Grounding device for gas insulated switchgear

Abstract

The invention discloses a grounding device for a gas insulated switchgear, which comprises a grounding conductor main body arranged on the outer wall of a gas chamber shell, a fixed flange arranged on the inner wall of the gas chamber shell, an inner grounding bar and an outer grounding bar, the grounding conductor main body consists of two sections of concentric reducing cylinders with small upper parts and large lower parts, the lower section of cylinder is connected with one end of the outer grounding bar, and the other end of the outer grounding bar is connected with the fixed flange. The other end of the external grounding bar is connected with an equipment grounding point, the fixing flange is a short cylinder with a central through hole, and the upper section cylinder of the grounding conductor main body penetrates through the air chamber shell, extends into the central through hole of the fixing flange, is fixed and extends out by a section to be connected with one end of the internal grounding bar; and the other end of the inner grounding bar is connected with a main switch grounding bar in the gas tank. According to the device, the sealing performance of the air chamber can be guaranteed, the short-time endurance capability and continuity of a grounding loop can be guaranteed, a stable and reliable fault current discharge channel is provided when a grounding fault occurs in the switch equipment or manual grounding maintenance is needed, and the device is convenient to disassemble and assemble.

Description

Technical Field

[0001] The present invention belongs to the grounding technology of main switches of metal-enclosed switchgear and control equipment in the power industry, relates to the structural design of transition points of internal and external grounding loops of box-type gas-filled switchgear and control equipment gas chambers, and particularly relates to a grounding device for gas-filled cabinets. Background Art

[0002] The short-term withstand capability of equipment grounding circuits is a core indicator in power system safety design, directly impacting the reliability and safety of equipment under extreme fault conditions. When a ground fault occurs within a ring main unit (RMU) or when manual grounding maintenance is required, the grounding circuit is the only path to dissipate the fault current. If the circuit's short-term withstand capability is insufficient, the high-impedance conductor will fuse before the circuit breaker can interrupt the fault current. This can easily lead to arc reignition or equipment explosion, endangering personnel. The RMU grounding circuit is a critical component for ensuring safe and stable operation in power systems.

[0003] Box-type gas-filled switchgear and control equipment are widely used in power systems due to their fully enclosed, modular, compact, high-security, intelligent, low-maintenance, environmentally friendly, and high-reliability characteristics. The prerequisite of full enclosure improves the reliability of product operation, but it also increases the difficulty of designing the grounding loop within the gas chamber. It is necessary to ensure the airtightness of the gas chamber, as well as the short-term withstand capability and continuity of the grounding loop, and the convenience of the grounding device. To meet these requirements, there are currently three main methods for grounding inside and outside the equipment gas chamber:

[0004] Method 1: The ground loop passes through the gas chamber, with studs welded face-to-face. The main switch outside the gas chamber is connected to the grounding system via the grounding bar inside the gas box, the studs, the gas box wall, and the grounding bar outside the gas box. Advantages include easy installation and guaranteed gas chamber sealing. Disadvantages include high impedance points in the ground loop. High fault currents can easily cause the grounding copper fittings at these points to fuse, preventing the fault current from dissipating.

[0005] Method 2: The ground loop passes through a hole in the gas chamber, with a copper block welded in between. The main switch outside the gas chamber is connected to the grounding system via a grounding bar inside the gas box, the welded copper block, and the grounding bar outside the gas box. Advantages include ease of installation and no high-impedance points in the ground loop. Disadvantages include welding the copper components to the stainless steel gas box wall, requiring a high welding process, making disassembly difficult, prone to leaks, and difficult to ensure a tight seal.

[0006] Method 3: The ground loop passes through a hole in the gas chamber, with a stainless steel component welded in between. The main switch inside the gas chamber is connected to the grounding system via a grounding bar inside the gas box, the stainless steel component, and the grounding bar outside the gas box. Advantages: The stainless steel component is welded to the stainless steel gas box wall, making it easy to weld and ensuring the airtightness of the gas chamber. Disadvantages: Disassembly is difficult, and high impedance points appear in the ground loop. High fault currents can easily cause the grounding copper fittings at these points to melt, preventing the fault current from discharging. Summary of the Invention

[0007] The object of the present invention is to provide a grounding device for an inflatable cabinet which can ensure the short-time tolerance and continuity of the grounding circuit while ensuring the airtightness of the air chamber and is easy to disassemble and replace.

