Arc protection device for outgoing busbar of distribution circuit breaker

Abstract

The application relates to an outgoing line busbar arc protection device of a distribution circuit breaker, which comprises a sliding-groove type insulating plugboard assembly, a universal support column insulator assembly, an insulating pull rod assembly and an arc extinguishing assembly. A closed loop is formed by an arc induction metal mesh and two adjacent phase busbar conductive layers, under the condition that the arc dI / dt is not lower than 10 9 A / s, an induced current of not less than 500 amperes is generated, a heat-sensitive rupture diaphragm is melted within 2.1 milliseconds, sulfur hexafluoride gas is released to complete arc extinguishing within 3.2 milliseconds; the sliding-groove type insulating plugboard is embedded with a copper foil conductive layer penetrating the thickness, one end is grounded, the other end is connected with the arc extinguishing unit to form a low-impedance induction path; the universal hinged structure allows a three-dimensional deflection of + / -8 degrees to cooperate with a sliding-groove displacement of + / -5 millimeters to adapt to the thermal deformation of the busbar; the insulating pull rod surrounds the four-phase busbar in a "mouth" shape with a pre-tightening force of 150 newtons to suppress surface creepage. The application realizes rapid suppression, physical isolation and reliable maintenance of the arc source.

Description

Technical Field

[0001] This invention relates to the field of electrical safety and low-voltage power distribution technology, and in particular to an arc protection device for the outgoing busbar of a power distribution circuit breaker. Background Technology

[0002] In low-voltage power distribution systems, the outgoing busbars of circuit breakers, as critical conductive connection components, bear large currents for extended periods and are highly susceptible to arcing under abnormal operating conditions (such as short circuits, overloads, or loose connections). Once an arcing fault occurs, it can not only burn out the busbars and surrounding components but also ignite the insulation materials inside the cabinet, causing serious safety accidents. Currently, although existing power distribution equipment has seen improvements in overall structure, heat dissipation, dust prevention, and fire prevention, there is a lack of dedicated and effective arc protection measures for this high-risk area—the outgoing busbars of circuit breakers—making it difficult to achieve rapid isolation and suppression in the initial stages of arcing.

[0003] Chinese Patent Publication No. CN119890961B discloses a power distribution device, comprising: a cabinet, with a mounting frame installed inside the cabinet; a power-off component, mounted on the mounting frame and electrically connected to an external power source, used to disconnect the power supply from the external power source when a fire occurs inside the cabinet; and a fire extinguishing component, also mounted on the mounting frame, used to extinguish a fire when a fire occurs inside the cabinet. The power-off component includes: a main cable and two counterweights, with a connector connected to the end of the main cable away from the mounting frame, and an interface plugged into the connector. The outer wall is connected to an outer plate, and the interface is connected to an external power supply. Two counterweights are slidably connected to both sides of the mounting bracket. The fire extinguishing assembly includes a fire extinguisher, which is located on the side close to the counterweight. It can be seen that the Chinese patent has the following problems: the triggering condition depends on an open flame or a significant temperature rise, and it is impossible to intervene in the initial stage before the electric arc ignites the surrounding materials; the source of the electric arc is not specifically isolated or arc-limiting designed, making it difficult to prevent the spread of the electric arc between busbars or between the busbars and the cabinet; there are problems of delayed response and inaccurate protection range. Summary of the Invention

[0004] To address these issues, the present invention provides an arc protection device for the outgoing busbars of a power distribution circuit breaker, which overcomes the problems of existing technologies where the triggering conditions depend on open flames or significant temperature rises, making it impossible to intervene in the initial stage before the arc ignites surrounding materials, failing to isolate or limit the source of the arc, making it difficult to prevent the arc from spreading between busbars or between busbars and cabinets, and having problems such as delayed response and inaccurate protection range.

[0005] To achieve the above objectives, the present invention provides an arc protection device for the outgoing busbar of a power distribution circuit breaker, comprising: an A-phase busbar, a B-phase busbar, a C-phase busbar, an N-phase busbar, a sliding groove type insulating insert plate assembly, a universal support post insulator assembly, an insulating tie rod assembly, and an arc extinguishing assembly; The A-phase busbar, B-phase busbar, C-phase busbar and N-phase busbar are arranged in parallel; The grooved insulating insert assembly consists of four rectangular epoxy resin-based composite insulating plates, namely the A-phase insulating insert, the B-phase insulating insert, the C-phase insulating insert, and the N-phase insulating insert, which are respectively installed on the outside of the A-phase busbar, the B-phase busbar, the C-phase busbar, and the N-phase busbar. The universal support post insulator assembly includes eight ceramic-epoxy composite post insulators, with two insulators installed above and below each phase busbar. The insulating tie rod assembly consists of four polytetrafluoroethylene-coated glass fiber reinforced tie rods, which are arranged in a "U" shape and surround the outer perimeter of the A-phase busbar, B-phase busbar, C-phase busbar and N-phase busbar. The arc extinguishing assembly includes four independent arc extinguishing sealing units, which are respectively arranged between two adjacent phase busbars. Each arc extinguishing sealing unit includes a cylindrical aluminum alloy shell, an arc-inducing metal mesh, a thermistor rupture diaphragm, and a sulfur hexafluoride gas storage bladder. The arc-inducing metal mesh is electrically connected to the non-grounded end of the conductive layer of the insulating plate of the two adjacent phases through leads to form a closed loop.

