Arc striking assembly and direct-current neutral point isolating switch

Abstract

The utility model discloses an arc striking assembly and a direct-current neutral point isolating switch, which are used for solving the problem that the service life and the reliability of a switch are influenced by contact ablation and insulation performance reduction caused by difficulty in quickly and stably extinguishing an arc in an existing oscillation circuit. The direct-current neutral point isolating switch comprises an operating mechanism, a transmission assembly, a base, operating insulators, a contact finger side conductive seat, a contact side conductive seat and an arc striking assembly, the output end of the operating mechanism is provided with a transmission rod, the operating insulators are rotationally installed on the upper portion of the base, and the transmission assembly is located between the transmission rod and the operating insulators; the contact finger side conductive seat and the contact side conductive seat are both fixed on the upper portion of the corresponding operation insulator, the square tube support of the arc striking assembly is fixedly connected with the corresponding contact finger side conductive seat or the contact side conductive seat, and the contact finger side conductive seat and the contact side conductive seat drive the square tube support arranged on the contact finger side conductive seat and the contact side conductive seat to rotate when rotating. According to the utility model, four fractures are provided, so that the total voltage can be equally distributed to each fracture, and the electric field intensity of a single fracture is obviously reduced.

Description

Technical Field

[0001] This utility model relates to the field of disconnecting switch technology, specifically an arc-starting component and a DC neutral point disconnecting switch. Background Technology

[0002] The neutral point disconnector (NBS) is a core device in high-voltage direct current (HVDC) transmission systems, enabling neutral bus potential regulation, system topology reconfiguration, and rapid fault isolation. In scenarios such as flexible DC grids and offshore wind power DC aggregation, the NBS needs to complete load tripping operations within milliseconds while simultaneously withstanding the coupled impact of bidirectional high current and high voltage gradients.

[0003] The existing DC neutral point disconnect switches in China widely adopt the technical solution with oscillation circuit. Although this design can achieve basic functions under traditional working conditions, it has gradually shown the following technical limitations in complex power system scenarios: (1) Inefficiency of arc energy management; the oscillation circuit artificially creates a current zero-crossing point through current oscillation to assist in arc extinguishing, but it faces the problem of excessively long arc burning time in DC systems. Studies have shown that when the transfer current exceeds 3000A, the arc plasma temperature can reach more than 15000K, while the energy dissipation efficiency of the traditional oscillation circuit is only about 85%. Under the frequent current impact caused by the grid connection of new energy, the contact erosion rate is as high as 0.12mm / thousandth operation, which is difficult to meet the mechanical life requirement of 20,000 times. (2) Insufficient dynamic voltage equalization capability; in the multi-break series structure, the oscillation circuit has extremely high requirements for the synchronization of the break opening, which needs to be ≤0.3ms. However, due to insufficient stiffness of the connecting rod and cumulative tolerance error, the actual opening time difference of the existing mechanical transmission system often exceeds 2ms, resulting in the first opening contact bearing more than 75% of the system voltage. For example, under the 21kV condition, the first opening contact voltage reaches 15.75kV, which significantly exceeds the 12kV design threshold, causing the risk of insulation breakdown. (3) Limitations of resonance suppression; NBS with oscillation circuit has inherent defects in suppressing ferroresonance. When the system experiences intermittent arc grounding fault, the high-frequency oscillation current can reach hundreds of amperes, and the traditional solution cannot effectively block the repeated charging and discharging process of capacitor energy, resulting in arc overvoltage or resonance overvoltage, which can reach 3-5 times the rated voltage, threatening the equipment insulation. For example, the ferroresonance phenomenon in the neutral point ungrounded system is prone to PT burnout and other faults due to the lack of an effective energy release channel. (4) Limited environmental adaptability; the oscillation circuit is highly sensitive to the operating environment. In offshore wind power scenarios, salt spray corrosion can cause contact resistance deviations of more than 5μΩ, accelerating oxide film formation; at the same time, mechanical vibration may cause circuit parameter deviations, such as inductance fluctuations of ±10%, resulting in inaccurate preset oscillation frequency and a decrease in arc extinguishing efficiency of more than 40%. Existing protective covers mostly use ordinary epoxy resin, which is difficult to resist arc heat radiation, and the risk of surface carbonization and leakage is significantly increased. (5) Disadvantages in operation and maintenance economy; the precision inductor components in the oscillation circuit need to be calibrated regularly, and a single maintenance takes more than 72 hours, and the core components rely on imports, with spare parts costing 2-3 times more than domestic alternatives; (6) Energy consumption problem: the oscillation circuit needs to continuously consume auxiliary power, forming significant additional losses in large DC power grids. From the perspective of technical performance, the NBS switch with oscillation circuit type still has room for improvement in arc extinguishing effect and suppression of neutral point potential fluctuations compared with some foreign NBS switches with unique and innovative structures.

