Anti-seismic and explosion-proof current transformer

Abstract

The invention provides an anti-seismic and anti-explosion current transformer. The current transformer comprises a composite anti-explosion sleeve, a transformer body arranged at the top of the composite anti-explosion sleeve, and a base arranged at the bottom of the composite anti-explosion sleeve, the composite explosion-proof sleeve comprises an inner pressure-bearing layer and an outer protective layer arranged outside the inner pressure-bearing layer in a sleeving mode. Internal pressure is borne through the inner pressure bearing layer, an internal structure is protected through the outer protection layer, especially even if the inner pressure bearing layer is broken, the outer protection layer can restrain fragments, secondary damage is completely eradicated, and the anti-explosion performance can be improved; the problems that an existing current transformer is low in silicon rubber voltage withstanding limit, and the fragment splashing radius is large after an outer protective layer is broken are solved.

Description

Technical Field

[0001] This invention relates to the field of high-voltage electrical equipment technology, and more specifically, to a shock-resistant and explosion-proof current transformer. Background Technology

[0002] Current transformers are core measuring devices in power systems, and traditional products mainly adopt a porcelain bushing structure. In recent years, research on current transformer equipment has focused on low power consumption, lightweight design, and environmental friendliness. However, the following key problems have been exposed during operation: 1. Lack of explosion-proof design: Current transformer explosion accidents have exposed serious deficiencies in the explosion-proof design of current transformers. When an internal insulation breakdown fault occurs, the electric arc causes the insulating oil to decompose rapidly, forming a transient impact pressure that can easily lead to the transformer exploding and catching fire. The deflagration rate after a fault is 100%.

[0003] 2. Insufficient seismic resistance: Existing instrument transformer housings mostly use welded structures, which are prone to cracking under seismic loads, posing a risk of structural failure under high-intensity vibration environments. Furthermore, the rigid connection between the bushing and the base is insufficient to absorb vibration energy, and excessive displacement will directly lead to seal failure.

[0004] A well-designed explosion-proof structure can significantly reduce the risk of secondary accidents caused by equipment failure, protecting surrounding equipment and on-site personnel. At the same time, excellent seismic design can greatly reduce the possibility of air or oil leaks, not only reducing maintenance burdens but also indirectly reducing environmental pollution caused by equipment leaks.

[0005] In the field of explosion-proof and seismic-resistant design of current transformers, two major trends are currently emerging. Explosion-proof: the focus is shifting from simply increasing shell strength (such as thickening steel plates) to the application of composite materials; Seismic-resistant: welded structures are gradually being replaced by casting processes, but this still cannot solve the stress concentration problem at the bushing-base connection.

[0006] Most current transformer equipment currently uses silicone rubber composite bushings (coated with liquid adhesive for aging prevention) or pure outer protective layers (increased wall thickness for pressure resistance). However, existing solutions have serious drawbacks such as the low pressure resistance limit of silicone rubber and the large radius of fragments that can fly after the outer protective layer breaks, failing to enhance the explosion-proof capability of the equipment and reduce the severity of secondary accidents. Summary of the Invention

[0007] In view of this, the present invention proposes a shock-resistant and explosion-proof current transformer, which aims to solve the problems of low withstand voltage limit of silicone rubber and large fragmentation radius after the outer protective layer is broken in the existing current transformer.

[0008] This invention proposes a shock-resistant and explosion-proof current transformer, which includes: a composite explosion-proof bushing, a transformer body disposed on the top of the composite explosion-proof bushing, and a base disposed at the bottom of the composite explosion-proof bushing; the composite explosion-proof bushing includes: an inner pressure-bearing layer and an outer protective layer sleeved outside the inner pressure-bearing layer.

[0009] Furthermore, in the aforementioned shock-resistant and explosion-proof current transformer, the inner pressure-bearing layer and the outer protective layer are bonded together; the outer protective layer has an upper outer connecting flange and a lower outer connecting flange at both ends, the upper outer connecting flange being used to connect to the transformer body, and the lower outer connecting flange being used to connect to the base.

