An external withstand voltage test device for a power transformer

Abstract

This invention belongs to the field of transformer withstand voltage testing technology, specifically an external withstand voltage testing device for power transformers. It includes a support plate with casters installed at the four corners of its lower end face. A base is installed on the upper end face of the support plate, and a limiting seat is fixedly connected to the upper end face of the base. A resistance tube is installed inside the limiting seat, and a protective shell is installed outside the resistance tube. Fastening bolts are rotatably connected to the upper end face of the protective shell at the four corners, and these fastening bolts are threadedly connected to the base. An adjustment component is provided outside the resistance tube to address the issue that power must be disconnected for each adjustment. If the metal contacts and resistance wire are adjusted directly without power, friction between the metal contacts and the resistance wire will generate high temperatures, accelerating the breakage of the resistance wire. While adjusting with power off increases the lifespan of the resistance wire and metal contacts, prolonged friction between the metal contacts and the resistance wire can still lead to poor contact and unstable resistance values.

Description

Technical Field

[0001] This invention belongs to the field of transformer withstand voltage testing technology, specifically an external withstand voltage testing device for power transformers. Background Technology

[0002] In the manufacturing and maintenance of power transformers, the external withstand voltage test is an important step to ensure the quality and safety of the transformer. Currently, the existing external withstand voltage test equipment for power transformers usually includes an adjustable voltage source and a resistor box connected to it. By adjusting the resistance value of the resistor box, the voltage applied to the transformer is changed, thereby achieving the test purpose.

[0003] A patent with publication number CN116736056B discloses an external withstand voltage test device for a power transformer. This patent uses a power mechanism to drive a transmission mechanism, causing a slider to slide. This, in turn, causes a lever to slide against the outer wall of a resistance tube, changing the resistance value of the tube and thus controlling the test device to apply voltage to the transformer. The included slide rail enhances the stability of the slider during sliding, making the test more accurate. A spring mechanism pushes the lever to keep it firmly against the resistance tube, preventing it from loosening and separating from the tube, which could lead to inaccurate test data. The included detection device applies pressure to the transformer, enabling a pressure test.

[0004] The above-mentioned solutions still have some problems in practical applications. Fixed or adjustable resistors are usually used to conduct withstand voltage tests on transformers. However, fixed resistors have a fixed resistance value and cannot adapt to the test requirements of different voltage levels. Although adjustable resistors can adapt to different voltage levels by adjusting their resistance value, each adjustment requires power off and then controlling the contact between the metal contacts and the resistance wire to change the resistance value. If the adjustment is performed without power off, the contact between the metal contacts and the resistance wire will rub against each other and generate high temperatures due to voltage, which will accelerate the breakage and damage of the resistance wire. When the contact position between the metal contacts and the resistance wire is adjusted with power off, the metal contacts and the resistance wire are in close contact. After a long period of use, the adjustment will also wear down due to friction, resulting in poor contact and unstable resistance value, which will affect the accuracy of the test results.

[0005] Therefore, the present invention provides an external withstand voltage test device for power transformers. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by the present invention to solve its technical problem is as follows: The present invention provides an external withstand voltage test device for a power transformer, comprising a support plate, universal wheels installed at the four corners of the lower end face of the support plate, a base installed on the upper end face of the support plate, a limiting seat fixedly connected to the upper end face of the base, a resistance tube installed in the inner cavity of the limiting seat, a protective shell installed on the outside of the resistance tube, fastening bolts rotatably connected to the upper end face of the protective shell at the four corners, and the fastening bolts being threadedly connected to the base, and an adjustment component provided on the outside of the resistance tube;

[0008] Furthermore, the adjustment assembly includes two threaded rods rotatably connected to the inner cavity of the protective housing, and the two threaded rods are externally threaded to a sliding frame for driving the sliding frame to move up and down within the inner cavity of the protective housing to adjust its position.

[0009] The sliding frame has two mounting plates symmetrically installed on its inner wall, and each of the two mounting plates has a sliding column slidably connected inside. One end of each sliding column is fixed with a lever, which is used to drive the sliding column to make the lever contact with the resistor tube.

[0010] Preferably, a transmission groove is formed inside the upper end face of the protective shell, and one end of the two threaded rods passes through the protective shell and is fixedly connected to a second bevel gear in the inner cavity of the transmission groove. The second bevel gear meshes with a first bevel gear, and a transmission shaft is fixedly connected inside the first bevel gear. The transmission shaft is rotatably connected to the inner wall of the transmission groove.

