A multi-hole elbow-type casing and its manufacturing method and casting mold

Abstract

The present invention specifically relates to a porous elbow-type sleeve and a manufacturing method and a casting mold thereof, characterized in that the front side of the shell is open, the lower end is open, a current-carrying component is arranged in the shell, the inner surface of the shell and the surface of the current-carrying component are provided with a semi-conductive buffer layer, the upper section of the conductive rod of the current-carrying component is provided with a conductive contact seat and a cable core socket cast or welded as one, the lower section of the conductive rod extends out of the shell, and a conductive or semi-conductive capacitor screen is arranged on the outside, and an integral insulator that wraps the current-carrying component and the capacitor screen is arranged inside and outside the shell, and an auxiliary jack and a cable terminal jack that communicate with the conductive contact seat and the cable core socket are arranged on the insulator, and the capacitor screen and the integral insulator together form a slender capacitor-type insulating sleeve, a sealing pressure ring is installed at the tail end of the capacitor-type insulating sleeve, and the capacitor-type insulating sleeve and the shell form an elbow-shaped structure that is thick at the top and thin at the bottom. The present invention has the advantages of compact structure, low cost, good conductivity, good electrical properties, high sealing reliability, high safety, and wide application range.

Description

Technical Field

[0001] The invention belongs to the technical field of high-voltage electrical equipment, and in particular relates to a porous elbow-type bushing, a manufacturing method thereof and a casting mold. Background Art

[0002] In traditional substations, when the transformer capacity is small and the current on the low-voltage side is small, direct cable connection is generally used; as the capacity of the main transformer of the substation increases, directly using a large-section low-voltage cable will cause the cross-section of the cable core conductor to be seriously enlarged due to the skin effect, which is very uneconomical. In addition, the high-current cable is too bulky to meet the requirements of on-site installation. Therefore, copper busbars or insulated copper tubes are usually used as busbar connections in previous projects.

[0003] However, using copper bars or insulated copper tubes as busbars also has its own shortcomings and defects.

[0004] When copper busbars are used as busbars, the sealing ring on the upper part of the low-voltage side bushing of the transformer is stretched by the hard busbar, which may cause uneven sealing and oil leakage. The leaked oil will form dirt after being stained with dust, which will cause insufficient insulation creepage of the bushing and easy discharge after being wet. In addition, the busbar is difficult to meet the requirements of busbar heating and electromotive force in terms of technology and structure, resulting in additional loss and increase of skin effect coefficient, resulting in decreased current carrying capacity and uneven current distribution. When the capacity of a single main transformer exceeds 200MVA, due to the increase of rated current and short-circuit current on the low-voltage side of the transformer, the outgoing line side of the low-voltage side of the main transformer not only has electromotive force problems and heating problems of the busbar bridge itself, but also heating problems caused by eddy currents induced by structures such as busbar bridge support insulators and steel brackets in the alternating strong magnetic field. Once the busbar is short-circuited, the busbar, support insulators, and transformer windings will be damaged, affecting the safe operation of the substation and the reliability of power supply. In addition, electrical accidents caused by short-circuit faults of small animals and overlapping of foreign objects in substations also occur from time to time. In order to prevent small animals from causing short circuits, insulating paint is often applied to the exposed busbars or heat shrink insulation is used for protection. However, long-term exposure to the external environment can easily cause aging or cracking. In severe cases, this can affect the protective performance of the insulation and easily cause safety hazards.

[0005] The main body of the insulated tubular busbar is a hollow copper tube or aluminum alloy tube with an insulating layer on the outside. The current density on the conductor cross section is evenly distributed. Compared with the copper busbar, the insulated tube busbar is an improvement. However, with the promotion of indoor substations, the main transformers and low-voltage distribution devices are increasingly arranged in a compact manner. The space is relatively small. The insulated copper tube busbar solution is less flexible, the installation is cumbersome, and the construction is inconvenient.

