Explosion-proof current transformer with composite porcelain sleeve

Abstract

The utility model relates to a composite porcelain bushing explosion-proof current transformer, which comprises a high-voltage shell, an explosion-proof bushing, a base and a secondary junction box, the secondary junction box is arranged on the bottom surface of the base, the high-voltage shell is connected and supported on a bottom plate at the upper end of the base through metal flanges adhered to the two ends of the porcelain bushing, a glass fiber reinforced plastic inner bushing is lined in the porcelain bushing, and the explosion-proof bushing is arranged on the bottom plate. Metal flanges are adhered to the two ends of the porcelain sleeve; the glass fiber reinforced plastic inner sleeve is connected with the shielding supporting pipe in a penetrating mode along the same center line, the shielding supporting pipe extends into the high-voltage shell and supports the secondary coil through the coil shielding cylinder, the shielding supporting pipe is located on a bottom plate at the upper end of the base, a lead is arranged in the shielding supporting pipe, and the two ends of the lead are connected into the secondary coil and the secondary junction box respectively. The shielding supporting pipe is made of hard aluminum alloy, and the space between the shielding supporting pipe and the glass fiber reinforced plastic inner sleeve is filled with insulating gas. The device is simple in structure, effectively guarantees the supporting of a high-voltage insulating part, is firm and stable in structure, can prevent the supporting sleeve from being damaged and leaked, and is safe to use.

Description

Technical Field

[0001] The utility model relates to a current transformer, in particular to an explosion-proof current transformer with a composite porcelain bushing. Background Art

[0002] Traditional porcelain bushing gas-insulated current transformers, because the porcelain bushing bears the internal inflation pressure, the brittle porcelain material is easy to break. Once an arc fault occurs inside the product, causing the gas pressure to rise or being hit by other objects outside, the porcelain bushing will shatter and splash, endangering other electrical equipment and the lives of maintenance personnel. In addition, the existing conventional 220kV transformer products need to be laid down for transportation. During the laying and transportation process, the weight of the secondary coil and the corresponding shielding tube and other parts increases the risk of supporting insulator rupture. The vibration and bumps caused by transportation cause the impact force to deteriorate the strength of the shielding support tube as a cantilever beam, which is easy to cause damage and affect the quality of the shielding support tube. Summary of the invention

[0003] The utility model provides an explosion-proof current transformer with a composite porcelain bushing which effectively guarantees support for high-voltage insulating parts, has a firm and stable structure, can prevent damage and leakage of the supporting bushing, and is safe to use.

[0004] The technical solution adopted by the utility model is: a composite porcelain bushing explosion-proof current transformer, comprising a high-voltage shell, an explosion-proof bushing, a base and a secondary junction box, the secondary junction box is arranged on the bottom surface of the base, and is characterized in that: the high-voltage shell is supported on the bottom plate at the upper end of the base through metal flanges bonded at both ends of the porcelain bushing, the porcelain bushing is lined with a glass fiber reinforced plastic inner bushing, and metal flanges are bonded at both ends of the porcelain bushing; the glass fiber reinforced plastic inner bushing is connected with a shielding support tube on the same center line, the shielding support tube extends into the high-voltage shell to support the secondary coil through the coil shielding tube, the shielding support tube is located on the bottom plate at the upper end of the base, a lead is arranged in the shielding support tube, and the two ends of the lead are respectively connected to the secondary coil and the secondary junction box, the shielding support tube is made of hard aluminum alloy, and insulating gas is filled between the shielding support tube and the glass fiber reinforced plastic inner bushing.

[0005] The insulating gas is a mixed gas of SF6 and N2, and the volume proportion of SF6 is 25% to 35%. In particular, when the volume proportion of SF6 is 30%, the product can take into account both insulation performance and cost.

[0006] The secondary junction box is made of 304 stainless steel.

[0007] The porcelain bushing is lined with a glass fiber reinforced plastic inner bushing, and there is a gap between the porcelain bushing and the glass fiber reinforced plastic inner bushing (sealed at both ends), the gap distance is 5 to 12 mm, and a proper amount of SF6 insulating gas is filled in the gap, and the SF6 insulating gas can further enhance the stability of the bushing.

[0008] Metal flanges are bonded to both ends of the porcelain sleeve, and the flanges are assembled and connected with the base and the high-pressure shell flange to form a sealed air chamber.