[0010] Furthermore, in the aforementioned earthquake-resistant and explosion-proof current transformer, an adhesive layer is provided along the axial length of the inner pressure-bearing layer between the inner pressure-bearing layer and the outer protective layer; and / or, an adhesive layer is provided at both ends of the inner pressure-bearing layer between the inner pressure-bearing layer and the outer protective layer.

[0011] Furthermore, in the aforementioned earthquake-resistant and explosion-proof current transformer, the inner pressure-bearing layer has an upper inner connecting flange and a lower inner connecting flange at both ends. The upper inner connecting flange is used to connect to the transformer body, and the lower inner connecting flange is used to connect to the base. The bottom end of the outer protective layer has a lower outer fixing flange for connecting to the base.

[0012] Furthermore, in the aforementioned shock-resistant and explosion-proof current transformer, a gap for expansion and contraction is reserved between the outer protective layer and the transformer body.

[0013] Furthermore, in the aforementioned shock-resistant and explosion-proof current transformer, the transformer body includes: a high-voltage housing, a primary conductor assembly, and a secondary winding assembly; wherein, the primary conductor assembly is a hollow cylinder, which passes through the cavity wall of the high-voltage housing, and both ends of the primary conductor assembly extend to the outside of the high-voltage housing for connection in series with a high-voltage line; the secondary winding assembly is disposed inside the high-voltage housing and wound along the outer wall of the primary conductor assembly.

[0014] Furthermore, in the aforementioned shock-resistant and explosion-proof current transformer, the interior of the composite explosion-proof bushing is provided with a secondary winding support assembly arranged along its axial direction, and the top of the secondary winding support assembly is connected to the secondary winding assembly.

[0015] Furthermore, in the aforementioned earthquake-resistant and explosion-proof current transformer, the secondary winding support assembly includes several support tubes that are connected end to end and arranged coaxially. Moreover, along the axial direction of the composite explosion-proof bushing and from one end of the base to one end of the transformer body, the outer diameter of the multiple support tubes decreases sequentially.

[0016] Furthermore, in the aforementioned shock-resistant and explosion-proof current transformer, the high-voltage housing has an elliptical structure, and the secondary winding assembly is arranged along the long side of the high-voltage housing.

[0017] Furthermore, in the aforementioned shock-resistant and explosion-proof current transformer, the interior of the composite explosion-proof bushing is provided with a high-voltage shielding cover with a cylindrical structure. The top of the high-voltage shielding cover is connected to the transformer body, and the bottom is provided with an arc-shaped flange.

[0018] The shockproof and explosion-proof current transformer provided by this invention uses an inner pressure-bearing layer to withstand internal pressure and an outer protective layer to protect the internal structure. In particular, even if the inner pressure-bearing layer breaks, the outer protective layer can restrain the fragments and prevent secondary damage, thereby improving the explosion-proof performance. This solves the problems of low pressure resistance of silicone rubber and large fragment splash radius after the outer protective layer breaks in existing current transformers. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the structure of the shock-resistant and explosion-proof current transformer provided in an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of a section at point A in the middle; Figure 3 for Figure 3 A magnified view of a section at point B in the middle; Figure 4 This is another structural schematic diagram of the shock-resistant and explosion-proof current transformer provided in an embodiment of the present invention; Figure 5 for Figure 4 A magnified view of a section at point C; Figure 6 for Figure 4 A magnified view of a section at point D; Figure 7 This is a schematic diagram of the high-pressure housing provided in an embodiment of the present invention; Figure 8 This is a side view of the high-pressure housing provided in an embodiment of the present invention; Figure 9 A top view of the high-pressure housing provided in an embodiment of the present invention; Figure 10 This is a simulation result diagram of the maximum stress during transportation of the shock-resistant and explosion-proof current transformer provided in an embodiment of the present invention; Figure 11This is a simulation result diagram of the maximum deformation displacement of the shock-resistant and explosion-proof current transformer during transportation, provided in an embodiment of the present invention. Figure 12 The figure shows the simulation results of the maximum stress of the earthquake-resistant and explosion-proof current transformer during an earthquake, as provided in the embodiments of the present invention. Figure 13 This is a diagram showing the maximum deformation displacement of an earthquake-resistant and explosion-proof current transformer provided in an embodiment of the present invention. Explanation of reference numerals in the attached figures: 1-Composite explosion-proof sleeve, 11-Inner pressure-bearing layer, 12-Outer protective layer, 13-Outer upper connecting flange, 14-Outer lower connecting flange, 15-Inner upper connecting flange, 16-Inner lower connecting flange, 17-Outer lower fixed flange, 2-Instrument body, 21-High voltage housing, 22-Primary conductor assembly, 221-Primary terminal block, 23-Secondary winding assembly, 24-Secondary winding support assembly, 241-Support tube, 3-Base, 4-High voltage shield. Detailed Implementation

