Test device and method for electrically conductive rod and voltage equalizing ball of high voltage outgoing terminal of transformer

Abstract

The application discloses a test device and method for a conductive rod and a voltage-sharing ball of a high-voltage outgoing terminal of a transformer, and the test device comprises a test shell and an inner support frame, the inner support frame is arranged at an inner wall of the test shell, and the inner support frame is used for mounting the conductive rod. A top mounting hole is formed in the top of the test shell and is used for inserting a bushing of the high-voltage outgoing terminal. The test shell is provided with a detachable end cover, and the end cover forms an operation opening after being opened. The test shell is also provided with a vacuum extraction valve and an oil inlet and outlet valve. According to the scheme, the conductive rod and the voltage-sharing ball are separated from the transformer body, and independent special tests are carried out in a closed oil-immersed space simulating a real electric field environment, so that the industry problem that the conductive rod and the voltage-sharing ball are not included in the verification range in the factory test stage and the local discharge risk cannot be found in advance is effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of transformer equipment technology, and relates to a test device and method for the conductive rod and equalizing ball at the high voltage lead-out end of a transformer. Background Technology

[0002] The high-voltage lead-out structure of a transformer consists of the transformer body winding leads, bushings, conductive rods, and external connecting components connected in sequence. The bushings serve as insulation channels, with conductive rods running through them. An equalizing ball is positioned at the end of the conductive rod closest to the transformer body, extending into the oil chamber inside the transformer tank during actual installation. Both the conductive rods and the equalizing ball constitute the critical connection area of ​​the high-voltage lead-out terminal, and their electric field distribution characteristics directly affect the insulation reliability of the transformer.

[0003] In transformer factory testing, partial discharge tests are typically performed only on the transformer body. For transformers with oil-to-oil bushing lead-out structures, the conductive rod and equipotential bonding ball are often not installed on the transformer body during actual factory testing, and the test circuit does not include these components. Furthermore, the industry lacks specific testing methods for the conductive rod and equipotential bonding ball under actual assembly electric field conditions. Therefore, existing partial discharge tests can only verify the insulation status of the transformer body and cannot obtain the discharge characteristics of the conductive rod and equipotential bonding ball under actual operating electric field conditions.

[0004] Because the conductive rod and equipotential bonding ball were not included in the verification scope during the factory testing phase, the risk of partial discharge in this area under actual operating conditions cannot be detected and eliminated in advance. After the transformer is put into operation, if partial discharge occurs in this area due to concentrated electric field, the characteristic gases generated by the discharge will directly enter the transformer oil, leading to abnormalities in the dissolved gas analysis of the oil. Since the discharge site is located in the internal oil region of the transformer, its characteristics are difficult to distinguish from the insulation fault of the transformer itself, making fault location and cause analysis difficult and threatening the safe and stable operation of the transformer. Therefore, there is an urgent need for a verification scheme that can conduct specialized tests on the connected conductive rod and equipotential bonding ball to fill the blind spots of existing testing methods. Summary of the Invention

[0005] The purpose of this invention is to provide a test device and method for the conductive rod and equalizing ball at the high voltage lead of a transformer, so as to solve the technical problem that the existing technology cannot test the conductive rod and equalizing ball separately.

[0006] To achieve the above objectives, the specific technical solution provided by the present invention is as follows.

[0007] A testing device for a conductive rod and equalizing ball at the high-voltage lead of a transformer includes a test housing and an inner support frame. The inner support frame is disposed on the inner wall of the test housing and is used to install the conductive rod. A top mounting hole is provided on the top of the test housing for inserting a bushing at the high-voltage lead of the transformer. The test housing has a detachable end cover, which forms an operating port when opened. The test housing is also equipped with a vacuum valve and an oil inlet / outlet valve.

[0008] Furthermore, the test housing includes a vertical cylinder and a horizontal cylinder, the lower end of the vertical cylinder has a horizontal connecting section, and the horizontal cylinder is detachably connected to the horizontal connecting section; the end cap is provided at the end of the horizontal cylinder away from the vertical cylinder.

[0009] Furthermore, the inner support frame includes two support components, which are sequentially disposed along the horizontal direction at the inner wall of the horizontal connecting section and the horizontal cylinder.