[0008] The objectives of the present invention are achieved through the following technical measures: A grounding device for an inflatable cabinet, characterized in that it includes a grounding conductor body arranged on the outer wall of the gas chamber shell, a fixed flange arranged on the inner wall of the gas chamber shell, an internal grounding bar and an external grounding bar, the grounding conductor body is composed of two concentric and different-diameter cylinders, the upper one is smaller and the lower one is larger, the lower one is connected to one end of the external grounding bar, and the other end of the external grounding bar is connected to the grounding point of the equipment, the fixed flange is a short cylinder with a central through hole, the upper one of the grounding conductor body passes through the gas chamber shell and extends into the central through hole of the fixed flange to be fixed and extends out a section to connect one end of the internal grounding bar, and the other end of the internal grounding bar is connected to the main switch grounding bar in the gas box.

[0009] The present invention can not only ensure the sealing of the gas chamber, but also ensure the short-term tolerance and continuity of the grounding loop, providing a stable and reliable fault current discharge channel when a grounding fault occurs inside the switchgear or manual grounding maintenance is required, thereby avoiding the risks of equipment explosion due to insufficient short-term tolerance of the grounding loop, further expansion of the fault, and causing personal injury and economic losses; and the device is easy to disassemble and assemble.

[0010] In the present invention, sealing structures are provided between the bottom surface of the fixed flange and the inner wall surface of the air chamber shell, and between the lower column of the grounding conductor body and the outer wall surface of the air chamber shell.

[0011] The sealing structures between the bottom surface of the fixed flange and the inner wall surface of the air chamber shell, and between the top surface of the lower cylindrical body of the grounding conductor body and the outer wall surface of the air chamber shell of the present invention are both inner and outer annular sealing grooves and sealing rings. The inner ring sealing ring adopts a U-shaped cross-section high-temperature resistant metal sealing ring, and the outer ring sealing ring adopts an O-shaped cross-section polytetrafluoroethylene sealing ring.

[0012] The upper column of the grounding conductor body of the present invention has a threaded side surface, the central through hole of the fixing flange is a threaded hole, and the upper column of the grounding conductor body is threadedly connected to the central through hole of the fixing flange.

[0013] The surface of the grounding conductor body of the present invention is all galvanized or silver-plated except for the threaded surface of the upper column.

[0014] The bottom surface of the lower column of the grounding conductor body of the present invention is provided with a first threaded hole, and the external grounding bar is fixed to the grounding conductor body by connecting the external grounding bar with a bolt and screwing it into the first threaded hole. The top surface of the upper column of the grounding conductor body is provided with a second threaded hole, and the internal grounding bar is fixed to the grounding conductor body by connecting the internal grounding bar with a bolt and screwing it into the second threaded hole.

[0015] The upper column and the lower column of the grounding conductor body of the present invention are made into one piece. The upper column is a cylinder, and the lower column is a regular hexagonal prism. The top surface of the upper column is a plane, which is also the overlapping surface with the internal grounding bar. The bottom surface of the lower column is a plane, which is also the overlapping surface with the external grounding bar.

[0016] The outer wall surface of the fixing flange of the present invention has at least one set of two opposite planes, and a pair of third threaded holes arranged radially are opened on one set of planes. The third threaded holes are used for flat-end set screws to penetrate and tightly press against the upper column of the grounding conductor body, effectively preventing it from loosening due to vibration or electric force.

[0017] The fixing flange and the grounding conductor body of the present invention are both made of copper material.

[0018] Compared with the prior art, the present invention has the following significant effects:

[0019] (1) The main body of the present invention is made of T2 copper, and the conductor cross-section design fully meets the requirements of the national and industry standards for the short-time withstand capability of the main switch grounding circuit, and the structure is reliable.