[0006] Furthermore, the A-phase insulating plate is embedded with a conductive layer along its thickness direction. The conductive layer is a copper foil strip that penetrates the thickness of the insulating plate. One end of the conductive layer is fixed to the grounding terminal of the corresponding phase busbar by a crimp terminal and an M6×20 stainless steel bolt with a double nut anti-loosening structure. The other end is suspended and wrapped with a silicone rubber insulating layer. The B-phase insulating plate, C-phase insulating plate and N-phase insulating plate have the same structure as the A-phase insulating plate.

[0007] The technical advantages of adopting the above-mentioned further solution are: forming the shortest electrical path from the busbar grounding terminal to the arc extinguishing unit, effectively reducing the loop inductance and resistance, and ensuring that ≥500A of eddy current can be induced under the action of high-frequency energy of the arc. Furthermore, the universal support post insulator assembly includes eight ceramic-epoxy composite post insulators, two at the top and two at the bottom of each phase busbar. The base of the ceramic-epoxy composite post insulator is fixed to the inner wall support of the distribution cabinet by M8 stainless steel bolts. The top ball socket structure cooperates with the ball head connector on the edge of the insulating plate to form a universal hinge. The ceramic-epoxy composite post insulator has a ceramic mass fraction of 65%, a bending strength of not less than 120 MPa, and a volume resistivity greater than 1×10⁻⁶. 14 The ohm-cm measurement is as follows: the inner diameter of the ball-and-socket structure is 12 mm, the diameter of the ball-and-socket connector is 11.8 mm, and the clearance is 0.2 mm.

[0008] The technical advantages of the above-mentioned further solution are as follows: By setting eight post insulators and adopting a ball-and-socket universal hinge structure, multi-point flexible support is achieved for the four insulating plates; the 0.2 mm gap design allows the insulating plates to self-adaptively deflect in three-dimensional space, effectively absorbing the thermal expansion displacement and mechanical vibration of the busbar caused by load changes, and avoiding stress concentration or structural damage caused by rigid connection; the ceramic-epoxy composite material has both high mechanical strength (flexural strength not less than 120 MPa) and excellent insulation performance (volume resistivity greater than 10 Ω·cm). 14 Ω·cm provides a stable support base for the insulating plug under the premise of ensuring electrical safety, and ensures that the spatial position accuracy between the arc extinguishing component and the busbar remains stable over a long period of time.

[0009] Furthermore, both ends of the PTFE-coated glass fiber reinforced tie rod are fixed to the side connection holes of the adjacent two-phase insulating plates by metal clamps. The axis of the PTFE-coated glass fiber reinforced tie rod is parallel to the busbar plane and located 50 mm above the busbar.

[0010] The technical effects of adopting the above-mentioned further solution are as follows: connecting four independent insulating plugs into a stable spatial frame structure significantly improves the overall resistance to mechanical impact; the axis of the pull rod is parallel to the busbar plane and located 50 mm above the busbar, which not only avoids the live area of ​​the busbar to ensure a safe distance, but also effectively restrains the lateral displacement of the plugs; the polytetrafluoroethylene coating gives the pull rod excellent resistance to arc erosion and pollution, while the glass fiber reinforced core provides high tensile strength, ensuring that the pull rod can still maintain preload under high temperature arc conditions and prevent surface flashover caused by plug vibration.

[0011] Furthermore, each arc-extinguishing sealing unit of the arc-extinguishing assembly consists of a cylindrical aluminum alloy shell, an internal arc-inducing metal mesh, a heat-sensitive rupture diaphragm, and a sulfur hexafluoride gas storage bladder; the aluminum alloy shell has a diameter of 60 mm and a height of 80 mm, and is fixed above the two-phase busbar by an L-shaped stainless steel bracket; the arc-inducing metal mesh is a 304 stainless steel woven mesh, with a mesh size of 1 mm × 1 mm in a 400 volt system and 0.8 mm × 0.8 mm in a 690 volt system; the edges of the arc-inducing metal mesh are connected to the shell via laser pulse welding points. The wall is connected by a conductive ring, which is electrically connected to the non-grounded end of the conductive layer of the adjacent two phase busbars via a lead wire; the thermosensitive rupture diaphragm is made of a low-melting-point alloy diaphragm with a melting point of 180°C and is installed at the bottom opening of the aluminum alloy shell; the sulfur hexafluoride gas storage bladder is made of an aluminum-plastic composite film with a thickness of 0.15 mm and has a release hole with a diameter of 8 mm at the bottom, which is directly opposite the center of the thermosensitive rupture diaphragm and is placed inside the upper part of the aluminum alloy shell. The inflation pressure is 0.30 MPa in areas below 2000 meters above sea level and 0.35 MPa in areas above 2000 meters above sea level.

[0012] The technical effects of adopting the above-mentioned further solutions are as follows: by independently encapsulating and fixing the arc-extinguishing sealing unit directly above the phases, precise and independent protection against arc risks between each pair of phases is achieved; eddy currents can be efficiently induced under various operating conditions; the combination of low-melting-point alloy diaphragms and aluminum-plastic composite membrane airbags enables rapid rupture and gas release at precise temperature thresholds; and the airbag inflation pressure is adjusted according to the air pressure differences in different altitude areas to ensure that the gas release and diffusion rate can meet the arc-extinguishing requirements under various environmental conditions.

