sealing sleeve is fixedly connected to the inner wall of the high-voltage arc-extinguishing chamber. Its exterior features a labyrinth structure with alternating multi-level annular protrusions and grooves to form a tortuous creepage path. The electromagnetic arc-extinguishing coil is fixedly connected to the top of the partitioned insulating baffle and surrounds the outer periphery of the stationary and moving contacts.

[0007] Preferably, a magnetic pad is fixedly connected to the bottom of the low-pressure chamber, and the central moving contact rod is slidably connected to the magnetic pad.

[0008] Preferably, a sealing isolation sleeve is fixedly connected to the outside of the central moving contact rod, and a tripping reset spring is fixedly connected to the bottom of the sealing isolation sleeve. The end of the tripping reset spring is fixedly connected to the magnetic pad.

[0009] Preferably, a fixed threaded groove is provided at the center of the bottom of the electromagnetic arc extinguishing coil, and a detachable self-cleaning scraper-type insulating ring is threaded into the fixed threaded groove.

[0010] Preferably, the inner wall of the self-cleaning scraper-type insulating ring is fixedly connected with multiple elastic scrapers, and the elastic scrapers are all in light contact with the outer wall of the central moving contact rod. The self-cleaning scraper-type insulating ring is also fixedly connected to a debris collection frame for collecting scraped dust. The debris collection frame is an annular groove with its opening facing the elastic scraper, and the inner wall of the debris collection frame is provided with an anti-static coating.

[0011] Preferably, the airflow guide baffle is inclined downwards, and a tortuous airflow path is formed between adjacent baffles to guide the high-temperature gas generated during arc extinguishing to flow to the top of the high-pressure arc extinguishing chamber.

[0012] Preferably, an equalizing ring is fitted onto the stationary contact near the center moving contact rod to reduce the risk of partial discharge and insulation breakdown.

[0013] Preferably, the low-voltage control terminal base has a wiring cavity inside for connecting external wires, the wiring cavity is connected to a cavity for accommodating an electromagnetic drive coil, and the outer wall of the low-voltage control terminal base has a sealed wiring port.

[0014] Preferably, an isolation plate is fixedly connected to the outside of the housing, and multiple ventilation holes are provided on the top of the housing.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This high- and low-voltage isolation structure of a DC contactor constructs a multi-layered insulation defense system combining active and passive methods by incorporating a composite resistive assembly consisting of an electromagnetic arc-extinguishing coil and a stepped labyrinth insulating seal. The electromagnetic arc-extinguishing coil generates a magnetic field perpendicular to the arc current direction, driving the arc to spread outward and enter the arc-extinguishing grid, accelerating its cooling and extinguishing. The stepped labyrinth insulating seal, through its complex multi-level convex and concave surface, significantly extends the surface creepage distance between the high-voltage end (stationary contact area) and the low-voltage end (insulating baffle). This extension is tortuous and non-linear; any leakage path attempting to develop along the surface is repeatedly blocked within the labyrinth structure, significantly increasing the surface flashover voltage and effectively suppressing the risk of high voltage breaking down the insulation through surface leakage.

[0016] 2. This high-low voltage isolation structure of a DC contactor cleverly solves the problem of insulation performance degradation caused by surface contamination of the moving contact rod during long-term operation by incorporating a detachable, self-cleaning scraper-type insulating ring. With each opening and closing action, the moving contact rod moves up and down, and the elastic scraper gently removes conductive contaminants such as carbides and metal spatter adhering to its surface. The scraped debris falls into the anti-static debris collection box below, preventing secondary re-entrainment. This design achieves automatic online cleaning during operation, maintaining the surface cleanliness and insulation strength of the moving contact rod, a key moving component between high and low voltage. Furthermore, the threaded connection of the insulating ring facilitates regular maintenance and replacement, improving the product's maintainability and long-term operational reliability.

[0017] 3. This high-low voltage isolation structure of a DC contactor alters the flow path of the impact airflow generated during arc extinguishing by using an airflow guide baffle positioned atop the partitioned insulating baffle. The high-temperature, high-speed airflow, which would normally impact the baffle vertically downwards and potentially seep into the low-pressure chamber through gaps, is forced to change direction, decelerating and turning within the tortuous channel formed by the baffle, ultimately being guided to the top of the housing for discharge. This significantly reduces the physical and thermal impact of the hot airflow on the partitioned insulating baffle, protecting the insulation performance of the baffle material. Simultaneously, it prevents high-temperature gas from entering the low-pressure chamber, which could lead to excessive coil temperature rise or aging of the insulation material, thus improving the overall environmental tolerance and lifespan of the contactor. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure in this invention; Figure 3 This is a structural schematic diagram from another cross-sectional perspective of the present invention; Figure 4 This is a schematic diagram of the electromagnetic arc-extinguishing coil in this invention; Figure 5 This is a schematic diagram of the fixed threaded groove structure in this invention; Figure 6 This is a schematic diagram of the structure of the self-cleaning scraper-type insulating ring in this invention.

