Explosion-proof flame-retardant oiled paper capacitive transformer bushing

Abstract

The invention discloses an explosion-proof flame-retardant oiled paper capacitive transformer bushing. An air-side outer insulator and an in-oil outer insulator of the bushing are made of flame-retardant insulating materials; a first anti-explosion sheet is mounted on the flange, and a second anti-explosion sheet and a third anti-explosion sheet are mounted on different sides of the oil conservator; wherein the blasting value of the first anti-explosion piece is smaller than or equal to that of the second anti-explosion piece, and the blasting value of the third anti-explosion piece is larger than that of the second anti-explosion piece; meanwhile, the blasting value of the third anti-explosion piece is smaller than the blasting value of the joint of the cover plate and the oil conservator, and the blasting value of the joint of the cover plate and the oil conservator is smaller than the blasting values of the remaining structures of the pipe body and the joint of the remaining structures of the pipe body; the blasting value of the assembly in the oil and the assembly joint is greater than the blasting value of the assembly on the air side and the assembly joint. The blasting values of all structures of the casing pipe are reasonably designed, so that when the pressure in the casing pipe is sharply increased due to the failure of the casing pipe, the pressure can be discharged in order, and the structure in oil cannot be damaged.

Description

Technical Field

[0001] The invention relates to an explosion-proof and flame-retardant oil-paper capacitor type transformer bushing, belonging to the technical field of bushings. Background Art

[0002] Traditional oil-paper capacitor transformer bushings have long held a dominant position in the market due to their low manufacturing costs, excellent insulation performance, and self-healing partial discharge. However, these bushings are inherently explosive and flammable. If faults such as internal discharge, insulation thermal aging, or insulation damage are not promptly detected and addressed, they can generate large amounts of hydrocarbon gas mixtures, causing a sharp increase in internal pressure and potentially leading to deflagration. In severe cases, this can cause secondary explosions. Summary of the Invention

[0003] The object of the present invention is to provide an explosion-proof and flame-retardant oil-paper capacitor transformer bushing. By rationally designing the explosion value of the structure of each part of the bushing, when the pressure in the tube rises sharply due to a bushing failure, the pressure can be released in an orderly manner without causing damage to the structure in the oil.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: An explosion-proof, flame-retardant oil-paper capacitor transformer bushing comprises a tube body consisting of an oil pillow, air-side external insulation, a flange, oil-intermediate external insulation, and end caps connected in sequence. A capacitor core is coaxially mounted within the tube body, with both ends of the capacitor core abutting against the end cap and a cover plate detachably mounted on the top of the oil pillow, respectively. The air-side external insulation and the oil-intermediate external insulation are both made of flame-retardant insulating material. A first bursting disc is mounted on the flange, and a second bursting disc and a third bursting disc are mounted on different sides of the oil pillow; wherein the bursting value of the first bursting disc is less than or equal to the bursting value of the second bursting disc, and the bursting value of the third bursting disc is greater than the bursting value of the second bursting disc; At the same time, the bursting value of the third explosion-proof plate is smaller than the bursting value between the cover plate and the oil pillow, and the bursting value between the cover plate and the oil pillow is smaller than the bursting value between the remaining structure of the pipe body and the connection between the remaining structure of the pipe body; the bursting value of the components located in the oil and the component connections is greater than the bursting value of the components located on the air side and the component connections.

[0005] Preferably, the burst value of the first burst disk is equal to the burst value of the second burst disk.

[0006] Preferably, an air-side terminal block is installed on the top of the cover plate.

[0007] Preferably, an oil terminal block is installed at the bottom of the end cover.

[0008] Preferably, a pressure equalizing ball is installed outside the end cover and the oil terminal block.

[0009] Preferably, the air-side external insulation and the oil pillow, the flange, as well as the oil-middle external insulation and the flange, the end cover are all interference fit and are bonded together by adhesive.

[0010] Preferably, multiple sealing rings are provided at the abutting ends of the air-side external insulation, the oil pillow, and the flange, as well as at the abutting ends of the oil-in-the-oil external insulation, the flange, and the end cover.

[0011] Preferably, the first explosion-proof disc and the second explosion-proof disc are double-layer stainless steel explosion-proof discs; and the third explosion-proof disc is a glass explosion-proof disc.