[0010] Furthermore, each of the support components includes four mounting blocks, two vertical mounting rods, a bottom mounting plate, and a top mounting plate; the four mounting blocks are evenly distributed along the circumference of the horizontal connecting section or the horizontal cylinder at corresponding inner walls, and the two ends of each vertical mounting rod are connected to the corresponding two mounting blocks; the bottom mounting plate is horizontally disposed between the two vertical mounting rods, and the top mounting plate is detachably disposed on the top of the bottom mounting plate; the two adjacent sides of the bottom mounting plate and the top mounting plate are provided with arc-shaped mounting grooves for mounting the conductive rods.

[0011] Furthermore, the top mounting plate and the bottom mounting plate are detachably connected by bolts or cable ties.

[0012] Furthermore, the oil inlet / outlet valve is located at the lower part of the horizontal cylinder at the end away from the vertical cylinder.

[0013] Furthermore, the vertical cylinder includes a cylinder body and a detachable top cover disposed on the top of the cylinder body, and the top mounting hole is disposed on the top cover; the top cover is provided with a plurality of bolt holes evenly distributed outside the top mounting hole for the installation of the sleeve.

[0014] Furthermore, the test device for the conductive rod and equalizing ball at the high-voltage lead of the transformer also includes an external support frame, which includes multiple inclined support rods, which are arranged along the circumference of the vertical cylinder on its outer wall.

[0015] Furthermore, the test device for the conductive rod and equalizing ball at the high-voltage lead of the transformer also includes a wire, the two ends of which are used to connect the conductive rod and the bushing.

[0016] The present invention also provides a test method using a test apparatus for a transformer high-voltage lead-out terminal with a conductive rod and an equalizing ball as described in any of the above claims, comprising the following steps: The bushing at the high-voltage lead of the transformer is installed onto the test housing through the top mounting hole; Install the conductive rod on the inner support frame and make the conductive rod electrically connected to the sleeve; install the equalizing ball at the end of the conductive rod away from the sleeve. The test housing is evacuated to a preset vacuum level using a vacuum valve, and then oil is injected into the test housing to a preset height using an oil inlet / outlet valve. A preset voltage is applied through the bushing, and the conductivity rod and equalizing ball are judged to be qualified based on the voltage change and transformer oil chromatography analysis.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The testing apparatus of this invention, by providing a detachable end cover, a top mounting hole, a vacuum valve, and oil inlet / outlet valves on the test housing, enables the separation of the conductive rod and equalizing ball from the transformer body. This allows for independent, specialized testing within a closed oil-immersed space simulating a real electric field environment. This effectively solves the industry problem in existing technologies where the conductive rod and equalizing ball are not included in the verification scope during factory testing, and the risk of partial discharge cannot be detected in advance. This testing apparatus allows for the early screening and elimination of defective products, preventing problems such as abnormal oil chromatography and difficulty in fault location caused by characteristic gases generated by discharge entering the transformer oil after commissioning. Simultaneously, the operating port formed by the end cover facilitates component loading and unloading, the top mounting hole facilitates bushing installation, and the vacuum and oil injection functions ensure that the test conditions are consistent with the transformer body. Furthermore, the testing apparatus is independent of the transformer body and can be operated independently, reducing testing costs and time, and providing a reliable pre-factory screening method for the safe and stable operation of transformers. Attached Figure Description

[0018] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. In the drawings: Figure 1 This is a front view of the test apparatus for the conductive rod and equalizing ball at the high-voltage lead end of the transformer according to the present invention. Figure 2 This is a top view of the test apparatus for the conductive rod and equalizing ball at the high-voltage lead end of the transformer according to the present invention. Figure 3 for Figure 2 View from point A in the middle.

[0019] Figure label: 1. Test shell; 11. End cap; 12. Vertical cylinder; 13. Horizontal cylinder; 2. Inner support frame; 21. Mounting block; 22. Vertical mounting rod; 23. Bottom mounting plate; 24. Top mounting plate; 3. Vacuum valve; 4. Oil inlet / outlet valve; 5. Outer support frame; 51. Diagonal support rod; 6. Wire; 7. Sleeve; 8. Conductive rod; 9. Equalizing ball. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] like Figure 1 , Figure 2 As shown, this invention provides a test device for the conductive rod and equalizing ball at the high-voltage lead of a transformer, including a test housing 1 and an inner support frame 2. The inner support frame 2 is located on the inner wall of the test housing 1 and is used to install the conductive rod 8. A top mounting hole is provided on the top of the test housing 1 for inserting the bushing 7 at the high-voltage lead of the transformer, and the bushing 7 is sealed to the top mounting hole. The test housing 1 has a detachable end cap 11, which forms an operating port when opened. The test housing 1 is also equipped with a vacuum valve 3 and an oil inlet / outlet valve 4. The bushing 7 used in this invention can be an oil-to-oil bushing or an oil-to-air bushing, and its main function is to connect to the high-voltage power supply.