[0020] In the diagram: 1. Isolation plate; 2. Housing; 3. Low-voltage control terminal base; 4. Top terminal block; 5. Stationary contact; 6. Electromagnetic drive coil; 7. Center moving contact rod; 8. Moving contact; 9. Magnetic pad; 10. Opening reset spring; 11. Sealing isolation sleeve; 12. Zoned insulating baffle; 13. Low-voltage chamber; 14. High-voltage arc-extinguishing chamber; 15. Electromagnetic arc-extinguishing coil; 16. Stepped labyrinth insulating sealing sleeve; 17. Equalizing ring; 18. Airflow guide baffle; 19. Self-cleaning scraper-type insulating ring; 20. Fixed threaded groove; 21. Elastic scraper; 22. Debris collection frame. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example: Figures 1-6 As shown, the present invention provides a high and low voltage isolation structure for a DC contactor, including a housing 2 and a central moving contact rod 7, characterized in that: a top terminal block 4 is fixedly connected to the top of the housing 2, and a low voltage control terminal base 3 is fixedly connected to the bottom; A partitioned insulating baffle 12 is fixedly connected inside the housing 2. The partitioned insulating baffle 12 divides the interior of the housing 2 into a low-pressure chamber 13 located at the bottom and a high-pressure arc-extinguishing chamber 14 located at the top. An electromagnetic drive coil 6 is installed inside the low-pressure chamber 13; a stationary contact 5 and a moving contact 8 are provided inside the high-pressure arc-extinguishing chamber 14, with the stationary contact 5 electrically connected to the top terminal 4; a through hole is provided in the center of the partitioned insulating baffle 12, through which the central moving contact rod 7 passes vertically and is slidably installed, with the lower end of the central moving contact rod 7 extending into the low-pressure chamber 13 and the upper end extending into the high-pressure arc-extinguishing chamber 14 and fixedly connected to the moving contact 8; a resistive component is provided inside the high-pressure arc-extinguishing chamber 14 to extend the creepage distance from high pressure to low pressure; an airflow guide baffle 18 is fixedly connected to the top of the partitioned insulating baffle 12 to change the flow direction of the arc-extinguishing gas and prevent it from directly impacting the low-pressure chamber 13.

[0023] It should be noted that in this embodiment, the housing 2 and the partitioned insulating baffle 12 together constitute the main frame of the equipment. The partitioned insulating baffle 12 is the core physical partition, spatially dividing the interior into a low-voltage chamber 13 that performs control functions and a high-voltage arc-extinguishing chamber 14 that performs high-current interruption functions, laying the structural foundation for electrical isolation. The central moving contact rod 7 is the core moving component that runs through the high and low voltage chambers, responsible for transmitting power from the electromagnetic drive coil 6, driving the moving contact 8 to close and separate from the stationary contact 5. This layout achieves the initial physical separation of the high-voltage main circuit and the control circuit.

[0024] The resistive component includes an electromagnetic arc-quenching coil 15 and a stepped labyrinth insulating sealing sleeve 16; The stepped labyrinth insulating sealing sleeve 16 is fixedly connected to the inner wall of the high-voltage arc-extinguishing chamber 14. Its exterior presents a labyrinth structure with alternating multi-level annular protrusions and grooves to form a tortuous creepage path. The electromagnetic arc-extinguishing ring 15 is fixedly connected to the top of the partitioned insulating baffle 12 and surrounds the outer periphery of the stationary contact 5 and the moving contact 8.

[0025] It should be noted that, in this embodiment, the stepped labyrinth insulating sealing sleeve 16, through its labyrinth structure, greatly extends the surface creepage distance from the high-voltage contact to the lower low-voltage area (i.e., the insulating baffle 12), forcing the potential leakage current to take an extremely tortuous path, thereby significantly increasing the surface flashover voltage. The electromagnetic arc extinguishing coil 15 generates a magnetic field perpendicular to the arc, driving the arc generated between the contacts to move rapidly and elongate, and guiding it to the arc extinguishing grid for cooling and extinguishing, thereby reducing the arc energy and duration at the source and alleviating the pressure on the insulation system. The combination of these two elements constitutes a dual protection of active arc extinguishing and passive insulation reinforcement.

