Three-phase box-sharing basin-type insulator for GIS (Gas Insulated Switchgear) taking friendly medium as insulation

Abstract

The invention provides a three-phase box-sharing basin-type insulator for a GIS (Gas Insulated Switchgear) taking a friendly medium as insulation, which comprises a resin casting piece, a metal insert, a shielding ring, a temperature measuring optical fiber and a switching end head which are cast in an epoxy resin matrix, the epoxy resin matrix is provided with a central vent hole and a first vent hole, a metal flange ring is connected with a shell flange, and the metal flange ring is connected with the switching end head; a first sealing groove is formed in the resin casting part, a switching end fixing hole, a sprue gate, an anti-lateral-rotation groove and a shielding ring fixing hole are evenly distributed in the outer side of the resin casting part, the first sealing groove is sealed with a second sealing groove of the resin casting part, the anti-lateral-rotation groove is matched with an anti-lateral-rotation protrusion on the resin casting part, a switching end is fixed to the switching end fixing hole, and a shielding ring is fixed to the shielding ring fixing hole. The two ends of the temperature measuring optical fiber are connected with the metal insert and the switching end respectively, the switching end is externally connected with a thermodetector, and the cover plate is fastened to a sprue gate of the metal flange ring. The three-phase common box type basin-type insulator for the GIS taking the friendly medium as insulation is stable in performance and safe and reliable in operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of high - voltage switches, and particularly relates to a three - phase co - boxed pot - type insulator for GIS insulated with a friendly medium. Background Art

[0002] Sulfur hexafluoride has been introduced into high - voltage electrical equipment due to its excellent insulation and arc - extinguishing performance. However, considering environmental protection, zero - carbon and fluorine - free gas - medium GIS equipment is the preferred solution. Pure nitrogen has become the first choice because of its zero GWP (Global Warming Potential), non - toxicity and low cost (only 5% of sulfur hexafluoride), but its inherent defects are significant: on the one hand, the insulation performance of nitrogen is insufficient. At a gas pressure of 0.4 MPa, the power - frequency breakdown field strength of nitrogen is only 17.8 kV / cm·bar, about 1 / 3.5 of sulfur hexafluoride; on the other hand, it is highly sensitive to the electric field. The non - polar characteristic of nitrogen molecules results in a very low tolerance to electric - field distortion. Streamer discharge occurs when the local field strength exceeds 25 kV / cm, while the critical field strength of sulfur hexafluoride can reach 89 kV / cm.

[0003] Currently, the electric - field strength at the triple - intersection area of the pot, along the surface of the pot, and at the low - potential shell flange of the conventional pot - type insulator is high. Moreover, the insulation problem is severe due to the fact that the insulation performance of the pure - nitrogen medium used is only 1 / 3 of that of the sulfur - hexafluoride medium. In addition, the traditional shell measures temperature externally, and the temperature change needs to be transmitted layer by layer through the conductor - gas - shell, which has a time delay and cannot detect the internal temperature anomaly of GIS in time. Summary of the Invention

[0004] In view of this, the present invention aims to provide a three - phase co - boxed pot - type insulator for GIS insulated with a friendly medium to solve the problems that the electric - field strength at the triple - intersection area of the pot, along the surface of the pot, and at the low - potential shell flange of the conventional pot - type insulator is high, and the severe insulation problem caused by the fact that the insulation performance of the pure - nitrogen medium used is only 1 / 3 of that of the sulfur - hexafluoride medium, and the problem that the traditional shell measures temperature externally, and the temperature change needs to be transmitted layer by layer through the conductor - gas - shell, which has a time delay and cannot detect the internal temperature anomaly of GIS in time.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows:

[0006] The present invention provides a three-phase coaxial pot insulator for GIS with a friendly medium as insulation, including a metal flange ring, a resin casting, and a cover plate. The resin casting includes a metal insert, a shielding ring, a temperature-measuring optical fiber, and a transition end embedded in an epoxy resin matrix. The epoxy resin matrix is provided with a central ventilation hole and three first ventilation holes distributed in an equilateral triangle. The metal flange ring is flange-connected to the housing, and is provided with a first sealing groove inside, and fixing holes for transition ends, a casting port, four anti-rotation grooves, and shielding ring fixing holes are evenly distributed on the outside. The first sealing groove and the second sealing groove of the resin casting form a double-sealing structure. The anti-rotation groove cooperates with the anti-rotation protrusion on the resin casting. The two ends of the temperature-measuring optical fiber are respectively connected to the metal insert and the transition end, and the transition end is externally connected to a temperature-measuring instrument. The cover plate is fastened to the casting port of the metal flange ring by screws. The transition end is fixed at the transition end fixing hole, and the shielding ring is fixed at the shielding ring fixing hole.