[0011] Preferably, a crank handle is rotatably connected to the upper end face of the protective housing. One end of the crank handle passes through the protective housing and is fixedly connected to a transmission bevel gear in the inner cavity of the transmission groove. The transmission bevel gear meshes with a driven bevel gear, and the driven bevel gear is fixed to the outside of the transmission shaft for driving the transmission shaft to rotate.

[0012] Preferably, the sliding frame has through slots on both sides, a first spring is fixedly connected to one end face of the mounting plate, and the first spring slides in the cavity of the through slot. A stop block is fixedly connected to one end of the first spring, and the stop block is fixedly connected to one end of the sliding column.

[0013] Preferably, two corrugated blocks are symmetrically fixed to the two walls of the inner cavity of the protective shell, and the abutment block is slidably connected to the corrugated blocks to drive the lever to abut against the resistor tube for the transformer external withstand voltage test. The protective shell is made of insulating wood material. Multiple cross-shaped through slots are evenly opened at the front and rear ends of the protective shell, and a scale slot is opened on one side of the cross-shaped through slots at the front and rear ends of the protective shell to display the voltage adjustment.

[0014] Preferably, a display block is slidably connected to the inner cavity of the cross-shaped groove, and the display block is located in a semi-circular shape in the recessed part of the wave block. Connecting blocks are fixed to both sides of the display block in the inner cavity of the cross-shaped groove. A second spring is fixed to one end of the connecting block, and one end of the second spring abuts against the inner wall of the cross-shaped groove to indicate the position of the lever outside the resistor tube.

[0015] Preferably, a support frame is installed on one side of the protective shell, a groove is formed on one side of the support frame, a slot is formed on the inner wall of the groove, a third spring is fixedly connected to the upper wall of the inner cavity of the groove, and a grounding component is fixedly connected to one end of the third spring, wherein the slot is used to receive the grounding component.

[0016] Preferably, the grounding assembly includes a slider that slides in the inner cavity of a groove, a grounding post is installed on one side of the lower end of the slider, a conductive slide post is fixedly connected to the inner cavity of the groove, an annular carbon brush is provided inside the slider, and the annular carbon brush is slidably connected to the outside of the conductive slide post, and the annular carbon brush is used to transmit overload voltage to the grounding post.

[0017] Preferably, both ends of the slider are provided with grooves, an elastic element is fixedly connected to the bottom of the inner cavity of the groove, an insert is fixedly connected to one end of the elastic element, and the insert is slidably connected to the inner cavity of the groove. A traction rope is fixedly connected to one end of the insert in the inner cavity of the groove, and a handle is fixedly connected to one end of the traction rope, and the handle is slidably connected inside the slider.

[0018] Preferably, a pull rod assembly is installed on one side of the upper end face of the pallet, and the pull rod assembly includes a fixing block fixedly connected to one side of the upper end face of the pallet. A rotating groove is opened inside the fixing block, and a rotating column is rotatably connected to the inner cavity of the rotating groove. The rotating column passes through the fixing block and is fixedly connected to the rotating block at both ends. A pull rod is fixedly connected to one end of the rotating block. A fixing plate is fixedly connected to the rotating column outside the inner cavity of the rotating groove. Torsion springs are fixedly connected to both ends of the fixing plate, and the torsion springs are fixedly connected to the inner wall of the rotating groove.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The present invention discloses an external withstand voltage test device for power transformers. A drive adjustment component moves a sliding frame within the protective housing cavity, causing the sliding frame to move a sliding column upwards. Simultaneously, a lever moves synchronously, adjusting the contact position between the lever and the surface of the resistance tube. When the lever is at the bottom of the resistance tube, the resistance increases, and the voltage conducted to the transformer decreases. As the lever continues to move upwards, the resistance gradually decreases, increasing the voltage conducted to the transformer. Initially, the lever is at the bottom of the protective housing cavity. By driving the lever upwards, the voltage conducted to the transformer gradually increases, improving the stability of the transformer withstand voltage test. Furthermore, the contact position between the lever and the resistance tube is displayed in real-time via a stop block against a display block, further improving the adjustment accuracy. This solves the problem in existing external withstand voltage test devices for transformers where it is difficult to control the voltage conducted to the transformer, leading to excessive voltage being directly conducted to the transformer during withstand voltage testing, causing transformer overload and damage to the transformer or the test device.