[0006] Korean patent 20-2005-0033755 discloses a two-hole transformer elbow socket, which uses two symmetrical cable insertion holes to distribute the cable load, effectively solving the defects of copper busbars and tube busbars. However, this technical solution also has obvious shortcomings, mainly:

[0007] 1) In this technical solution, the conductive rod and the cable core socket are fixed and crimped by bolts, which has poor conductivity and the heating of contact resistance can easily cause insulation breakdown.

[0008] 2) In this technical solution, the insulating sleeve part has no capacitor screen, the electric field distribution of the main insulation is uneven, the electrical performance is poor, and the operating safety performance is low.

[0009] 3) There is no auxiliary socket specifically used for plugging in PT or lightning arrester in this technical solution. The conductor cross-section used for plugging in PT or lightning arrester is relatively small. If it is designed according to the cable core socket, it will waste copper materials. Moreover, when the current is large, it is still insufficient to distribute the cable load with all the cable terminal sockets. There are no extra sockets for plugging in PT or lightning arrester, and it is impossible to monitor the voltage and protect the transformer, which is easy to cause transformer insulation breakdown accidents.

[0010] 4) In this technical solution, no sealing element is provided at the tail end of the insulating sleeve, and the problem of air leakage or oil leakage may easily occur due to thermal expansion and contraction caused by environmental changes or under strong mechanical vibration. Summary of the invention

[0011] The object of the present invention is to provide a porous elbow-type bushing, a manufacturing method thereof and a casting mold, wherein an auxiliary jack and a cable terminal jack are arranged, and a current-carrying component welded or cast into one is buried inside an insulator, and a capacitive insulating bushing and an insulator are integrally formed by vacuum casting, which can improve the safety of substation facilities, facilitate the installation of equipment such as transformers, and facilitate inspection and measurement.

[0012] The present invention is achieved through the following technical solutions:

[0013] That is, a porous elbow-type casing, characterized in that it includes a square shell, the front side of the shell is open, the lower end is open, a current-carrying component is arranged in the shell, the inner surface of the shell and the surface of the current-carrying component are provided with a semi-conductive buffer layer, the current-carrying component includes a conductive rod, the upper section of the conductive rod is located in the shell, and is provided with a conductive contact seat and a cable core socket cast or welded as one, the lower section of the conductive rod extends out of the shell, and a conductive or semi-conductive capacitor screen is provided on the outside, an integrated insulator wrapping the current-carrying component and the capacitor screen is provided inside and outside the shell, the insulator is provided with an auxiliary jack and a cable terminal jack connected to the conductive contact seat and the cable core socket, the capacitor screen and its integrated insulator together form a slender capacitor-type insulating casing, a sealing pressure ring is installed at the tail end of the capacitor-type insulating casing, and the capacitor-type insulating casing and the shell form an elbow-shaped structure that is thick at the top and thin at the bottom.

[0014] After the assembly of the invention is completed, the insulator is integrally formed by vacuum casting, and the insulator is epoxy resin.

[0015] Furthermore, the capacitive screen inside the capacitive insulating sleeve of the present invention is a carbon fiber capacitive screen.

[0016] Furthermore, the present invention has two conductive contact seats, which are symmetrically mounted on both sides of the conductive rod through copper bars, and the number of auxiliary jacks matches the number of conductive contact seats.

[0017] Furthermore, the cable core sockets of the present invention are provided with four, two in a group, which are symmetrically installed on both sides of the conductive rod through copper bars, and the number of the cable terminal jacks matches the cable core sockets.

[0018] Furthermore, the cross-section of the conductive contact seat of the present invention is smaller than the cross-section of the cable core socket.

[0019] Furthermore, a semi-conductive buffer layer is provided on the inner surface of the shell and the surface of the current-carrying component of the present invention.

[0020] The semiconductive buffer layer of the present invention is an epoxy resin-based semiconductive adhesive, or a semiconductive paper or a semiconductive cloth that can penetrate epoxy resin.