[0012] The beneficial effects of the present invention are: By rationally designing the bursting values ​​of various structures within the bushing, when a bushing failure causes a sharp rise in pressure inside the pipe, the pressure can be released in an orderly manner without damaging the structure in the oil. This also protects the air-side external insulation and the oil pillow (only if the bursting disc is destroyed will the cover be ejected under pressure, separating from the sealed connection with the oil pillow to form a pressure relief channel). Furthermore, both the air-side external insulation and the oil-in-oil external insulation are made of flame-retardant insulating materials, giving the bushing excellent flame-retardant insulating properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the main view of the casing; Figure 2 is a cross-sectional view of the casing; Figure 3 This is a schematic diagram of the structure of the first explosion-proof disk and the second explosion-proof disk; Figure 4 This is a structural diagram of the third explosion-proof piece.

[0014] The main reference numerals in the figures have the following meanings: 1. Oil pillow, 2. Air-side external insulation, 3. Flange, 4. Oil-side external insulation, 5. End cover, 6. Capacitor core, 7. Cover, 8. Air-side terminal block, 9. Oil-side terminal block, 10. Equalizing ball, 11. First explosion-proof disk, 12. Second explosion-proof disk, 13. Third explosion-proof disk, 14. Stainless steel explosion-proof disk, 15. Glass explosion-proof disk, 16. Metal base, 17. Lower clamp, 18. Upper clamp, 19. Silicone rubber protective sleeve, 20. Gland. DETAILED DESCRIPTION

[0015] Aiming at the problem that traditional oil-paper capacitor transformer bushings are prone to explosion, this embodiment provides an explosion-proof and flame-retardant oil-paper capacitor transformer bushing. Figure 1 、 2As shown, it includes a tubular body consisting of an oil pillow 1, air-side external insulation 2, flange 3, oil-internal external insulation 4, and end cap 5, which are connected in sequence. A capacitor core 6 is coaxially mounted within the tubular body, with its ends respectively abutting the end cap 5 and a cover plate 7 detachably mounted on the top of the oil pillow 1. An air-side terminal block 8 is mounted on the top of the cover plate 7, an oil-internal terminal block 9 is mounted on the bottom of the end cap 5, and a pressure-equalizing ball 10 is mounted outside the end cap 5 and the oil-internal terminal block 9. Simultaneously, a first explosion-proof disc 11 is mounted on the flange 3, and a second explosion-proof disc 12 and a third explosion-proof disc 13 are mounted on different sides of the oil pillow 1. The explosion-proof discs are all detachably connected to the flange 3 or the oil pillow 1.

[0016] The flange 3, end cap 5, and oil-insulated outer insulation 4 utilize a combination of "interference fit + glue assembly + double sealing rings." This interference fit + glue assembly creates a mechanical seal, while the double sealing rings create a combined sealing structure. This combination of interference fit and glue assembly ensures mechanical strength, meeting both sealing performance and mechanical strength requirements, preventing insulation leakage or component loss. The interference fit is controlled within a range of 0.1-0.2mm to ensure the mechanical connection strength between the oil-insulated outer insulation 4, flange 3, and end cap 5. The gluing process utilizes high-temperature curing epoxy resin adhesive. The contact surfaces are cleaned before assembly. After application, the oil-insulated outer insulation 4 is pressed into the mounting holes of the bushing flange 3 and end cap 5. After curing, a secure connection is formed. The assembly process between the air-side outer insulation 2 and the flange 3 and oil pillow 1 also utilizes a combination of "interference fit + glue assembly + double sealing rings."

[0017] In terms of material, the explosion-proof and flame-retardant oil-paper capacitor transformer bushing provided in this embodiment differs from the traditional oil-paper bushing in that the air-side external insulation 2 adopts a hollow composite insulator, and the oil-side external insulation 4 adopts a glass fiber epoxy resin impregnated molded tube instead of the traditional porcelain bushing. Both the hollow composite insulator and the glass fiber epoxy resin impregnated molded tube are flame-retardant insulating materials.

[0018] Structurally, traditional oil-paper bushing components rely on spring pressure to form a single unit, and each interface seal ring relies on spring pressure for sealing. If a component fails or breaks, the spring pressure on the entire bushing is removed, causing the entire bushing to disintegrate, losing its structural stability and potentially causing a burst of flames. The explosion-proof, flame-retardant oil-paper capacitor transformer bushing provided in this embodiment eliminates the springs, and instead connects components with removable bolts or adhesives, ensuring overall structural stability in the event of a bushing failure.