[0021] 2. The external withstand voltage test device for power transformers described in this invention, before conducting the withstand voltage test on the transformer, drives the grounding component to disengage from the slot, causing the grounding post to contact the ground. This facilitates current conduction through the ground wire to the conductive slide column when electrical equipment leaks current or the voltage is too high. Simultaneously, the current is conducted through the conductive slide column to the annular carbon brush, and then through the annular carbon brush to the ground via the grounding post, increasing the safety of the experiment. When it is necessary to move the test device, the grounding component is driven to move the grounding post upwards, causing the grounding component to engage with the slot for secure storage, improving the convenience of using the withstand voltage test device. This solves the problem that in existing external withstand voltage test devices for power transformers, the grounding post is usually fixedly installed with the withstand voltage test device, making it difficult to avoid bumping the grounding post during transport, causing the grounding post to break or the internal circuit to short-circuit, affecting the grounding post's conduction efficiency for overload voltage, and compromising the safety of the withstand voltage test device. Attached Figure Description

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the overall structure of the main view of the present invention;

[0024] Figure 2 This is a left-view stereoscopic structural diagram of the present invention;

[0025] Figure 3 This is a schematic diagram of the internal structure of the protective shell of the present invention in half section;

[0026] Figure 4 This is a partial cross-sectional view of the protective shell of the present invention;

[0027] Figure 5 This is a schematic diagram of the overall structure of the adjustment component of the present invention;

[0028] Figure 6 This is a schematic diagram of the internal structure of the sliding frame of the present invention in half section;

[0029] Figure 7 This is a schematic diagram of the overall structure of the grounding component of the present invention;

[0030] Figure 8 This is a schematic diagram of the internal structure of the slider in half section of the present invention;

[0031] Figure 9 This is a schematic diagram of the internal structure of the fixing block of the present invention in half section;

[0032] In the diagram: 1. Tray; 2. Base; 3. Protective casing; 4. Support frame;

[0033] 5. Tie rod assembly; 51. Fixing block; 52. Rotating groove; 53. Rotating column; 54. Rotating block; 55. Tie rod; 56. Fixing plate; 57. Torsion spring;

[0034] 6. Grounding component; 61. Slider; 62. Grounding post; 63. Groove; 64. Elastic element; 65. Traction rope; 67. Handle; 68. Annular carbon brush; 69. Conductive sliding post; 610. Insert block;

[0035] 7. Adjustment assembly; 71. Handle; 72. Drive bevel gear; 73. Driven bevel gear; 74. Drive shaft; 75. First bevel gear; 76. Second bevel gear; 78. Threaded rod;

[0036] 8. Scale groove; 9. Slot; 10. Caster wheel; 11. Sliding bracket; 12. Mounting plate; 13. Paddle; 14. Stop block; 15. Sliding column; 16. Through groove; 17. First spring; 18. Cross through groove; 19. Second spring; 20. Display block; 21. Connecting block; 22. Wave block; 23. Resistance tube; 24. Transmission groove; 25. Limit seat; 26. Fastening bolt; 27. Slide groove; 28. Third spring. Detailed Implementation

[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0038] Example 1

[0039] like Figures 1 to 9As shown in the embodiment of the present invention, an external withstand voltage test device for a power transformer includes a support plate 1. Universal wheels 10 are installed at the four corners of the lower end face of the support plate 1. A base 2 is installed on the upper end face of the support plate 1. A limiting seat 25 is fixedly connected to the upper end face of the base 2. A resistance tube 23 is installed inside the cavity of the limiting seat 25. A protective shell 3 is installed outside the resistance tube 23. Fastening bolts 26 are rotatably connected to the upper end face of the protective shell 3 at the four corners, and the fastening bolts 26 are threadedly connected to the base 2. An adjustment component 7 is provided outside the resistance tube 23.

[0040] Furthermore, the adjustment assembly 7 includes two threaded rods 78 rotatably connected in the inner cavity of the protective housing 3, and the two threaded rods 78 are externally threaded with a sliding frame 11, which is used to drive the sliding frame 11 to move up and down in the inner cavity of the protective housing 3 to adjust its position.

[0041] Two mounting plates 12 are symmetrically installed on the inner wall of the sliding frame 11, and two mounting plates 12 are slidably connected to sliding columns 15. One end of the sliding column 15 is fixedly connected to a lever 13, which is used to drive the sliding column 15 to drive the lever 13 to make contact with the resistor tube 23. The entire adjustment assembly 7 is made of insulating material, so that the position of the lever 13 can be adjusted without interrupting power.