[0004] Existing domestic oscillation circuits struggle to quickly and stably extinguish arcs when handling high-amplitude, high-frequency transient currents, easily leading to contact erosion and decreased insulation performance, thus affecting the switch's lifespan and reliability. Simultaneously, their control precision for the neutral point potential is relatively low, failing to effectively maintain the neutral point potential within a safe range during rapid changes in the power system, increasing potential risks to system operation. Utility Model Content

[0005] The purpose of this invention is to provide an arc-initiating component and a DC neutral point disconnecting switch to solve the problem that existing oscillation circuits are unable to quickly and stably extinguish the arc, leading to contact erosion and decreased insulation performance, which in turn affects the service life and reliability of the switch.

[0006] The technical solution adopted by this utility model to solve its technical problem is: an arc-initiating assembly, including a finger-side arc-initiating contact, a head-side arc-initiating contact, an arc-initiating shaft, a square tube bracket, and a shaft support cylinder. The first end of the finger-side arc-initiating contact and the first end of the head-side arc-initiating contact both have a contact plate. The second end of the finger-side arc-initiating contact and the second end of the head-side arc-initiating contact are respectively fixed on the corresponding side of the arc-initiating shaft. The arc-initiating shaft passes through the shaft support cylinder and is rotatably connected to the shaft support cylinder. The square tube bracket is fixed to the lower part of the shaft support cylinder. The lower end of the arc-initiating shaft passes through the square tube bracket. The square tube bracket has a tension spring inside. The first end of the tension spring is fixedly connected to the square tube bracket through a first tension spring rod. The second end of the tension spring is fixedly connected to the lower end of the arc-initiating shaft through a second tension spring rod.

[0007] Furthermore, the second end of both the finger-side arc-initiating contact and the contact-side arc-initiating contact are fixedly connected to the arc-initiating shaft via clamps.

[0008] Furthermore, the first end of the finger-side arc-inducing contact, the first end of the contact-side arc-inducing contact, and their corresponding contact plate sidewalls all have slots.

[0009] Furthermore, the first end of the first tension spring rod is fixedly connected to the square tube bracket, and the first end of the tension spring is hooked onto the second end of the first tension spring rod; the first end of the second tension spring rod passes through the arc-inducing shaft, and the second end of the tension spring is hooked onto the second end of the second tension spring rod.

[0010] This utility model also provides a DC neutral point disconnect switch, including an operating mechanism, a transmission assembly, a base, an operating insulator, a finger-side conductive seat, a contact-side conductive seat, and an arc-starting assembly. The operating mechanism is located below the base and has a transmission rod at its output end. The operating insulator is rotatably mounted on the upper part of the base. The transmission assembly is located between the transmission rod and each operating insulator. When the transmission rod rotates, it drives the operating insulator to rotate through the transmission assembly. The finger-side conductive seat has a finger, and the contact-side conductive seat has a contact. Both the finger-side and contact-side conductive seats are fixed to the upper part of the corresponding operating insulator. The square tube support of the arc-starting assembly is fixedly connected to the corresponding finger-side or contact-side conductive seat. When the finger-side and contact-side conductive seats rotate, they drive the square tube support mounted on them to rotate.