[0020] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] See Figures 1 to 6This figure illustrates a preferred structure of the shock-resistant and explosion-proof current transformer provided in an embodiment of the present invention. As shown, the shock-resistant and explosion-proof current transformer includes: a composite explosion-proof bushing 1, a transformer body 2, and a base 3. The transformer body 2 is disposed on top of the composite explosion-proof bushing 1, and the base 3 is disposed on the bottom of the composite explosion-proof bushing 1. The composite explosion-proof bushing 1 includes: an inner pressure-bearing layer 11 and an outer protective layer 12; wherein the outer protective layer 12 is sleeved outside the inner pressure-bearing layer 11. Specifically, the top end of the composite explosion-proof bushing 1 is connected to the transformer body 2 and can be fixed by a flange or other connecting structure. The bottom end of the composite explosion-proof bushing 1 is connected to the base 3 and can be fixed by a flange or other connecting structure. In this embodiment, the top end of the composite explosion-proof bushing 1 is sealable to the transformer body 2, and the bottom end is sealed to the base 3 to form a sealed gas chamber. The sealed gas chamber can be filled with an insulating medium, and the insulation cutoff can be a 25% SF6 / 75% N2 mixed gas. The composite explosion-proof sleeve 1 adopts a composite structure design with internal and external dual-material pressure bearing. The inner pressure bearing layer 11 can be an epoxy glass fiber tube, which can withstand 100% operating air pressure under normal operation. The outer protective layer 12 is a silicone rubber composite insulator. Silicone rubber has high tear resistance. When equipment failure causes the inner pressure bearing layer 11 to burst, it can limit the fragments after the inner layer breaks and prevent the fragments from flying.

[0022] In this embodiment, the composite explosion-proof bushing 1 has a cylindrical high-voltage shield 4 inside. The top of the high-voltage shield 4 is connected to the transformer body 2, and the bottom has an arc-shaped flange. Specifically, the top of the high-voltage shield 4 is connected to the transformer body 2, especially to the high-voltage housing 21 of the transformer body 2. The high-voltage shield 4 can be a cylindrical structure, supported by metal material. The high-voltage shield 4 is placed between the composite explosion-proof bushing 1 and the internal secondary winding support assembly 24, which can improve the electric field distribution and play a role in uniform electric field. In this embodiment, the top of the high-voltage shield 4 has a transverse fold for connection and fixation to the high-voltage housing 21, and the bottom has an arc-shaped flange, which makes the curvature of the lower end of the high-voltage shield 4 smaller, avoiding the formation of a local strong electric field, thereby making the electric field distribution uniform, avoiding the generation of discharge phenomenon, and also improving the insulation performance of the transformer.

[0023] In this embodiment, there are two ways to connect and fix the inner pressure-bearing layer 11 and the outer protective layer 12: an adhesive structure and an assembled structure to achieve the connection and fixation of the composite explosion-proof sleeve 1.