[0020] (2) The grounding conductor body and the fixed flange of the present invention are connected by threaded locking, which is reliable and easy to assemble and disassemble. There is no need for copper-copper or copper-stainless steel welding processes, and it is easy to construct and replace.

[0021] (3) The double sealing surface structure of the present invention, that is, the inner and outer sides of the air chamber wall are both sealing surfaces. During operation, as long as one of the sealing surfaces is normal, the air tightness of the air chamber can be guaranteed, and the risk of arc extinguishing and insulation medium leakage in the air chamber is reduced.

[0022] (4) The grounding conductor body and the fixing flange of the present invention are structured in a combined manner. In fact, only the integrated copper grounding conductor body runs through the inside and outside of the gas box. The contact resistance and the transmission resistance are extremely small, which can effectively eliminate the high impedance points in the grounding loop.

[0023] (5) The present invention changes from an axial seal to a static end face radial seal design. The grounding conductor body runs through the inside and outside of the air box. The grounding conductor body and the flange that were originally to be sealed are transferred to a static end face seal between the grounding conductor body, the fixed flange and the air chamber wall through a double sealing surface structure, which has higher reliability.

[0024] (6) The double-ring sealing design at the sealing surface of the present invention ensures that the sealing effect of one surface is guaranteed if the other is normal. The inner ring adopts an annular U-shaped cross-section high-temperature resistant metal sealing ring, and the outer ring adopts a polytetrafluoroethylene sealing ring to reduce the impact of the thermal effect of the fault current on the sealing performance here.

[0025] (7) The fixed flange of the present invention adopts a flat-end tightening bolt installation method to prevent loosening, thereby reducing the influence of the electrodynamic effect on the sealing effect here.

[0026] (8) The present invention meets the requirements of relevant standards on the short-time withstand capability of grounding circuits for power switchgear and control equipment. After theoretical calculation and careful design, compared with grounding methods such as grounding studs, gas box shells, stainless steel weldments, and copper grounding block assemblies, the present invention has high reliability, good sealing, and convenient installation without affecting the air tightness of the gas chamber. It is applicable to most box-type inflatable metal-enclosed switchgear and control equipment of medium and low voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1 This is a schematic diagram of the structure of the present invention installed on the air chamber housing;

[0029] Figure 2 yes Figure 1 S-direction view;

[0030] Figure 3 is a top view of the fixed flange of the present invention;

[0031] Figure 4 It is a front view of the fixed flange of the present invention;

[0032] Figure 5 is a top view of the grounding conductor body of the present invention;

[0033] Figure 6 It is a front view of the grounding conductor body of the present invention.

[0034] In the figure: 1-inner grounding bar, 2-fixing flange, 3-first sealing ring, 4-second sealing ring, 5-air chamber housing, 6-fourth sealing ring, 7-third sealing ring, 8-grounding conductor body, 9-external grounding bar, 10-main switch grounding bar, 11-lower column, 12-center through hole, 13-upper column, 14-first threaded hole, 15-second threaded hole, 16-plane, 17-third threaded hole, 18-first annular sealing groove, 19-second annular sealing groove, 20-third annular sealing groove, 21-fourth annular sealing groove, 22-flat end set screw. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the embodiments and the accompanying drawings to help those skilled in the art better understand the inventive concept of the present invention. However, the scope of protection of the claims of the present invention is not limited to the following embodiments. For those skilled in the art, all other embodiments obtained without creative work without departing from the inventive concept of the present invention shall fall within the scope of protection of the present invention.

[0036] like Figures 1 to 6 As shown, the present invention provides a grounding device for an inflatable cabinet, comprising a grounding conductor body 8 provided on the bottom surface of the outer wall of the gas chamber shell 5, a fixed flange 2 provided on the bottom surface of the inner wall of the gas chamber shell 5, an internal grounding bar 1 and an external grounding bar 9. The fixed flange 2 and the grounding conductor body 8 are both made of red copper. The grounding conductor body 8 consists of two concentric cylinders with different diameters, the upper one being smaller and the lower one being larger. The lower cylinder 11 is connected to one end of the external grounding bar 9, and the other end of the external grounding bar 9 is connected to the grounding point of the equipment. The fixed flange 2 is a short cylinder with a central through hole 12. The upper cylinder 13 of the grounding conductor body 8 passes through the gas chamber shell 5 and extends into the central through hole 12 of the fixed flange 2 to be fixed and extends a section to connect one end of the internal grounding bar 1, and the other end of the internal grounding bar 1 is connected to the main switch grounding bar 10 in the gas box.

