An etg bushing electrical test system

Abstract

The present application relates to a kind of ETG sleeve electrical test system, including cylinder, and the upper end of cylinder is equipped with connecting sleeve, lower end is equipped with ETG test sleeve, cylinder interior is filled with SF6 gas;Connecting sleeve lower end and ETG test sleeve upper end are placed in cylinder interior, and connecting sleeve lower end is equipped with equalizing ball, ETG test sleeve upper end is equipped with test sleeve connector, and the upper end of test sleeve connector is equipped with spring and equalizing ball contact;Connecting sleeve upper end is electrically connected with test transformer, and ETG test sleeve lower end is inserted into oil tank and is electrically connected with ground electrode arranged in oil tank.The present application can simulate the GIS side environment and transformer side environment of ETG test sleeve, and simultaneously reduces background interference through shielding equalizing and spring elastic connection design, provides cleaner electromagnetic environment for partial discharge measurement, and guarantees the reliability of test result.

Description

Technical Field

[0001] This invention relates to the field of transformer ETG bushing testing technology, specifically to an ETG bushing electrical testing system. Background Technology

[0002] Transformer ETG (oil-SF6) bushings are key components in power transformers, serving the dual functions of insulation support and internal electrical protection. The bushing body is formed by rolling paper-based material into a core, which is then impregnated with epoxy resin and cured. After curing, the blank core is machined to allow it to be installed between the oil-immersed transformer and the SF6 gas-insulated switchgear. Structurally, the bushing is a composite insulating bushing with one end immersed in transformer oil and the other end in an SF6 gas environment.

[0003] Traditional bushings operate with their heads in air (or within the equipment enclosure) and tails in transformer oil. Therefore, the wiring method used in bushing electrical testing—"head connected to high voltage, tail inserted into oil tank"—effectively simulates the electric field distribution during actual operation. However, ETG bushings, acting as a bridge between GIS (Gas Insulated Switchgear) and the transformer, operate with the GIS end in a high-pressure SF6 gas environment. This environment is crucial for the bushing's electric field distribution and external insulation. Therefore, electrical testing of ETG bushings cannot simply employ the "head connected to high voltage, tail inserted into oil tank" method. It must accurately reproduce the operating conditions; that is, the SF6 end must be immersed in SF6 medium to simulate the real electric field distribution. Otherwise, flashover will occur directly under test voltage in air.

[0004] Furthermore, in traditional sleeve testing connection methods, burrs and sharp corners at connection points with poor shielding can generate strong local electric fields, leading to corona discharge. This discharge produces significant electromagnetic interference, severely "polluting" the background noise of partial discharge measurements, causing distorted measurement data, and even failing to effectively detect minute defects inside the sleeve.

[0005] Furthermore, the traditional sleeve test installation method is also quite cumbersome. It is installed by bolt crimping or wrapping, which is time-consuming and labor-intensive. In test site environments where test samples need to be changed frequently, it will lead to low test efficiency.

[0006] Therefore, there is an urgent need for a testing system that can simulate the actual operating conditions of ETG bushings, has excellent shielding performance, and is easy to operate. Summary of the Invention

[0007] The purpose of this invention is to provide an ETG bushing electrical testing system that can simulate the GIS side environment and transformer side environment of the ETG test bushing. At the same time, it reduces background interference through shielded voltage equalization and spring elastic contact design, providing a cleaner electromagnetic environment for partial discharge measurement and other purposes, thus ensuring the reliability of the test results.

[0008] The objective of this invention is achieved through the following technical solution: An ETG bushing electrical testing system includes a cylinder, with a connecting bushing at the upper end and an ETG test bushing at the lower end. The cylinder is filled with SF6 gas. The lower end of the connecting bushing and the upper end of the ETG test bushing are both placed inside the cylinder. The lower end of the connecting bushing is equipped with an equalizing ball, and the upper end of the ETG test bushing is equipped with a test bushing connector. A spring is provided on the upper end of the test bushing connector, which contacts the equalizing ball. The upper end of the connecting bushing is electrically connected to a test transformer, and the lower end of the ETG test bushing is inserted into an oil tank and electrically connected to a grounding electrode located inside the oil tank.

[0009] The equalizing ball includes an annular plate, and a connecting plate is provided inside the annular plate. The lower end of the connecting sleeve is connected to the connecting plate, and the spring is in contact with the connecting plate.