[0024] See also Figures 1 to 3The inner bearing layer 11 and the outer protective layer 12 are connected and fixed by an adhesive structure, that is, the inner bearing layer 11 and the outer protective layer 12 are bonded together and can be bonded into a single structure. Specifically, the inner bearing layer 11 is nested and bonded to the inner surface of the outer protective layer 12, and the inner bearing layer 11 and the outer protective layer 12 can be bonded together with an adhesive, which can be an epoxy resin adhesive. An adhesive layer is provided along the entire axial length of the inner pressure-bearing layer 11 between the inner pressure-bearing layer 11 and the outer protective layer 12. This means that the inner pressure-bearing layer 11 and the outer protective layer 12 can be bonded together using a fully adhesive method. For example, adhesive can be applied to the entire outer surface of the inner pressure-bearing layer 11 and the inner surface of the outer protective layer 12 to bond them together, forming an integral structure. That is, the inner pressure-bearing layer 11 and the outer protective layer 12 are entirely bonded along the axial direction, achieving full adhesion. Alternatively, adhesive can be injected between the outer surface of the inner pressure-bearing layer 11 and the inner surface of the outer protective layer 12 to achieve full adhesion. Of course, the inner pressure-bearing layer 11 and the outer protective layer 12 are bonded at both ends of the inner pressure-bearing layer 11 (e.g., ...). Figure 1 An adhesive layer is provided at both the top and bottom ends (as shown). The inner pressure-bearing layer 11 and the outer protective layer 12 can also be bonded by end bonding. In particular, adhesive is applied or injected at both ends of the inner pressure-bearing layer 11 and the outer protective layer 12 to achieve bonding and fixation. That is to say, there is an adhesive layer between the two ends of the inner pressure-bearing layer 11 and the outer protective layer 12. An air gap can be retained between the upper and lower adhesive layers at the middle position of the inner pressure-bearing layer 11 and the outer protective layer 12. The air gap can be filled with insulating gas to further improve the insulation performance of the composite explosion-proof sleeve 1.

[0025] In this embodiment, the two ends of the outer protective layer 12 (such as...) Figure 1 The upper and lower ends (as shown) are respectively provided with an upper outer connecting flange 13 and an lower outer connecting flange 14. The upper outer connecting flange 13 is used to connect to the transformer body 2, and the lower outer connecting flange 14 is used to connect to the base 3. Specifically, the integrated structure formed by bonding the inner pressure-bearing layer 11 and the outer protective layer 12 can be connected, fixed, and sealed to the transformer body 2 and the base 3 through flanges. The upper outer connecting flange 13 and the lower outer connecting flange 14 are both sleeved on the outer periphery of the outer protective layer 12 and are respectively bonded to both ends of the outer protective layer 12. The upper outer connecting flange 13 is assembled and connected to the housing flange of the base 3, and the lower outer connecting flange 14 is assembled and connected to the housing flange of the transformer body 2, forming a sealed air chamber. That is to say, the internal hollow cavity of the inner pressure-bearing layer 11 is connected to the inner cavity of the high-pressure housing 21 of the transformer body 2. The bottom is sealed by the base 3, and the top is sealed by the top plate of the high-pressure housing 21, forming a sealed air chamber. Both the outer upper connecting flange 13 and the outer lower connecting flange 14 can be metal flanges, and the two ends of the inner pressure-bearing layer 11 can also be bonded to the outer upper connecting flange 13 and the outer lower connecting flange 14 with adhesive.