[0042] Specifically, in existing technologies, the resistance value is usually changed by using metal contacts to make contact with the resistance wire to adapt to the test requirements of different voltage levels. However, power must be turned off each time it is adjusted. If the metal contacts are adjusted directly without powering off, the friction between the metal contacts and the resistance wire will generate high temperatures, which will accelerate the breakage of the resistance wire. Although adjusting with power off increases the service life of the resistance wire and the metal contacts, poor contact and unstable resistance value will still occur due to long-term friction between the metal contacts and the resistance wire, thus affecting the accuracy of the transformer withstand voltage test results.

[0043] In this invention, when conducting a withstand voltage test on a transformer, the external withstand voltage test device is moved using casters 10. Upon reaching the transformer, the power cord of the external withstand voltage test device is correctly connected to the output terminal of the transformer under test according to electrical safety regulations. Simultaneously, the grounding wire of the transformer under test is connected to the grounding terminal of the external withstand voltage test device, thus completing the preparation work for the transformer test. Then, the threaded rod 78 is driven to rotate, causing the threaded transmission sliding frame 11 of the threaded rod 78 to move upwards from the bottom of the inner cavity of the protective housing 3. This causes the sliding frame 11 to move synchronously with the mounting plate 12, which in turn moves the sliding column 15 upwards, thereby moving the lever 13 synchronously. During this movement, the sliding column 15 abuts against the inner wall of the protective housing 3, pushing the lever 13 to abut against the resistor tube 23, thus initiating the external withstand voltage test on the power transformer. As the threaded rod 78 continues to rotate, the threaded transmission sliding frame 11 moves upwards from the bottom of the inner cavity of the protective housing 3. This causes the mounting plate 12 to move synchronously with the mounting plate 12, which in turn moves the sliding column 15 upwards, thereby moving the lever 13 synchronously. During this movement, the sliding column 15 abuts against the inner wall of the protective housing 3, pushing the lever 13 to abut against the resistor tube 23, thus initiating the external withstand voltage test on the power transformer. The rod 78 drives the sliding frame 11 via a threaded transmission to continuously move the sliding column 15 upward. Simultaneously, the sliding column 15 drives the lever 13 to move upward in sync. Multiple protrusions are intermittently arranged on the inner wall of the protective housing 3. These protrusions intermittently abut against the sliding column 15, pushing the lever 13 into contact with the resistor tube 23. Since the resistance of the resistor tube 23 increases from bottom to top, the resistance value at the contact point between the lever 13 and the resistor tube 23 also changes. According to the principles of series and parallel resistors, when the contact point between the lever 13 and the resistor tube 23 changes, the resistance value of the entire circuit also changes accordingly. In the external withstand voltage test of the power transformer, the test device controls the voltage output to the transformer by changing the resistance value of the circuit. When the resistance value increases, the voltage output to the transformer decreases accordingly; conversely, when the resistance value decreases, the voltage output to the transformer increases. This effectively allows for withstand voltage tests on different transformers, thus solving the aforementioned problems.

[0044] like Figure 1 , Figure 3 and Figure 5 As shown, a transmission groove 24 is provided inside the upper end face of the protective shell 3. Two threaded rods 78 have one end passing through the protective shell 3 and are fixedly connected to a second bevel gear 76 in the inner cavity of the transmission groove 24. The second bevel gear 76 is meshed with a first bevel gear 75, and a transmission shaft 74 is fixedly connected inside the first bevel gear 75. The transmission shaft 74 is rotatably connected to the inner wall of the transmission groove 24.

[0045] like Figure 1 , Figure 3 and Figure 5 As shown, a crank handle 71 is rotatably connected to the upper end face of the protective housing 3. One end of the crank handle 71 passes through the protective housing 3 and is fixedly connected to a transmission bevel gear 72 in the inner cavity of the transmission groove 24. The transmission bevel gear 72 is meshed with a driven bevel gear 73, and the driven bevel gear 73 is fixedly connected to the outside of the transmission shaft 74 for driving the transmission shaft 74 to rotate.