[0010] The annular plate has a support plate inside, and the support plate has a through hole for the lower end of the connecting sleeve to pass through.

[0011] The test sleeve connector includes a top post and a base. The top post has a spring groove at its upper end to accommodate the spring and its lower end is fixedly connected to the base. The base is fixedly connected to the upper end of the ETG test sleeve.

[0012] The base is fixed to the upper end of the ETG test sleeve by bolts. The base is provided with a connecting hole for bolt insertion. The upper end of the ETG test sleeve is provided with a connecting plate, and the connecting plate is provided with a threaded hole that mates with the bolt.

[0013] The cylinder has a top plate at the upper end and a bottom plate at the lower end. The connecting sleeve has a connecting flange that is sealed and fixed to the top plate. The ETG test sleeve has a sleeve flange that is sealed and fixed to the bottom plate.

[0014] The cylinder is equipped with a valve and a mounting port for a detection element.

[0015] The upper end of the connecting bushing is provided with a test transformer connection terminal and an upper equalizing ball, wherein the test transformer connection terminal is located in the upper equalizing ball and is electrically connected to the test transformer.

[0016] The ETG test sleeve has a terminal on one side that is electrically connected to the internal terminal screen, and the terminal screen is connected to the partial discharge instrument via a line.

[0017] The lower end of the ETG test sleeve is equipped with an electrical connector that is electrically connected to the grounding electrode inside the oil tank.

[0018] The advantages and positive effects of this invention are as follows: 1. This invention utilizes a cylinder filled with SF6 gas at the upper end of the ETG test bushing to simulate the GIS side environment of the bushing, and uses an oil tank at the lower end of the ETG test bushing to simulate the transformer side environment of the bushing, thereby meeting the test environment simulation requirements of the ETG test bushing.

[0019] 2. This invention moves the high-voltage connection point (i.e., the lower end of the connecting bushing) from the open arc zone to the interior of the SF6 gas insulating medium in the cylinder. Furthermore, this invention uses an equalizing ball to achieve shielding and equalizing of the connection point, and utilizes the elastic contact between the equalizing ball and the spring at the upper end of the test bushing connector to achieve electrical connection. This completely eliminates problems such as sharp corners and burrs at the connection point, suppressing corona discharge at the source and providing a clean background environment for high-precision partial discharge measurement. This greatly reduces the fluctuation of test data caused by connection method and external interference, making the test results of the same type of bushing at different times and locations more comparable and ensuring the reliability of the test results.

[0020] 3. This invention eliminates the need for bolting or winding to connect the equalizing ball to the ETG test sleeve. Once the ETG test sleeve is installed, the spring on the test sleeve connector automatically abuts against the connecting plate inside the equalizing ball to achieve sufficient compression, thereby ensuring the electrical connection between the equalizing ball and the test sleeve connector. This allows the invention to meet the needs of field testing where samples are frequently changed, thus improving testing efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention. Figure 2 for Figure 1 A schematic diagram of the structure of a medium-pressure ball. Figure 3 for Figure 1 A schematic diagram showing the connection between the intermediate sleeve connector and the ETG test sleeve.

[0022] Among them, 1 is the connecting bushing, 101 is the test transformer connecting terminal, 2 is the cylinder, 201 is the top plate, 202 is the bottom plate, 3 is the equalizing ball, 301 is the connecting plate, 302 is the support plate, 3021 is the through hole, 303 is the annular plate, 4 is the test bushing connector, 401 is the spring, 402 is the top column, 4021 is the spring groove, 403 is the seat, 4031 is the connecting hole, 5 is the ETG test bushing, 501 is the connecting plate, 502 is the end screen terminal, 503 is the electrical plug socket, and 504 is the bushing flange. Detailed Implementation

[0023] The invention will now be described in further detail with reference to the accompanying drawings.