[0023] The working principle of the test device for the conductive rod and equalizing ball at the high-voltage lead end of the transformer in this embodiment of the invention is as follows: First, the bushing 7 at the high-voltage lead end of the transformer is passed through the top mounting hole from the outside of the test housing 1, so that the lower end of the bushing 7 extends into the interior of the test housing 1, and the bushing 7 is sealed to the top mounting hole. Second, the detachable end cap 11 at the end of the test housing 1 is opened. The opening exposed after the end cap 11 is opened is the operating port. The conductive rod 8 to be tested is sent into the interior of the test housing 1 through the operating port, placed on the inner support frame 2 and tightened. Then, the lower end of the bushing 7 is electrically connected to one end of the conductive rod 8 through the wire 6 or by direct connection. Then, the equalizing ball 9 is fixedly connected to the other end of the conductive rod 8. After installation, the end cap 11 is tightened and sealed to ensure the oil tightness and air tightness of the entire test housing 1. Finally, an external vacuum pump is connected via vacuum valve 3 to evacuate the interior of test housing 1 to remove internal air and moisture. After reaching the preset vacuum level, strictly treated high-voltage transformer oil is injected into test housing 1 through oil inlet / outlet valves 4 until the oil level covers all high-voltage live parts and reaches the preset height. After oil injection, high voltage can be applied to conductive rod 8 and equalizing ball 9 through bushing 7 to conduct partial discharge and withstand voltage tests.

[0024] The testing device of this invention, by providing a detachable end cover 11, a top mounting hole, a vacuum valve 3, and oil inlet / outlet valves 4 on the test housing 1, enables the separation of the conductive rod 8 and the equalizing ball 9 from the transformer body. This allows for independent, specialized testing within a closed oil-immersed space simulating a real electric field environment. This effectively solves the industry problem in existing technologies where the conductive rod 8 and equalizing ball 9 are not included in the verification scope during the factory testing phase, and the risk of partial discharge cannot be detected in advance. This testing device allows for the early screening and elimination of substandard products, preventing problems such as abnormal oil chromatography and difficulty in fault location caused by characteristic gases generated by discharge entering the transformer oil after commissioning. Simultaneously, the operating port formed by the end cover 11 facilitates component loading and unloading, the top mounting hole facilitates the installation of the bushing 7, and the vacuum and oil injection functions ensure that the test conditions are consistent with the transformer body. Furthermore, the testing device is independent of the transformer body and can be operated independently, reducing testing costs and time, and providing a reliable pre-factory screening method for the safe and stable operation of transformers.

[0025] In some embodiments of the present invention, such as Figure 1 , Figure 2 As shown, the test housing 1 includes a vertical cylinder 12 and a horizontal cylinder 13. The lower end of the vertical cylinder 12 has a horizontal connecting section, and the horizontal cylinder 13 is detachably connected to the horizontal connecting section. The end cap 11 is located at the end of the horizontal cylinder 13 away from the vertical cylinder 12.

[0026] In this embodiment, the vertical cylinder 12 is dedicated to the vertical installation of the sleeve 7, and the horizontal cylinder 13 is dedicated to the horizontal installation of the conductive rod 8. The clear functional division of the two allows for smooth insertion of the conductive rod 8 during assembly, eliminating the need for repeated alignment adjustments at bends and greatly facilitating the loading and unloading of long conductive rods 8. The horizontal connecting section at the lower end of the vertical cylinder 12 facilitates a detachable connection with the horizontal cylinder 13. The vertical cylinder 12 and the horizontal cylinder 13 can be processed, transported, and maintained separately, reducing overall manufacturing difficulty and maintenance costs. Furthermore, when different specifications of sleeve 7 need to be adapted, only the vertical cylinder 12 needs to be replaced without modifying the horizontal cylinder 13, improving the interchangeability of components. Furthermore, compared to designing the entire shell as a single vertical cylinder 12 or an integral L-shaped cast structure, this device adopts a combination of a split vertical cylinder 12 and a horizontal cylinder 13, which makes the center of gravity of the entire test device significantly lower and closer to the support surface of the horizontal cylinder 13. This effectively enhances the device's anti-tipping stability under vacuum and oil injection conditions, reduces the need for an additional external support frame 5, and improves the safety and convenience of test operations.