[0019] In order to ensure smooth pressure release, the bursting values ​​of various parts of the casing are reasonably designed. Specifically, the bursting value of the first bursting disc 11 is less than or equal to the bursting value of the second bursting disc 12, and the exposure pressure (i.e., the bursting value, the same below) is between 0.15MPa and 0.35MPa; the bursting value of the third bursting disc 13 is greater than the bursting value of the second bursting disc 12, and the exposure pressure is between 1MPa and 2MPa; at the same time, the bursting value of the third bursting disc 13 is less than the bursting value between the connection between the cover plate 7 and the oil pillow 1 (between 2.5MPa and 5MPa), and the bursting value of the connection between the cover plate 7 and the oil pillow 1 is less than the bursting value of the remaining structure of the pipe body and the connection between the remaining structure of the pipe body, and the exposure pressure range of the remaining components on the air side and the connection between the remaining components is 6MPa-9MPa, and the exposure pressure range of the remaining components in the oil and the connection between the remaining components is 10MPa-50MPa.

[0020] The idea behind the above design is as follows: when a short circuit fault occurs inside the casing, the internal pressure of the casing increases instantly. First, the pressure is relieved through the first explosion-proof disc 11 at the flange 3 (pressure relief here means that under the action of pressure, the explosion-proof disc is ruptured and the gas leaks out through the ruptured explosion-proof disc, the same below). At the same time, the pressure is relieved through the second explosion-proof disc 12 at the oil pillow 1. However, the pressure relief capacity of the first explosion-proof disc 11 and the second explosion-proof disc 12 is limited, and the internal pressure of the casing continues to increase. At this time, the pressure is relieved through the third explosion-proof disc 13.

[0021] At the same time, during the design, the connection between the cover plate 7 and the oil pillow 1 is set as a weak point, that is, the bursting value of the connection between the cover plate 7 and the oil pillow 1 is smaller than the bursting value of the connection between the remaining structure of the pipe body and the remaining structure of the pipe body. In this way, when the internal pressure of the casing increases to the bursting design value between the cover plate 7 and the oil pillow 1, the cover plate 7 will be pushed out to form the largest pressure relief channel.

[0022] That is, when there is a short circuit fault inside the casing, the pressure is first relieved through the first explosion-proof disc 11 and the second explosion-proof disc 12 within a few milliseconds, reducing the energy accumulation inside the casing and the pressure increase rate inside the casing. At the same time, part of the oil and gas components inside the casing are ejected to reduce the oil volume inside the casing. When the pressure inside the casing increases to the bursting pressure of the third explosion-proof disc 13, the third explosion-proof disc 13 relieves the pressure, further reducing the energy accumulation inside the casing and the pressure increase rate inside the casing. The pressure inside the casing increases to the pressure between the oil pillow 1 and the cover plate 7. When the explosion design value is reached, the bolts at the cover plate 7 will be pulled out from the inside of the oil pillow 1. At this time, the largest pressure relief channel is formed on the top of the oil pillow 1, which rapidly reduces the energy inside the bushing and the pressure inside the bushing. At the same time, all the insulating oil and gas above the flange 3 inside the bushing will be ejected. The oil and gas inside the bushing are ejected rapidly in a graded manner. Firstly, it can reduce the internal fault pressure of the bushing to prevent the bushing from exploding. Secondly, after the oil and gas are ejected, it can prevent the internal combustion of the bushing (the bushing cannot ignite without insulating oil inside), thereby achieving the explosion-proof and flame-retardant performance of the bushing.

[0023] Considering that the part below the bushing flange 3 is installed inside the transformer, in order to ensure the safety of the transformer and the bushing, the explosion resistance of the part below the bushing flange 3 needs to be strengthened. The explosion resistance (explosion value) of the part below the bushing flange 3 is much greater than the explosion resistance of the part above the bushing flange 3. When designing the bushing, the bonding strength between the flange 3, the end cover 5 and the oil-in-oil external insulation 4 is strengthened, the strength of the oil-in-oil external insulation 4 is strengthened (the part below the bushing flange 3), the strength of the air-side external insulation 2 is relatively strengthened, and the connection strength between the air-side external insulation 2 and the oil pillow 1 is strengthened (the part above the bushing flange 3). The connection between the oil pillow 1 cover plate 7 and the oil pillow 1 is set as a weak point (the largest pressure relief channel, controlling the number and depth of the connecting bolts between the cover plate 7 and the oil pillow 1, setting it as a weak point, while meeting the sealing and mechanical load performance of the bushing itself).