[0013] Furthermore, the length of the A-phase insulating plug, B-phase insulating plug, C-phase insulating plug, and N-phase insulating plug is the width of the corresponding busbar plus 40 mm, and the width is the height of the corresponding busbar plus 60 mm; each insulating plug has a T-shaped sliding groove on both sides, which cooperates with the sliding rail on the inner wall of the distribution cabinet, allowing the insulating plug to move ±5 mm in the direction perpendicular to the busbar axis; the cooperation structure of the ball socket structure and the ball head connector allows the A-phase insulating plug, B-phase insulating plug, C-phase insulating plug, and N-phase insulating plug to deflect at a maximum angle of ±8° in three-dimensional space.

[0014] The technical effects of adopting the above-mentioned further solutions are as follows: the size design of the insulating insert plate is designed with sufficient margin to ensure that a physical isolation barrier that completely covers the busbar is formed; the deformation of the insert plate or connection failure caused by thermal stress is avoided; it can fully compensate for the complex mechanical deformation of the busbar caused by factors such as high current switching and ambient temperature changes, and ensure that the insulating insert plate always maintains the best relative position with the busbar, thereby maintaining the working accuracy of the arc extinguishing sealing unit.

[0015] Furthermore, the four independent arc-extinguishing sealing units are respectively arranged at the center above the A-phase busbar and the B-phase busbar, the B-phase busbar and the C-phase busbar, the C-phase busbar and the N-phase busbar, and the N-phase busbar and the A-phase busbar; the bottom of each aluminum alloy housing is 30 mm away from the surface of the busbar, and the plane of the arc-inducing metal mesh is parallel to the plane of the busbar; the arc-extinguishing assembly also includes a detachable and replaceable interface structure, which consists of quick-release buckles and sealing O-rings; the quick-release buckles are spring-loaded stainless steel claws, numbering three, and evenly distributed on the outer periphery of the aluminum alloy housing; the sealing O-rings are made of fluororubber, with a cross-sectional diameter of 3 mm and a compression rate of 25%.

[0016] The technical effects of adopting the above-mentioned further solutions are as follows: it ensures the electromagnetic coupling strength between the induction metal mesh and the busbar, and reserves the optimal working distance for gas diffusion, so that the sulfur hexafluoride gas flow can effectively cover the arc area; the design of the metal mesh plane and the busbar plane being parallel maximizes the mutual inductance coefficient between the two and improves the energy coupling efficiency; the detachable interface composed of quick-release buckles and O-rings enables modular and rapid replacement of the arc extinguishing sealing unit.

[0017] Furthermore, the diameter of the laser pulse weld point between the arc-inducing metal mesh and the conductive ring is 1.5 mm, the weld point spacing is 5 mm, and the welding depth penetrates 80% of the thickness of the arc-inducing metal mesh.

[0018] The technical effects of adopting the above-mentioned further solutions are as follows: while ensuring a low-resistance, high-reliability electrical connection between the metal mesh and the conductive ring, it avoids damage to the metal mesh wires caused by excessive welding; the uniform distribution of 5mm weld point spacing ensures the uniformity of current distribution on the entire circumference of the metal mesh and avoids local overheating; the 80% weld penetration design ensures sufficient mechanical connection strength while retaining the flexible structure of the metal mesh, allowing it to be freely fine-tuned when heated and preventing the weld points from cracking due to thermal stress fatigue.

[0019] Furthermore, the circuit resistance of the closed loop formed by the arc-inducing metal mesh and the conductive layer is not higher than 0.5 milliohms, the melting point of the thermistor rupture diaphragm is not higher than 200°C, and the thermistor rupture diaphragm is disposed between the release hole of the sulfur hexafluoride gas storage bladder and the bottom opening of the aluminum alloy shell.

[0020] The technical advantage of adopting the above-mentioned further solution is that when an interphase electric arc is generated, the arc channel is equivalent to a high-frequency alternating current source, and its dI / dt is not less than 10. 9 An eddy current with a peak value of not less than 500 amperes is induced in the metal mesh circuit at a rate of A / s. This eddy current generates Joule heat power P=I on the metal mesh. 2 R, where R is the total resistance of the circuit, not exceeding 0.5 milliohms, has been verified by thermal simulation to raise the local temperature of the metal mesh to above 200°C within 2.0 milliseconds, melting through the thermistor rupture diaphragm made of a low-melting-point alloy at 180°C, triggering the release of sulfur hexafluoride gas and completing arc extinguishing within 3.2 milliseconds.

[0021] Furthermore, one end of the copper foil strip connected to the grounding terminal is located on the outside of the insulating insert plate to form a detachable maintenance structure. The preload of the polytetrafluoroethylene-coated glass fiber reinforced tie rod is 100N-200N, and the torque of the connecting bolt is 10N·m-14N·m.

[0022] The technical effects of adopting the above-mentioned further solutions are as follows: When the copper foil strip is corroded, a low-impedance induction path cannot be formed, and the arc-inducing metal mesh cannot generate a temperature sufficient to melt through the thermistor rupture diaphragm, resulting in ineffective arc extinguishing. The detachable structural design allows the copper foil strip to be replaced separately without scrapping the entire insulating insert if corrosion or fatigue occurs after long-term operation, reducing maintenance costs and resource waste, and improving the overall life-cycle economy of the device. The pre-tightening force of the tie rod is controlled within the optimal range of 100N-200N. When the pre-tightening force is below 100N, it is difficult to effectively suppress the micro-vibration of the insert under the high temperature of the arc, and the creepage probability increases significantly. When the pre-tightening force is above 200N, it will excessively restrict the free displacement of the insert, hindering the normal compensation of the busbar thermal expansion, leading to gas coverage failure or structural stress concentration.