[0026] A magnetic pad 9 is fixedly connected to the bottom of the low-pressure chamber 13, and the central moving contact rod 7 is slidably connected to the magnetic pad 9.

[0027] It should be noted that, in this embodiment, firstly, it serves as a sliding guide component at the lower end of the central moving contact rod 7, ensuring the straightness and stability of the moving contact rod during its reciprocating motion. Secondly, and more importantly, it is made of a high-permeability material. When the electromagnetic drive coil 6 is working, it, together with the moving iron core of the drive coil (usually connected to the lower end of the moving contact rod 7), forms an optimized magnetic circuit, which enhances the electromagnetic attraction, thereby improving the speed and reliability of the contactor's closing action.

[0028] A sealing isolation sleeve 11 is fixedly connected to the outside of the center moving contact rod 7. A tripping reset spring 10 is fixedly connected to the bottom of the sealing isolation sleeve 11. The end of the tripping reset spring 10 is fixedly connected to the magnetic pad 9.

[0029] It should be noted that in this embodiment, the sealing sleeve 11 constitutes a dynamic sealing barrier. It fits onto the moving contact rod 7 and precisely engages with the central through-hole of the partitioned insulating baffle 12. This allows the rod to slide freely while effectively preventing contaminants such as arc plasma and metal dust from leaking into the lower low-pressure chamber 13 through this movement gap, serving as a crucial line of defense for the low-pressure control components. The tripping reset spring 10 provides a reliable tripping driving force. When the electromagnetic drive coil 6 is de-energized, the spring force ensures that the moving contact rod 7 moves downward quickly and stably, reliably separating the moving and stationary contacts.

[0030] The electromagnetic arc extinguishing coil 15 has a fixed threaded groove 20 at the bottom center, and a detachable self-cleaning scraper-type insulating ring 19 is connected to the fixed threaded groove 20.

[0031] It should be noted that, in this embodiment, the threaded connection allows this crucial cleaning component to be easily unscrewed for inspection, cleaning, or replacement without disassembling the entire arc-extinguishing system or contactor body. This design significantly improves the convenience and cost-effectiveness of product maintenance during long-term use.

[0032] Multiple elastic scrapers 21 are fixedly connected to the inner wall of the self-cleaning scraper-type insulating ring 19, and the elastic scrapers 21 are all in light contact with the outer wall of the center moving contact rod 7. The self-cleaning scraper-type insulating ring 19 is also fixedly connected to a debris collection frame 22 for collecting scraped dust. The debris collection frame 22 is an annular groove with its opening facing the elastic scraper 21, and the inner wall of the debris collection frame 22 is provided with an anti-static coating.

[0033] It should be noted that in this embodiment, the surface of the center moving contact rod 7 is automatically cleaned online. Each time the contactor operates, the center moving contact rod 7 moves up and down, and multiple elastic scrapers 21 lightly touch its surface, scraping away conductive carbides, molten metal spatter, and other insulating contaminants that adhere to the rod during operation. This maintains the cleanliness and insulation performance of the rod surface and prevents contaminants from accumulating and forming conductive channels. The scraped-off contaminant debris falls directly into the debris collection frame 22 below. The antistatic coating on the inner wall of the collection frame prevents fine particles from being re-adsorbed by static electricity and ensures the durability of the cleaning effect.

[0034] The airflow guide baffle 18 is inclined downwards, and a tortuous airflow path is formed between adjacent baffles to guide the high-temperature gas generated by the arc extinguishing to flow to the top of the high-pressure arc extinguishing chamber 14.

[0035] It should be noted that in this embodiment, when a large current is interrupted to generate an electric arc, high-temperature and high-pressure incandescent gas is produced. The main function of the baffle is to change the direction of this impacting airflow. Its inclined and tortuous design forces the high-speed hot airflow, which would originally be vertically downward and violently impacting the partitioned insulating baffle 12 (top of the low-pressure chamber), to change direction. Within the labyrinthine channel formed by the baffle, the airflow slows down, changes direction, and its kinetic energy is dissipated. Finally, it is guided to the top of the housing 2 and discharged through the vent. This effectively prevents the high-temperature gas and uncooled arc products from directly impacting and thermally eroding the top of the low-pressure chamber, and also reduces the impact of thermal shock on the lifespan of the insulating material.