[0007] Further, multiple layers of stepped protrusions are provided on the periphery of the resin casting with the installed metal insert as the axis. The height of the stepped protrusions is 50 mm. A first annular stress relief groove with a width of 5 mm and a depth of 7 mm is provided within a range of 1 cm outside the end face of the resin casting where the metal insert is installed. The first annular stress relief groove is arranged with the metal insert as the axis. A rectangular second sealing groove is provided on the outside of the resin casting. The height difference at the air gap where the second sealing groove cooperates with the housing flange is 9 mm. The overall thickness of the plane of the resin casting is 40 mm.

[0008] Further, after the resin casting is initially cured, a PTFE coating with a thickness of 30 - 50 μm is applied to it for secondary curing.

[0009] Further, the metal insert is a cylindrical and centrally rotated structure with a concave middle part as a whole. A second annular stress relief groove is provided on the metal insert. The outer cylindrical surface of the metal insert is partially knurled and coated with semi-conductive glue, and the conductive connection surfaces on both sides of the metal insert are silver-plated. The core material of the metal insert is copper, and the part in contact with the resin casting on the outside is aluminum.

[0010] Further, the diameter of the end face of the metal insert is 10 mm smaller than the diameter of the concave section in the middle of the metal insert. A number of threaded connection holes are provided on the upper end face of the metal insert, and the threaded connection holes are connected to conductors.

[0011] Further, the shielding ring is made of aluminum and includes a support and a single shielding ring. The two single shielding rings and the three supports are welded together. The single shielding ring is a non-closed ring and has an opening at the casting port. The support and the metal flange ring are fixed at the shielding ring fixing hole by bolts.

[0012] Further, the material of the metal flange ring is forged aluminum, the flange thickness is 80 mm, and the same number of two types of connection holes are evenly distributed on the metal flange ring. The connection holes include M12 threaded connection holes and Φ14 through holes.

[0013] Further, the temperature-measuring optical fiber is subjected to surface roughening treatment and is a two-strand wire.

[0014] Further, when there is a bay with partial discharge monitoring in the GIS, the cover plate is removed and then the partial discharge sensor is installed.

[0015] Compared with the prior art, the three-phase coaxial pot-type insulator for GIS with a friendly medium as insulation has the following advantages:

[0016] (1) The three-phase coaxial pot-type insulator of the present invention enhances the mechanical strength of the pot-type insulator: on the one hand, stress relief grooves are provided on both the metal insert and the resin on the outer ring of the metal insert; on the other hand, the structure and material of the metal insert are optimized, and the resin thickness and structure are verified by simulation calculation, maximizing the utilization rate of the resin material while ensuring the mechanical strength of the three-phase coaxial pot-type insulator. A temperature-measuring optical fiber is preset in the three-phase coaxial pot-type insulator, which can realize the monitoring of the internal temperature of the pot-type insulator. The three-phase coaxial pot-type insulator as a whole has the advantages of reasonable structure, stable performance, low manufacturing cost, and safe and reliable operation.

[0017] (2) In the present invention, the multi-layer stepped protrusions are used to evenly distribute the electric field, reduce partial discharge, and at the same time improve the mechanical strength of the connection with the metal insert. The first annular stress relief groove can disperse the stress distribution at the interface between the metal insert and the insulating material, avoid stress concentration, and when an initial crack occurs due to fatigue or impact of the material, the geometric interruption characteristic of the first annular stress relief groove can effectively prevent the crack from further extending into the insulating material area; the coated PTFE nano-coating can make the surface of the resin casting have the ability of moisture and humidity resistance, chemical corrosion resistance, and improve surface cleanliness; at the same time, due to its low dielectric constant, it can make the dielectric difference at the N2-resin interface transition smoothly, inhibit charge accumulation, and optimize the electric field distribution.