[0021] Furthermore, the housing of the present invention is divided into an upper housing and a lower housing, and the upper housing and the lower housing are connected by bolts.

[0022] The lower part of the shell of the present invention is provided with a flange plate for connecting with the casing oil end forming die.

[0023] As a preferred solution, the upper shell of the present invention is larger than the lower shell.

[0024] The housing of the present invention is preferably, but not limited to, a metal housing, which is strong and durable.

[0025] The method for manufacturing the porous elbow casing of the present invention is characterized by the following steps:

[0026] 1) Prepare a copper rod as a conductive rod, the upper section of the conductive rod and the copper bar, the copper bar and the cable core socket and the conductive contact seat are cast or welded together to form a current-carrying component, the outer surface of the current-carrying component is covered with a semi-conductive buffer layer, and the lower section of the conductive rod is fixed with an insulating fixing ring to fix the prefabricated carbon fiber capacitor screen;

[0027] 2) The lower opening of the shell is connected to the casing oil end forming mold, and a layer of grounding shielding net is laid on the inner surface of the casing oil end forming mold, and the grounding shielding net is fixed to the inner wall of the shell by grounding bolts;

[0028] 3) The upper section of the conductive rod together with the cable core socket and the conductive contact seat are installed in the shell, and the lower section of the conductive rod together with the carbon fiber capacitor screen are fixed in the tail end casing oil end molding mold, a conductive or semi-conductive shielding ring is connected to the opening of the cable core socket and fixed with a conductive tape, a semi-conductive buffer layer is coated or pasted on the inner surface of the shell, and the front end template with the core is combined with the shell to form a closed complete mold waiting for casting;

[0029] 4) The mold was pre-baked at a constant temperature of 130°C for 5 hours, and the mold pouring port was tightly covered and moved into a normal temperature drying oven for cooling. The mold base temperature after cooling was tested to be 62°C;

[0030] 5) Prepare the epoxy resin mixture, let it stand for 10 minutes, and the final mixture temperature is 70℃~75℃, ready for pouring;

[0031] 6) Quickly evacuate the mold through the vacuum port. When the vacuum time is up, start pouring the material from the injection port;

[0032] 7) The poured model is transferred to a curing oven for gel treatment at 70°C for 6 hours, and then the temperature of the curing oven is raised to 80°C for curing for 2 hours to solidify it into shape. After the casting mold is removed from the mold and demoulded, it is transferred to a curing oven for post-curing and cooled to room temperature;

[0033] 8) Install the sealing ring at the tail end of the elbow sleeve and the production is completed.

[0034] The casting mold of the porous elbow-type sleeve of the present invention includes a shell, and is characterized in that it also includes a front end template and a sleeve oil end molding mold, the front end template is installed on the front side of the shell, a core is provided on the inner side of the front end template, a vacuum port communicating with the inside of the shell is provided on the front end template, and the sleeve oil end molding mold is a hollow cylindrical structure with an upper end opening, the upper end of which is connected to the lower end opening of the shell, the inner cavity of which matches the shape of the capacitor-type insulating sleeve, and a glue injection port communicating with the inner cavity is provided on one side.

[0035] The present invention has the following advantages and positive effects:

[0036] 1) The current-carrying component welded or cast into one piece in the present invention has good electrical conductivity. The structure is bolt-free and non-crimped, which can effectively avoid insulation breakdown caused by heating caused by contact resistance of the bolt crimping structure;

[0037] 2) The electric field distribution of the capacitive insulating bushing of the present invention is more uniform, which ensures good electrical performance and improves the safety of bushing operation; at the same time, the thickness of the insulating layer is reduced under the same voltage, saving resin materials;

[0038] 3) The present invention has an auxiliary socket specially used for plugging in PT or lightning arrester, which is used for measuring voltage and protecting transformer and other equipment respectively. The conductive contact seat of the auxiliary socket adopts a smaller conductor cross-section to save copper material;