[0027] In some embodiments of the present invention, such as Figure 1 As shown, the inner support frame 2 includes two support components, which are arranged sequentially along the horizontal direction at the inner wall of the horizontal connecting section and the horizontal cylinder 13.

[0028] In this embodiment, two support components are respectively installed at predetermined positions on the horizontal connecting section and the inner wall of the horizontal cylinder 13. During installation, the spacing between the two support components is determined according to the total length of the conductive rod 8. The two support components include a first support component and a second support component. The first support component is fixed near the bend in the horizontal connecting section to support the inner end of the conductive rod 8 (near the sleeve 7 side); the second support component is fixed near the end cap 11 on the inner wall of the horizontal cylinder 13 to support the outer end of the conductive rod 8 (near the equalizing ball 9 side). When installing the conductive rod 8, one end of the conductive rod 8 is first supported by the first support component, then the horizontal cylinder 13 is connected to the vertical cylinder 12, and then the other end of the conductive rod 8 is supported by the second support component. After the conductive rod 8 is fixed, its weight is evenly transmitted to the test housing 1 through the two support components.

[0029] This embodiment provides balanced support for the conductive rod 8 by setting two support components spaced apart in the horizontal direction, which effectively prevents the conductive rod 8 from bending or shifting under the action of gravity, oil pressure fluctuation or vibration, and ensures the installation accuracy of the conductive rod 8.

[0030] In some embodiments of the present invention, such as Figure 3As shown, each support assembly includes four mounting blocks 21, two vertical mounting rods 22, a bottom mounting plate 23, and a top mounting plate 24. The four mounting blocks 21 are evenly distributed along the circumference of the horizontal connecting section or the horizontal cylinder 13 at corresponding inner walls. Each vertical mounting rod 22 is connected at both ends to two corresponding mounting blocks 21. The bottom mounting plate 23 is horizontally positioned between the two vertical mounting rods 22, and the top mounting plate 24 is detachably mounted on top of the bottom mounting plate 23. Both the bottom mounting plate 23 and the top mounting plate 24 have arc-shaped mounting grooves on their adjacent sides for mounting the conductive rods 8.

[0031] In this embodiment, at each installation position of the support component, four mounting blocks 21 are fixed to the inner wall of the corresponding cylinder in a circumferentially evenly distributed manner. The four mounting blocks 21 are divided into upper and lower pairs. Two vertical mounting rods 22 are passed through the corresponding upper and lower mounting blocks 21 and locked in place to form two parallel vertical columns. The bottom mounting plate 23 is horizontally fixed between the two vertical mounting rods 22, and an arc-shaped mounting groove is provided on its upper part to support the lower half of the conductive rod 8. After the conductive rod 8 is placed in, the top mounting plate 24 is placed on top, and its lower surface is also provided with an arc-shaped mounting groove. The upper and lower grooves form a circular clamping hole that matches the outer diameter of the conductive rod 8. Finally, the top mounting plate 24 and the bottom mounting plate 23 are fixed.

[0032] In this embodiment, an arc-shaped mounting groove is used to form a surface contact with the outer wall of the conductive rod 8, avoiding damage to the insulation layer caused by point contact. The four mounting blocks 21 are evenly arranged circumferentially to ensure the verticality and uniform force distribution of the vertical mounting rod 22. Different diameter conductive rods 8 can be adapted by replacing mounting plates with different apertures, providing good interchangeability and flexibility.

[0033] In some embodiments of the present invention, the top mounting plate 24 and the bottom mounting plate 23 are detachably connected by bolts or strapping.

[0034] In this embodiment, when using bolted connections, the bolts are passed through the through holes of the top mounting plate 24 and screwed into the threaded holes of the bottom mounting plate 23, or passed through both through holes and then tightened with nuts. By controlling the tightening torque, the clamping force is moderate, ensuring reliable fixation without damaging the insulation layer. When using cable ties for connections, high-strength insulating cable ties are wrapped around the bottom mounting plate 23 and the top mounting plate 24 and the buckles are tightened, using pre-tension to achieve a close and fixed fit between the two.