[0018] (3) In the present invention, an aluminum-copper transition material is used for the metal insert. The difference in the coefficient of thermal expansion between the aluminum on the outer ring of the metal insert and the epoxy resin is small, which can reduce the risk of interface cracking and extend the service life. The copper in the core of the metal insert improves the current-carrying capacity of the conductor butt joint surface and is also beneficial to the heat dissipation of the product. The concave structure in the middle part of the metal insert increases the contact area and the biting depth between the metal insert and the epoxy resin, forming a more firm mechanical interlock. At the same time, it also has an advantage in the relative electric field strength, and the electric field on the shell is significantly reduced. The use of the semi-conductive glue can reduce the potential difference between the insert and the insulating material, improve the electric field on the surface of the metal insert, and at the same time can buffer the thermal expansion stress and improve the stress problem caused by the different coefficients of thermal expansion between the metal insert and the insulating material.

[0019] (4) In the present invention, the diameter difference between the end face diameter of the metal insert and the diameter of the concave section in the middle of the metal insert is matched with the conductor butt-jointed with the metal insert to form an electric field shielding pit, which wraps the triple intersection area in the electric field shielding pit to avoid the distortion of the electric field at the triple intersection area of the three-phase coaxial pot-type insulator. Only 3 holes out of the 6 threaded holes on the metal insert are required for fixing in actual application. The design of 6 holes facilitates the angular variation of the installation of the conductor 19 and is applicable to various installation directions.

[0020] (5) In the present invention, the shielding ring is designed as a double-layer large ring structure, that is, it is formed by welding two single shielding rings and three support members. The large ring surrounds the three-phase insert inside, effectively shielding the electric field at the shell flange. Compared with the traditional single-layer structure, the double-layer structure of the shielding ring is more conducive to evenly distributing the potential line density at the shell flange and can effectively avoid the electric field concentration at the shell flange. The 4-shielding ring is not a closed ring and has an opening, and the opening faces the casting port of the pot-type insulator. An external partial discharge sensor can be installed at the casting port, and this opening design is beneficial to the transmission of electromagnetic signals.

[0021] (6) In the present invention, the forged aluminum has a low density. The lightweight design can optimize the support structure of the metal flange ring, reduce the mechanical requirements for the surrounding components, and has high strength and toughness, and still maintains good toughness in a low-temperature environment, making it suitable for cold regions. By increasing the number of bolt connections and the flange thickness, the flange connection strength is greatly enhanced, and through calculation, it can fully withstand the mechanical strength requirements brought by the increase in the pure N2 gas chamber pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0023] In the drawings:

[0024] Figure 1Isometric schematic diagram of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0025] Figure 2 Front view schematic diagram of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0026] Figure 3 Appearance schematic diagram of the metal flange of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0027] Figure 4 Cross - sectional view schematic diagram of the metal flange of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0028] Figure 5 Overall schematic diagram of the resin casting part of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0029] Figure 6 Cross - sectional view schematic diagram of the resin casting part of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0030] Figure 7 Overall schematic diagram of the metal insert of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0031] Figure 8 Schematic diagram of the knurling range of the metal insert of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0032] Figure 9 Cross - sectional view schematic diagram of the metal insert of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0033] Figure 10 Overall schematic diagram of the shielding ring of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention;

[0034] Figure 11 Schematic diagram of the installation of the partial discharge sensor of a three - phase co - box pot - type insulator for GIS with friendly medium as insulation according to an embodiment of the present invention.

[0035] Explanation of reference numerals:

[0036] 1. Metal flange ring; 2. Resin casting; 3. Metal insert; 4. Shielding ring; 5. Cover plate; 6. Temperature-measuring optical fiber; 7. Adapter end; 8. Shielding ring fixing hole; 9. Adapter end fixing hole; 10. Pouring port; 11. Anti-rotation groove; 12. First sealing groove; 13. Anti-rotation protrusion; 14. First ventilation hole; 15. Central ventilation hole; 16. Multi-layer stepped protrusion; 17. Second sealing groove; 18. First annular stress relief groove; 19. Conductor; 20. Aluminum material range; 21. Copper material range; 22. Knurling range; 23. Threaded connection hole; 24. Support; 25. Single shielding ring; 26. Partial discharge sensor; A. Protrusion height; B. Air gap; C. End face diameter of metal insert; D. Diameter of middle concave section of metal insert. Detailed implementation mode

