A contact box and switchgear using the same

Abstract

The utility model relates to the switchgear field with the bracket that can draw out for isolation, especially touch head box and use the switchgear cabinet of this touch head box. Touch head box includes insulating box body, the insulating box body has the far end for connecting copper row and is used for with the near end of switchgear cabinet connection, the radial side of insulating box body close to the switchgear cabinet in the partition board is near partition board side, and the side opposite near partition board side is far partition board side, the far end of insulating box body is provided with static contact insert and high voltage shielding net, high voltage shielding net is offset to far partition board side relative to the center of insulating box body, to make high voltage shielding net and corresponding middle partition board between have the set insulation distance. The utility model has solved the problem that the touch head box of existing switchgear and middle partition board between are easy to breakdown discharge.

Description

Technical Field

[0001] This utility model relates to the field of switchgear having a removable bracket for isolation, and in particular to a contact box and a switch cabinet using the contact box. Background Technology

[0002] Switchgear is a key piece of equipment in a power system used for receiving, distributing, and controlling electrical energy. It integrates various electrical components and has comprehensive protection functions. The cabinet, which houses and supports these electrical components, is typically divided into multiple independent compartments by metal partitions. These independent compartments include busbar compartments, circuit breaker compartments, cable compartments, and instrument compartments.

[0003] The busbar compartment is typically located at the upper rear or top of the cabinet and is used to install the main busbars and branch busbars. Busbars are generally made of copper or aluminum and are supported and fixed by insulators. Busbars between adjacent cabinets pass through insulating bushings for electrical connection and insulation. The circuit breaker compartment is used to install high-voltage circuit breakers (such as vacuum circuit breakers, SF6 circuit breakers, etc.). Depending on the cabinet type, circuit breakers can be fixedly installed or mounted on a retractable trolley. The cable compartment is typically located at the lower rear of the cabinet and is the connection area for power cable inlets and outlets. Besides connecting cable terminals, this compartment usually houses current transformers, voltage transformers, grounding switches, surge arresters, and other components. The instrument compartment is typically located at the upper front of the cabinet and is used to install secondary equipment, such as relay protection devices, metering instruments, indicator lights, buttons, changeover switches, and microprocessor-based integrated protection devices. In addition, the cabinet is equipped with a pressure relief device as a safety guarantee. Pressure relief channels or pressure relief plates are usually installed above the circuit breaker compartment, busbar compartment and cable compartment. When an arc short circuit occurs in the cabinet due to a fault, generating high temperature and high pressure gas, the pressure relief device can quickly release the pressure in a directional manner to prevent the cabinet from exploding and protect the safety of personnel and adjacent equipment.

[0004] A stationary contact box is an insulating enclosure used to fix and install stationary contacts, primarily used in the circuit breaker compartment of a handcart-type switchgear. The primary function of the stationary contact box is to provide reliable phase-to-phase and phase-to-ground insulation. In addition, it provides mechanical support for the branch busbars connected to the stationary contact box and withstands the enormous electrodynamic forces generated by short-circuit currents. It also provides a sealed, insulated space for the moving and stationary contacts of the circuit breaker to engage and disengage, thus limiting and guiding the electric arc to a certain extent. After installation, the front end of the stationary contact box, i.e., the moving contact side, faces the circuit breaker handcart compartment for the moving contact on the handcart to insert and achieve electrical connection; the rear end or side end, i.e., the stationary contact side, connects to the main busbar or branch busbar, serving to introduce or extract electrical energy.

[0005] The applicant's patent application, with publication number CN117526099A and publication date of February 6, 2024, shows the installation structure of the static contact box. According to the description and drawings of the patent application, the contact box is installed on the partition between the busbar compartment and the cable compartment and the circuit breaker compartment. The busbar compartment and the cable compartment are separated by a middle partition. The far end of the contact box is located near the middle partition on the side facing away from the far end inlet hole.