[0046] Specifically, when adjusting the position of the lever 13 against the resistor tube 23, turning the handle 71 drives the transmission bevel gear 72 to rotate, which in turn meshes with the driven bevel gear 73 to rotate. Simultaneously, the driven bevel gear 73 drives the transmission shaft 74 to rotate, which in turn drives the two first bevel gears 75 to rotate. Then, the first bevel gears 75 mesh with the second bevel gear 76 to rotate, which in turn drives the threaded rod 78 to rotate. This causes the threaded rod 78 to drive the sliding frame 11 to move within the protective housing 3, thereby causing the sliding frame 11 to move synchronously with the mounting plate 12. Simultaneously, the mounting plate 12 drives the sliding column 15 to move upwards, which in turn drives the lever 13 to move synchronously, thus adjusting the position of the lever 13 against the resistor. When the contact point on the surface of tube 23 is such that the contact plate 13 is at the bottom of the resistance tube 23, the resistance increases and the voltage conducted to the transformer decreases. As the contact plate 13 continues to move upward, the resistance gradually decreases, thereby increasing the voltage conducted to the transformer. In the initial stage, the contact plate 13 is at the bottom of the inner cavity of the protective shell 3. By driving the contact plate 13 upward, the voltage conducted to the transformer gradually increases, improving the stability of the transformer withstand voltage test. This solves the problem that existing external withstand voltage test devices for transformers are inconvenient to control the voltage conducted to the transformer, causing excessive voltage to be directly conducted to the transformer during withstand voltage tests, resulting in transformer overload and damage to the transformer or test device.

[0047] like Figure 3 , Figure 4 and Figure 6 As shown, the sliding frame 11 has through slots 16 on both sides. A first spring 17 is fixedly connected to one end face of the mounting plate 12, and the first spring 17 slides in the inner cavity of the through slot 16. A stop block 14 is fixedly connected to one end of the first spring 17, and the stop block 14 is fixedly connected to one end of the sliding column 15.

[0048] like Figure 1 , Figures 3 to 6 As shown, two corrugated blocks 22 are symmetrically fixed to the two walls of the inner cavity of the protective shell 3, and the abutment block 14 is slidably connected to the corrugated blocks 22 for driving the lever 13 to abut against the resistor tube 23 to perform the transformer external withstand voltage test. The protective shell 3 is made of insulating wood material. Multiple cross slots 18 are evenly opened at the front and rear ends of the protective shell 3, and scale slots 8 are opened on one side of the cross slots 18 on the front and rear end faces of the protective shell 3 for displaying the voltage adjustment.

[0049] like Figures 3 to 6As shown, a display block 20 is slidably connected to the inner cavity of the cross-shaped through groove 18, and the display block 20 is located in a semi-circular shape in the recessed part of the wave block 22. Connecting blocks 21 are fixedly connected to both sides of the display block 20 in the inner cavity of the cross-shaped through groove 18. A second spring 19 is fixedly connected to one end of the connecting block 21, and one end of the second spring 19 abuts against the inner wall of the cross-shaped through groove 18 to display the position of the lever 13 outside the resistor tube 23.

[0050] Specifically, during the withstand voltage test of the transformer, the sliding frame 11 is driven to move upward from the bottom of the inner cavity of the protective housing 3, thereby causing the mounting plate 12 to move synchronously. Simultaneously, the mounting plate 12 causes the sliding column 15 to move upward, which in turn causes the lever 13 to move synchronously. As the sliding column 15 moves upward, it causes the abutment 14 to contact the protruding part of the corrugated block 22, thus squeezing the first spring 17 and pushing the sliding column 15 to move. At the same time, the sliding column 15 pushes the lever 13 to contact the surface of the resistor tube 23, thus performing the first stage AC withstand voltage test on the transformer. While continuously driving the sliding frame 11 upward, the sliding frame 11 will cause the sliding column 15 to move upward to the recessed part of the corrugated block 22. At this point, the first spring 17 springs up the abutment 14, causing the sliding column 15 to return to its original position. Simultaneously, the sliding column 15 causes the lever 13 to contact the surface of the resistor tube 23. The surface of tube 23 is disengaged to prevent prolonged contact and friction between the lever 13 and the surface of the resistor tube 23, which could damage the lever 13 or the resistor tube 23. When the abutment block 14 moves to the recessed part of the wave block 22, the abutment block 14 will press the display block 20 to move, and the display block 20 will drive the connecting block 21 to squeeze the second spring 19 out of the cross slot 18. This makes it easier for the operator to observe the position of the lever 13 disengaging from the resistor tube 23 by sliding the display block 20 out of the cavity of the cross slot 18 in conjunction with the scale slot 8. This solves the problem that existing transformer external withstand voltage test devices, when conducting withstand voltage tests on transformers of different sizes, are inconvenient to observe the contact position between the lever and the resistor tube, which leads to excessive voltage conduction to small transformers, causing voltage breakdown of the transformer's ball gap and damage to the transformer and test equipment.

[0051] Example 2

[0052] like Figure 2 , Figure 7 and Figure 8 As shown, a support frame 4 is installed on one side of the protective shell 3. A groove 27 is formed on one side of the support frame 4. A slot 9 is provided on the inner wall of the groove 27. A third spring 28 is fixedly connected to the upper wall of the inner cavity of the groove 27, and a grounding component 6 is fixedly connected to one end of the third spring 28. The slot 9 is used to receive the grounding component 6.