[0024] like Figures 1-3 As shown, the present invention includes a cylinder 2, with a connecting sleeve 1 at the upper end and an ETG test sleeve 5 at the lower end. The cylinder 2 is filled with SF6 gas. The lower end of the connecting sleeve 1 and the upper end of the ETG test sleeve 5 are both located inside the cylinder 2. The lower end of the connecting sleeve 1 is provided with an equalizing ball 3, and the upper end of the ETG test sleeve 5 is provided with a test sleeve connector 4. The upper end of the test sleeve connector 4 is provided with a spring 401 that contacts the equalizing ball 3 to achieve electrical connection. The upper end of the connecting sleeve 1 is electrically connected to a test transformer, and the lower end of the ETG test sleeve 5 is inserted into an oil tank and electrically connected to a grounding electrode located inside the oil tank. The test transformer is a technology known in the art.

[0025] like Figures 2-3 As shown, in this embodiment, the equalizing ball 3 includes an annular plate 303, and a connecting plate 301 is provided inside the annular plate 303. The lower end of the connecting sleeve 1 is connected to the connecting plate 301, and the spring 401 is in contact with the connecting plate 301.

[0026] like Figure 2 As shown, in this embodiment, the annular plate 303 is provided with a support plate 302 inside, and the support plate 302 is provided with a through hole 3021 for the lower end of the connecting sleeve 1 to pass through.

[0027] like Figures 2-3 As shown, in this embodiment, the test sleeve connector 4 includes a top post 402 and a seat 403. The top post 402 has a spring groove 4021 at its upper end to accommodate the spring 401, and its lower end is integrally fixed to the seat 403. The seat 403 is fixedly connected to the upper end of the ETG test sleeve 5.

[0028] like Figure 3 As shown, in this embodiment, the base 403 is fixedly connected to the upper end of the ETG test sleeve 5 by bolts. The base 403 is provided with a connecting hole 4031 for bolt insertion. The upper end of the ETG test sleeve 5 is provided with a connecting plate 501, and the connecting plate 501 is provided with a threaded hole that mates with the bolt.

[0029] like Figure 1As shown in this embodiment, the cylinder 2 has a top plate 201 at the upper end and a bottom plate 202 at the lower end. The connecting sleeve 1 has a connecting flange that is sealed and fixed to the top plate 201. A first sealing element (such as a sealing ring) can be provided between the connecting flange and the top plate 201 as needed to ensure a seal. The ETG test sleeve 5 has a sleeve flange 504 that is sealed and fixed to the bottom plate 202. A second sealing element (such as a sealing ring) can be provided between the sleeve flange 504 and the bottom plate 202 as needed to ensure a seal.

[0030] like Figure 1 As shown in this embodiment, the cylinder 2 is provided with a gas valve and a detection element mounting port. The gas valve is used to connect to relevant pipelines for charging and discharging SF6 gas. The detection element mounting port can be threaded with corresponding detection elements, such as pressure gauges, as needed to ensure that the gas environment inside the cylinder 2 meets the test requirements.

[0031] like Figure 1 As shown, in this embodiment, the upper end of the connecting bushing 1 is provided with a test transformer connecting terminal 101 and an upper equalizing ball, wherein the test transformer connecting terminal 101 is disposed in the upper equalizing ball and is electrically connected to the test transformer. Furthermore, in this embodiment, the connecting bushing 1 is an oil-paper capacitor type bushing.

[0032] like Figure 1 As shown, in this embodiment, the ETG test sleeve 5 is provided with a terminal 502 that is electrically connected to the internal terminal screen on one side, and the terminal 502 is connected to a partial discharge instrument via a line to perform partial discharge detection. The partial discharge instrument is a commercially available product.

[0033] like Figure 1 As shown, in this embodiment, the lower end of the ETG test sleeve 5 is provided with an electrical connector 503 that is electrically connected to the grounding electrode inside the oil tank.

[0034] The working principle of this invention is as follows: During operation, the cylinder 2, filled with SF6 gas at the upper end of the ETG test bushing 5, simulates the GIS side environment of the bushing, while the oil tank at the lower end of the ETG test bushing 5 simulates the transformer side environment. Simultaneously, this invention moves the high-voltage connection point (i.e., the lower end of the connecting bushing 1) from the open arc zone to the SF6 gas insulating medium inside the cylinder 2. Furthermore, this invention uses an equalizing ball 3 in elastic contact with a spring 401 at the upper end of the test bushing connector 4, thus completely eliminating problems such as sharp corners and burrs at the connection point, suppressing corona discharge at its source, and providing a clean background environment for high-precision partial discharge measurement. In addition, this invention eliminates the need for bolt pressing or winding to connect the equalizing ball 3 to the test bushing connector 4. After the ETG test bushing 5 is installed, the spring 401 automatically abuts against the connecting plate 301 inside the equalizing ball 3, achieving sufficient compression, thereby ensuring the electrical connection between the equalizing ball 3 and the test bushing connector 4. Therefore, this invention can meet the needs of on-site testing with frequent sample changes, improving testing efficiency.