[0011] Furthermore, the operating insulator has two sets, each set including three operating insulators arranged on the left, middle and right. The contact-side conductive seat is fixed to the upper part of the middle insulator, and the contact-finger-side conductive seat is fixed to the upper part of the left and right operating insulators.

[0012] Furthermore, the two sets of operating insulators are fixedly connected by a connecting plate between the upper contact finger side conductive seat of the right operating insulator in the first set and the upper contact finger side conductive seat of the left operating insulator in the second set.

[0013] Further, the transmission assembly includes a crank arm, a main pull rod, a driving flange, phase-to-phase pull rods, pole-to-pole pull rods, a horizontal connecting rod, a first driven flange, and a second driven flange; in the first group of operating insulators, the lower end of the right operating insulator is fixed with a driving flange, the lower end of the left operating insulator is fixed with a first driven flange, and the lower end of the middle operating insulator is fixed with a second driven flange; in the second group of operating insulators, the lower ends of the left and right operating insulators are fixed with first driven flanges, and the lower end of the middle operating insulator is fixed with a second driven flange; the first end of the crank arm is fixedly connected to the upper end of the transmission rod, and the second end of the crank arm... The active flange is hinged to the main blade tie rod and connected to the active flange hinged to the first driven flange on the first set of operating insulators via phase-to-phase tie rods. The active flange is hinged to the second driven flange on the first set of operating insulators via pole-to-pole tie rods. The active flange is hinged to the first driven flange on the left operating insulator in the second set via a horizontal connecting rod. The two first driven flanges on the second set of operating insulators are connected by another phase-to-phase tie rod hinge. The second driven flange on the second set of operating insulators is hinged to the first driven flange on the right operating insulator in the second set via another pole-to-pole tie rod.

[0014] Furthermore, the active flange, the first driven flange, and the second driven flange are all rotatably connected to the base via bearing seats.

[0015] Furthermore, the bearing housing includes a skeleton oil seal, a gasket, a flange support bearing, a cover, and a housing. The driving flange, the first driven flange, and the second driven flange each have a flange shaft. The flange shaft extends into the housing, and there are two flange support bearings arranged vertically between them. The skeleton oil seal and the gasket are located between the upper end of the flange shaft and the housing. The lower end of the flange shaft is fixed with a plate by bolts. The cover is located at the lower end of the housing to seal the housing.

[0016] The beneficial effects of this utility model are as follows: This utility model adopts a DC neutral point isolating switch with a total of four breaks, which can evenly distribute the total voltage to each break, significantly reduce the electric field strength of a single break, avoid the risk of partial discharge or dielectric breakdown, resist transient overvoltage impact, and improve the system's withstand capability by more than 30%; the symmetrical layout of the four breaks can balance the bidirectional arc energy distribution and adapt to the DC system's power flow reversal requirements; the arc-initiating component between the breaks forces the arc to transfer synchronously and quickly between the four breaks, avoiding single-break overload, and the four breaks share the current, reducing the contact and contact finger ablation rate, and improving the arc extinguishing efficiency to more than 95%. At the same time, the protective cover prevents the arc from spreading upward and thus ablating the arc-initiating contacts. Attached Figure Description

[0017] Figure 1 This is a front view of the DC neutral point disconnecting switch of this utility model;

[0018] Figure 2 for Figure 1 A partial view in the middle;

[0019] Figure 3 This is a top view of the transmission assembly;

[0020] Figure 4 This is a half-sectional view of the bearing housing;

[0021] Figure 5 A 3D diagram of the arc-starting component;

[0022] Figure 6 Assembly drawing of the arc-starting shaft, shaft support cylinder and square tube bracket;

[0023] Figure 7 for Figure 6 BB section view in the middle;

[0024] Figure 8 This is an assembly drawing of the finger-side arc-starting contact, arc-starting shaft, square tube bracket, and shaft support cylinder;