[0006] To achieve a uniform electric field distribution, a remote shielding mesh is installed at the far end of the contact box. This remote shielding mesh is directly connected to the stationary contact and operates at a high potential during operation. Since the stationary contact connecting insert is located at the center of the box, and the remote shielding mesh and the stationary contact connecting insert are coaxially arranged in existing technologies, discharge phenomena frequently occur due to insufficient insulation distance between the remote shielding mesh and the central partition. Furthermore, the electric field distortion region of the box (at the stationary end) is close to the strong field region between the remote shielding mesh and the central partition, further increasing the probability of these discharge phenomena. Therefore, existing contact boxes are difficult to apply to high-voltage or high-altitude environments. Utility Model Content

[0007] The purpose of this utility model is to provide a contact box to solve the problem of easy breakdown and discharge between the contact box and the partition plate in existing switch cabinets.

[0008] Meanwhile, the purpose of this utility model is also to provide a switch cabinet that uses the above-mentioned contact box.

[0009] To solve the above problems, the contact box of this utility model adopts the following technical solution: A contact box includes an insulating housing having a distal end for connecting copper busbars and a proximal end for connecting to the cabinet of a switchgear. When in use, the radial side of the insulating housing closest to the partition of the switchgear is the near-partition side, and the side opposite to the near-partition side is the distal-partition side. A stationary contact insert and a high-voltage shielding mesh are provided at the distal end of the insulating housing. The high-voltage shielding mesh is offset relative to the center of the insulating housing toward the distal-partition side so that there is a set insulation distance between the high-voltage shielding mesh and the corresponding partition.

[0010] Furthermore, the far end of the insulating box is provided with an axially outwardly protruding flange at least on the side near the partition, so that the electric field distortion area at the top of the insulating box is away from the strong field area of ​​the high voltage shield and the middle partition.

[0011] Furthermore, the flange covers at least 1 / 2 of the insulating housing in the circumferential direction.

[0012] Furthermore, the high-voltage shielding mesh is a circular shielding mesh.

[0013] Furthermore, an inner wall skirt is provided on the inner wall near the near end of the insulating box. The height of the inner wall skirt near the mounting structure of the insulating box is lower than the height of the other inner wall skirts, so as to have a greater insulation distance between it and the copper busbar.

[0014] Furthermore, the height of the inner wall skirts closest to the insulating box mounting structure is 1 / 3 of the height of the other inner wall skirts.

[0015] Furthermore, the near end of the insulating box is provided with a grounding shield and a mounting insert for electrical connection with the cabinet of the switchgear, and the mounting insert is electrically connected to the grounding shield.

[0016] Furthermore, the grounding shield and the mounting insert are electrically connected via a Z-shaped connecting wire.

[0017] Furthermore, the stationary contact insert and the high-voltage shielding mesh are integrated into one unit.

[0018] The beneficial effects of the contact box of this utility model: The contact box of this utility model is an improved invention. By setting its high-voltage shielding mesh as an eccentric structure, the insulation distance between the high-voltage shielding mesh and the middle partition of the switchgear is increased, thereby solving the problem of easy breakdown discharge between the contact box and the middle partition of the existing switchgear.

[0019] The switch cabinet of this utility model adopts the following technical solution: A switch cabinet includes a cabinet body. A contact box is provided on a mounting plate in the cabinet body. The contact box includes an insulating box. The insulating box has a distal end for connecting copper busbars and a proximal end for connecting to the cabinet body of the switch cabinet. When in use, the radial side of the insulating box closest to the partition of the switch cabinet is the near partition side, and the side opposite to the near partition side is the distal partition side. A stationary contact insert and a high-voltage shielding mesh are provided at the distal end of the insulating box. The high-voltage shielding mesh is offset towards the distal partition side relative to the center of the insulating box so that there is a set insulation distance between the high-voltage shielding mesh and the corresponding partition.

[0020] Furthermore, the far end of the insulating box is provided with an axially outwardly protruding flange at least on the side near the partition, so that the electric field distortion area at the top of the insulating box is away from the strong field area of ​​the high voltage shield and the middle partition.