[0035] This embodiment utilizes bolted connections for reliable fastening and controllable torque, making it suitable for high-pressure testing conditions. The strapping connection is quick, tool-free, and produces no metal debris, making it suitable for clean, insulated assembly environments. Furthermore, the strapping is made of insulating material and does not interfere with the electric field distribution. Both methods allow for quick disassembly, facilitating the replacement and repeated assembly / disassembly of the conductive rod 8 without causing scratches or permanent deformation.

[0036] In some embodiments of the present invention, such as Figure 1 As shown, the inlet / outlet oil valve 4 is located at the lower part of the horizontal cylinder 13, away from the vertical cylinder 12.

[0037] In this embodiment, during oil injection, the oil filter outlet pipe is connected to the inlet / outlet valve 4. Hot oil is slowly injected from the low inlet, steadily rising from the bottom, gradually submerging the conductive rod 8 and the equalizing ball 9, and filling the entire L-shaped cavity. A vent plug can be installed on the top of the test housing 1 and kept open to release residual gas. During oil discharge, the inlet / outlet valve 4 is in the lowest position, allowing most of the oil to flow out smoothly using gravity.

[0038] In this embodiment, the inlet / outlet valve 4 is located at the lowest point of the entire test housing 1. During oil injection, it forms a stable laminar flow, reducing air bubble entrainment and impact on the insulation layer, and preventing cavitation at the L-shaped bend of the test housing 1. During oil drainage, it achieves maximum evacuation, facilitating subsequent disassembly and cleaning. At the same time, the inlet / outlet valve 4 is far from the bushing 7, avoiding interference with the high-voltage electric field distribution and improving test accuracy.

[0039] In some embodiments of the present invention, the vertical cylinder 12 includes a cylinder body and a top cover detachably disposed on the top of the cylinder body, with a top mounting hole disposed on the top cover. The top cover has a plurality of bolt holes evenly distributed outside the top mounting hole for mounting the sleeve 7.

[0040] In this embodiment, a flange can be provided at the top opening of the cylinder body, and the top cover is detachably and sealingly connected to the flange by bolts. A top mounting hole is provided in the center of the top cover, the diameter of which matches the outer diameter of the mounting flange of the sleeve 7. Multiple bolt holes are evenly distributed circumferentially around the outer side of the top mounting hole, the diameter of the distribution circle and the hole spacing matching the flange mounting holes of the sleeve 7 to be installed. During installation, the flange of the sleeve 7 is aligned with the bolt holes of the top cover, a sealing gasket is placed, and then it is tightened with bolts. When replacing sleeves 7 of different specifications, only the corresponding top cover needs to be replaced.

[0041] This embodiment features a separate design for the top cover and the main body of the cylinder. By replacing different top covers, various models of sleeves 7 can be accommodated, greatly expanding the applicability of the device and reducing the equipment investment cost for multi-variety testing. Evenly distributed bolt holes ensure the verticality and concentricity of the sleeves 7 after installation, guaranteeing the symmetry of the electric field at the high-voltage inlet, making the test results more accurate and reliable. The removable top cover also facilitates cleaning and inspection of the interior of the vertical cylinder 12.

[0042] In some embodiments of the present invention, such as Figure 1 , Figure 2 As shown, the test device for the conductive rod and equalizing ball at the high voltage lead of the transformer also includes an outer support frame 5. The outer support frame 5 includes multiple inclined support rods 51, which are arranged along the circumference of the vertical cylinder 12 on its outer wall.

[0043] In this embodiment, multiple inclined support rods 51 are fixed circumferentially to the outer wall of the vertical cylinder 12. Their upper ends are fixed to the reinforcing ring on the outer wall of the vertical cylinder 12, and their lower ends extend outwards and support the ground. During installation, each inclined support rod 51 is adjusted to ensure even force distribution and is fixed to the ground using anchor bolts. During vacuuming, the shell bears external pressure; after oil injection, it bears internal pressure; and under high voltage, electrodynamic forces may be generated. These loads are all distributed and transmitted to the ground through the inclined support rods 51.