[0023] Compared with the prior art, the beneficial effect of the present invention is that it constructs a completely passive, localized arc suppression system in the source area of ​​arc occurrence, which does not require external energy supply and has the ability to respond instantly, thereby realizing the source prevention and control of arc faults on the outgoing busbars of low-voltage circuit breakers.

[0024] In particular, by forming a closed loop between the arc-induced metal mesh and the conductive layers of the adjacent two phase busbars, the arc dI / dt is not less than 10. 9 Under A / s conditions, an eddy current of no less than 500 amperes is induced, causing the thermistor to melt within 2.1 milliseconds and completing arc extinguishing within 3.2 milliseconds, which is significantly better than existing technologies that rely on temperature rise or flame detection. Furthermore, a copper foil conductive layer with a penetrating thickness is embedded in the slotted insulating plate, with one end grounded and the other end connected to the arc extinguishing unit, forming a low-impedance induction path to ensure that the arc energy is efficiently coupled to the induction metal mesh, ensuring triggering reliability. With the universal support post insulator assembly allowing ±8° three-dimensional deflection and ±5 mm slot displacement, the thermal deformation and mechanical vibration of the busbar are effectively compensated, maintaining the precise spatial relationship between the arc extinguishing unit and the busbar, and preventing gas coverage failure or secondary arcing due to displacement. Through the insulating tie rod with a preload of 100N-200N, it surrounds the four-phase busbar in a "U" shape, which has been experimentally verified to effectively suppress surface flashover caused by micro-vibration of the plate under high arc temperature. Attached Figure Description

[0025] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the arc protection device for the outgoing busbar of the power distribution circuit breaker of the present invention; Figure 2 This is an enlarged exploded view of the connection between the slotted insulating plug assembly and the busbar; Figure 3 This is an enlarged structural diagram of the connection between the universal support post insulator assembly and the insulating plate; Figure 4 This is a top view of the connection structure between the insulating tie rod assembly and the adjacent insulating insert plate; Figure 5 This is a longitudinal cross-sectional view of the arc-extinguishing assembly; Figure 6 This is a schematic diagram showing the relative installation positions of the arc extinguishing assembly, the L-shaped stainless steel bracket, and the busbar. Figure 7 This is a magnified view of a portion of the detachable and replaceable interface structure of the arc extinguishing component; Legend: 1. Phase A busbar; 2. Phase B busbar; 3. Phase C busbar; 4. Phase N busbar; 5. Slotted insulating insert assembly; 51. Phase A insulating insert; 52. Phase B insulating insert; 53. Phase C insulating insert; 54. Phase N insulating insert; 55. Conductive layer; 56. Copper foil strip; 57. Silicone rubber insulation layer; 58. Crimped terminal; 59. M6×20 stainless steel bolt; 6. Universal support post insulator assembly; 61. Ceramic-epoxy composite post insulator; 62. M8 stainless steel bolt; 63. Distribution cabinet 64. Inner wall support; 65. Ball-and-socket structure; 7. Ball head connector; 8. Insulating tie rod assembly; 91. PTFE-coated glass fiber reinforced tie rod; 102. Metal clamp; 11. Side connection hole; 12. Arc extinguishing assembly; 13. Aluminum alloy shell; 14. Arc induction metal mesh; 15. Thermistor rupture diaphragm; 16. Sulfur hexafluoride gas storage bladder; 17. L-shaped stainless steel bracket; 18. Conductive ring; 19. Lead wire; 20. Quick-release buckle; 31. Sealing O-ring; 42. Low melting point alloy diaphragm; 53. Laser pulse welding point. Detailed Implementation

[0026] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0027] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0029] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly 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 of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Please see Figures 1 to 7 As shown, the present invention provides an arc protection device for the outgoing busbar of a power distribution circuit breaker, comprising: a sliding groove type insulating plug assembly 5, a universal support post insulator assembly 6, an insulating tie rod assembly 7, and an arc extinguishing assembly 8. The components work together to form a completely passive, fast arc suppression system that requires no external energy.

[0031] Please see Figure 1 As shown, the grooved insulating insert assembly 5 is composed of four rectangular epoxy resin-based composite insulating plates, namely A-phase insulating insert 51, B-phase insulating insert 52, C-phase insulating insert 53 and N-phase insulating insert 54. The four insulating inserts are respectively installed on the outside of A-phase busbar 1, B-phase busbar 2, C-phase busbar 3 and N-phase busbar 4, forming a physical isolation barrier surrounding the busbars, effectively preventing the direct spread of electric arc between the busbars.

[0032] Please see Figure 2 As shown, each insulating insert has a conductive layer 55 embedded along its thickness direction. The conductive layer 55 is composed of a copper foil strip 56 that penetrates the thickness of the insulating insert. One end of the conductive layer 55 is fixed to the grounding terminal of the corresponding phase busbar by a crimp terminal 58 and an M6×20 stainless steel bolt 59 with a double nut anti-loosening structure. The contact resistance is less than 10 microohms, forming a reliable grounding connection. The other end is suspended and wrapped with a silicone rubber insulating layer 57 for subsequent connection of the arc extinguishing component. This copper foil strip design that penetrates the thickness creates a low-impedance induction path inside the insulating insert, providing an electrical basis for the energy coupling of the arc extinguishing component. The low-impedance induction path refers to a closed loop with a resistance of no more than 0.5 milliohms.