[0053] like Figure 2 , Figure 7 and Figure 8As shown, the grounding assembly 6 includes a slider 61 that slides in the inner cavity of the slide groove 27. A grounding post 62 is installed on one side of the lower end of the slider 61. A conductive slide post 69 is fixedly connected to the inner cavity of the slide groove 27. An annular carbon brush 68 is provided inside the slider 61 and is slidably connected to the outside of the conductive slide post 69. The annular carbon brush 68 is used to transmit overload voltage to the grounding post 62.

[0054] like Figure 2 , Figure 7 and Figure 8 As shown, both ends of the slider 61 are provided with grooves 63. An elastic element 64 is fixedly connected to the bottom of the inner cavity of the groove 63. An insert block 610 is fixedly connected to one end of the elastic element 64, and the insert block 610 is slidably connected to the inner cavity of the groove 63. A traction rope 65 is fixedly connected to one end of the insert block 610 located in the inner cavity of the groove 63. A handle 67 is fixedly connected to one end of the traction rope 65, and the handle 67 is slidably connected inside the slider 61.

[0055] Specifically, before conducting a withstand voltage test on the transformer, by grasping the handle 67 and moving it upwards, the handle 67 pulls the traction rope 65 to move synchronously. At the same time, the traction rope 65 pulls the plug 610 into the inner cavity of the groove 63 and squeezes the elastic element 64. Then, the third spring 28 is used to lift the slider 61 and move it downwards, causing the slider 61 to drive the annular carbon brush 68 to slide outside the conductive slide column 69. Simultaneously, the slider 61 drives the grounding post 62 to contact the ground. This facilitates the conduction of current through the ground wire to the conductive slide column 69 when the electrical equipment leaks current or the voltage is too high. At the same time, the current is conducted through the conductive slide column 69 to the annular carbon brush 68, and then through the annular carbon brush 68 to the ground via the grounding post 62. This increases the safety of the test and solves the problem that in existing power transformer external withstand voltage test devices, the grounding post is usually fixedly installed with the withstand voltage test device, which makes it difficult to avoid bumping the grounding post when moving the withstand voltage test device. This can cause the grounding post to break or the internal circuit to short-circuit, affecting the conduction efficiency of the grounding post for overload voltage and affecting the safety of the withstand voltage test device.

[0056] like Figure 1 , Figure 2 and Figure 9 As shown, a pull rod assembly 5 is installed on one side of the upper end face of the pallet 1, and the pull rod assembly 5 includes a fixing block 51 fixedly connected to one side of the upper end face of the pallet 1. A rotating groove 52 is opened inside the fixing block 51. A rotating column 53 is rotatably connected to the inner cavity of the rotating groove 52. A rotating block 54 is fixedly connected to both ends of the rotating column 53 through the fixing block 51. A pull rod 55 is fixedly connected to one end of the rotating block 54. A fixing plate 56 is fixedly connected to the rotating column 53 outside the inner cavity of the rotating groove 52. Torsion springs 57 are fixedly connected to both ends of the fixing plate 56, and the torsion springs 57 are fixedly connected to the inner wall of the rotating groove 52.

[0057] Specifically, when the withstand voltage test device needs to be moved, the pull rod 55 is held to rotate the rotating block 54, which in turn rotates the rotating column 53. Simultaneously, the rotating column 53 rotates the fixed plate 56, and the torsion spring 57 is twisted to adjust the angle. Then, the pull rod 55 pulls the rotating block 54 to move the rotating column 53, which in turn moves the pallet 1 via the fixed block 51, thus moving the withstand voltage test device. This improves the ease of use of the withstand voltage test device. After moving, the pull rod 55 is released, and the torsion spring 57 rotates the fixed plate 56 to reset it. The fixed plate 56 then rotates the rotating column 53 to reset, and the rotating column 53 rotates the rotating block 54 to reset, which in turn rotates the pull rod 55 to reset. This facilitates the automatic retraction and reset of the pull rod 55, improving the ease of use of the withstand voltage test device. This solves the problem that existing external withstand voltage test devices for power transformers are large in size and typically require trailer transport, making them inconvenient to use.