[0025] In the diagram: 1. Connecting plate; 2. Finger-side conductive seat; 3. Contact-side conductive seat; 4. Operating insulator; 5. Arc-starting assembly; 51. Finger-side arc-starting contact; 511. Contact plate; 512. Slot; 51'. Contact-side arc-starting contact; 52. Clamping plate; 53. Arc-starting shaft; 54. Square tube bracket; 541. First tension spring rod; 542. Second tension spring rod; 543. Tension spring; 55. Shaft support cylinder; 56. Shaft support bearing; 57. Limiting rod; 58. Screw; 59. Limiting block; 6. Base; 7. Transmission... Moving components, 71 transmission rod, 72 crank arm, 73 transition plate, 74 stop block, 75 main cutter tie rod, 76 driving flange, 761 flange fixing rod, 762 flange shaft, 77 interphase tie rod, 78 interphase tie rod, 79 first driven flange, 79' second driven flange, 710 horizontal connecting rod, 8 operating mechanism, 9 bearing housing, 91 skeleton oil seal, 92 gasket, 93 flange support bearing, 94 plate, 95 bolt, 96 cover, 97 housing. Detailed Implementation

[0026] like Figures 1 to 8 As shown, the arc-initiating assembly 5 of this utility model includes a finger-side arc-initiating contact 51, a contact-side arc-initiating contact 51′, an arc-initiating shaft 53, a square tube bracket 54, and a shaft support cylinder 55. The DC neutral point disconnecting switch of this utility model includes an operating mechanism 8, a transmission assembly 7, a base 6, an operating insulator 4, a finger-side conductive seat 2, a contact-side conductive seat 3, and an arc-initiating assembly 5. The structure and working principle of this utility model will be described in detail below with reference to the accompanying drawings.

[0027] like Figure 5 , Figure 6 As shown, the arc-starting assembly 5 includes a finger-side arc-starting contact 51, a contact-side arc-starting contact 51', an arc-starting shaft 53, a square tube bracket 54, and a shaft support cylinder 55. Both the first end of the finger-side arc-starting contact 51 and the first end of the contact-side arc-starting contact 51' have a contact plate 511. The contact plate 511 is a rectangular copper-tungsten alloy plate with a tungsten content greater than 80%. The entire surface of the contact plate 511 is silver-plated to increase conductivity and heat resistance. The contact surface of the contact plate 511 has uniformly arranged teeth. Both the finger-side arc-starting contact 51 and the contact-side arc-starting contact 51' are rod-shaped and made of T2Y copper.

[0028] like Figure 5As shown, the second end of the finger-side arc-initiating contact 51 and the second end of the contact-side arc-initiating contact 51' are respectively fixed on the corresponding arc-initiating shaft 53. The arc-initiating shaft 53 passes through the shaft support cylinder 55 and is rotatably connected to the shaft support cylinder 55. The square tube bracket 54 is fixed to the lower part of the shaft support cylinder 55. The lower end of the arc-initiating shaft 53 passes through the square tube bracket 54. The square tube bracket 54 contains a tension spring 543. The first end of the tension spring 543 is fixedly connected to the square tube bracket 54 through the first tension spring rod 541, and the second end of the tension spring 543 is fixedly connected to the lower end of the arc-initiating shaft 53 through the second tension spring rod 542. Specifically, the second end of the finger-side arc-initiating contact 51 and the second end of the contact-side arc-initiating contact 51' are both fixedly connected to the arc-initiating shaft 53 through the clamping plate 52. During installation, the upper end of the arc-initiating shaft 53 can be inserted between the first and second clamping plates 52, and the second ends of the finger-side arc-initiating contact 51 and the contact-side arc-initiating contact 51' can be inserted between the second and third clamping plates 52. Bolts are installed between adjacent clamping plates 52 to achieve a fixed connection between the finger-side arc-initiating contact 51 and the contact-side arc-initiating contact 51' and the arc-initiating shaft 53. A shaft support bearing 56 is provided between the outer wall of the arc-initiating shaft 53 and the inner wall of the shaft support cylinder 55, thereby achieving a rotatable connection between the arc-initiating shaft 53 and the shaft support cylinder 55. The square tube bracket 54 is fixedly connected to the shaft support cylinder 55 by screws 58. Figure 7 As shown, the first end of the first tension spring rod 541 is fixedly connected to the square tube bracket 54, and the first end of the tension spring 543 is hooked onto the second end of the first tension spring rod 541; the first end of the second tension spring rod 542 passes through the arc-initiating shaft 53 and is perpendicular to the arc-initiating shaft 53, and the second end of the tension spring 543 is hooked onto the second end of the second tension spring rod 542. Figure 6 , Figure 8 As shown, a limit rod 57 is fixed to the lower end of the arc-initiating shaft 53, and a limit block 59 is fixed to the side wall of the square tube bracket 54. The limit block 59 is used to limit the swing amplitude of the limit rod 57. When the limit rod 57 touches the limit block 59, it ensures that the arc-initiating contact 51' on the contact side and the arc-initiating contact 51 on the contact finger side are at a suitable angle to facilitate good contact during closing.