[0033] Please see Figure 1 and Figure 3As shown, the universal support pillar insulator assembly 6 includes eight ceramic-epoxy composite pillar insulators 61, with two arranged above and below each phase of the busbars, that is, one is arranged above and one below the A-phase busbar 1, one is arranged above and one below the B-phase busbar 2, one is arranged above and one below the C-phase busbar 3, and one is arranged above and one below the N-phase busbar 4; the base of the ceramic-epoxy composite pillar insulator 61 is fixed to the inner wall bracket 63 of the power distribution cabinet by M8 stainless steel bolts 62, and its top is provided with a ball socket structure 64, which cooperates with the ball head connector 65 arranged at the edge of the insulating insert plate to form a universal hinge structure. Preferably, the mass fraction of ceramic in the ceramic-epoxy composite pillar insulator 61 is 65%, the flexural strength is not less than 120 MPa, and the volume resistivity is greater than 1×10 14 ohm·cm, having both high mechanical strength and excellent insulation performance; the inner diameter of the ball socket structure 64 is 12 mm, the diameter of the ball head connector 65 is 11.8 mm, and the clearance fit is 0.2 mm. This universal hinge structure allows the insulating insert plate to adaptively deflect in three-dimensional space, can effectively absorb the thermal expansion displacement and mechanical vibration generated by the busbar due to load changes, avoid stress concentration or structural damage caused by rigid connection, and ensure the long-term stability of the spatial position accuracy between the arc extinguishing component and the busbar.

[0034] Please refer to Figure 1 and Figure 4 As shown, the insulating pull rod assembly 7 is composed of four polytetrafluoroethylene-coated glass fiber reinforced pull rods 71. Both ends of each polytetrafluoroethylene-coated glass fiber reinforced pull rod 71 are respectively fixed to the side connection holes 73 of the insulating insert plates of adjacent two phases through metal clamps 72; specifically, the first glass fiber reinforced pull rod 71 connects the A-phase insulating insert plate 51 and the B-phase insulating insert plate 52, the second glass fiber reinforced pull rod 71 connects the B-phase insulating insert plate 52 and the C-phase insulating insert plate 53, the third glass fiber reinforced pull rod 71 connects the C-phase insulating insert plate 53 and the N-phase insulating insert plate 54, and the fourth glass fiber reinforced pull rod 71 connects the N-phase insulating insert plate 54 and the A-phase insulating insert plate 51, forming a "square" shape surrounding arrangement. The axis of the polytetrafluoroethylene-coated glass fiber reinforced pull rod 71 is parallel to the busbar plane and is located 50 mm above the busbar; preferably, the pre-tightening force of the polytetrafluoroethylene-coated glass fiber reinforced pull rod 71 is 120N - 180N, and the torque of the connecting bolt is 10N·m - 14N·m. This "square" shape surrounding structure connects the four independent insulating insert plates into a stable spatial framework, significantly enhancing the overall anti-mechanical impact ability; the pre-tightening force is controlled within the optimal range, which can not only effectively suppress the micro-vibration of the insert plate under the high temperature of the arc and prevent surface flashover, but also allow the insert plate to displace moderately under thermal stress, achieving the balance between structural stability and thermal compensation ability.

[0035] Please refer to Figure 1 、 Figure 5 、 Figure 6 and Figure 7 As shown, the arc extinguishing assembly 8 includes four independent arc extinguishing sealing units, which are respectively arranged at the center above the A-phase busbar 1 and B-phase busbar 2, B-phase busbar 2 and C-phase busbar 3, C-phase busbar 3 and N-phase busbar 4, and N-phase busbar 4 and A-phase busbar 1. In this embodiment, the arc extinguishing sealing unit refers to a sealing unit composed of a cylindrical aluminum alloy shell 81, an internal arc-inducing metal mesh 82, a heat-sensitive rupture diaphragm 83, and a sulfur hexafluoride gas storage bladder 84.

[0036] Please see Figure 5 As shown, the aluminum alloy housing 81 has a diameter of 60 mm and a height of 80 mm. It is fixed above the two-phase busbars by an L-shaped stainless steel bracket 85. The arc-inducing metal mesh 82 is a 304 stainless steel woven mesh, and its edges are connected to the conductive ring 86 on the inner wall of the housing through laser pulse welding points 91. The conductive ring 86 is electrically connected to the non-grounded end of the corresponding conductive layer 55 of the two adjacent phase busbars via lead wires 87. Preferably, the mesh size is 1 mm × 1 mm in a 400 volt system and 0.8 mm × 0.8 mm in a 690 volt system, so that the inductance parameters of the metal mesh match the expected arc spectrum characteristics of the system, ensuring efficient eddy current induction. The laser pulse welding points 91 have a diameter of 1.5 mm and a welding point spacing of 5 mm. The welding depth penetrates 80% of the thickness of the arc-inducing metal mesh 82, ensuring low-resistance connection while avoiding damage to the metal mesh from excessive welding. In this embodiment, the low-resistance connection means that the resistance at the welding point is not higher than 0.5 milliohms.