[0039] 4) The capacitive insulating bushing of the present invention is provided with a sealing ring at the tail end, which can effectively deal with the problem of thermal expansion and contraction caused by environmental changes or air or oil leakage caused by strong mechanical vibration, thereby ensuring the reliability of bushing sealing;

[0040] 5) The housing of the present invention is divided into an upper housing and a lower housing, and the two housings are connected by bolts, so the overall manufacturing and installation are convenient;

[0041] 6) The main body of the present invention is integrally formed by vacuum casting with high-performance epoxy resin, which is not only waterproof and moisture-proof, and resistant to mechanical damage, but also can effectively overcome electrical accidents caused by short-circuit failures of small animals and overlap of foreign objects;

[0042] 7) The product shell of the present invention is fully shielded, with no exposed live parts, compact overall structure, small size, and saving installation space;

[0043] 8) The present invention makes full use of mass-produced power cables as busbars, which can reduce the overall cost of the system;

[0044] 9) The present invention has a wide range of applications and can be used for transformer outgoing lines as well as for connecting other equipment, such as a high-voltage switch cabinet. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of the present invention;

[0046] Figure 2 for Figure 1 AA section view in;

[0047] Figure 3 It is a schematic structural diagram of the current-carrying component of the present invention;

[0048] Figure 4 It is a schematic diagram of the structure during vacuum casting of the present invention.

[0049] As shown in the figure: 1. Auxiliary jack; 2. Cable terminal jack; 3. Upper shell; 4. Insulator; 5. Lower shell; 6. Current-carrying component; 7. Capacitive insulating sleeve; 8. Sealing pressure ring; 9. Conductive contact seat; 10. Cable core socket; 11. Conductive rod; 12. Semi-conductive buffer layer; 13. Grounding bolt; 14. Grounding shielding net; 15. Carbon fiber capacitor screen; 16. Insulating fixing ring; 17. Shielding ring; 18. Copper busbar; 19. Sleeve oil end molding mold; 20. Glue injection port; 21. Vacuum port; 22. Front template; 23. Core. DETAILED DESCRIPTION

[0050] The embodiments of the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and the protection scope of the present invention cannot be limited thereto. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should be the common meanings understood by those skilled in the art to which the present invention belongs.

[0051] like Figure 1 , Figure 2 , Figure 3 As shown: the square metal shell is composed of a larger upper shell 3 and a smaller lower shell 5, the upper shell 3 and the lower shell 5 are connected by bolts, the lower end of the lower shell 5 is open, and a flange is provided, the front side of the entire shell is open, and a current-carrying component 6 is provided in the shell, and the current-carrying component 6 includes a conductive rod 11, two conductive contact seats 9 and four cable core sockets 10, the upper section of the conductive rod 11 is located in the shell, the two conductive contact seats 9 are symmetrically installed on both sides of the conductive rod 11 by welding with a copper bus 18, and the four cable core sockets 10 are in groups of two and are symmetrically installed on both sides of the conductive rod 11 by welding with a copper bus 18, and the conductive contact seat 9 has a small cross-section. In the cross section of the cable core socket 10, the lower section of the conductive rod 11 extends out of the shell through the opening at the lower end of the shell, a carbon fiber capacitor screen 15 is provided on the outside of the lower section of the conductive rod 11, and an integrated insulator 4 that wraps the current-carrying component 6 and the carbon fiber capacitor screen 15 is provided inside and outside the shell. The insulator 4 in the shell is provided with an auxiliary jack 1 and a cable terminal jack 2 that are communicated with the conductive contact seat 9 and the cable core socket 10. The carbon fiber capacitor screen 15 and its integrated insulator 4 together form a slender capacitive insulating sleeve 7. A sealing pressure ring 8 is installed at the tail end of the capacitive insulating sleeve 7. The capacitive insulating sleeve 7 and the shell form an elbow-shaped structure that is thick at the top and thin at the bottom.