[0009] The base and the bottom plate are made of hard aluminum alloy.

[0010] The two ends of the FRP inner sleeve and the porcelain sleeve are grooved, with a total of 3 groups of square grooves. The square grooves can increase the bonding surface with the filler and improve the bonding degree between the FRP inner sleeve and the porcelain sleeve.

[0011] The adhesive bonding layer is filled with epoxy resin, a material with high shear strength and suitable expansion rate. A buffer medium exists between the filled epoxy resin and the FRP inner sleeve and the porcelain sleeve, which can avoid cracking of the seal caused by stress difference between the FRP inner sleeve and the porcelain sleeve due to different material expansion rates.

[0012] By adopting the above technical solution, the beneficial effects of the utility model are:

[0013] 1. The porcelain bushing and the FRP inner bushing are connected. The explosion-proof principle is that the internal inflation pressure and the external support pressure are borne by the FRP inner bushing made of non-brittle materials, while the outer high-strength porcelain bushing does not bear the internal inflation pressure and the external support pressure, and only plays the role of external insulation and UV resistance, which can further improve the explosion-proof and anti-leakage performance; the gap between the two is filled with SF6 insulating gas to further enhance the stability of the bushing;

[0014] 2. The porcelain bushing is lined with glass fiber reinforced plastic inner bushing support, which effectively prevents the leakage of internal insulating gas after the porcelain bushing is broken by impact. Even if the porcelain bushing is broken, it can still operate normally for a short time, leaving enough time for maintenance, taking into account the support strength while improving the safe operation of the system under overvoltage;

[0015] 3. The coil shielding tube made of hard aluminum alloy can effectively reduce the weight of the secondary end, reduce the cantilever load during horizontal placement and transportation, and improve the firmness and safety of the overall structure. The bottom plate, base and high-voltage shell are made of lightweight hard aluminum alloy, which effectively takes into account both weight reduction and weight counterweight;

[0016] 4. One end of the shielding support tube is inserted into the high-voltage shell to support the secondary coil through the coil shielding tube, and the other end is located on the bottom plate to improve the overall support rigidity and strength, and effectively avoid quality problems caused by insulation support;

[0017] 5. Grooves are carved between the ends of the FRP inner sleeve and the porcelain sleeve. There are 3 groups of square grooves in total. The square grooves can increase the bonding surface with the filler and improve the bonding between the FRP inner sleeve and the porcelain sleeve.

[0018] 6. The adhesive bonding layer is filled with epoxy resin, a material with high shear strength and suitable expansion rate. There is a buffer medium between the filled epoxy resin and the FRP inner casing and the porcelain casing, which can avoid the stress difference caused by the different expansion rates of the materials of the FRP inner casing and the porcelain casing, resulting in cracks in the seal, effectively improving the bonding strength and the supporting strength of the side placement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the first embodiment of the utility model;

[0020] Figure 2 It is an enlarged schematic diagram of the groove structure between the two ends of the glass fiber reinforced plastic inner sleeve and the porcelain sleeve in the second embodiment of the utility model.

[0021] In the figure: high-voltage shell 1, secondary coil 2, coil shielding tube 3, porcelain bushing 4, fiberglass inner bushing 5, shielding support tube 6, lead wire 7, bottom plate 8, base 9, secondary junction box 10, metal flange 11, epoxy resin 12. DETAILED DESCRIPTION

[0022] The following is a further description with reference to the accompanying drawings.

[0023] Figure 1 The first embodiment shown is a composite porcelain bushing explosion-proof current transformer, comprising a high-voltage housing 1, a secondary coil 2, a coil shielding tube 3, a porcelain bushing 4, a glass fiber reinforced plastic inner bushing 5, a shielding support tube 6, a lead wire 7, a bottom plate 8, a base 9, a secondary junction box 10, a metal flange 11, and an epoxy resin 12. The secondary junction box 10 is arranged on the bottom surface of the base 9, and the base 9 supports the metal flange 11 bonded to the lower end of the outer porcelain bushing 4 through the bottom plate 8, the porcelain bushing 4 is lined with a glass fiber reinforced plastic inner bushing 5, and the glass fiber reinforced plastic inner bushing 4 is connected with the shielding support tube 6 on the same center line, and the shielding support tube 6 is located on the bottom plate 8, and the shielding support tube 6 is provided with a lead wire 7, and the two ends of the lead wire 7 are respectively connected to the secondary coil 2 and the secondary junction box 10, and the high-voltage housing 1 is connected and supported on the bottom plate 9 at the upper end of the base 8 through the metal flange 11 bonded to the two ends of the porcelain bushing 4, and the shielding support tube 6 extends into the high-voltage housing 1 to support the secondary coil 2 through the coil shielding tube 3.