[0044] This embodiment uses multiple diagonal support rods 51 arranged circumferentially to form a stable triangular support structure, effectively enhancing the overturning resistance and structural rigidity of the vertical cylinder 12. This is particularly beneficial for the L-shaped structure's inherent center of gravity shift, preventing tilting or displacement during testing. Simultaneously, it improves resistance to external pressure instability under vacuum conditions, ensuring structural safety under high vacuum levels, and allowing for appropriate reduction in shell wall thickness, thus lowering manufacturing costs and weight.

[0045] In some embodiments of the present invention, such as Figure 1 As shown, the test device for the conductive rod and equalizing ball at the high voltage lead of the transformer also includes a wire 6, the two ends of which are used to connect the conductive rod 8 and the bushing 7.

[0046] In this embodiment, after the conductive rod 8 and the sleeve 7 are installed in place, a flexible wire 6 of appropriate length and cross-sectional area is selected according to the actual distance and angle between them. One end is connected to the lower terminal of the sleeve 7, and the other end is connected to the terminal of the conductive rod 8, and fixed by bolts or crimping. The routing of the wire 6 should ensure that no corona discharge occurs under the test voltage, and maintain sufficient insulation distance from the inner wall of the housing and the grounding components. When high voltage is applied, the voltage sequentially passes through the central conductor of the sleeve 7, the wire 6, and the conductive rod 8 to the equalizing sphere 9, forming a complete test circuit.

[0047] This embodiment compensates for installation alignment errors and distance deviations between the conductive rod 8 and the sleeve 7 by using a flexible conductor 6, eliminating assembly stress caused by rigid connections and avoiding mechanical damage to the terminals. The length and cross-sectional area of ​​the conductor 6 can be selected as needed, flexibly adapting to combinations of different specifications of sleeves 7 and conductive rods 8 of different lengths, further enhancing the versatility and engineering practicality of the device.

[0048] This invention also provides a test method for the conductive rod and equalizing ball at the high-voltage lead of a transformer, comprising the following steps: Step S1: Install the bushing 7 of the high voltage lead-out end of the transformer onto the test housing 1 through the top mounting hole.

[0049] Step S2: Install the conductive rod 8 on the inner support frame 2 and make the conductive rod 8 electrically connected to the sleeve 7. Install the equalizing ball 9 at the end of the conductive rod 8 away from the sleeve 7.

[0050] Step S3: Vacuum the test housing 1 to the preset vacuum level through the vacuum valve 3, and inject oil into the test housing 1 to the preset height through the oil inlet / outlet valve 4.

[0051] Step S4: Apply a preset voltage through bushing 7, and determine whether the conductive rod 8 and equalizing ball 9 are qualified based on the voltage change and transformer oil chromatography analysis.

[0052] In step S1, select the matching sleeve 7, check that the appearance and sealing surface are correct, align the mounting flange on the sleeve 7 with the top mounting hole of the test housing 1, place the sealing gasket and tighten it with bolts, and the conductive terminal at the lower end of the sleeve 7 extends into the interior of the test housing 1.

[0053] In step S2, open the end cap 11 to expose the operating port, install the conductive rod 8 on the inner support frame 2, so that the conductive rod 8 is electrically connected to the sleeve 7, fix the equalizing ball 9 to the end of the conductive rod 8 away from the sleeve 7 through the operating port, then seal the end cap 11 and check all sealing surfaces.

[0054] In step S3, close the inlet and outlet oil valves 4, open the vacuum valve 3 and connect the vacuum pump, evacuate to below 100 Pa and maintain for 6 hours to fully remove the gas and moisture adsorbed on the insulating material and the inner wall of the casing. After the vacuuming is completed, connect the oil filter outlet pipe to the inlet and outlet oil valves 4, and inject the preheated and degassed transformer oil at a flow rate of no more than 3 tons / hour until the oil reaches 200 mm from the top of the casing. Close the valve and release the residual gas through the vent plug.

[0055] In step S4, the high-voltage test power supply is connected to the top terminal of bushing 7. A withstand voltage is applied and maintained for the specified time according to GB / T 16927.1 and GB / T1094.3, and the test voltage and partial discharge signal are continuously monitored. If there is no sudden drop in voltage and no destructive discharge, the withstand voltage performance is qualified. After the test, an oil sample is taken from the sampling valve for chromatographic analysis. If there are no discharge characteristic gases such as acetylene and ethylene, and no significant increase in total hydrocarbons, the insulation coordination and internal cleanliness are qualified. If both are qualified, the conductive rod 8 and the equalizing ball 9 are deemed qualified and can be reinstalled in the transformer body.