[0052] like Figure 4 As shown, when the present invention is manufactured, a front end template 22 and a casing oil end molding die 19 are required. The front end template 22 is provided with a core 23 matching the auxiliary jack 1 and the cable terminal jack 2. The casing oil end molding die 19 is a cylindrical structure with an upper end opening, and a flange matching the flange on the lower shell 5 is provided at its upper end. The inner cavity of the casing oil end molding die 19 matches the shape of the capacitive insulating casing 7.

[0053] Before pouring the present invention, a copper rod with a diameter of φ48 is prepared as a conductive rod 11. The upper section of the conductive rod 11 and the copper bar 18, the copper bar 18 and the cable core socket 10 and the conductive contact seat 9 are cast or welded together to form a current-carrying component 6. The metal outer surface of the current-carrying component 6 is coated with a semi-conductive buffer layer 12, and the lower section of the conductive rod 11 is fixed with a prefabricated carbon fiber capacitor screen 15 by an insulating fixing ring 16. The lower shell 5 is connected to the casing oil end forming mold 19 through a flange, and a grounding shielding net 14 is laid on the inner surface of the casing oil end forming mold 19, and the grounding shielding net 14 is fixed to the inner wall of the lower shell 5 by a grounding bolt 13. The current-carrying component 6 with the carbon fiber capacitor screen 15 passes through the lower shell 5 and is fixed in the tail end casing oil end forming mold 19. A conductive or semi-conductive shielding ring 17 is connected to the opening of the cable core socket 10 and fixed with a conductive tape. A semi-conductive buffer layer 12 is coated or pasted on the inner surface of the upper shell 3 and the lower shell 5, and then the upper and lower shells are firmly connected with bolts. Finally, the front end template 22 with the core 23 is combined with the shell to form a closed complete mold waiting for pouring.

[0054] When pouring the present invention, the mold is first pre-baked at a constant temperature of 130° C. for 5 hours, and the mold pouring port is tightly covered and moved into a normal temperature drying oven for cooling. The mold base temperature after cooling is tested to be 62° C. The epoxy resin mixture is prepared, including epoxy resin and curing agent, etc., and is allowed to stand for 10 minutes. The temperature of the final mixture is 70° C. to 75° C., and it is ready for pouring. The mold is quickly vacuumed through the vacuum port 21, and the material is poured from the injection port 20 when the vacuuming time is up. The whole process is as low viscosity, high vacuum, and slow pouring as possible.

[0055] After the pouring is completed, the pouring model is transferred to a pre-set curing furnace to minimize the time it stays in a low-temperature environment to avoid affecting the fluidity of the material in the mold due to the decrease in mold temperature. The gel treatment is performed at 70°C for 6 hours, and then the temperature of the curing furnace is raised to 80°C for curing for 2 hours to solidify the mold. After the pouring mold is removed from the mold and demoulded, it is transferred to a curing furnace for post-curing and cooled to room temperature.

[0056] Finally, a sealing pressure ring 8 is installed at the tail end of the elbow sleeve, and a vacuum-casting integrally formed elbow sleeve is manufactured.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and should all be included in the scope of the claims and specification of the present invention.

Claims

1. A porous elbow casing, characterized in that The utility model comprises a square shell, which is divided into an upper shell and a lower shell. The two shells are connected by bolts. The front side of the shell is open and the lower end is open. A current-carrying component is arranged in the shell. A semi-conductive buffer layer is arranged on the inner surface of the shell and the surface of the current-carrying component. The current-carrying component comprises a conductive rod. The upper section of the conductive rod is located in the shell and is provided with a conductive contact seat and a cable core socket which are cast or welded as one. The lower section of the conductive rod extends out of the shell and is provided with a conductive or semi-conductive capacitor screen on the outside. An integrated insulator which wraps the current-carrying component and the capacitor screen is arranged inside and outside the shell. The insulator is integrally formed by vacuum casting with epoxy resin. An auxiliary jack and a cable terminal jack which are communicated with the conductive contact seat and the cable core socket are arranged on the insulator. The capacitor screen and the integrated insulator together form a slender capacitor-type insulating sleeve. A sealing pressure ring is installed at the tail end of the capacitor-type insulating sleeve. The capacitor-type insulating sleeve and the shell form an elbow-shaped structure which is thick at the top and thin at the bottom. The shell is fully shielded.