[0037] Please see Figure 5 and Figure 7 As shown, the thermistor rupture diaphragm 83 is made of a low-melting-point alloy diaphragm 90 with a melting point of 180°C and is installed at the bottom opening of the aluminum alloy shell 81. The sulfur hexafluoride gas storage bladder 84 has a release hole with a diameter of 8 mm at the bottom, which is directly opposite the center of the thermistor rupture diaphragm 83 and is placed inside the upper part of the aluminum alloy shell 81. Preferably, the inflation pressure is 0.30 MPa in areas below 2000 meters above sea level and 0.35 MPa in areas above 2000 meters above sea level, ensuring that the gas release and diffusion rate can meet the arc extinguishing requirements under various environmental conditions. The circuit resistance of the closed loop formed by the arc induction metal mesh 82 and the conductive layer 55 is not higher than 0.5 milliohms, ensuring that when an eddy current of more than 500A is generated, the Joule heat power on the metal mesh is large enough to raise the local temperature to more than 200°C within 2 milliseconds, achieving rapid triggering. In this embodiment, the sulfur hexafluoride gas storage bladder 84 is made of an aluminum-plastic composite film with a thickness of 0.15 mm.

[0038] Please see Figure 6 and Figure 7As shown, the bottom of each aluminum alloy housing 81 is 30 mm away from the surface of the busbar. The plane of the arc-inducing metal mesh 82 is parallel to the plane of the busbar. This arrangement ensures the electromagnetic coupling strength between the induction metal mesh and the busbar, and also reserves the optimal action distance for gas diffusion. The arc-extinguishing component 8 also includes a detachable and replaceable interface structure, which consists of quick-release buckles 88 and sealing O-rings 89. The quick-release buckles 88 are spring-loaded stainless steel claws, three in number, and evenly distributed on the outer periphery of the aluminum alloy housing 81. This detachable interface design enables modular and rapid replacement of the arc-extinguishing sealing unit. That is, after a failure, only three buckles need to be loosened to remove the old unit and insert the new unit. The replacement time is no more than 10 minutes, which greatly improves the maintenance convenience of the device. In this embodiment, the sealing O-ring 89 is made of fluororubber, with a cross-sectional diameter of 3 mm and a compression rate of 25%.

[0039] Please see Figure 1 and Figure 2 As shown, as a further preferred embodiment, the lengths of the A-phase insulating plug 51, B-phase insulating plug 52, C-phase insulating plug 53, and N-phase insulating plug 54 are the corresponding busbar width plus 40 mm, and the widths are the corresponding busbar height plus 60 mm, ensuring a complete physical isolation barrier covering the busbar. Each insulating plug has T-shaped grooves on both sides, which cooperate with the slide rails on the inner wall of the distribution cabinet, allowing the insulating plug to move ±5 mm in the direction perpendicular to the busbar axis to adapt to the displacement caused by the thermal expansion and contraction of the busbar. Combined with the ±8° three-dimensional deflection allowed by the ball-and-socket structure, a multi-degree-of-freedom adaptive system of "translation + rotation" is formed, which can comprehensively compensate for the complex mechanical deformation of the busbar caused by factors such as large current switching and ambient temperature changes.

[0040] Please see Figure 2 As shown, as a further preferred embodiment, one end of the copper foil strip 56 connected to the grounding terminal is located on the outside of the insulating plug plate, forming a detachable maintenance structure. This design allows maintenance personnel to inspect, tighten, or replace the conductive layer connection status without disassembling the entire insulating plug plate, reducing maintenance costs and improving the economic efficiency of the device throughout its entire life cycle.

[0041] Working principle and process: Please see Figures 1 to 7 As shown, under normal operating conditions of the low-voltage power distribution system, the sliding groove type insulating plug assembly 5 is suspended outside the circuit breaker outgoing busbar by the universal support post insulator assembly 6, forming a physical isolation barrier surrounding the busbar. The insulating tie rod assembly 7 maintains the spatial relative position stability of the four plugs with a pre-tightening force of 120N-180N. The arc extinguishing assembly 8 is in standby state, and its internal sulfur hexafluoride gas storage bladder 84 is well sealed. The heat-sensitive rupture diaphragm 83 completely seals the bottom opening of the aluminum alloy shell 81.

[0042] When an electric arc is generated on the busbar due to a short circuit, overload, or loose connection, the arc channel is equivalent to a high-frequency alternating current source with dI / dt ≥ 10. 9 A / s; At this time, in the closed loop formed by the non-grounded end of the conductive layer 55 of two adjacent phase busbars, such as phase B busbar 2 and phase C busbar 3, and the arc-inducing metal mesh 82 located directly above the phase, eddy currents with a peak value of not less than 500 amperes will be induced. These eddy currents generate Joule heat power P=I on the arc-inducing metal mesh 82. 2 R, because the total resistance of the circuit is no more than 0.5 milliohms, the heat is highly concentrated, and the local temperature of the metal mesh can rise to more than 200°C within 2.0 milliseconds.