[0056] This invention provides a complete and standardized testing method that enables independent verification of the conductive rod 8 and the equalizing ball 9 under a simulated actual oil-immersed electric field. Through rigorous vacuuming and oil injection, interference from moisture and gas in the insulation is eliminated. Withstand voltage and partial discharge detection effectively screen for substandard components with processing defects or potential electric field concentration hazards. Oil chromatography analysis further confirms the insulation stability. This method fills the inspection blind spot for the conductive rod 8 and equalizing ball 9 in transformer factory testing. It is independent of the transformer itself, has a short testing cycle, low cost, and can be operated in parallel, making it suitable for batch application in quality control as a pre-factory screening method.

[0057] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including disclosures in patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0058] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A test apparatus for a conductive rod and equalizing ball at the high-voltage lead of a transformer, characterized in that, The test housing (1) includes an inner support frame (2), which is located on the inner wall of the test housing (1) and is used to install a conductive rod (8). The test housing (1) has a top mounting hole for inserting a bushing (7) of the high voltage lead-out end of the transformer. The test housing (1) has a detachable end cover (11), which forms an operating port when opened. The test housing (1) is also equipped with a vacuum valve (3) and an oil inlet / outlet valve (4).

2. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead end of the transformer according to claim 1, characterized in that, The test housing (1) includes a vertical cylinder (12) and a horizontal cylinder (13). The lower end of the vertical cylinder (12) has a horizontal connecting section, and the horizontal cylinder (13) is detachably connected to the horizontal connecting section. The end cap (11) is located at the end of the horizontal cylinder (13) away from the vertical cylinder (12).

3. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 2, characterized in that, The inner support frame (2) includes two support components, which are arranged sequentially along the horizontal direction at the inner wall of the horizontal connecting section and the horizontal cylinder (13).

4. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 3, characterized in that, Each of the support components includes four mounting blocks (21), two vertical mounting rods (22), a bottom mounting plate (23), and a top mounting plate (24); the four mounting blocks (21) are evenly arranged on the corresponding inner wall along the circumference of the horizontal connecting section or the horizontal cylinder (13), and the two ends of each vertical mounting rod (22) are connected to the corresponding two mounting blocks (21); the bottom mounting plate (23) is horizontally arranged between the two vertical mounting rods (22), and the top mounting plate (24) is detachably arranged on the top of the bottom mounting plate (23); the two adjacent sides of the bottom mounting plate (23) and the top mounting plate (24) are provided with arc-shaped mounting grooves for mounting the conductive rod (8).

5. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 4, characterized in that, The top mounting plate (24) and the bottom mounting plate (23) are detachably connected by bolts or strapping.

6. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 2, characterized in that, The inlet / outlet valve (4) is located at the lower part of the horizontal cylinder (13) away from the vertical cylinder (12).

7. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 2, characterized in that, The vertical cylinder (12) includes a cylinder body and a detachable top cover located on the top of the cylinder body. The top mounting hole is located on the top cover. The top cover has multiple bolt holes evenly distributed outside the top mounting hole for the installation of the sleeve (7).

8. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 2, characterized in that, It also includes an outer support frame (5), which includes a plurality of inclined support rods (51), which are arranged along the circumference of the vertical cylinder (12) on its outer wall.

9. The test apparatus for the conductive rod and equalizing ball at the high-voltage lead of the transformer according to claim 1, characterized in that, It also includes a wire (6), the two ends of which are used to connect the conductive rod (8) and the sleeve (7).

10. A test method for a test apparatus using the conductive rod and equalizing ball at the high-voltage lead-out end of a transformer as described in any one of claims 1 to 9, characterized in that, Includes the following steps: The bushing (7) of the high voltage lead-out end of the transformer is installed on the test housing (1) through the top mounting hole; Install the conductive rod (8) on the inner support frame (2) and make the conductive rod (8) electrically connected to the sleeve (7). Install the equalizing ball (9) at the end of the conductive rod (8) away from the sleeve (7). The test housing (1) is evacuated to a preset vacuum level by the vacuum valve (3), and oil is injected into the test housing (1) to a preset height by the oil inlet / outlet valve (4); A preset voltage is applied through the bushing (7), and the conductor rod (8) and equalizing ball (9) are judged to be qualified based on the voltage change and transformer oil chromatography analysis.

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