[0026] See also Figures 4 to 6The inner pressure-bearing layer 11 and the outer protective layer 12 are connected and fixed using an assembled structure. In particular, the inner pressure-bearing layer 11 and the outer protective layer 12 can be connected to the top transformer body 2 and the bottom base 3 respectively using flanges to achieve the assembled structure fixation of the inner pressure-bearing layer 11 and the outer protective layer 12. In this embodiment, there is an annular air cavity between the inner pressure-bearing layer 11 and the outer protective layer 12, which can be filled with insulating gas. The two ends of the inner pressure-bearing layer 11 are respectively provided with an upper inner layer connecting flange 15 and a lower inner layer connecting flange 16. The upper inner layer connecting flange 15 is used to connect to the transformer body 2, and the lower inner layer connecting flange 16 is used to connect to the base 3. The bottom end of the outer protective layer 12 is provided with a lower outer layer fixing flange 17 for connecting to the base 3 to achieve the connection between the outer protective layer 12 and the base 3.

[0027] Specifically, the inner pressure-bearing layer 11 and the outer protective layer 12 are not bonded together with adhesive, but rather use an assembled structure. In this embodiment, the two ends of the inner pressure-bearing layer 11 (e.g., Figure 4 The upper and lower inner connecting flanges 15 and 16 are respectively bonded to the upper and lower ends of the inner protective layer 11. Specifically, both the upper and lower inner connecting flanges 15 and 16 are sealed to the inner pressure-bearing layer 11, ensuring the airtightness of the hollow interior of the inner pressure-bearing layer 11. The upper inner connecting flange 15 is assembled and connected to the base 3, and the lower inner connecting flange 16 is assembled and connected to the transformer body 2, forming a sealed air chamber. That is, the hollow cavity inside the inner pressure-bearing layer 11 is connected to the inner cavity of the high-voltage housing 21 of the transformer body 2. The bottom is sealed by the base 3, and the top is sealed by the top plate of the high-voltage housing 21, forming a sealed air chamber. An outer lower fixing flange 17 is bonded to the bottom periphery of the outer protective layer 12, and it is fixedly connected to the base 3. To prevent deformation due to axial expansion and contraction of the outer protective layer 12, preferably, a expansion gap is reserved between the outer protective layer 12 and the transformer body 2 to accommodate expansion and contraction. Specifically, a 5mm expansion gap is reserved between the top of the outer protective layer 12 and the high-voltage housing 21 of the transformer body 2. The inner upper connecting flange 15, the inner lower connecting flange 16, and the outer lower fixed flange 17 can all be metal flanges.

[0028] See also Figure 1 The transformer body 2 includes: a high-voltage housing 21, a primary conductor assembly 22, and a secondary winding assembly 23; wherein, the primary conductor assembly 22 is a hollow cylinder, the primary conductor assembly 22 passes through the cavity wall of the high-voltage housing 21, and both ends of the primary conductor assembly 22 extend to the outside of the high-voltage housing 21 for connection in series with the high-voltage line; the secondary winding assembly 23 is disposed inside the high-voltage housing 21 and wound along the outer wall of the primary conductor assembly 22.

[0029] Specifically, the primary conductor assembly 22 can be a conductive rod structure. In particular, the primary conductor assembly 22 is hollow inside and passes through the cavity wall of the high-voltage housing 21. Both ends of the high-voltage housing 21 extend to the outside of the high-voltage housing 21. Furthermore, both ends of the primary conductor assembly 22 can be connected to primary terminals 221, allowing the primary conductor assembly 22 to be connected in series with the high-voltage line via the primary terminals. The secondary winding assembly 23 is disposed inside the high-voltage housing 21 and wound along the outer wall of the primary conductor assembly 22. That is, the secondary winding assembly 23, located inside the high-voltage housing 21, is wound along the outer wall of the primary conductor assembly 22. The secondary winding assembly 23 can be a ring structure, with the primary conductor assembly 22 passing through its geometric center, functioning as a primary winding. The top end of the composite explosion-proof sleeve 1 is connected to the high-voltage housing 21, and the bottom center of the high-voltage housing 21 has a through hole communicating with the composite explosion-proof sleeve 1. The high-voltage housing 21 and the composite explosion-proof sleeve 1 form a sealed gas chamber, which can be filled with SF6 insulating gas. In this embodiment, the top of the high-pressure housing 21 is provided with an explosion-proof device. The explosion-proof device is used to rupture first when the gas pressure inside the high-pressure housing 21 is too high, so as to discharge the gas inside the high-pressure housing 21 and prevent the high-pressure housing 21, the composite explosion-proof sleeve 1 or the base 3 from bursting.