[0024] In this embodiment, the shielding support tube 6 is made of hard aluminum alloy, and insulating gas is filled between the shielding support tube 6 and the glass fiber reinforced plastic inner sleeve 5. The secondary junction box 10 is made of 304 stainless steel. The base 9 is made of hard aluminum alloy. The bottom plate 8 is made of hard aluminum alloy.

[0025] In the above embodiment, the insulating gas filled in the inner cavity of the FRP inner sleeve 5 is preferably a mixed gas of SF6 and N2, and the volume ratio of the two is about 3:7.

[0026] Figure 2The second embodiment shown is a composite porcelain bushing explosion-proof current transformer. Compared with the first embodiment, the porcelain bushing 4 is lined with a glass fiber reinforced plastic inner bushing 5, and metal flanges 11 are bonded to both ends of the porcelain bushing 4. Grooves are cut between the glass fiber reinforced plastic inner bushing 5 and the porcelain bushing 4, and there are 3 groups of square grooves. The adhesive bonding layer is filled with epoxy resin 12 of high shear strength and suitable expansion and contraction rate, and a buffer medium exists between the filled epoxy resin 12 and the glass fiber reinforced plastic inner bushing 5 and the porcelain bushing 4.

Claims

1. A composite porcelain bushing explosion-proof current transformer, comprising a high-voltage housing, an explosion-proof bushing, a base and a secondary junction box, wherein the secondary junction box is arranged on the bottom surface of the base, and is characterized in that: The high-voltage shell is supported on the bottom plate at the upper end of the base through metal flanges bonded at both ends of the porcelain bushing. The porcelain bushing is lined with a glass fiber reinforced plastic inner bushing, and metal flanges are bonded at both ends of the porcelain bushing. The glass fiber reinforced plastic inner bushing is connected to a shielding support tube on the same center line. The shielding support tube extends into the high-voltage shell and supports the secondary coil through the coil shielding tube. The shielding support tube is located on the bottom plate at the upper end of the base. Leads are arranged in the shielding support tube, and both ends of the leads are respectively connected to the secondary coil and the secondary junction box. The shielding support tube is made of hard aluminum alloy, and insulating gas is filled between the shielding support tube and the glass fiber reinforced plastic inner bushing.

2. The composite porcelain bushing explosion-proof current transformer according to claim 1 is characterized in that: The insulating gas is a mixed gas of SF6 and N2, and the volume proportion of SF6 is 25% to 35%.

3. The composite porcelain bushing explosion-proof current transformer according to claim 2 is characterized in that: The volume proportion of the insulating gas SF6 is 30%.

4. The composite porcelain bushing explosion-proof current transformer according to claim 1 is characterized in that: The secondary junction box is made of 304 stainless steel.

5. The composite porcelain bushing explosion-proof current transformer according to claim 1, characterized in that: The porcelain bushing is lined with a glass fiber reinforced plastic inner bushing, and there is a gap between the porcelain bushing and the glass fiber reinforced plastic inner bushing, the gap distance is 5 to 12 mm, and a proper amount of SF6 insulating gas is filled in the gap.

6. The composite porcelain bushing explosion-proof current transformer according to claim 1, characterized in that: Metal flanges are bonded to both ends of the porcelain sleeve, and the flanges are assembled and connected with the base and the high-pressure shell flange to form a sealed air chamber.

7. The composite porcelain bushing explosion-proof current transformer according to claim 1, characterized in that: The base and the bottom plate are made of hard aluminum alloy.

8. The composite porcelain bushing explosion-proof current transformer according to claim 1, characterized in that: The two ends of the FRP inner sleeve and the porcelain sleeve are grooved, with a total of 3 groups of square grooves. The square grooves can increase the bonding surface with the filler and improve the bonding degree between the FRP inner sleeve and the porcelain sleeve.

9. The composite porcelain bushing explosion-proof current transformer according to claim 1, characterized in that: The space between the fiberglass inner sleeve and the porcelain sleeve is filled with epoxy resin having high shear strength and suitable expansion / contraction rate.

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