[0036] A voltage equalization ring 17 is sleeved on the stationary contact 5 near the center moving contact rod 7 to reduce the risk of partial discharge and insulation breakdown.

[0037] It should be noted that in this embodiment, under high-voltage DC conditions, uneven electric field distribution can easily generate excessively high field strength at conductor tips or edges (such as the root of stationary contact 5), thereby triggering corona discharge or even local insulation breakdown. The equalizing ring 17 is fitted onto stationary contact 5 and is at potential with it. Its smooth annular structure can effectively equalize the electric field distribution in its surrounding space, making the electric field lines more uniform, thereby significantly reducing the probability of partial discharge and improving the long-term insulation reliability of the components inside the high-voltage arc-extinguishing cavity.

[0038] The low-voltage control terminal base 3 has a wiring cavity inside for connecting external wires. The wiring cavity is connected to the cavity for accommodating the electromagnetic drive coil 6, and the outer wall of the low-voltage control terminal base 3 is provided with a sealed wiring port.

[0039] It should be noted that, in this embodiment, its main function is to provide an independent, sealed connection channel for external low-voltage control circuits (such as signal lines controlling the on / off state of the electromagnetic drive coil 6). The design of the wiring cavity and sealed wiring port ensures that the connection of the control circuit is completed entirely inside the low-voltage control terminal base 3, isolated from the external environment.

[0040] An isolation plate 1 is fixedly connected to the outside of the housing 2, and multiple ventilation holes are provided on the top of the housing 2.

[0041] It should be noted that in this embodiment, the insulating plate 1 is a large-area additional insulating plate installed on the outside of the contactor housing (shell 2). Its function is to increase the additional air gap and creepage distance between the contactor and external grounding components (such as mounting backplates) when the contactor is installed in a metal distribution cabinet or other equipment, thereby enhancing the overall insulation level of the machine to ground. The vent at the top of the shell 2 is an outlet designed for internal gas flow, allowing the heated expansion gas in the high-voltage arc-extinguishing chamber and the airflow guided by the airflow guide baffle to be discharged smoothly, so as to balance the internal air pressure and prevent pressure accumulation. At the same time, the vent is covered with a filter screen to prevent external foreign objects from entering.

[0042] In summary, the high-low voltage isolation structure of this DC contactor requires a complex system engineering approach to achieve its isolation function. Firstly, the partitioned insulating baffles 12 form the main isolation barrier. When an arc is generated within the high-voltage arc-extinguishing chamber 14, the stepped labyrinth insulating sealing sleeve 16 significantly extends the creepage path downwards along the inner wall of the housing 14, forcing potential leakage currents to bypass the long and tortuous surface, thus making it difficult for flashover to develop. Simultaneously, the magnetic field generated by the electromagnetic arc-extinguishing coil 15 drives the arc movement, accelerating its entry into the arc-extinguishing grid where it is segmented and cooled, fundamentally reducing the arc energy and duration. During the upward movement of the high-temperature gas generated during arc extinguishing, it encounters the airflow guide baffles 18, forcibly changing its flow direction. Most of the kinetic and thermal energy is consumed within the labyrinthine channels formed by the baffles, and the finally cooled residual gas is gently discharged from the top vent, reducing direct thermal impact on the lower insulating baffles. During operation, the elastic scraper 21 on the self-cleaning scraper-type insulating ring 19 continuously scrapes away deposits on the surface of the center moving contact rod 7, maintaining the rod's insulation performance. The sealing isolation sleeve 11 forms a dynamic seal at the movement gap. The equalizing ring 17 optimizes the electric field at the high-voltage end, while the magnetic pad 9 and the tripping spring 10 ensure reliable operation. These structures work together synergistically, ensuring that even under harsh conditions of frequent interruption of high-current DC loads, the electrical, thermal, and contamination effects on the high-voltage side are maximally confined within the high-voltage arc-extinguishing chamber 14. This reliably protects the electromagnetic drive system within the low-voltage chamber 13, significantly improving the overall electrical life, insulation reliability, and environmental adaptability of the DC contactor.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-low voltage isolation structure for a DC contactor, comprising a housing (2) and a central moving contact rod (7), characterized in that: The top of the housing (2) is fixedly connected to a top terminal (4), and the bottom is fixedly connected to a low-voltage control terminal base (3). The interior of the housing (2) is fixedly connected to a partitioned insulating baffle (12), which divides the interior of the housing (2) into a low-pressure chamber (13) located at the bottom and a high-pressure arc-extinguishing chamber (14) located at the top. An electromagnetic drive coil (6) is installed in the low-pressure chamber (13); a stationary contact (5) and a moving contact (8) are provided in the high-pressure arc-extinguishing chamber (14), and the stationary contact (5) is electrically connected to the top terminal (4); a through hole is provided in the center of the partitioned insulating baffle (12), and the central moving contact rod (7) passes through the through hole in the vertical direction and is slidably provided. The lower end of the central moving contact rod (7) extends into the low-pressure chamber (13), and the upper end extends into the high-pressure arc-extinguishing chamber (14) and is fixedly connected to the moving contact (8); a current-blocking component is provided in the high-pressure arc-extinguishing chamber (14) to extend the creepage distance from high pressure to low pressure; an airflow guide baffle (18) is fixedly connected to the top of the partitioned insulating baffle (12) to change the flow direction of the arc-extinguishing gas and prevent it from directly impacting the low-pressure chamber (13).