[0029] In addition, the first end of the finger-side arc-starting contact 51, the first end of the contact-side arc-starting contact 51', and the corresponding sidewall of the contact plate 511 are all provided with slots 512. The slots 512 make the first end of the finger-side arc-starting contact 51 and the first end of the contact-side arc-starting contact 51' elastic.

[0030] like Figure 1As shown, the DC neutral point disconnector includes an operating mechanism 8, a transmission assembly 7, a base 6, operating insulators 4, contact-side conductive seats 2, contact-side conductive seats 3, and an arc-starting assembly 5. The operating mechanism 8 is located below the base 6, and its output end has a transmission rod 71. The operating insulators 4 are rotatably mounted on the upper part of the base 6. The transmission assembly 7 is located between the transmission rod 71 and each operating insulator 4. When the transmission rod 71 rotates, it drives the operating insulators 4 to rotate through the transmission assembly 7. The contact-side conductive seats 2 have contact fingers, and the contact-side conductive seats 3 have contacts. Both the contact-side conductive seats 2 and the contact-side conductive seats 3 are fixed to the upper part of the corresponding operating insulators 4. The square tube bracket 51 of the arc-starting assembly 5 is fixedly connected to the corresponding contact-side conductive seat 2 or contact-side conductive seat 3. When the contact-side conductive seats 2 and contact-side conductive seats 3 rotate, they drive the square tube bracket 54 mounted on them to rotate.

[0031] Specifically, the operating insulators 4 have two sets, each set including three operating insulators 4 arranged on the left, middle, and right. The contact-side conductive seat 3 is fixed to the upper part of the middle insulator 4, and the contact-finger-side conductive seat 2 is fixed to the upper parts of the left and right operating insulators 4. In the two sets of operating insulators 4, such as Figure 2 As shown, the contact finger-side conductive seat 2 on the upper part of the right operating insulator 4 in the first group and the contact finger-side conductive seat 2 on the upper part of the left operating insulator 4 in the second group are fixedly connected by a connecting plate 1. The connecting plate 1 enhances the overall structural stability. In each group of three operating insulators 4, the left and right operating insulators 4 rotate in the same direction, while the middle operating insulator 4 rotates in the opposite direction to the left operating insulator 4.

[0032] The square tube bracket 54 on the arc-starting assembly 5, corresponding to the finger-side arc-starting contact 51, is fixed to the bottom of the finger-side conductive base 2. The square tube bracket 54 on the arc-starting assembly 5, corresponding to the contact-side arc-starting contact 51′, is fixed to the bottom of the contact-side conductive base 3. When the operating insulator 4 corresponding to the finger-side conductive base 2 rotates, the square tube bracket 54 on the finger-side conductive base 2 rotates accordingly, thereby causing the corresponding finger-side arc-starting contact 51 to rotate in the horizontal plane. When the operating insulator 4 corresponding to the contact-side conductive base 3 rotates, the square tube bracket 54 on the contact-side conductive base 3 rotates accordingly, thereby causing the corresponding contact-side arc-starting contact 51′ to rotate in the horizontal plane. The finger-side arc-starting contact 51 and the contact-side arc-starting contact 51′ rotate in opposite directions, causing the contact plates 511 on the finger-side arc-starting contact 51 and the contact-side arc-starting contact 51′ to move closer or further apart, thus achieving closing or opening of the circuit.