[0037] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0038] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0039] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0040] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0041] Refer to Figures 1 - 11As shown in the figure, this embodiment provides a three-phase coaxial pot-type insulator for GIS insulated with a friendly medium, including a metal flange ring 1, a resin casting 2, and a cover plate 5. The resin casting 2 includes a metal insert 3, a shielding ring 4, a temperature-measuring optical fiber 6, and a transfer end 7 cast in an epoxy resin matrix. The epoxy resin matrix is provided with a central vent hole 15 and three first vent holes 14 distributed in an equilateral triangle. The metal flange ring 1 is flange-connected to the housing and is provided with a first sealing groove 12 inside, and transfer end fixing holes 9, pouring ports 10, four anti-rotation grooves 11, and shielding ring fixing holes 8 are evenly distributed on the outside. The first sealing groove 12 and the second sealing groove 17 of the resin casting 2 form a double-sealing structure. The anti-rotation grooves 11 cooperate with the anti-rotation protrusions 13 on the resin casting 2. The transfer end 7 is fixed at the transfer end fixing hole 9, and the shielding ring 4 is fixed at the shielding ring fixing hole 8. The two ends of the temperature-measuring optical fiber 6 are respectively connected to the metal insert 3 and the transfer end 7. The transfer end is externally connected to a temperature-measuring instrument, and the cover plate 5 is fastened to the pouring port 10 of the metal flange ring 1 by screws.

[0042] Before the epoxy resin casting of the three-phase coaxial pot-type insulator, the shielding ring 4 and the conversion end 7 are fixed on the metal flange ring 1. The metal insert 3 is fixed by the pot-type insulator mold. A pouring port 10 is provided at the edge of the metal flange ring 1. The treated epoxy casting material is poured through the pouring port 10. After the casting is completed, the metal insert 3, the shielding ring 4, the temperature-measuring optical fiber 6, and the transfer end 7 are integrally formed inside the resin casting 2. Finally, the 1 pouring port 10 on the metal flange ring 1 is blocked by the cover plate 5. When it is necessary to install the partial discharge sensor 26, the cover plate 5 is removed, and the cover plate fixing hole on the metal flange ring 1 is the partial discharge sensor fixing hole. The anti-rotation groove prevents the relative rotation between the flanges through the fitting structure of the flange depression and the resin protrusion, ensuring the mechanical stability of the connection. Under extreme working conditions (such as the strong electromagnetic force caused by the short-circuit current), the anti-rotation groove can share the lateral stress and avoid structural displacement. Rectangular sealing grooves are provided on both end faces of the metal flange ring 1, which cooperate with O-ring seals to form a physical barrier to prevent external dust, moisture, or chemical pollutants from invading the equipment interior and ensure the insulation performance. The side of the metal flange ring 1 also has a shielding ring fixing hole, a conversion end fixing hole for the optical fiber temperature measurement module, and a pouring port. The shielding ring 4 and the conversion end 7 are installed in the corresponding fixing holes of the flange. During the casting stage of the three-phase coaxial pot-type insulator, the epoxy casting material is poured along the pouring port. The 3 large vent holes are distributed in an equilateral triangle. Such a design facilitates the circulation of the insulating gas in the gas chamber to increase the heat dissipation efficiency of the product and improve the temperature rise performance of the product. One end of the temperature-measuring optical fiber is connected to the metal insert, and the other end is connected to the transfer end. In actual use, the transfer end is externally connected to a temperature-measuring instrument to monitor the temperature change inside the pot-type insulator.

[0043] Specifically, in this embodiment, a multi-layer stepped protrusion 16 is provided on the periphery of the resin casting 2 with the installed metal insert 3 as the axis. The height A of the multi-layer stepped protrusion 16 is 50 mm. The resin casting 2 is provided with a first annular stress relief groove 18 with a width of 5 mm and a depth of 7 mm within a range of 1 cm outside the end face of the installed metal insert 3. The first annular stress relief groove 18 is arranged with the metal insert 3 as the axis. A rectangular second sealing groove 17 is provided on the outside of the resin casting 2. The height difference at the air gap B where the second sealing groove 17 mates with the housing flange is 9 mm. The overall planar thickness of the resin casting 2 is 40 mm.