[0021] Furthermore, the flange covers at least 1 / 2 of the insulating housing in the circumferential direction.

[0022] Furthermore, the high-voltage shielding mesh is a circular shielding mesh.

[0023] Furthermore, an inner wall skirt is provided on the inner wall near the near end of the insulating box. The height of the inner wall skirt near the mounting structure of the insulating box is lower than the height of the other inner wall skirts, so as to have a greater insulation distance between it and the copper busbar.

[0024] Furthermore, the height of the inner wall skirts closest to the insulating box mounting structure is 1 / 3 of the height of the other inner wall skirts.

[0025] Furthermore, the near end of the insulating box is provided with a grounding shield and a mounting insert for electrical connection with the cabinet of the switchgear, and the mounting insert is electrically connected to the grounding shield.

[0026] Furthermore, the grounding shield and the mounting insert are electrically connected via a Z-shaped connecting wire.

[0027] Furthermore, the stationary contact insert and the high-voltage shielding mesh are integrated into one unit.

[0028] The beneficial effects of the technical solution of the switchgear of this utility model: The switchgear of this utility model is an improved invention. The switchgear of this utility model improves the structure of the contact box used. By setting the high-voltage shielding mesh of the contact box as an eccentric structure, the insulation distance between the high-voltage shielding mesh and the middle partition of the switchgear is increased, thereby solving the problem of easy breakdown discharge between the contact box and the middle partition of the existing switchgear. Attached Figure Description

[0029] Figure 1 This is a perspective view of one embodiment of the contact box of this utility model; Figure 2 yes Figure 1 A cross-sectional view of the contact box in the middle; Figure 3 yes Figure 2 A schematic diagram of the stationary contact insert and the high-voltage shielding mesh in the diagram; Figure 4 yes Figure 2 A schematic diagram of the grounding shielding mesh and its installation inserts; Figure 5 yes Figure 1 A schematic diagram of the inner wall skirt of the insulating box; Figure 6 This is a structural schematic diagram of one embodiment of the switch cabinet of this utility model.

[0030] In the diagram: 1. Insulating box; 101. Copper busbar outlet; 102. Flange; 103. Outer wall skirt; 104. Inner wall skirt; 105. Flange; 2. Stationary contact insert; 3. High-voltage shielding mesh; 4. Grounding shielding mesh; 5. Mounting insert; 6. Z-shaped metal connecting wire; 7. Busbar compartment; 8. Cable compartment; 9. Middle partition; 10. Mounting plate. Detailed Implementation

[0031] The features and performance of this utility model will be further described in detail below with reference to specific embodiments.

[0032] A typical structure of a contact box includes an insulating box 1, a stationary contact insert 2 disposed within the insulating box 1, a high-voltage shielding mesh 3, and a copper busbar outlet 101 disposed on the insulating box 1. In existing contact boxes, the far end of the insulating box 1 (i.e., the end closest to the connected busbar and the end furthest from the mounting plate) is a flush, closed structure. The stationary contact insert is located at the center of the far end of the insulating box, typically coaxially arranged with the insulating box. The high-voltage shielding mesh is disc-shaped and coaxially arranged with the stationary contact insert. The copper busbar outlet is located on one radial side of the insulating box. The end of the insulating box with the copper busbar outlet is positioned away from the central partition of the switchgear during use, forming the far-partition side. The opposite side is positioned close to the central partition of the switchgear during use, forming the near-partition side.

[0033] In practical applications, discharge often occurs at the distal end of the contact box relative to the partition plate. The applicant's research revealed that the main reason for this is that the high-voltage shielding mesh is directly connected to the copper busbar, which is at a high potential, and the insulation distance between the high-voltage shielding mesh and the partition plate is insufficient. Furthermore, because the distal end of the contact box has a flush structure, the radius of curvature at the junction of the end face and the side is small. Charge is densely distributed in this area with a small radius of curvature, resulting in an abnormally concentrated electric field intensity at this location, forming an electric field distortion region. This distortion region happens to be located in the strong field region between the high-voltage shielding mesh and the partition plate. The combination of these two factors further exacerbates the breakdown phenomenon of the contact box relative to the partition plate.