[0033] like Figure 3As shown, the transmission assembly 7 includes a crank arm 72, a main blade pull rod 75, an active flange 76, phase-to-phase pull rods 77, pole-to-pole pull rods 78, a horizontal connecting rod 710, a first driven flange 79, and a second driven flange 79'. In the first set of operating insulators 4, the lower end of the right operating insulator 4 is fixed with the active flange 76, the lower end of the left operating insulator 4 is fixed with the first driven flange 79, and the lower end of the middle operating insulator 4 is fixed with the second driven flange 79. In the second set of operating insulators 4, the lower ends of the left and right operating insulators are fixed with the first driven flange 79, and the lower end of the middle operating insulator 4 is fixed with the second driven flange 79'. The first end of the crank arm 72 is fixedly connected to the upper end of the transmission rod 71, and the second end of the crank arm 72 is hinged to the active flange 76 via the main blade pull rod 75. The active flange 76 is hinged to the first driven flange 79 on the first set of operating insulators 4 via phase-to-phase tie rods 77, and is hinged to the second driven flange 79' on the first set of operating insulators 4 via pole-to-pole tie rods 78. The active flange 76 is also hinged to the first driven flange 79 on the left side of the second set of operating insulators 4 via a horizontal connecting rod 710. The two first driven flanges 79 on the second set of operating insulators 4 are hinged together via another phase-to-phase tie rod 77, and the second driven flange 79 on the second set of operating insulators 4 is hinged to the first driven flange 79' on the right side of the second set of operating insulators 4 via another pole-to-pole tie rod 78. For ease of assembly, three flange fixing rods 761 are fixed to the active flange 76. In the second group, two flange fixing rods 761 are fixed to the first driven flange 79 on the right-side operating insulator 4. One flange fixing rod 761 is provided on the other first driven flange 79 and second driven flange 79′. A transition plate 73 is fixed to the base 6. The upper end of the transmission rod 71 passes through the transition plate 73 and is fixedly connected to the crank arm 72. The transition plate 73 provides auxiliary support for the transmission rod 71. A stop block 74 is fixed to the transition plate 73. The stop block 74 is used to limit the rotation of the crank arm 72.

[0034] The working principle of the transmission assembly is described below: (1) The operating mechanism 8 drives the transmission rod 71 to rotate, which in turn drives the crank arm 72 to rotate synchronously. (2) The rotation of the crank arm 72 drives the active flange 76 to rotate synchronously and in the same direction through the main pull rod 75. (3) The rotation of the active flange 76 drives the corresponding second driven flange 79' to rotate through the inter-pole pull rod 78, and the rotation direction of the active flange 76 is opposite to that of the second driven flange 79' on the first set of operating insulators 4; on the other hand, the rotation of the active flange 76 drives the first driven flange 79 on the first set of operating insulators 4 to rotate through the inter-phase pull rod 77, and the rotation direction of the active flange 76 is the same as that of the first driven flange 79 on the first set of operating insulators 4; in addition, the rotation of the active flange 76 also drives the first driven flange 79 on the left side of the second set of operating insulators 4 to rotate through the horizontal pull rod 710, and the rotation direction is the same. (5) The rotation of the first driven flange 79 on the left operating insulator 4 in the second group drives the rotation of the first driven flange 79 on the right operating insulator 4 in the second group through the phase-to-phase tie rod 77, and the rotation directions are the same. (6) The rotation of the first driven flange 79 on the right operating insulator 4 in the second group drives the rotation of the second driven flange 79' on the operating insulator 4 in the second group, and the rotation direction of the first driven flange 79 on the operating insulator 4 in the second group is opposite to the rotation direction of the second driven flange 79' on the operating insulator 4 in the second group. Therefore, in each group of operating insulators 4, the left and right operating insulators 4 rotate in the same direction, and the rotation direction of the middle operating insulator 4 is opposite to the rotation direction of the two side operating insulators 4. (7) When closing, the component of the tension of the tension spring 543 ensures that the arc-inducing contact 51′ on the contact side and the arc-inducing contact 51 on the finger side are in close contact; when opening, the contact and the finger are separated for a period of time, and the component of the tension of the tension spring 543 keeps the arc-inducing contact 51′ on the contact side and the arc-inducing contact 51 on the finger side in contact, ensuring the flow-guiding effect of the arc-inducing contact 51′ on the contact side and the arc-inducing contact 51 on the finger side during the opening process. As the opening angle increases, the square tube support 54 rotates continuously with the conductive seat 2 on the finger side and the conductive seat 3 on the contact side, changing the direction of the tension of the tension spring 543. The component of the tension spring 543 drives the arc-inducing shaft 53 to rotate, causing the arc-inducing contact 51′ on the contact side and the arc-inducing contact 51 on the finger side to separate continuously. The limit rod 57 touches the limit block 58 to ensure that the arc-inducing contact 51′ on the contact side and the arc-inducing contact 51 on the finger side are at a suitable angle for good contact when closing. (8) When the circuit is closed, the crank arm 72 contacts the stop block 74. At this time, the crank arm 72 and the main cutter rod 75 are in the dead point position to ensure the stability of the circuit.