[0044] The multi-layer stepped protrusion is used to evenly distribute the electric field, reduce partial discharge, and at the same time improve the mechanical strength of the connection with the metal insert. The first annular stress relief groove can disperse the stress distribution at the interface between the metal insert and the insulating material, avoid stress concentration, and when an initial crack occurs due to fatigue or impact of the material, the geometric interruption characteristic of the first annular stress relief groove can effectively prevent the crack from further extending into the insulating material area. Through electric field simulation calculation, it is optimal that the height of the multi-layer stepped protrusion relative to the resin base surface is designed to be 50 m. This structure reduces the electric field strength from 20 kV / mm to 15 kV / mm, confirming the effect of evenly distributing the electric field, and has a significant effect on improving the mechanical strength of the connection with the metal insert.

[0045] During the casting or curing process of the three-phase coaxial pot-type insulator, the second stress relief groove on the metal insert can provide a local flexible deformation space, absorb the deformation caused by the thermal expansion difference, and reduce the risk of interface peeling at the three-phase intersection area between the metal insert and the resin casting.

[0046] Specifically, in this embodiment, after the resin casting 2 is initially cured, a PTFE nano-coating with a thickness of 30 - 50 μm is coated on it for secondary curing. The coated PTFE nano-coating enables the surface of the resin casting to have the ability of moisture and humidity resistance, chemical corrosion resistance, and improved surface cleanliness; at the same time, due to its low dielectric constant, it can make the dielectric difference at the N2-resin interface transition smoothly, inhibit charge accumulation, and optimize the electric field distribution. The initial curing of the resin casting is the initial stage of the transition of the resin from the liquid state to the solid state, which is a conventional step for the resin casting. This step is common knowledge for those skilled in the art and will not be elaborated here.

[0047] Specifically, in this embodiment, as Figures 7 - 9 shown, Figure 8 the aluminum material range is 20, and the copper material range is 20. Figure 9The knurling range is 20. The metal insert 3 is a cylindrical integral center-of-rotation structure with an inward concave middle part. A second annular stress relief groove is provided on the metal insert 3. The outer cylindrical surface of the metal insert 3 is partially knurled and coated with semi-conductive glue. The conductive connection surfaces on both sides of the metal insert 3 are silver-plated. The core material of the metal insert 3 is copper, and the part where it is bonded to the resin casting 2 on the outside is aluminum.

[0048] The metal insert uses an aluminum-copper transition material. The difference in the coefficient of thermal expansion between the aluminum on the outer ring of the metal insert and the epoxy resin is small, which can reduce the risk of interface cracking and extend the service life. The copper in the core of the metal insert improves the current-carrying capacity of the conductor docking surface and is also beneficial to the heat dissipation of the product. The inward concave structure in the middle part of the metal insert increases the contact area and the biting depth between the metal insert and the epoxy resin, forming a more firm mechanical interlock. At the same time, it also has an advantage in the relative electric field strength, and the electric field on the shell is significantly reduced. The use of semi-conductive glue can reduce the potential difference between the insert and the insulating material, improve the electric field on the surface of the metal insert, and at the same time can buffer the thermal expansion stress and improve the stress problem caused by the different expansion coefficients of the metal insert and the insulating material.

[0049] Specifically, in this embodiment, as Figure 8 shown, the end face diameter C of the metal insert 3 of the metal insert is 10 mm smaller than the diameter D of the middle concave section of the metal insert. A number of threaded connection holes 23 are provided on the upper end face of the metal insert 3, and the threaded connection holes 23 are connected to the conductor 19. The diameter difference between the end face diameter of the metal insert and the diameter of the middle concave section of the metal insert cooperates with the conductor docked with the metal insert to form an electric field shielding pit, which wraps the triple intersection area in the electric field shielding pit to avoid the distortion of the electric field at the triple intersection area of the three-phase coaxial pot-type insulator. Only 3 holes of the 6 threaded holes on the metal insert need to be fixed in actual application. 6 angles for convenient installation of the conductor 19 are designed, which are applicable to various installation directions.