[0058] The working principle is as follows: When the adjustment lever 13 is in contact with the resistor tube 23, turning the handle 71 drives the transmission bevel gear 72 to rotate, which in turn meshes with the driven bevel gear 73 to rotate. Simultaneously, the driven bevel gear 73 drives the transmission shaft 74 to rotate, which in turn drives the two first bevel gears 75 to rotate. Then, the first bevel gears 75 mesh with the second bevel gear 76 to rotate, which in turn drives the threaded rod 78 to rotate. This causes the threaded rod 78 to drive the sliding frame 11 to move within the cavity of the protective housing 3, thereby causing the sliding frame 11 to move synchronously with the mounting plate 12. Simultaneously, the mounting plate 12 drives the sliding column 15 to move upward, which in turn drives the lever 13 to move synchronously, thereby adjusting the contact position between the lever 13 and the surface of the resistance tube 23. When the lever 13 is at the bottom of the resistance tube 23, the resistance will increase and the voltage conducted to the transformer will decrease. As the lever 13 continues to move upward, the resistance will gradually decrease, thereby increasing the voltage conducted to the transformer. In the initial stage, the lever 13 will be at the bottom of the inner cavity of the protective shell 3. By driving the lever 13 upward, the voltage conducted to the transformer will gradually increase, thereby improving the stability of the transformer withstand voltage test.

[0059] During the withstand voltage test of the transformer, the sliding frame 11 is driven to move upward from the bottom of the inner cavity of the protective shell 3, which in turn causes the mounting plate 12 to move synchronously. Simultaneously, the mounting plate 12 causes the sliding column 15 to move upward, which in turn causes the lever 13 to move synchronously. As the sliding column 15 moves upward, it causes the abutment 14 to abut against the protruding part of the corrugated block 22, thereby squeezing the first spring 17 and pushing the sliding column 15 to move. At the same time, the sliding column 15 pushes the lever 13 to contact the surface of the resistor tube 23, thus performing the first stage AC withstand voltage test on the transformer. While continuously driving the sliding frame 11 upward, the sliding frame 11 will cause the sliding column 15 to move upward. When the wave block 22 is in the recessed part, the first spring 17 springs up the abutment 14 to drive the slide column 15 to reset. At the same time, the slide column 15 drives the lever 13 to disengage from the surface of the resistor tube 23 to prevent the lever 13 from being in contact with the surface of the resistor tube 23 for a long time and causing damage to the lever 13 or the resistor tube 23. When the abutment 14 moves to the recessed part of the wave block 22, the abutment 14 will press the display block 20 to move and cause the display block 20 to drive the connecting block 21 to squeeze the second spring 19 to slide out of the cross groove 18. This makes it easier for the operator to observe the position of the lever 13 releasing the resistor tube 23 by sliding the display block 20 out of the cavity of the cross groove 18 in conjunction with the scale groove 8.