[0030] In this embodiment, the interior of the composite explosion-proof bushing 1 is provided with a secondary winding support assembly 24 arranged axially thereon. The top of the secondary winding support assembly 24 is connected to the secondary winding assembly 23 to support the secondary winding assembly 23. Specifically, the secondary winding support assembly 24 arranged axially inside the composite explosion-proof bushing 1 is connected to the top of the secondary winding assembly 23 to support the secondary winding assembly 23. Compared with supporting the insulator, the secondary winding support assembly 24 is placed inside the composite explosion-proof bushing 1, resulting in a compact structure. In this embodiment, the secondary winding support assembly 24 includes several support tubes 241 that are connected end to end and arranged coaxially. Furthermore, along the axial direction of the composite explosion-proof bushing and from one end of the base 3 to one end of the transformer body 2 (e.g., ... Figure 1As shown from bottom to top, the outer diameter of the multiple support tubes 241 decreases sequentially. In this embodiment, the three-section structure, compared to a single section of the same diameter, not only meets the support requirements for weighing and swinging but also avoids the outer diameter from being too large, causing the top to not match the high-voltage shield 4. In particular, a large outer diameter results in a small gap between the support tube 241 and the shield, leading to high electric field strength and low insulation. Therefore, multiple support tubes 241 with different diameters not only meet the support requirements for weighing and swinging but also the insulation performance requirements. In addition, the tubular structure is hollow inside, allowing for wire threading, especially conductive connecting wires, which can pass through the support tubes 241 to connect with the secondary winding assembly 23, etc. In this embodiment, the secondary winding support assembly 24 also serves as a shield, with both ends connected to the shielding structure of the secondary winding assembly 23 and the base 3, respectively, preventing the internal conductive connecting wires from being affected by high-voltage electromagnetic interference.

[0031] See Figures 7 to 9 This illustrates a preferred structure of the high-voltage housing 21 provided in an embodiment of the present invention. As shown in the figure, the high-voltage housing 21 has an elliptical structure, and the secondary winding assembly 23 is located along the long side of the high-voltage housing 21 (e.g., ...). Figure 9 The high-voltage housing 21 is arranged in the vertical direction shown. Specifically, the cross-section of the high-voltage housing 21 is elliptical, which can further reduce the footprint and the weight of the head, and further improve the seismic performance of the current transformer.

[0032] This shock-resistant and explosion-proof current transformer has achieved multiple breakthroughs: First, a significant improvement in explosion-proof performance: the gas-insulated composite insulator shows no visible damage under 2.76 MPa pressure. Furthermore, it can withstand 1.8 MPa of gas pressure (3.6 times the operating pressure) even when the porcelain bushing is broken, with zero fragments escaping.

[0033] Current transformers use a 25% SF6 / 75% N2 mixed gas as the insulating medium. For their metal-enclosed components, a type test pressure test of the enclosure is required. The enclosure pressure test equipment is a enclosure hydrostatic testing machine. Under the type test pressure conditions, the pressure rise rate should not exceed 400 kPa / min. For welded aluminum and welded steel enclosures, the type test pressure can be calculated using the following formula and maintained for 1 minute. The current transformer should not show signs of cracking or permanent deformation.

[0034] ; in: This is the welding effect coefficient; The allowable design stress at the test temperature is 113 MPa; The allowable design stress at the design temperature is 0.69 MPa.