[0034] By analyzing the causes of the contact box breakdown relative to the partition plate, the applicant identified an inventive concept to solve the problem: increasing the distance between the high-voltage shielding mesh 3 and the partition plate, and moving the electric field distortion region of the insulating box 1 away from the high-voltage shielding mesh 3 to the strong field region of the partition plate. Based on the above inventive concept, this utility model proposes a technical solution for the contact box and further proposes a technical solution for the switchgear, the core of which is the aforementioned contact box.

[0035] Based on the above inventive concept, the specific implementation of the contact box of this utility model is as follows: like Figure 1-5 As shown, the contact box of this utility model includes an insulating box body 1, a stationary contact insert 2, a high-voltage shielding mesh 3, a grounding shielding mesh 4, and a mounting insert 5.

[0036] The insulating box 1 is generally cylindrical, with its far end closed and the other end open, featuring a flange 102 for connecting to the cabinet. The far end connects to a copper busbar during use, while the near end connects to the corresponding partition within the switchgear (such as the circuit breaker compartment partition). As the core insulating component of the contact box, the insulating box 1 is typically made of epoxy resin, integrally molded using epoxy resin APG (pressure gel) technology or vacuum casting. This results in excellent insulation performance, a dense structure, uniform and stable electrical performance, and high mechanical strength.

[0037] To ensure structural insulation performance, an outer wall skirt 103 is provided on the outer wall of the insulating box 1, and an inner wall skirt 104 is provided on the inner wall of the insulating box 1. Figure 2 In the illustrated embodiment, both the inner wall skirt 104 and the outer wall skirt 103 are V-shaped skirts, with multiple V-shaped skirts arranged continuously to form a wave shape. The inner and outer wall skirts are designed to increase the creepage distance on the surface of the insulating box 1, preventing surface flashover and adapting to different environments. Regarding the arrangement structure of the inner wall skirt 104 and the outer wall skirt 103, any structure from the prior art can be used, such as skirts of varying heights or skirts of equal height, etc., which will not be elaborated upon here.

[0038] A copper busbar outlet 101 is provided on the radial side of the far end of the insulating housing 1. During use, the copper busbar can be connected to the stationary contact inside the insulating housing 1 through the copper busbar outlet 101. For example... Figure 2 As shown, both the stationary contact insert 2 and the high-voltage shielding mesh 3 are located at the far end of the insulating housing 1. A portion of the stationary contact insert 2 is embedded within the wall of the insulating housing 1; this embedding method can be, for example, being encapsulated within the insulating housing 1 during its molding. Another portion of the stationary contact insert 2 is located within the inner cavity of the insulating housing 1, thus allowing it to be used to connect copper busbars. As is customary in the art, the stationary contact insert 2 is arranged coaxially with the insulating housing 1. The high-voltage shielding mesh 3 is completely embedded within the wall of the insulating housing 1, and like the stationary contact insert 2, it can also be encapsulated within the insulating housing 1 during its molding.

[0039] like Figure 3 As shown, the stationary contact insert 2 and the high-voltage shielding mesh 3 can be an integral structure. Of course, in other embodiments, the stationary contact insert 2 and the high-voltage shielding mesh 3 can also be assembled together after being manufactured separately, as long as the conductive connection between the two is guaranteed. The conductive connection can be achieved by welding, by connecting with bolts / screws, or by riveting, etc., which will not be elaborated here.

[0040] As a key difference from existing technologies, to increase the insulation distance between the high-voltage shielding mesh 3 and the intermediate partition of the switchgear, the high-voltage shielding mesh 3 is designed with an eccentric structure relative to the stationary contact insert 2 and the insulating box 1, that is, the high-voltage shielding mesh 3 is offset as a whole towards the far partition side of the insulating box 1. Figure 2 , 3 In the embodiment shown, the high-voltage shielding mesh 3 is a circular shielding mesh. In other embodiments, the high-voltage shielding mesh 3 may not be limited to a circular structure. For example, it may also be an elliptical structure, as long as it has a smooth outer peripheral surface to avoid the generation of tip discharge at the outer edge.