[0060] Before conducting the withstand voltage test on the transformer, by grasping the handle 67 and moving it upwards, the handle 67 pulls the traction rope 65 to move synchronously. At the same time, the traction rope 65 pulls the plug 610 into the inner cavity of the groove 63 and squeezes the elastic element 64. Then, the third spring 28 is used to lift the slider 61 and move it downwards, causing the slider 61 to drive the annular carbon brush 68 to slide outside the conductive slide post 69. At the same time, the slider 61 drives the grounding post 62 to contact the ground. This facilitates the current to be conducted to the conductive slide post 69 through the ground wire when the electrical equipment leaks current or the voltage is too high. At the same time, the current is conducted to the annular carbon brush 68 through the conductive slide post 69, and then conducted to the ground through the annular carbon brush 68 via the grounding post 62, increasing the safety of the experiment.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An external withstand voltage test device for a power transformer, characterized in that: The device includes a tray (1), with casters (10) installed at the four corners of the lower end face of the tray (1), a base (2) installed on the upper end face of the tray (1), a limit seat (25) fixedly connected to the upper end face of the base (2), a resistance tube (23) installed in the inner cavity of the limit seat (25), a protective shell (3) installed on the outside of the resistance tube (23), a fastening bolt (26) rotatably connected to the upper end face of the protective shell (3) at the four corners, and the fastening bolt (26) is threadedly connected to the base (2), and an adjustment component (7) is provided on the outside of the resistance tube (23). The adjustment assembly (7) includes two threaded rods (78) rotatably connected in the inner cavity of the protective housing (3). The two threaded rods (78) are externally threaded with a sliding frame (11) for driving the sliding frame (11) to move up and down in the inner cavity of the protective housing (3) to adjust its position. The sliding frame (11) has two mounting plates (12) symmetrically installed on its inner wall, and each of the two mounting plates (12) is slidably connected with a sliding column (15). One end of the sliding column (15) is fixedly connected to a lever (13), which is used to drive the sliding column (15) to drive the lever (13) to contact the resistor tube (23). The upper end face of the protective shell (3) is provided with a transmission groove (24). One end of the two threaded rods (78) penetrates the protective shell (3) and is fixedly connected to the inner cavity of the transmission groove (24) with a second bevel gear (76). The second bevel gear (76) meshes with the first bevel gear (75), and the first bevel gear (75) is fixedly connected to the inner wall of the transmission groove (24). The transmission shaft (74) is rotatably connected to the inner wall of the transmission groove (24). A crank handle (71) is rotatably connected to the upper end face of the protective shell (3). One end of the crank handle (71) passes through the protective shell (3) and is fixedly connected to the transmission bevel gear (72) in the inner cavity of the transmission groove (24). The transmission bevel gear (72) is meshed with a driven bevel gear (73), and the driven bevel gear (73) is fixed to the outside of the transmission shaft (74) for driving the transmission shaft (74) to rotate. The sliding frame (11) has through slots (16) on both sides. A first spring (17) is fixedly connected to one end face of the mounting plate (12), and the first spring (17) slides in the cavity of the through slot (16). A stop block (14) is fixedly connected to one end of the first spring (17), and the stop block (14) is fixedly connected to one end of the sliding column (15). The inner walls of the protective shell (3) are symmetrically fixed with two wave blocks (22), and the abutment block (14) is slidably connected to the wave blocks (22) to drive the lever (13) to abut against the resistor tube (23) for the transformer external withstand voltage test. The protective shell (3) is made of insulating wood material. Multiple cross slots (18) are evenly opened at the front and rear ends of the protective shell (3), and scale slots (8) are opened on the front and rear end faces of the protective shell (3) on one side of the cross slots (18) to display the voltage adjustment. The display block (20) is slidably connected to the inner cavity of the cross-shaped through groove (18), and the display block (20) is located in the recessed part of the wave block (22) in a semi-circular shape. The display block (20) is fixedly connected to both sides of the inner cavity of the cross-shaped through groove (18) with connecting blocks (21). One end of the connecting block (21) is fixedly connected to a second spring (19), and one end of the second spring (19) abuts against the inner wall of the cross-shaped through groove (18) to display the position of the lever (13) outside the resistor tube (23).

2. The external withstand voltage test device for a power transformer according to claim 1, characterized in that: A support frame (4) is installed on one side of the protective shell (3). A groove (27) is formed on one side of the support frame (4). A slot (9) is provided on the inner wall of the groove (27). A third spring (28) is fixed to the upper wall of the inner cavity of the groove (27), and a grounding component (6) is fixed to one end of the third spring (28). The slot (9) is used to receive the grounding component (6).

3. The external withstand voltage test device for a power transformer according to claim 2, characterized in that: The grounding assembly (6) includes a slider (61) that slides in the inner cavity of a groove (27). A grounding post (62) is installed on one side of the lower end of the slider (61). A conductive post (69) is fixedly connected to the inner cavity of the groove (27). An annular carbon brush (68) is provided inside the slider (61) and is slidably connected to the outside of the conductive post (69). The annular carbon brush (68) is used to transmit overload voltage to the grounding post (62).

4. The external withstand voltage test device for a power transformer according to claim 3, characterized in that: The slider (61) has grooves (63) at both ends. An elastic element (64) is fixedly connected to the bottom of the inner cavity of the groove (63). An insert (610) is fixedly connected to one end of the elastic element (64), and the insert (610) is slidably connected to the inner cavity of the groove (63). A traction rope (65) is fixedly connected to one end of the insert (610) in the inner cavity of the groove (63). A handle (67) is fixedly connected to one end of the traction rope (65), and the handle (67) is slidably connected inside the slider (61).

5. The external withstand voltage test device for a power transformer according to claim 1, characterized in that: A pull rod assembly (5) is installed on one side of the upper end face of the pallet (1), and the pull rod assembly (5) includes a fixing block (51) fixedly connected to one side of the upper end face of the pallet (1). A rotating groove (52) is opened inside the fixing block (51). A rotating column (53) is rotatably connected to the inner cavity of the rotating groove (52). A rotating block (54) is fixedly connected to both ends of the rotating column (53) through the fixing block (51). A pull rod (55) is fixedly connected to one end of the rotating block (54). A fixing plate (56) is fixedly connected to the outside of the inner cavity of the rotating groove (52) of the rotating column (53). A torsion spring (57) is fixedly connected to both ends of the fixing plate (56), and the torsion spring (57) is fixedly connected to the inner wall of the rotating groove (52).

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