[0050] Specifically, in this embodiment, as Figure 10 shown, the shielding ring 4 is made of aluminum and includes a support member 24 and a single shielding ring 25. The two single shielding rings 25 and the three support members 24 are welded together. The single shielding ring 25 is a non-closed ring shape and has an opening at the casting port 10. The support member 24 and the metal flange ring 1 are fixed at the shielding ring fixing hole 8 by bolts.

[0051] The shielding ring is designed as a double-layer large ring structure, that is, it is formed by welding two single shielding rings and three support members. The large ring surrounds the three-phase insert inside, effectively shielding the electric field at the shell flange. The double-layer structure of the shielding ring is more conducive to evenly distributing the potential line density at the shell flange compared with the traditional single-layer structure, and can effectively avoid the electric field concentration at the shell flange. The 4-shielding ring is not a closed ring and has an opening. The opening faces the casting port of the pot-type insulator, and an external partial discharge sensor can be installed at the casting port. This opening design is beneficial to the transmission of electromagnetic signals.

[0052] Specifically, in this embodiment, the metal flange ring 1 is made of forged aluminum, and the flange thickness is 80 mm. The metal flange ring 1 is evenly distributed with the same number of two types of connection holes, including M12 threaded connection holes and Φ14 through holes.

[0053] Forged aluminum has a relatively low density. The lightweight design can optimize the support structure of the metal flange ring, reduce the mechanical requirements for surrounding components, and has high strength and toughness, and still maintains good toughness in low-temperature environments, making it suitable for cold regions. In actual application, 20×M12 threaded connection holes and 20×φ14 through holes are respectively set on the metal flange ring, which can be selected according to the actual use environment. The thickness of the metal flange ring is 80 mm, which is designed to be 1.5 times the original. By increasing the number of bolt connections and the flange thickness, the flange connection strength is greatly enhanced, and through calculation, it can fully withstand the mechanical strength requirements brought by the increase in the pure N2 gas chamber pressure.

[0054] Specifically, in this embodiment, the temperature-measuring optical fiber 6 is subjected to matting treatment and is a double-strand wire. One end of the temperature-measuring optical fiber is connected to the metal insert, and the other end is connected to the adapter head. In actual use, the adapter head is externally connected to a temperature-measuring instrument to monitor the temperature change inside the pot-type insulator. The temperature-measuring optical fiber is designed as a double-strand wire to ensure that it will not lose its effectiveness when one optical fiber breaks. In actual use, the adapter head 7 is externally connected to a temperature-measuring instrument to monitor the temperature change inside the three-phase common-box pot-type insulator. The temperature-measurement point of the traditional temperature-measurement method is the housing, but the temperature change of the conductor is transmitted to the housing through the insulating gas with a delay. The temperature-measurement point in the device is the metal insert 3, and its temperature change can be observed in a timely manner.

[0055] Specifically, in this embodiment, as Figure 11 shown, when there is a compartment with partial discharge monitoring in the GIS, the cover plate 5 is removed and then the partial discharge sensor 26 is installed.

[0056] In the GIS product, when there is a compartment with partial discharge monitoring, only the cover plate 5 of the three-phase common-box pot-type insulator needs to be removed, and then the partial discharge sensor is installed to meet the requirements of partial discharge monitoring. This design has a simple structure, convenient operation, and low on-site replacement difficulty.

[0057] The three-phase common-box pot-type insulator for GIS with a friendly medium as insulation has better mechanical strength and insulation performance compared with the traditional pot-type insulator, and can meet the more stringent insulation strength requirements of pure N2 high-voltage switch products. At the same time, the overall structure design of the three-phase common-box pot-type insulator improves the insulation strength of the pot-type insulator. On the one hand, a stepped convex structure is designed around the metal insert to optimize the electric field distribution; on the other hand, the structures of the shielding ring and the metal insert are improved, and a PTFE nano-coating is coated on the surface layer of the pot resin.