[0041] Based on the above embodiments, as a further improvement, such as Figure 1 , 2 As shown, the far end of the insulating box 1, that is, the closed end, is also provided with an axially protruding flange 105. The protruding tip of the flange 105 will form a charge concentration area, that is, an electric field distortion area, during use. The purpose of setting the flange 105 is to keep the electric field distortion area on the side of the insulating box 1 near the partition away from the strong field area between the high voltage shielding mesh 3 and the middle partition, thereby optimizing the electric field distribution on the surface of the contact box near the top (far end) of the middle partition and eliminating the problem of counter-discharge.

[0042] Based on the above analysis of the function of flange 105, it is clear that flange 105 only needs to be provided on the side of the top of the insulating box 1 near the middle partition. Therefore, as a preferred embodiment, flange 105 is provided only at the circumferential half-section near the middle partition when used on the top of the insulating box 1, and flange 105 roughly forms a U-shape. In other embodiments, whether to provide flange 105 or the arrangement range of flange 105 in the circumferential direction of the insulating box can be determined by considering the voltage level of the switchgear and the shortest distance between the high-voltage shielding mesh 3 and the middle partition. However, under any conditions, it is preferred to ensure that the arrangement range of flange 105 in the circumferential direction of the insulating box 1 is not less than half the circumference of the insulating box 1.

[0043] Furthermore, the protrusion height of flange 105 should also be determined based on the voltage level of the switchgear and the distance between the high-voltage shielding mesh 3 and the intermediate partition. As a general rule, the higher the voltage level of the switchgear and the smaller the distance between the high-voltage shielding mesh 3 and the intermediate partition, the higher the height of flange 105 should be designed. Based on this principle, those skilled in the art should know how to calculate the height of flange 105 so that the contact box can meet the insulation requirements. This will not be elaborated upon here.

[0044] In practical applications, besides the counter-discharge with the partition plate, the contact box also suffers from localized corona discharge due to the wedge-shaped air gap between the contact box mounting plate and the insulating box 1. To address this issue, this invention proposes an improved solution for the contact box, based on the fundamental concept of improving the electric field distribution at this location. Specifically, as follows... Figure 2 , 4 As shown in Figure 5, the contact box of this utility model has a grounding shield 4 embedded at one end of the insulating box 1 near the flange 102. The flange 102 is provided with a mounting insert 5 for connecting the corresponding mounting plate. The grounding shield 4 is electrically connected to the mounting insert 5, thereby realizing the electrical connection between the grounding shield 4 and the mounting plate and even the switch cabinet.

[0045] exist Figure 4 In the preferred embodiment shown, the grounding shield 4 and the mounting insert 5 are integrally cast during the molding process of the insulating box 1, and are connected by a Z-shaped metal connecting wire 6. Of course, in other embodiments, the electrical connection between the grounding shield 4 and the mounting insert 5 does not necessarily use a Z-shaped metal wire connection. For example, in order to achieve a conductive connection between the two, conductors without a fixed shape or of any shape can be used. This will not be elaborated here.

[0046] To further optimize the electric field at the bottom of the insulating box 1, while ensuring the creepage distance meets requirements, it is also possible to make the electric field uniform at the top and bottom of the inner wall skirt 104, such as... Figure 5 As shown, compared to other umbrella skirts, the inner wall umbrella skirt 104 near the grounding shield at the bottom of the insulating box 1 has a shallower umbrella bottom and a lower umbrella top. The umbrella height H is one-third of that of other umbrella skirts (the lower the umbrella height, the farther it will be from the copper busbar during future use, the greater the insulation distance, and the smoother the umbrella tip, making it less prone to tip discharge). This changes the electric field distribution at this location and also ensures that the grounding shield 4 can be embedded within the insulating box during casting. Figure 5 The "S" in the middle refers to the spacing between the umbrella skirts.