[0043] Heat is rapidly conducted to the thermistor rupture diaphragm 83, causing it to melt and rupture within 2.1 milliseconds. The release hole at the bottom of the sulfur hexafluoride gas storage bladder 84 then opens, and sulfur hexafluoride gas at 0.30 MPa in the bladder below 2000 meters altitude or 0.35 MPa in the bladder above 2000 meters altitude is injected downward through the release hole. Guided by the conical diffuser at the bottom of the aluminum alloy shell 81, the gas expands at a 30° angle, forming a fan-shaped airflow covering a 30 mm × 30 mm area below. The sulfur hexafluoride gas reaches the surface of the busbar in 85 milliseconds. The sulfur hexafluoride gas molecules capture free electrons to form negative ions, reducing the electron density in the arc channel. At the same time, the gas expands to form a local high-voltage zone, compressing the cross-sectional area of ​​the arc channel, increasing the arc voltage gradient, and causing the arc to extinguish naturally at the current zero-crossing point. The entire arc extinguishing process is completed within 3.2 milliseconds.

[0044] Throughout the process, the slotted insulating insert assembly 5 withstands thermal shock when the arc energy is released. Its epoxy resin matrix has a high thermal deformation temperature, and together with the flexible structure of the conductive layer 55 leads, it avoids connection breakage due to busbar thermal displacement. The ball-and-socket structure of the universal support post insulator assembly 6 absorbs busbar vibration and deformation stress, maintaining the stability of the insulating insert position. The insulating tie rod assembly 7 limits the lateral displacement of the insert with optimal preload, preventing arc creep along the insert surface.

[0045] After the arc is extinguished, only the arc-extinguishing sealing unit that triggered the action needs to be replaced, such as the arc-extinguishing sealing unit between phases B and C. The rest of the structure remains intact. The operator can remove the old unit from the L-shaped stainless steel bracket 85 by loosening the quick-release buckle 88. After the new unit is inserted, the quick-release buckle 88 will automatically lock. The replacement time is less than 10 minutes, achieving rapid maintenance.

[0046] This embodiment achieves source control of arc faults in the outgoing busbar area of ​​low-voltage circuit breakers through the above structural design and working process. That is, it can quickly isolate and suppress the arc at the moment of its inception without the need for external energy supply. The response speed is significantly better than the existing technology that relies on temperature rise or flame detection, effectively improving the intrinsic safety level of the power distribution system.

[0047] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An arc protection device for the outgoing busbar of a distribution circuit breaker, characterized in that, Including: Phase A busbar (1), Phase B busbar (2), Phase C busbar (3), Phase N busbar (4), chute-type insulating plugboard assembly (5), universal support post insulator assembly (6), insulating pull rod assembly (7) and arc extinguishing assembly (8); The Phase A busbar (1), Phase B busbar (2), Phase C busbar (3) and Phase N busbar (4) are arranged side by side; The chute-type insulating plugboard assembly (5) is composed of four rectangular epoxy resin-based composite insulating boards, namely Phase A insulating plugboard (51), Phase B insulating plugboard (52), Phase C insulating plugboard (53) and Phase N insulating plugboard (54), which are respectively installed on the outer sides of the Phase A busbar (1), Phase B busbar (2), Phase C busbar (3) and Phase N busbar (4); The universal support post insulator assembly (6) includes eight ceramic-epoxy composite post insulators (61), with two arranged above and below each phase of the busbar; The insulating pull rod assembly (7) is composed of four polytetrafluoroethylene-coated fiberglass-reinforced pull rods (71), and the polytetrafluoroethylene-coated fiberglass-reinforced pull rods (71) are arranged in a "mouth" shape, surrounding the peripheries of the Phase A busbar (1), Phase B busbar (2), Phase C busbar (3) and Phase N busbar (4); The arc extinguishing assembly (8) includes four independent arc extinguishing and sealing units, which are respectively arranged between adjacent phases of the busbars. Each arc extinguishing and sealing unit includes a cylindrical aluminum alloy housing (81), an arc induction metal mesh (82), a thermosensitive rupture diaphragm (83) and a sulfur hexafluoride gas storage bladder (84); the arc induction metal mesh (82) is electrically connected to the non-grounded ends of the conductive layers (55) of the insulating plugboards of adjacent two phases through leads (87) to form a closed loop.

2. The arc protection device for the outgoing busbar of a power distribution circuit breaker according to claim 1, characterized in that, A conductive layer (55) is embedded in the Phase A insulating plugboard (51) along its thickness direction. The conductive layer (55) is a copper foil strip (56) that penetrates the thickness of the insulating plugboard. One end of it is fixed to the grounding terminal of the corresponding phase of the busbar through a crimping terminal (58) and a double-nut anti-loosening structure with an M6×20 stainless steel bolt (59), and the other end is suspended and wrapped with a silicone rubber insulating layer (57). The Phase B insulating plugboard (52), Phase C insulating plugboard (53) and Phase N insulating plugboard (54) have the same structure as the Phase A insulating plugboard (51).

3. The arc protection device for the outgoing busbar of the distribution circuit breaker according to claim 1, characterized in that, The ceramic-epoxy composite post insulator (61) base is fixed to the inner wall bracket (63) of the distribution cabinet by M8 stainless steel bolts (62). The top ball socket structure (64) cooperates with the ball head connector (65) on the edge of the insulating plate to form a universal hinge. The ceramic-epoxy composite post insulator (61) has a ceramic mass fraction of 65%, a bending strength of not less than 120 MPa, and a volume resistivity greater than 1×10⁻⁶. 14 Ohm-cm; the inner diameter of the ball-and-socket structure (64) is 12 mm, the diameter of the ball-and-socket connector (65) is 11.8 mm, and the fit clearance is 0.2 mm.