[0035] For ease of assembly, the driving flange 76, the first driven flange 79, and the second driven flange 79' are all rotatably connected to the base 6 via bearing seats 9. For example... Figure 4As shown, the bearing housing 9 includes a skeleton oil seal 91, a gasket 92, a flange support bearing 93, a cover 96, and a housing 97. The driving flange 76, the first driven flange 79, and the second driven flange 79' each have a flange shaft 761. The flange shaft 761 extends into the housing 97, and two flange support bearings 93 are positioned vertically between them. The skeleton oil seal 91 and the gasket 92 are located between the upper end of the flange shaft 761 and the housing 97. A plate 94 is fixed to the lower end of the flange shaft 761 by bolts 95. The plate 94 is located below the lower flange support bearing 93. The cover 96 is located at the lower end of the housing 97 and seals the opening at the bottom of the housing 97. The housing 97 is fixedly connected to the base 6, thus the driving flange 76, the first driven flange 79, and the second driven flange 79' are rotatably connected to the base 6.

[0036] This utility model adopts a DC neutral point isolating switch with a total of four breaks, which can evenly distribute the total voltage to each break, significantly reducing the electric field strength of a single break, avoiding the risk of partial discharge or dielectric breakdown, resisting transient overvoltage impacts, and improving the system's withstand capability by more than 30%. The symmetrical layout of the four breaks can balance the bidirectional arc energy distribution and adapt to the DC system's power flow reversal requirements. An arc-initiating component is used between the breaks to force the arc to transfer synchronously and quickly between the four breaks, avoiding single-break overload. The four breaks share the current, reducing the contact and contact finger ablation rate, and improving the arc extinguishing efficiency to more than 95%. At the same time, the protective cover prevents the arc from spreading upward and thus ablating the arc-initiating contacts.

Claims

1. An arc-starting assembly, characterized in that, The device includes a finger-side arc-initiating contact, a head-side arc-initiating contact, an arc-initiating shaft, a square tube support, and a shaft support cylinder. Both the first end of the finger-side and head-side arc-initiating contacts have a contact plate. The second ends of the finger-side and head-side arc-initiating contacts are respectively fixed to the corresponding arc-initiating shafts. The arc-initiating shaft passes through the shaft support cylinder and is rotatably connected to it. The square tube support is fixed to the lower part of the shaft support cylinder. The lower end of the arc-initiating shaft passes through the square tube support. A tension spring is located inside the square tube support. The first end of the tension spring is fixedly connected to the square tube support via a first tension spring rod, and the second end of the tension spring is fixedly connected to the lower end of the arc-initiating shaft via a second tension spring rod.

2. The arc-starting assembly according to claim 1, characterized in that, The second end of both the finger-side arc-initiating contact and the contact-side arc-initiating contact are fixedly connected to the arc-initiating shaft via clamps.