[0035] For the internal pressure test of gas-insulated composite insulators of current transformers, the current transformer is installed vertically with end caps at both ends, which are sealed. The end caps are equipped with devices that allow the internal pressure medium to enter or exit. A pressure of 4 times the design pressure (2.76 MPa) is applied and maintained for 5 minutes. After the pressure is smoothly released, the residual strain after the pressure application is allowed to be greater than ±5% of the maximum strain (irreversible plastic state), and it should be confirmed that no visible damage occurs. The test results are shown in Table 1, indicating that the current transformer meets the pressure test requirements.

[0036] surface Pressure test results Second, enhanced seismic resistance: The seismic design of the current transformer is carried out in accordance with GB / T 13540-2009 "Seismic Requirements for High Voltage Switchgear and Controlgear". The seismic performance is as follows: displacement of 3.4mm under a 9-degree earthquake (national standard limit of 5mm), and peak stress of 10.47MPa under transportation conditions (4g acceleration).

[0037] Four iron-core coils are installed inside the product's shielding cylinder. The product is installed and transported vertically. The horizontal forces experienced during earthquakes and transportation are calculated. Simulation results are attached. Figures 10 to 13 The seismic horizontal acceleration is taken as 0.5g, the product damping ratio is taken as 2%, and the frequency is taken as 9Hz. The simulation results of the data in the two figures are summarized in Table 2.

[0038] Table 2 Seismic Simulation Results Simulation object Maximum stress / MPa Maximum displacement / mm earthquake level 16.04 3.4 Vertical transportation 10.47 2.45 Third, long-term reliability: After 2000 temperature cycles and vibration tests, the seal maintains an annual leakage rate of <0.1%.

[0039] The shockproof and explosion-proof current transformer uses a 25% SF6 / 75% N2 mixed gas as the insulating medium and undergoes a sealing performance test at an ambient temperature of 18℃ and a relative humidity of 71%. The test equipment includes a sealing enclosure and a characteristic gas leak detector. The gas leak detector must have a detection accuracy of no less than 10⁻⁶ volume ratio to ensure accurate identification of trace amounts of gas escaping from the sealing components. When testing the gas-tight system of the current transformer, all interface connections must maintain their original sealed state, using the sealing materials and technical specifications provided by the equipment manufacturer. During the test, leaked gas continuously accumulates in the sealed testing chamber. By periodically collecting gas samples and applying a quantitative algorithm, combined with the chamber volume parameters and pressure, the standardized leakage rate is finally calculated. The test steps are as follows: (1) The current transformer should be filled with a mixture of 25% SF6 / 75% N2 gas to ensure that the current transformer reaches the rated internal pressure required by the specification under an ambient temperature of 20℃. (2) After the low-power SF6 / N2 current transformer has been left to stand for 6 hours, the entire current transformer is hermetically sealed with a special sealing cover. (3) After 24 hours of sealing, the concentration of characteristic gas inside the enclosure is detected using a gas leak detector. The standardized leakage rate R is derived based on the quantitative calculation formula for gas leakage, as follows.

[0040] ; In the formula: R is the leakage rate, in Pa·m3 / s; For volume measurement, unit is m3; The concentration of the tracer gas is expressed in cm³ / m³. The time interval is in seconds (s). The pressure on the outer surface of the current transformer is 105 Pa.

[0041] The relative annual leakage rate FP (% / year) is calculated as follows: ; In the formula: The volume of the gas-tight system for the current transformer is expressed in m³. The rated inflation pressure of the current transformer is given in Pa. The sealing performance test results are shown in Table 3, which meets the requirement of a relative leakage rate of less than 0.5% per year.