[0037] In this embodiment, the upper column 13 of the grounding conductor body 8 has a threaded side surface, and the central through hole 12 of the fixing flange 2 is a threaded hole. The upper column 13 of the grounding conductor body 8 is threadedly connected to the central through hole 12 of the fixing flange 2.

[0038] The surface of the grounding conductor body 8 , except for the threaded surface of the upper column 13 , is galvanized or silver-plated to prevent rust and reduce contact resistance.

[0039] A first threaded hole 14 is provided on the bottom surface of the lower column 11 of the grounding conductor body 8, and the external grounding bar 9 is fixed to the grounding conductor body 8 by means of bolts connected to the external grounding bar 9 and screwed into the first threaded hole 14; a second threaded hole 15 is provided on the top surface of the upper column 13 of the grounding conductor body 8, and the internal grounding bar 1 is fixed to the grounding conductor body 8 by means of bolts connected to the internal grounding bar 1 and screwed into the second threaded hole 15.

[0040] The upper column 13 and the lower column 11 of the grounding conductor body 8 are made of an integral body. The upper column 13 is a cylinder, and the lower column 11 is a regular hexagonal prism. The top surface of the upper column 13 is a plane, which is also the overlapping surface with the internal ground bar 1. The bottom surface of the lower column 11 is a plane, which is also the overlapping surface with the external ground bar 9. The top surface of the lower column 11 is a sealing surface with double sealing grooves.

[0041] The top surface of the fixed flange 2 is flat, and the lower surface is a sealing surface with dual sealing grooves. The outer wall of the fixed flange 2 has at least one set of two opposing flat surfaces 16 (for use with a locking tool for fastening). A pair of radially arranged third threaded holes 17 are formed in one set of flat surfaces 16. These third threaded holes 17 allow flat-ended set screws 22 to penetrate and tighten against the upper column 13 of the grounding conductor body 8. The flat-ended set screw installation method uses a loose-proof design to reduce the impact of the current flow effect on the sealing effect here.

[0042] In this embodiment, sealing structures are provided between the bottom surface of the fixing flange 2 and the inner wall surface of the air chamber shell 5 , and between the top surface of the lower column 11 of the grounding conductor body 8 and the outer wall surface of the air chamber shell 5 . The sealing structure consists of two inner and outer annular sealing grooves and sealing rings. The two annular sealing grooves on the fixed flange 2 are the first annular sealing groove 18 of the inner ring and the second annular sealing groove 19 of the outer ring. The first sealing ring 3 of the inner ring installed in the first annular sealing groove 18 adopts a high-temperature resistant annular U-shaped cross-section metal sealing ring, which is the first sealing line of defense for the double sealing surfaces. The second sealing ring 4 of the outer ring installed in the second annular sealing groove 19 adopts a high-temperature resistant annular O-shaped cross-section polytetrafluoroethylene sealing ring, which is the second sealing line of defense for the double sealing surfaces; the two annular sealing grooves on the lower section column 11 of the grounding conductor body 8 are the third annular sealing groove 20 of the inner ring and the fourth annular sealing groove 21 of the outer ring. The third sealing ring 7 of the inner ring installed in the third annular sealing groove 20 adopts a high-temperature resistant annular U-shaped cross-section metal sealing ring, which is the first sealing line of defense for the double sealing surfaces. The fourth sealing ring 6 of the outer ring installed in the fourth annular sealing groove 21 adopts a high-temperature resistant annular O-shaped cross-section polytetrafluoroethylene sealing ring, which is the second sealing line of defense for the double sealing surfaces.