[0024] The explosion-proof discs are made of two materials: one is a stainless steel explosion-proof disc 14, which requires a quick response and a low explosion relief pressure; the other is a glass explosion-proof disc 15, which has a high explosion relief pressure and can observe the casing oil level at the same time. The outside of the glass explosion-proof disc 15 is pasted with a polyurethane-silicone composite film to fix glass fragments when the glass explodes.

[0025] The explosion-proof discs are designed in two structures: a single-layer structure for glass explosion-proof discs 15 and a double-layer structure for stainless steel explosion-proof discs 14. Because glass explosion-proof discs 15 are difficult to vent, they are designed as a single-layer structure. Stainless steel explosion-proof discs are prone to malfunctioning during explosion venting, so they are designed as a double-layer structure.

[0026] Specifically, refer to Figure 3In the structure shown, when installing the first explosion-proof disc 11 or the second explosion-proof disc 12, a sealing ring is first placed in the upper opening groove of the metal base 16. The upper and lower stainless steel explosion-proof discs 14 are then fixed sequentially by the lower clamping member 17 and the upper clamping member 18 and welded together. The silicone rubber protective sleeve 19 is then blocked at the opening of the upper clamping member 18 by interference filling or bonding (the force between the silicone rubber protective sleeve 19 and the upper clamping member 18 is less than the burst value of the metal explosion-proof disc, that is, the silicone rubber protective sleeve 19 can be easily removed from the opening of the upper clamping member 18). Then, a sealing ring is placed in the lower opening groove of the metal base 16, and the metal base 16 is fixed to the flange 3 or the oil pillow 1 with bolts (the connection strength is greater than the burst value of the stainless steel explosion-proof disc 14).

[0027] Reference Figure 4 In the structure shown, when the third explosion-proof disk 13 is set, the sealing ring is first inserted into the corresponding opening on the oil pillow 1, and then the glass explosion-proof disk 15 is inserted. Then, the sealing ring is placed in the groove of the pressure cover 20 and then inserted into the opening of the oil pillow 1. The pressure cover 20 is connected to the oil pillow 1 with bolts (the connection strength is greater than the burst value of the glass explosion-proof disk 15).

[0028] The above is only a preferred embodiment of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. An explosion-proof and flame-retardant oil-paper capacitor transformer bushing, characterized in that: The device comprises a tubular body consisting of an oil pillow, air-side external insulation, a flange, oil-intermediate external insulation, and end caps connected in sequence. A capacitor core is coaxially mounted within the tubular body, with both ends of the capacitor core abutting against the end cap and a cover plate detachably mounted on the top of the oil pillow. Both the air-side external insulation and the oil-intermediate external insulation are made of flame-retardant insulating material. A first bursting disc is mounted on the flange, and a second bursting disc and a third bursting disc are mounted on different sides of the oil pillow; wherein the bursting value of the first bursting disc is less than or equal to the bursting value of the second bursting disc, and the bursting value of the third bursting disc is greater than the bursting value of the second bursting disc; At the same time, the bursting value of the third explosion-proof disk is smaller than the bursting value between the cover plate and the oil pillow, and the bursting value of the connection between the cover plate and the oil pillow is smaller than the bursting value of the connection between the remaining structure of the pipe body and the remaining structure of the pipe body; The bursting values ​​of components and component connections located in the oil are greater than those located on the air side.

2. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 1, characterized in that: The burst value of the first burst disk is equal to the burst value of the second burst disk.

3. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 1, characterized in that: An air-side terminal block is installed on the top of the cover.

4. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 1, characterized in that: An oil terminal block is installed at the bottom of the end cover.

5. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 4, characterized in that: Pressure equalizing balls are installed outside the end cover and the oil terminal board.

6. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 1, characterized in that: The external insulation on the air side and the oil pillow, flange, as well as the external insulation in the oil and the flange, end cover are all interference fit and bonded together by adhesive.

7. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 6, characterized in that: Multiple sealing rings are provided at the abutting ends of the external insulation on the air side, the oil pillow and the flange, as well as at the abutting ends of the external insulation in the oil side, the flange and the end cover.

8. The explosion-proof and flame-retardant oil-paper capacitor transformer bushing according to claim 1, characterized in that: The first explosion-proof disc and the second explosion-proof disc are double-layer stainless steel explosion-proof discs; the third explosion-proof disc is a glass explosion-proof disc.

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