[0042] Table 3. Results of sealing performance test Time interval (s) Measure volume (m3) air chamber volume (m3) Rated inflation pressure (MPa) tracer gas concentration (cm3 / m3) Relative annual leakage rate (% / year) 86400 0.35 0.76 0.55 3.50 Less than 0.1 In summary, the earthquake-resistant and explosion-proof current transformer provided in this embodiment uses an inner pressure-bearing layer 11 to withstand internal pressure and an outer protective layer 12 to protect the internal structure. In particular, even if the inner pressure-bearing layer 11 breaks, the outer protective layer 12 can restrain the fragments, preventing secondary damage and improving explosion-proof performance. This solves the problems of low pressure resistance of silicone rubber and large fragment scattering radius after the outer protective layer 12 breaks in existing current transformers. Simultaneously, this earthquake-resistant and explosion-proof current transformer can withstand continuous seismic impacts with high-intensity horizontal acceleration, ensuring structural integrity. Furthermore, this earthquake-resistant and explosion-proof current transformer uses composite protective coupling, i.e., a double-layer structural coupling, to cope with multiple stresses from air pressure, mechanical vibration, and extreme temperatures.

[0043] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0044] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A shock-resistant and explosion-proof current transformer, characterized in that, include: Composite explosion-proof bushing, current transformer body disposed on the top of the composite explosion-proof bushing, and base disposed at the bottom of the composite explosion-proof bushing; The composite explosion-proof sleeve includes: an inner pressure-bearing layer and an outer protective layer sleeved outside the inner pressure-bearing layer.

2. The shock-resistant and explosion-proof current transformer according to claim 1, characterized in that, The inner pressure-bearing layer and the outer protective layer are bonded together; The outer protective layer has an upper outer connecting flange and a lower outer connecting flange at both ends. The upper outer connecting flange is used to connect to the transformer body, and the lower outer connecting flange is used to connect to the base.

3. The shock-resistant and explosion-proof current transformer according to claim 2, characterized in that, An adhesive layer is provided along the axial length of the inner pressure-bearing layer between the inner pressure-bearing layer and the outer protective layer; and / or, an adhesive layer is provided at both ends of the inner pressure-bearing layer between the inner pressure-bearing layer and the outer protective layer.

4. The shock-resistant and explosion-proof current transformer according to claim 1, characterized in that, The inner pressure-bearing layer is provided with an upper inner layer connecting flange and a lower inner layer connecting flange at both ends. The upper inner layer connecting flange is used to connect to the transformer body, and the lower inner layer connecting flange is used to connect to the base. The bottom of the outer protective layer is provided with an outer lower fixing flange for connecting to the base.

5. The shock-resistant and explosion-proof current transformer according to claim 4, characterized in that, A gap for expansion and contraction is reserved between the outer protective layer and the transformer body.

6. The shock-resistant and explosion-proof current transformer according to any one of claims 1 to 5, characterized in that, The transformer body includes: a high-voltage housing, a primary conductor assembly, and a secondary winding assembly; wherein... The primary conductor assembly is a hollow cylinder. The primary conductor assembly passes through the cavity wall of the high-voltage housing, and both ends of the primary conductor assembly extend to the outside of the high-voltage housing for connection in series with the high-voltage line. The secondary winding assembly is disposed inside the high-voltage housing and wound along the outer wall of the primary conductor assembly.

7. The shock-resistant and explosion-proof current transformer according to claim 6, characterized in that, The composite explosion-proof sleeve has a secondary winding support assembly arranged along its axial direction inside, and the top of the secondary winding support assembly is connected to the secondary winding assembly.

8. The shock-resistant and explosion-proof current transformer according to claim 7, characterized in that, The secondary winding support assembly includes several support tubes that are connected end to end and arranged coaxially. Furthermore, along the axial direction of the composite explosion-proof bushing and from one end of the base to one end of the transformer body, the outer diameter of the multiple support tubes decreases sequentially.

9. The shock-resistant and explosion-proof current transformer according to claim 6, characterized in that, The high-voltage housing has an elliptical structure, and the secondary winding assembly is arranged along the long side of the high-voltage housing.

10. The shock-resistant and explosion-proof current transformer according to any one of claims 1 to 5, characterized in that, The composite explosion-proof sleeve has a high-voltage shield with a cylindrical structure inside. The top of the high-voltage shield is connected to the transformer body, and the bottom is provided with an arc-shaped flange.

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