4. The arc protection device for the outgoing busbar of the distribution circuit breaker according to claim 1, characterized in that, Both ends of the polytetrafluoroethylene-coated fiberglass-reinforced pull rod (71) are fixed to the side connection holes (73) of the insulating plugboards of adjacent two phases through metal clamps (72). The axis of the polytetrafluoroethylene-coated fiberglass-reinforced pull rod (71) is parallel to the busbar plane and is located 50 millimeters above the busbar.

5. The arc protection device for the outgoing busbar of a distribution circuit breaker according to claim 1, characterized in that, Each arc-extinguishing sealing unit of the arc-extinguishing assembly (8) consists of a cylindrical aluminum alloy shell (81), an internal arc-inducing metal mesh (82), a thermosensitive rupture diaphragm (83), and a sulfur hexafluoride gas storage bladder (84). The aluminum alloy shell (81) has a diameter of 60 mm and a height of 80 mm, and is fixed above the two-phase busbar by an L-shaped stainless steel bracket (85). The arc-inducing metal mesh (82) is a 304 stainless steel woven mesh with a mesh size of 1 mm × 1 mm in a 400 volt system and 0.8 mm × 0.8 mm in a 690 volt system. The edges of the arc-inducing metal mesh (82) are electrically connected to the inner wall of the shell through laser pulse welding points (91). The ring (86) is connected, and the conductive ring (86) is electrically connected to the non-grounded end of the conductive layer (55) of the adjacent two phase busbars via the lead wire (87); the thermosensitive rupture diaphragm (83) is made of a low melting point alloy diaphragm (90) with a melting point of 180°C, and is installed at the bottom opening of the aluminum alloy shell (81); the sulfur hexafluoride gas storage bladder (84) is made of an aluminum-plastic composite film with a thickness of 0.15 mm, and has a release hole with a diameter of 8 mm at the bottom, which is directly opposite the center of the thermosensitive rupture diaphragm (83), and is placed inside the upper part of the aluminum alloy shell (81). The inflation pressure is 0.30 MPa in areas below 2000 meters above sea level and 0.35 MPa in areas above 2000 meters above sea level.

6. The arc protection device for the outgoing busbar of a distribution circuit breaker according to claim 1, characterized in that, The length of the A-phase insulating plug (51), B-phase insulating plug (52), C-phase insulating plug (53) and N-phase insulating plug (54) is the width of the corresponding busbar plus 40 mm, and the width is the height of the corresponding busbar plus 60 mm. Each insulating plug is provided with a T-shaped sliding groove on both sides, which cooperates with the sliding rail on the inner wall of the distribution cabinet, allowing the insulating plug to move ±5 mm in the direction perpendicular to the busbar axis. The cooperation structure of the ball socket structure (64) and the ball head connector (65) allows the A-phase insulating plug (51), B-phase insulating plug (52), C-phase insulating plug (53) and N-phase insulating plug (54) to deflect at a maximum angle of ±8° in three-dimensional space.

7. The arc protection device for the outgoing busbar of a distribution circuit breaker according to claim 5, characterized in that, The four independent arc-extinguishing sealing units are respectively arranged at the center above the A-phase busbar (1) and the B-phase busbar (2), the B-phase busbar (2) and the C-phase busbar (3), the C-phase busbar (3) and the N-phase busbar (4), and the N-phase busbar (4) and the A-phase busbar (1); the bottom of each aluminum alloy shell (81) is 30 mm away from the surface of the busbar, and the plane of the arc-inducing metal mesh (82) is parallel to the plane of the busbar; the arc-extinguishing assembly (8) also includes a detachable and replaceable interface structure, which consists of a quick-release buckle (88) and a sealing O-ring (89); the quick-release buckle (88) is a spring-loaded stainless steel claw, there are three of them, and they are evenly distributed on the outer periphery of the aluminum alloy shell (81); the sealing O-ring (89) is made of fluororubber, with a cross-sectional diameter of 3 mm and a compression rate of 25%.

8. The arc protection device for the outgoing busbar of a distribution circuit breaker according to claim 5, characterized in that, The laser pulse weld (91) between the arc-induction metal mesh (82) and the conductive ring (86) has a diameter of 1.5 mm, a weld spacing of 5 mm, and a welding depth that penetrates 80% of the thickness of the arc-induction metal mesh (82).

9. The arc protection device for the outgoing busbar of a distribution circuit breaker according to claim 5, characterized in that, The circuit resistance of the closed loop formed by the arc-inducing metal mesh (82) and the conductive layer (55) is not higher than 0.5 milliohms, the melting point of the thermosensitive rupture diaphragm (83) is not higher than 200°C, and the thermosensitive rupture diaphragm (83) is disposed between the release hole of the sulfur hexafluoride gas storage bladder (84) and the bottom opening of the aluminum alloy shell (81).

10. The arc protection device for the outgoing busbar of a distribution circuit breaker according to claim 1, characterized in that, One end of the copper foil strip (56) connected to the grounding terminal is located on the outside of the insulating plug plate to form a detachable maintenance structure. The preload of the polytetrafluoroethylene-coated glass fiber reinforced tie rod (71) is 100N-200N, and the torque of the connecting bolt is 10N·m-14N·m.

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