3. The arc-starting assembly according to claim 2, characterized in that, The first end of the finger-side arc-initiating contact, the first end of the contact-side arc-initiating contact, and the sidewall of the corresponding contact plate all have slots.

4. The arc-starting assembly according to claim 3, characterized in that, The first end of the first tension spring rod is fixedly connected to the square tube bracket, and the first end of the tension spring is hooked on the second end of the first tension spring rod; the first end of the second tension spring rod passes through the arc-inducing shaft, and the second end of the tension spring is hooked on the second end of the second tension spring rod.

5. A DC neutral point disconnecting switch comprising the arc-initiating component according to any one of claims 1 to 4, characterized in that, The assembly includes an operating mechanism, a transmission component, a base, operating insulators, a finger-side conductive seat, and a contact-side conductive seat. The operating mechanism is located below the base and has a transmission rod at its output end. The operating insulators are rotatably mounted on the upper part of the base. The transmission component is located between the transmission rod and each operating insulator. When the transmission rod rotates, it drives the operating insulators to rotate through the transmission component. The finger-side conductive seat has a finger, and the contact-side conductive seat has a contact. The finger-side conductive seat and the contact-side conductive seat are respectively fixed to the upper part of the corresponding operating insulator. The square tube support of the arc-starting assembly is fixedly connected to the corresponding finger-side conductive seat or contact-side conductive seat. When the finger-side conductive seat and the contact-side conductive seat rotate, they drive the square tube support mounted on them to rotate.

6. The DC neutral point disconnect switch according to claim 5, characterized in that, The operating insulator has two sets, each set including three operating insulators arranged on the left, middle and right. The contact side conductive seat is fixed on the upper part of the middle insulator, and the contact finger side conductive seat is fixed on the upper part of the left and right operating insulators.

7. The DC neutral point disconnect switch according to claim 6, characterized in that, The contact finger side conductive seat on the upper part of the right operating insulator in the first group and the contact finger side conductive seat on the upper part of the left operating insulator in the second group are fixedly connected by a connecting plate.

8. The DC neutral point disconnect switch according to claim 7, characterized in that, The transmission assembly includes a crank arm, a main pull rod, a driving flange, phase-to-phase pull rods, pole-to-pole pull rods, a horizontal connecting rod, a first driven flange, and a second driven flange. In the first set of operating insulators, the lower end of the right operating insulator is fixed with a driving flange, the lower end of the left operating insulator is fixed with a first driven flange, and the lower end of the middle operating insulator is fixed with a second driven flange. In the second set of operating insulators, the lower ends of the left and right operating insulators are fixed with first driven flanges, and the lower end of the middle operating insulator is fixed with a second driven flange. The first end of the crank arm is fixedly connected to the upper end of the transmission rod, and the second end of the crank arm is connected to the main... The knife-handle rod is hinged to the active flange. The active flange is hinged to the first driven flange on the first set of operating insulators via phase-to-phase tie rods. The active flange is hinged to the second driven flange on the first set of operating insulators via pole-to-pole tie rods. The active flange is hinged to the first driven flange on the left operating insulator in the second set via a horizontal connecting rod. The two first driven flanges on the second set of operating insulators are hinged together via another phase-to-phase tie rod. The second driven flange on the second set of operating insulators is hinged to the first driven flange on the right operating insulator in the second set via another pole-to-pole tie rod.

9. The DC neutral point disconnecting switch according to claim 8, characterized in that, The active flange, the first driven flange, and the second driven flange are all rotatably connected to the base via bearing seats.

10. The DC neutral point disconnect switch according to claim 9, characterized in that, The bearing housing includes a skeleton oil seal, a gasket, a flange support bearing, a cover, and a housing. The driving flange, the first driven flange, and the second driven flange each have a flange shaft. The flange shaft extends into the housing, and there are two flange support bearings arranged vertically between them. The skeleton oil seal and the gasket are located between the upper end of the flange shaft and the housing. The lower end of the flange shaft is fixed with a plate by bolts. The cover is located at the lower end of the housing to seal the housing.

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