2. The high and low voltage isolation structure of a DC contactor according to claim 1, characterized in that: The resistive component includes an electromagnetic arc-quenching coil (15) and a stepped labyrinth insulating sealing sleeve (16). The stepped labyrinth insulating sealing sleeve (16) is fixedly connected to the inner wall of the high-voltage arc-extinguishing cavity (14), and its exterior presents a labyrinth structure with alternating multi-level annular protrusions and grooves to form a tortuous creepage path; the electromagnetic arc-extinguishing coil (15) is fixedly connected to the top of the partitioned insulating baffle (12) and surrounds the outer periphery of the stationary contact (5) and the moving contact (8).

3. The high and low voltage isolation structure of a DC contactor according to claim 2, characterized in that: A magnetic pad (9) is fixedly connected to the bottom of the low-pressure chamber (13), and the central moving contact rod (7) is slidably connected to the magnetic pad (9).

4. The high and low voltage isolation structure of a DC contactor according to claim 3, characterized in that: The center moving contact rod (7) is fixedly connected to a sealing isolation sleeve (11), and the bottom of the sealing isolation sleeve (11) is fixedly connected to a tripping reset spring (10). The end of the tripping reset spring (10) is fixedly connected to a magnetic pad (9).

5. The high and low voltage isolation structure of a DC contactor according to claim 4, characterized in that: The electromagnetic arc extinguishing coil (15) has a fixed threaded groove (20) at the bottom center position, and a detachable self-cleaning scraper-type insulating ring (19) is threaded into the fixed threaded groove (20).

6. The high and low voltage isolation structure of a DC contactor according to claim 5, characterized in that: The inner wall of the self-cleaning scraper insulating ring (19) is fixedly connected with multiple elastic scrapers (21), and the elastic scrapers (21) all lightly touch the outer wall of the central moving contact rod (7). The self-cleaning scraper insulating ring (19) is also fixedly connected to a debris collection frame (22) for carrying the scraped dust. The debris collection frame (22) is an annular groove with its opening facing the elastic scraper (21), and the inner wall of the debris collection frame (22) is provided with an antistatic coating.

7. The high and low voltage isolation structure of a DC contactor according to claim 6, characterized in that: The airflow guide baffle (18) is inclined downwards, and a tortuous airflow path is formed between adjacent baffles to guide the high-temperature gas generated by the arc extinguishing to flow to the top of the high-pressure arc extinguishing chamber (14).

8. The high and low voltage isolation structure of a DC contactor according to claim 7, characterized in that: The stationary contact (5) is fitted with an equalizing ring (17) near the center moving contact rod (7) to reduce the risk of partial discharge and insulation breakdown.

9. The high and low voltage isolation structure of a DC contactor according to claim 8, characterized in that: The low-voltage control terminal base (3) has a wiring cavity inside for connecting external wires. The wiring cavity is connected to the cavity for accommodating the electromagnetic drive coil (6), and the outer wall of the low-voltage control terminal base (3) is provided with a sealed wiring port.

10. The high and low voltage isolation structure of a DC contactor according to claim 9, characterized in that: An isolation plate (1) is fixedly connected to the outside of the housing (2), and multiple ventilation holes are provided on the top of the housing (2).

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