[0047] This utility model's contact box meets the usage requirements of 24kV switchgear in high-altitude conditions. An asymmetrical structure (eccentric arrangement) of the high-voltage shielding mesh 3 is adopted to increase the electrical distance between the high voltage and the middle partition of the cabinet, thereby optimizing the electric field distribution on the top of the contact box near the middle partition and improving insulation capability. Extending a U-shaped flange at the top of the contact box increases the creepage distance at the top of the insulating box 1, also moving the electric field distortion area of ​​the insulating box 1 away from the strong field area of ​​the high-voltage shielding mesh 3 and the middle partition, thus improving the electric field distribution on the top of the contact box near the middle partition. Furthermore, optimizing the shape of the umbrella skirt on the bottom inner wall of the insulating box 1 and embedding a grounding shielding mesh 4 at the bottom improves and reduces the local corona generated by the mounting plate and the wedge-shaped air gap between the mounting plate and the insulating box, also changing the electric field distribution at the umbrella skirt. This example can meet the insulation performance requirements at altitudes of 3000m and below, solving the problem of discharge from the top of the contact box to the middle partition.

[0048] The specific implementation method of the switch cabinet of this utility model is as follows: like Figure 6 As shown, the switchgear of this utility model includes a cabinet, within which a busbar compartment 7, a cable compartment 8, a partition plate 9, and a mounting plate 10 are provided. A contact box is mounted on the mounting plate 10; this contact box is the contact box of this utility model. Apart from this, all other parts of the switchgear of this utility model are prior art, and therefore will not be described in detail here. Furthermore, since the specific implementation of the contact box of this utility model has already described its structure and working principle in detail, it will not be described again here.

[0049] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. The patent protection scope of the present utility model shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present utility model shall also be included within the protection scope of the present utility model.

Claims

1. A contact box, comprising an insulating housing having a distal end for connecting a copper busbar and a proximal end for connecting to the cabinet of a switchgear, wherein, in use, the radial side of the insulating housing closest to the partition in the switchgear is the near-partition side, and the side opposite to the near-partition side is the distal-partition side; a stationary contact insert and a high-voltage shielding mesh are provided at the distal end of the insulating housing, characterized in that... The high-voltage shielding mesh is offset from the center of the insulating box towards the far partition side, so that there is a set insulation distance between the high-voltage shielding mesh and the corresponding middle partition.

2. The contact box according to claim 1, characterized in that, The far end of the insulating box is provided with a flange that protrudes outward in the axial direction at least on the side near the partition, so that the electric field distortion area at the top of the insulating box is away from the strong field area of ​​the high voltage shield and the middle partition.

3. The contact box according to claim 2, characterized in that, The flange covers at least 1 / 2 of the insulating box in the circumferential direction.

4. The contact box according to any one of claims 1-3, characterized in that, The high-voltage shielding mesh is a circular shielding mesh.

5. The contact box according to any one of claims 1-3, characterized in that, The insulating box has an inner wall skirt on its inner wall near the end. The height of the inner wall skirt closest to the insulating box mounting structure is lower than the height of the other inner wall skirts, so as to have a greater insulation distance between it and the copper busbar.

6. The contact box according to claim 5, characterized in that, The height of the inner wall skirts near the insulating box mounting structure is 1 / 3 of the height of the other inner wall skirts.

7. The contact box according to any one of claims 1-3, characterized in that, The near end of the insulating box is provided with a grounding shield and a mounting insert for electrical connection with the switch cabinet. The mounting insert is electrically connected to the grounding shield.

8. The contact box according to claim 7, characterized in that, The grounding shielding mesh and the mounting insert are electrically connected by a Z-shaped connecting wire.

9. The contact box according to any one of claims 1-3, characterized in that, The stationary contact insert and the high-voltage shielding mesh are integrated into one unit.

10. A switch cabinet, comprising a cabinet body, wherein a contact box is provided on a mounting plate within the cabinet body, characterized in that, The contact box is the contact box as described in any one of claims 1-9.

Images