[0043] The fixed flange 2 and the grounding conductor body 8 of the present invention are respectively placed inside and outside the gas chamber shell, and are mechanically connected by threaded locking. A double sealing surface and double sealing structure are used to ensure the sealing of the gas chamber. After the locking is completed, the upper cylindrical end face of the grounding conductor body exceeds the upper end face of the fixed flange by a certain distance. One end of the grounding bar 1 inside the gas box is connected to the main switch grounding bar 10 inside the gas box, and the other end is connected to the grounding conductor body 8 by bolts; one end of the grounding bar 2 outside the gas chamber is connected to the equipment grounding point, and the other end is connected to the grounding conductor body 8 by bolts, thereby realizing the connection between the grounding conductors inside and outside the gas chamber. After the above installation is completed, the fixed flange 2 is fixed and prevented from loosening by a flat-end set screw 22.

Claims

1. A grounding device for an inflatable cabinet, characterized by: It includes a grounding conductor body arranged on the outer wall of the air chamber shell, a fixing flange arranged on the inner wall of the air chamber shell, an internal grounding bar and an external grounding bar. The grounding conductor body is composed of two concentric cylinders with different diameters, the upper one is smaller and the lower one is larger. The lower cylinder is connected to one end of the external grounding bar, and the other end of the external grounding bar is connected to the equipment grounding point. The fixing flange is a short cylinder with a central through hole. The upper cylinder of the grounding conductor body passes through the air chamber shell and extends into the central through hole of the fixing flange for fixation and extends out a section to connect one end of the internal grounding bar, and the other end of the internal grounding bar is connected to the main switch grounding bar in the gas box.

2. The grounding device for an inflatable cabinet according to claim 1, characterized in that: A sealing structure is provided between the bottom surface of the fixing flange and the inner wall surface of the air chamber shell, and between the top surface of the lower column of the grounding conductor body and the outer wall surface of the air chamber shell.

3. The grounding device for an inflatable cabinet according to claim 2, characterized in that: The sealing structures between the bottom surface of the fixed flange and the inner wall surface of the air chamber shell, and between the top surface of the lower cylindrical body of the grounding conductor body and the outer wall surface of the air chamber shell are both inner and outer annular sealing grooves and sealing rings. The inner ring sealing ring adopts a U-shaped cross-section high-temperature resistant metal sealing ring, and the outer ring sealing ring adopts an O-shaped cross-section polytetrafluoroethylene sealing ring.

4. The grounding device for an inflatable cabinet according to claim 3, characterized in that: The side surface of the upper column of the grounding conductor body is threaded, the central through hole of the fixing flange is a threaded hole, and the upper column of the grounding conductor body is threadedly connected to the central through hole of the fixing flange.

5. The grounding device for an inflatable cabinet according to claim 4, characterized in that: The surface of the grounding conductor body except the threaded surface of the upper column is all zinc-plated or silver-plated.

6. The grounding device for an inflatable cabinet according to claim 5, characterized in that: A first threaded hole is provided on the bottom surface of the lower column of the grounding conductor body, and the external grounding bar is fixed to the grounding conductor body by connecting the external grounding bar with a bolt and screwing it into the first threaded hole. A second threaded hole is provided on the top surface of the upper column of the grounding conductor body, and the internal grounding bar is fixed to the grounding conductor body by connecting the internal grounding bar with a bolt and screwing it into the second threaded hole.

7. The grounding device for an inflatable cabinet according to claim 6, characterized in that: The upper column and the lower column of the grounding conductor body are made in one piece. The upper column is a cylinder and the lower column is a regular hexagonal prism. The top surface of the upper column is a plane, which is also the overlapping surface with the internal grounding bar. The bottom surface of the lower column is a plane, which is also the overlapping surface with the external grounding bar.

8. The grounding device for an inflatable cabinet according to claim 7, characterized in that: The outer wall surface of the fixing flange has at least one set of two opposite planes, and a pair of radially arranged third threaded holes are opened on one set of planes. The third threaded holes are used for flat-end set screws to penetrate and tightly press against the upper column of the grounding conductor body.

9. The grounding device for an inflatable cabinet according to claim 8, characterized in that: The fixing flange and the grounding conductor body are both made of copper.

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