[0035] During the test of this invention, the high-voltage current is drawn from the test transformer to the top of the connecting bushing 1, and then conducted to the ETG test bushing 5 under test. The current loop is formed through the grounding electrode in the oil tank. In the entire high-voltage loop, all potential transition points are encased in SF6 gas, transformer oil, or solid insulating material, with no exposed sharp corners. This results in extremely low background noise during partial discharge measurements, enabling accurate evaluation of the bushing's insulation performance.

Claims

1. An ETG bushing electrical testing system, characterized in that: The cylinder (2) includes a connecting sleeve (1) at the upper end and an ETG test sleeve (5) at the lower end. The cylinder (2) is filled with SF6 gas. The lower end of the connecting sleeve (1) and the upper end of the ETG test sleeve (5) are both placed inside the cylinder (2). The lower end of the connecting sleeve (1) is provided with an equalizing ball (3), and the upper end of the ETG test sleeve (5) is provided with a test sleeve connector (4). The upper end of the test sleeve connector (4) is provided with a spring (401) that contacts the equalizing ball (3). The upper end of the connecting sleeve (1) is electrically connected to the test transformer, and the lower end of the ETG test sleeve (5) is inserted into the oil tank and electrically connected to the grounding electrode located in the oil tank. The equalizing ball (3) includes an annular plate (303), and a connecting plate (301) is provided inside the annular plate (303). The lower end of the connecting sleeve (1) is connected to the connecting plate (301), and the spring (401) is in contact with the connecting plate (301). The test sleeve connector (4) includes a top post (402) and a seat (403). The top post (402) has a spring groove (4021) at its upper end to accommodate the spring (401) and is fixedly connected to the seat (403) at its lower end. The seat (403) is fixedly connected to the upper end of the ETG test sleeve (5). The cylinder (2) has a top plate (201) at the upper end and a bottom plate (202) at the lower end. The connecting sleeve (1) has a connecting flange that is sealed and fixed to the top plate (201). The ETG test sleeve (5) has a sleeve flange (504) that is sealed and fixed to the bottom plate (202). The upper end of the ETG test bushing (5) is filled with SF6 gas cylinder (2) to simulate the GIS side environment, and the lower end of the ETG test bushing (5) is filled with oil tank to simulate the transformer side environment. High-voltage current is drawn from the test transformer to the top of the connecting bushing (1), and then conducted to the ETG test bushing (5) to be tested. The current loop is formed through the grounding electrode in the oil tank.

2. The ETG bushing electrical testing system according to claim 1, characterized in that: The annular plate (303) has a support plate (302) inside, and the support plate (302) has a through hole (3021) for the lower end of the connecting sleeve (1) to pass through.

3. The ETG bushing electrical testing system according to claim 1, characterized in that: The base (403) is fixed to the upper end of the ETG test sleeve (5) by bolts. The base (403) is provided with a connecting hole (4031) for bolt insertion. The upper end of the ETG test sleeve (5) is provided with a connecting plate (501) and the connecting plate (501) is provided with a threaded hole that mates with the bolt.

4. The ETG bushing electrical testing system according to claim 1, characterized in that: The cylinder (2) is equipped with a valve and a detection element mounting port.

5. The ETG bushing electrical testing system according to claim 1, characterized in that: The upper end of the connecting sleeve (1) is provided with a test transformer connecting terminal (101) and an upper equalizing ball, wherein the test transformer connecting terminal (101) is located in the upper equalizing ball and is electrically connected to the test transformer.

6. The ETG bushing electrical testing system according to claim 1, characterized in that: The ETG test sleeve (5) has a terminal (502) on one side that is electrically connected to the internal terminal screen, and the terminal (502) is connected to the partial discharge instrument via a line.

7. The ETG bushing electrical testing system according to claim 1, characterized in that: The lower end of the ETG test sleeve (5) is provided with an electrical connector (503) that is electrically connected to the grounding electrode inside the oil tank.

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