[0058] The three-phase common-box pot insulator enhances the mechanical strength of the pot insulator: on the one hand, stress relief grooves are provided on both the metal insert and the resin on the outer ring of the metal insert; on the other hand, the structure and material of the metal insert are optimized, and the resin thickness and structure are verified by simulation calculation, maximizing the utilization rate of the resin material while ensuring the mechanical strength of the three-phase common-box pot insulator. A temperature-measuring optical fiber is preset in the three-phase common-box pot insulator, which can realize the monitoring of the internal temperature of the pot insulator. The three-phase common-box pot insulator as a whole has the advantages of reasonable structure, stable performance, low manufacturing cost, and safe and reliable operation.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-phase common-box pot insulator for GIS insulated with a friendly medium, characterized in that, It includes a metal flange ring, a resin casting, and a cover plate. The resin casting includes a metal insert, a shielding ring, a temperature-measuring optical fiber, and a transfer end head cast in an epoxy resin matrix. The epoxy resin matrix is provided with a central ventilation hole and three first ventilation holes distributed in an equilateral triangle. The metal flange ring is flange-connected to the housing and is provided with a first sealing groove inside, and transfer end head fixing holes, a casting port, four anti-rotation grooves, and shielding ring fixing holes are evenly distributed on the outside. The first sealing groove and the second sealing groove of the resin casting form a double-sealing structure. The anti-rotation grooves cooperate with the anti-rotation protrusions on the resin casting. The cover plate is fastened to the casting port of the metal flange ring by screws. The transfer end head is fixed at the transfer end head fixing hole, and the shielding ring is fixed at the shielding ring fixing hole. The two ends of the temperature-measuring optical fiber are respectively connected to the metal insert and the transfer end head, and the transfer end head is externally connected to a temperature-measuring instrument.

2. The three-phase coaxial pot insulator for GIS insulated with a friendly medium according to claim 1, characterized in that, The resin casting is provided with multiple layers of stepped protrusions on the periphery with the installed metal insert as the axis. The height of the multiple layers of stepped protrusions is 50 mm. The resin casting is provided with a first annular stress relief groove with a width of 5 mm and a depth of 7 mm within a range of 1 cm outside the end face where the metal insert is installed. The first annular stress relief groove is arranged with the metal insert as the axis. A rectangular second sealing groove is provided on the outside of the resin casting. The height difference at the air gap where the second sealing groove cooperates with the housing flange is 9 mm. The overall planar thickness of the resin casting is 40 mm.

3. The three-phase coaxial pot insulator for GIS insulated with a friendly medium according to claim 1, characterized in that, After the resin casting is initially cured, a PTFE coating with a thickness of 30 - 50 μm is applied to it for secondary curing.

4. The three-phase coaxial pot insulator for GIS insulated with a friendly medium according to claim 1, characterized in that The metal insert is a cylindrical and centrally rotating body structure with a concave middle part as a whole. The metal insert is provided with a second annular stress relief groove. The outer cylindrical surface of the metal insert is partially knurled and coated with semi-conductive glue, and the conductive connection surfaces on both sides of the metal insert are silver-plated. The core material of the metal insert is copper and the part bonded to the resin casting on the outside is aluminum.

5. The three-phase common-box pot-type insulator for GIS insulated with a friendly medium according to claim 3, characterized in that, The diameter of the end face of the metal insert is 10 mm smaller than the diameter of the concave section in the middle of the metal insert. A number of threaded connection holes are provided on the upper end face of the metal insert, and the threaded connection holes are connected to conductors.

6. The three-phase coaxial pot-type insulator for GIS insulated with a friendly medium according to claim 1, characterized in that The shielding ring is made of aluminum and includes a support and a single shielding ring. The two single shielding rings and the three supports are welded together. The single shielding ring is a non-closed ring and has an opening at the casting port. The support and the metal flange ring are fixed at the shielding ring fixing hole by bolts.

7. The three-phase common box pot insulator for GIS insulated with a friendly medium according to claim 1, characterized in that, The metal flange ring is made of forged aluminum and the flange thickness is 80 mm. The metal flange ring is evenly provided with two types of connection holes with the same number. The connection holes include M12 threaded connection holes and Φ14 through holes.

8. The three-phase common-box pot-type insulator for GIS insulated with a friendly medium according to claim 1, characterized in that, The temperature-measuring optical fiber is subjected to surface roughening treatment and is a double-strand wire.

9. The three-phase common-box pot insulator for GIS insulated with a friendly medium according to claim 1, characterized in that, When there is a compartment in the GIS for partial discharge monitoring, the cover plate is removed and then a partial discharge sensor is installed.

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