2. A porous elbow casing according to claim 1, characterized in that The capacitive screen inside the capacitive insulating sleeve is a carbon fiber capacitive screen.

3. A porous elbow casing according to claim 1, characterized in that There are two conductive contact seats, which are symmetrically installed on both sides of the conductive rod through copper bars, and the number of auxiliary jacks matches the number of conductive contact seats.

4. A porous elbow casing according to claim 1, characterized in that There are 4 cable core sockets, two in a group, which are symmetrically installed on both sides of the conductive rod through copper bars. The number of cable terminal jacks matches the cable core sockets.

5. A porous elbow casing according to claim 1, 3 or 4, characterized in that The cross section of the conductive contact seat is smaller than the cross section of the cable core socket.

6. A porous elbow casing according to claim 1, characterized in that The semiconductive buffer layer is epoxy resin-based semiconductive glue or semiconductive paper or semiconductive cloth that can penetrate epoxy resin.

7. A method for manufacturing a porous elbow casing according to claim 1, characterized in that Here are the steps: 1) Prepare a copper rod as a conductive rod. The upper part of the conductive rod is welded with the copper bar, the copper bar, the cable core socket and the conductive contact seat to form a current-carrying component. The outer surface of the current-carrying component is covered with a semi-conductive buffer layer. The lower part of the conductive rod is fixed with an insulating fixing ring to fix the prefabricated carbon fiber capacitor screen; 2) The lower opening of the shell is connected to the casing oil end forming mold, and a layer of grounding shielding net is laid on the inner surface of the casing oil end forming mold, and the grounding shielding net is fixed to the inner wall of the shell by grounding bolts; 3) The upper section of the conductive rod together with the cable core socket and the conductive contact seat are installed in the shell, and the lower section of the conductive rod together with the carbon fiber capacitor screen are fixed in the tail end casing oil end forming mold, a conductive shielding ring is connected to the opening of the cable core socket and fixed with a conductive tape, a semi-conductive buffer layer is coated on the inner surface of the shell, and the front template with the core is combined with the shell to form a closed complete mold waiting for casting; 4) Pre-bake the mold at a constant temperature of 130°C for 5 hours, cover the mold pouring port tightly, and move it into a room temperature drying oven to cool down. The mold base temperature after cooling down is tested to be 62°C; 5) Prepare the epoxy resin mixture, let it stand for 10 minutes, and the final mixture temperature is 70℃~75℃, ready for pouring; 6) Quickly evacuate the mold through the vacuum port. When the vacuum time is up, start pouring the material from the injection port; 7) The poured model is transferred to the curing oven for gel treatment at 70°C for 6 hours, and then the temperature of the curing oven is raised to 80°C for curing for 2 hours to solidify it into shape. After the casting mold is removed from the mold and transferred to the curing oven for post-curing and cooling to room temperature; 8) Install the sealing ring at the tail end of the elbow sleeve and the production is completed.

8. A casting mold for a porous elbow sleeve according to claim 1, comprising a shell, characterized in that It also includes a front end template and a casing oil end forming mold. The front end template is installed on the front side of the shell, and a core is provided on the inner side of the front end template. A vacuum port communicating with the inside of the shell is provided on the front end template. The casing oil end forming mold is a hollow cylindrical structure with an upper opening, and its upper end is connected to the lower end opening of the shell. Its inner cavity matches the shape of the capacitor-type insulating casing, and a glue injection port communicating with the inner cavity is provided on one side.

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